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Russo A, Örzsik B, Yalin N, Simpson I, Nwaubani P, Pinna A, De Marco R, Sharp H, Kartar A, Singh N, Blockley N, Stone AJL, Turkheimer FE, Young AH, Cercignani M, Zelaya F, Asllani I, Colasanti A. Altered oxidative neurometabolic response to methylene blue in bipolar disorder revealed by quantitative neuroimaging. J Affect Disord 2024; 362:790-798. [PMID: 39019231 DOI: 10.1016/j.jad.2024.07.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Revised: 06/05/2024] [Accepted: 07/12/2024] [Indexed: 07/19/2024]
Abstract
BACKGROUND Cerebral mitochondrial and hemodynamic abnormalities have been implicated in Bipolar Disorder pathophysiology, likely contributing to neurometabolic vulnerability-leading to worsen clinical outcomes and mood instability. To investigate neurometabolic vulnerability in patients with BD, we combined multi-modal quantitative MRI assessment of cerebral oxygenation with acute administration of Methylene Blue, a neurometabolic/hemodynamic modulator acting on cerebral mitochondria. METHODS Fifteen euthymic patients with chronic BD-type 1, and fifteen age/gender-matched healthy controls underwent two separate MRI sessions in a single-blinded randomized cross-over design, each after intravenous infusion of either MB (0.5 mg/kg) or placebo. MRI-based measures of Cerebral Blood Flow and Oxygen Extraction Fraction were integrated to compute Cerebral Metabolic Rate of Oxygen in Frontal Lobe, Anterior Cingulate, and Hippocampus-implicated in BD neurometabolic pathophysiology. Inter-daily variation in mood rating was used to assess mood instability. RESULTS A decrease in global CBF and CMRO2 was observed after acutely administrating MB to all participants. Greater regional CMRO2 reductions were observed after MB, in patients compared to controls in FL (mean = -14.2 ± 19.5 % versus 2.3 ± 14.8 %), ACC (mean = -14.8 ± 23.7 % versus 2.4 ± 15.7 %). The effects on CMRO2 in those regions were primarily driven by patients with longer disease duration and higher mood instability. LIMITATIONS Sample size; medications potentially impacting on response to MB. CONCLUSIONS An altered neurometabolic response to MB, a mitochondrial/hemodynamic modulator, was observed in patients, supporting the hypothesis of vulnerability to neurometabolic stress in BD. Integrating quantitative imaging of cerebral oxygen metabolism with a mitochondrial-targeting pharmacological challenge could provide a novel biomarker of neurometabolic and cerebrovascular pathophysiology in BD.
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Affiliation(s)
- Alfonso Russo
- Department of Clinical Neuroscience, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, UK; Sussex Partnership NHS Foundation Trust, Worthing, UK.
| | - Balázs Örzsik
- Department of Clinical Neuroscience, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, UK; Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Nefize Yalin
- Section on the Neurobiology and Treatment of Mood Disorders, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland, USA
| | - Ivor Simpson
- School of Engineering and Informatics, University of Sussex, Falmer, Brighton, UK
| | - Prince Nwaubani
- Institute of Psychiatry, Psychology and Neuroscience, King's College, London, UK
| | - Antonello Pinna
- Department of Clinical Neuroscience, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, UK
| | - Riccardo De Marco
- Department of Clinical Neuroscience, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, UK
| | - Harriet Sharp
- Department of Clinical Neuroscience, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, UK
| | - Amy Kartar
- Department of Clinical Neuroscience, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, UK
| | - Nisha Singh
- Institute of Psychiatry, Psychology and Neuroscience, King's College, London, UK; Department of Paediatrics, University of Oxford, Oxford, UK
| | | | | | | | - Allan H Young
- Institute of Psychiatry, Psychology and Neuroscience, King's College, London, UK
| | - Mara Cercignani
- Cardiff University Brain Research Imaging Centre, Cardiff University, Cardiff, UK
| | - Fernando Zelaya
- Institute of Psychiatry, Psychology and Neuroscience, King's College, London, UK
| | - Iris Asllani
- Department of Clinical Neuroscience, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, UK; Biomedical Engineering, Rochester Institute of Technology, Rochester, USA
| | - Alessandro Colasanti
- Department of Clinical Neuroscience, Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton, UK; Sussex Partnership NHS Foundation Trust, Worthing, UK
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Katagiri A, Fujii N, Dobashi K, Lai YF, Tsuji B, Nishiyasu T. Effects of sodium bicarbonate ingestion on ventilatory and cerebrovascular responses in resting heated humans. Am J Physiol Regul Integr Comp Physiol 2024; 327:R400-R409. [PMID: 39102461 DOI: 10.1152/ajpregu.00161.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2024] [Revised: 07/22/2024] [Accepted: 07/23/2024] [Indexed: 08/07/2024]
Abstract
Hyperthermia stimulates ventilation in humans. This hyperthermia-induced hyperventilation may be mediated by the activation of peripheral chemoreceptors implicated in the regulation of respiration in reaction to various chemical stimuli, including reductions in arterial pH. Here, we investigated the hypothesis that during passive heating at rest, the increases in arterial pH achieved with sodium bicarbonate ingestion, which could attenuate peripheral chemoreceptor activity, mitigate hyperthermia-induced hyperventilation. We also assessed the effect of sodium bicarbonate ingestion on cerebral blood flow responses, which are associated with hyperthermia-induced hyperventilation. Twelve healthy men ingested sodium bicarbonate (0.3 g/kg body weight) or sodium chloride (0.208 g/kg). One hundred minutes after the ingestion, the participants were passively heated using hot-water immersion (42°C) combined with a water-perfused suit. Increases in esophageal temperature (an index of core temperature) and minute ventilation (V̇E) during the heating were similar in the two trials. Moreover, when V̇E is expressed as a function of esophageal temperature, there were no between-trial differences in the core temperature threshold for hyperventilation (38.0 ± 0.3 vs. 38.0 ± 0.4°C, P = 0.469) and sensitivity of hyperthermia-induced hyperventilation as assessed by the slope of the core temperature-V̇E relation (13.5 ± 14.2 vs. 15.8 ± 15.5 L/min/°C, P = 0.831). Furthermore, middle cerebral artery mean blood velocity (an index of cerebral blood flow) decreased similarly with heating duration in both trials. These results suggest that sodium bicarbonate ingestion does not mitigate hyperthermia-induced hyperventilation and the reductions in cerebral blood flow index in resting heated humans.NEW & NOTEWORTHY Hyperthermia leads to hyperventilation and associated cerebral hypoperfusion, both of which may impair heat tolerance. This hyperthermia-induced hyperventilation may be mediated by peripheral chemoreceptors, which can be activated by reductions in arterial pH. However, our results suggest that sodium bicarbonate ingestion, which can increase arterial pH, is not an effective intervention in alleviating hyperthermia-induced hyperventilation and cerebral hypoperfusion in resting heated humans.
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Affiliation(s)
- Akira Katagiri
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
| | - Naoto Fujii
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
- Advanced Research Initiative for Human High Performance, University of Tsukuba, Ibaraki, Japan
| | - Kohei Dobashi
- Faculty of Education, Hokkaido University of Education, Hokkaido, Japan
| | - Yin-Feng Lai
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
| | - Bun Tsuji
- Department of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Takeshi Nishiyasu
- Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki, Japan
- Advanced Research Initiative for Human High Performance, University of Tsukuba, Ibaraki, Japan
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Caldwell HG, Hoiland RL, Bain AR, Howe CA, Carr JMJR, Gibbons TD, Durrer CG, Tymko MM, Stacey BS, Bailey DM, Sekhon MS, MacLeod DB, Ainslie PN. Evidence for direct CO 2 -mediated alterations in cerebral oxidative metabolism in humans. Acta Physiol (Oxf) 2024; 240:e14197. [PMID: 38958262 DOI: 10.1111/apha.14197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 06/18/2024] [Accepted: 06/20/2024] [Indexed: 07/04/2024]
Abstract
AIM How the cerebral metabolic rates of oxygen and glucose utilization (CMRO2 and CMRGlc, respectively) are affected by alterations in arterial PCO2 (PaCO2) is equivocal and therefore was the primary question of this study. METHODS This retrospective analysis involved pooled data from four separate studies, involving 41 healthy adults (35 males/6 females). Participants completed stepwise steady-state alterations in PaCO2 ranging between 30 and 60 mmHg. The CMRO2 and CMRGlc were assessed via the Fick approach (CBF × arterial-internal jugular venous difference of oxygen or glucose content, respectively) utilizing duplex ultrasound of the internal carotid artery and vertebral artery to calculate cerebral blood flow (CBF). RESULTS The CMRO2 was altered by 0.5 mL × min-1 (95% CI: -0.6 to -0.3) per mmHg change in PaCO2 (p < 0.001) which corresponded to a 9.8% (95% CI: -13.2 to -6.5) change in CMRO2 with a 9 mmHg change in PaCO2 (inclusive of hypo- and hypercapnia). The CMRGlc was reduced by 7.7% (95% CI: -15.4 to -0.08, p = 0.045; i.e., reduction in net glucose uptake) and the oxidative glucose index (ratio of oxygen to glucose uptake) was reduced by 5.6% (95% CI: -11.2 to 0.06, p = 0.049) with a + 9 mmHg increase in PaCO2. CONCLUSION Collectively, the CMRO2 is altered by approximately 1% per mmHg change in PaCO2. Further, glucose is incompletely oxidized during hypercapnia, indicating reductions in CMRO2 are either met by compensatory increases in nonoxidative glucose metabolism or explained by a reduction in total energy production.
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Affiliation(s)
- Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, British Columbia, Canada
| | - Anthony R Bain
- Department of Kinesiology, Faculty of Human Kinetics, University of Windsor, Windsor, Ontario, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Travis D Gibbons
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Cody G Durrer
- Centre for Physical Activity Research, Rigshospitalet, Copenhagen, Denmark
| | - Michael M Tymko
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Human Cerebrovascular Physiology Laboratory, Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, Ontario, Canada
| | - Benjamin S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Mypinder S Sekhon
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, British Columbia, Canada
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - David B MacLeod
- Human Pharmacology and Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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Kajiki M, Katagiri A, Matsutake R, Lai YF, Hashimoto H, Nishiyasu T, Fujii N. Ingesting carbonated water post-exercise in the heat transiently ameliorates hypotension and enhances mood state. Exp Physiol 2024. [PMID: 39141787 DOI: 10.1113/ep091925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 07/26/2024] [Indexed: 08/16/2024]
Abstract
The objective was to assess if post-exercise ingestion of carbonated water in a hot environment ameliorates hypotension, enhances cerebral blood flow and heat loss responses, and positively modulates perceptions and mood states. Twelve healthy, habitually active young adults (five women) performed 60 min of cycling at 45% peak oxygen uptake in a hot climate (35°C). Subsequently, participants consumed 4°C carbonated or non-carbonated (control) water (150 and 100 mL for males and females regardless of drink type) at 20 and 40 min into post-exercise periods. Mean arterial pressure decreased post-exercise at 20 min only (P = 0.032) compared to the pre-exercise baseline. Both beverages transiently (∼1 min) increased mean arterial pressure and middle cerebral artery mean blood velocity (cerebral blood flow index) regardless of post-exercise periods (all P ≤ 0.015). Notably, carbonated water ingestion led to greater increases in mean arterial pressure (2.3 ± 2.8 mmHg vs. 6.6 ± 4.4 mmHg, P < 0.001) and middle cerebral artery mean blood velocity (1.6 ± 2.5 cm/s vs. 3.8 ± 4.1 cm/s, P = 0.046) at 20 min post-exercise period compared to non-carbonated water ingestion. Both beverages increased mouth exhilaration and reduced sleepiness regardless of post-exercise periods, but these responses were more pronounced with carbonated water ingestion at 40 min post-exercise (mouth exhilaration: 3.1 ± 1.4 vs. 4.7 ± 1.7, P = 0.001; sleepiness: -0.7 ± 0.91 vs. -1.9 ± 1.6, P = 0.014). Heat loss responses and other perceptions were similar between the two conditions throughout (all P ≥ 0.054). We show that carbonated water ingestion temporarily ameliorates hypotension and increases the cerebral blood flow index during the early post-exercise phase in a hot environment, whereas it enhances mouth exhilaration and reduces sleepiness during the late post-exercise phase.
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Affiliation(s)
- Masanobu Kajiki
- Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Akira Katagiri
- Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Ryoko Matsutake
- Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Yin-Feng Lai
- Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Hideki Hashimoto
- Research & Development Strategy Department, Research & Development Headquarters, Asahi Soft Drinks Co. Ltd, Moriya, Japan
| | - Takeshi Nishiyasu
- Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
- Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba, Tsukuba, Japan
| | - Naoto Fujii
- Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
- Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba, Tsukuba, Japan
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Hu Y, Shi W, Jiang D, Zhao L, Lu H, Wu D, Lin Z. MR Assessment of Acute Changes of Cerebral Perfusion, Metabolism, and Blood-Brain Barrier Permeability in Response to Aerobic Exercise. J Magn Reson Imaging 2024. [PMID: 39096314 DOI: 10.1002/jmri.29544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 07/07/2024] [Accepted: 07/08/2024] [Indexed: 08/05/2024] Open
Abstract
BACKGROUND It remains unclear how a single bout of exercise affects brain perfusion, oxygen metabolism, and blood-brain barrier (BBB) permeability. Addressing this unresolved issue is essential to understand the acute changes in cerebral physiology induced by aerobic exercise. PURPOSE To dynamically monitor the acute changes in cerebral physiology subsequent to a single aerobic exercise training session using noninvasive MRI measurements. STUDY TYPE Prospective. POPULATION Twenty-three healthy participants (18-35 years, 10 females/13 males) were enrolled and divided into 10-minute exercising (N = 10) and 20-minute exercising (N = 13) groups. FIELD STRENGTH/SEQUENCE 3.0 T/Phase Contrast (PC) MRI (gradient echo), T2-Relaxation-Under-Spin-Tagging (TRUST) MRI (gradient echo EPI), Water-Extraction-with-Phase-Contrast-Arterial-Spin-Tagging (WEPCAST) MRI (gradient echo EPI) and T1-weighted magnetization-prepared-rapid-acquisition-of-gradient-echo (MPRAGE) (gradient echo). ASSESSMENT A baseline MR measurement plus four repeated MR measurements immediately after 10 or 20 minutes moderate running exercise. MR measurements included cerebral blood flow (CBF) as measured by PC MRI, venous oxygenation (Yv) and cerebral metabolic rate of oxygen (CMRO2) as assessed by TRUST MRI, water extraction fraction (E), and BBB permeability-surface-area product (PS) as determined by WEPCAST MRI. STATISTICAL TESTS The time dependence of the physiological parameters was studied with a linear mixed-effect model. Additionally, pairwise t-tests comparison of the physiological parameters at each time point was conducted. A P-value of <0.05 was considered statistically significant. RESULTS There was an initial drop (8.22 ± 2.60%) followed by a recovery in CBF after exercise, while Yv revealed a significant decrease (6.37 ± 0.92%), i.e., an increased oxygen extraction, and returned to baseline at later time points. CMRO2 showed a trend of increase (5.68 ± 3.04%) and a significant interaction between time and group. In addition, E increased significantly (3.86% ± 0.89) and returned to baseline level at later time points, while PS remained elevated (13.33 ± 4.79%). DATA CONCLUSION A single bout of moderate aerobic exercise can induce acute alterations in cerebral perfusion, metabolism, and BBB permeability. EVIDENCE LEVEL 2 TECHNICAL EFFICACY: Stage 2.
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Affiliation(s)
- Yizhe Hu
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Wen Shi
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Dengrong Jiang
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Li Zhao
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hanzhang Lu
- The Russell H. Morgan Department of Radiology & Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Dan Wu
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
| | - Zixuan Lin
- Key Laboratory for Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, Zhejiang, China
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Davies A, Gurung D, Ladthavorlaphatt K, Mankoo A, Panerai RB, Robinson TG, Minhas JS, Beishon LC. The effect of CO 2 on the age dependence of neurovascular coupling. J Appl Physiol (1985) 2024; 137:445-459. [PMID: 38961823 DOI: 10.1152/japplphysiol.00695.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 06/27/2024] [Accepted: 06/27/2024] [Indexed: 07/05/2024] Open
Abstract
Prior studies have identified variable effects of aging on neurovascular coupling (NVC). Carbon dioxide (CO2) affects both cerebral blood velocity (CBv) and NVC, but the effects of age on NVC under different CO2 conditions are unknown. Therefore, we investigated the effects of aging on NVC in different CO2 states during cognitive paradigms. Seventy-eight participants (18-78 yr), with well-controlled comorbidities, underwent continuous recordings of CBv by bilateral insonation of middle (MCA) and posterior (PCA) cerebral arteries (transcranial Doppler), blood pressure, end-tidal CO2, and heart rate during poikilocapnia, hypercapnia (5% CO2 inhalation), and hypocapnia (paced hyperventilation). Neuroactivation via visuospatial (VS) and attention tasks (AT) was used to stimulate NVC. Peak percentage and absolute change in MCAv/PCAv, were compared between CO2 conditions and age groups (≤30, 31-60, and >60 yr). For the VS task, in poikilocapnia, younger adults had a lower NVC response compared with older adults [mean difference (MD): -7.92% (standard deviation (SD): 2.37), P = 0.004], but comparable between younger and middle-aged groups. In hypercapnia, both younger [MD: -4.75% (SD: 1.56), P = 0.009] and middle [MD: -4.58% (SD: 1.69), P = 0.023] age groups had lower NVC responses compared with older adults. Finally, in hypocapnia, both older [MD: 5.92% (SD: 2.21), P = 0.025] and middle [MD: 5.44% (SD: 2.27), P = 0.049] age groups had greater NVC responses, compared with younger adults. In conclusion, the magnitude of NVC response suppression from baseline during hyper- and hypocapnia, did not differ significantly between age groups. However, the middle age group demonstrated a different NVC response while under hypercapnic conditions, compared with hypocapnia.NEW & NOTEWORTHY This study describes the effects of age on neurovascular coupling under altered CO2 conditions. We demonstrated that both hypercapnia and hypocapnia suppress neurovascular coupling (NVC) responses. Furthermore, that middle age exhibits an NVC response comparable with younger adults under hypercapnia, and older adults under hypocapnia.
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Affiliation(s)
- Aaron Davies
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - Dewarkar Gurung
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - Kannaphob Ladthavorlaphatt
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - Alex Mankoo
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
| | - Ronney B Panerai
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- NIHR Leicester Biomedical Research Centre, Glenfield Research Centre, British Heart Foundation Cardiovascular Centre, Leicester, United Kingdom
| | - Thompson G Robinson
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- NIHR Leicester Biomedical Research Centre, Glenfield Research Centre, British Heart Foundation Cardiovascular Centre, Leicester, United Kingdom
| | - Jatinder S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- NIHR Leicester Biomedical Research Centre, Glenfield Research Centre, British Heart Foundation Cardiovascular Centre, Leicester, United Kingdom
| | - Lucy C Beishon
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- NIHR Leicester Biomedical Research Centre, Glenfield Research Centre, British Heart Foundation Cardiovascular Centre, Leicester, United Kingdom
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Persson NDÅ, Lohela TJ, Mortensen KN, Rosenholm M, Li Q, Weikop P, Nedergaard M, Lilius TO. Anesthesia Blunts Carbon Dioxide Effects on Glymphatic Cerebrospinal Fluid Dynamics in Mechanically Ventilated Rats. Anesthesiology 2024; 141:338-352. [PMID: 38787687 DOI: 10.1097/aln.0000000000005039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
BACKGROUND Impaired glymphatic clearance of cerebral metabolic products and fluids contribute to traumatic and ischemic brain edema and neurodegeneration in preclinical models. Glymphatic perivascular cerebrospinal fluid flow varies between anesthetics possibly due to changes in vasomotor tone and thereby in the dynamics of the periarterial cerebrospinal fluid (CSF)-containing space. To better understand the influence of anesthetics and carbon dioxide levels on CSF dynamics, this study examined the effect of periarterial size modulation on CSF distribution by changing blood carbon dioxide levels and anesthetic regimens with opposing vasomotor influences: vasoconstrictive ketamine-dexmedetomidine (K/DEX) and vasodilatory isoflurane. METHODS End-tidal carbon dioxide (ETco2) was modulated with either supplemental inhaled carbon dioxide to reach hypercapnia (Etco2, 80 mmHg) or hyperventilation (Etco2, 20 mmHg) in tracheostomized and anesthetized female rats. Distribution of intracisternally infused radiolabeled CSF tracer 111In-diethylamine pentaacetate was assessed for 86 min in (1) normoventilated (Etco2, 40 mmHg) K/DEX; (2) normoventilated isoflurane; (3) hypercapnic K/DEX; and (4) hyperventilated isoflurane groups using dynamic whole-body single-photon emission tomography. CSF volume changes were assessed with magnetic resonance imaging. RESULTS Under normoventilation, cortical CSF tracer perfusion, perivascular space size around middle cerebral arteries, and intracranial CSF volume were higher under K/DEX compared with isoflurane (cortical maximum percentage of injected dose ratio, 2.33 [95% CI, 1.35 to 4.04]; perivascular size ratio 2.20 [95% CI, 1.09 to 4.45]; and intracranial CSF volume ratio, 1.90 [95% CI, 1.33 to 2.71]). Under isoflurane, tracer was directed to systemic circulation. Under K/DEX, the intracranial tracer distribution and CSF volume were uninfluenced by hypercapnia compared with normoventilation. Intracranial CSF tracer distribution was unaffected by hyperventilation under isoflurane despite a 28% increase in CSF volume around middle cerebral arteries. CONCLUSIONS K/DEX and isoflurane overrode carbon dioxide as a regulator of CSF flow. K/DEX could be used to preserve CSF space and dynamics in hypercapnia, whereas hyperventilation was insufficient to increase cerebral CSF perfusion under isoflurane. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Niklas Daniel Åke Persson
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Terhi J Lohela
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Department of Anaesthesiology, Intensive Care and Pain Medicine, HUS Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Kristian Nygaard Mortensen
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Marko Rosenholm
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Qianliang Li
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Pia Weikop
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York
| | - Tuomas O Lilius
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Individualized Drug Therapy Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland; Department of Emergency Medicine and Services, HUS Helsinki University Hospital and University of Helsinki, Helsinki, Finland
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8
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Rosenberg AJ, Anderson GK, McKeefer HJ, Bird J, Pentz B, Byman BRM, Jendzjowsky N, Wilson RJ, Day TA, Rickards CA. Hemorrhage at high altitude: impact of sustained hypobaric hypoxia on cerebral blood flow, tissue oxygenation, and tolerance to simulated hemorrhage in humans. Eur J Appl Physiol 2024; 124:2365-2378. [PMID: 38489034 PMCID: PMC11321930 DOI: 10.1007/s00421-024-05450-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 02/22/2024] [Indexed: 03/17/2024]
Abstract
With ascent to high altitude (HA), compensatory increases in cerebral blood flow and oxygen delivery must occur to preserve cerebral metabolism and consciousness. We hypothesized that this compensation in cerebral blood flow and oxygen delivery preserves tolerance to simulated hemorrhage (via lower body negative pressure, LBNP), such that tolerance is similar during sustained exposure to HA vs. low altitude (LA). Healthy humans (4F/4 M) participated in LBNP protocols to presyncope at LA (1130 m) and 5-7 days following ascent to HA (3800 m). Internal carotid artery (ICA) blood flow, cerebral delivery of oxygen (CDO2) through the ICA, and cerebral tissue oxygen saturation (ScO2) were determined. LBNP tolerance was similar between conditions (LA: 1276 ± 304 s vs. HA: 1208 ± 306 s; P = 0.58). Overall, ICA blood flow and CDO2 were elevated at HA vs. LA (P ≤ 0.01) and decreased with LBNP under both conditions (P < 0.0001), but there was no effect of altitude on ScO2 responses (P = 0.59). Thus, sustained exposure to hypobaric hypoxia did not negatively impact tolerance to simulated hemorrhage. These data demonstrate the robustness of compensatory physiological mechanisms that preserve human cerebral blood flow and oxygen delivery during sustained hypoxia, ensuring cerebral tissue metabolism and neuronal function is maintained.
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Affiliation(s)
- Alexander J Rosenberg
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
- Integrative Physiology Laboratory, Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL, USA
- Physiology Department, Midwestern University, Downers Grove, IL, USA
| | - Garen K Anderson
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Haley J McKeefer
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | | | | | | | - Nicholas Jendzjowsky
- University of Calgary, Calgary, AB, Canada
- Institute of Respiratory Medicine & Exercise Physiology, The Lundquist Institute at UCLA Harbor Medical, Torrance, CA, USA
| | | | | | - Caroline A Rickards
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA.
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9
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Tomoto T, Zhang R. Arterial Aging and Cerebrovascular Function: Impact of Aerobic Exercise Training in Older Adults. Aging Dis 2024; 15:1672-1687. [PMID: 38270114 PMCID: PMC11272215 DOI: 10.14336/ad.2023.1109-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 11/09/2023] [Indexed: 01/26/2024] Open
Abstract
Advanced age is the major risk factor for dementia including Alzheimer's disease. The clinical effects of recently developed anti-amyloid therapy for Alzheimer's disease were modest and the long-term outcome is unknown. Thus, an in-depth understanding of the mechanisms of brain aging is essential to develop preventive interventions to maintain cognitive health in late life. Mounting evidence suggests that arterial aging manifested as increases in central arterial stiffness is associated closely with cerebrovascular dysfunction and brain aging while improvement of cerebrovascular function with aerobic exercise training contributes to brain health in older adults. We summarized evidence in this brief review that 1) increases in central arterial stiffness and arterial pulsation with age are associated with increases in cerebrovascular resistance, reduction in cerebral blood flow, and cerebrovascular dysfunction, 2) aerobic exercise training improves cerebral blood flow by modifying arterial aging as indicated by reductions in cerebrovascular resistance, central arterial stiffness, arterial pulsation, and improvement in cerebrovascular function, and 3) improvement in cerebral blood flow and cerebrovascular function with aerobic exercise training may lead to improvement in cognitive function. These findings highlight the associations between arterial aging and cerebrovascular function and the importance of aerobic exercise in maintaining brain health in older adults.
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Affiliation(s)
- Tsubasa Tomoto
- Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan.
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA.
- Departments of Neurology,
| | - Rong Zhang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA.
- Departments of Neurology,
- Internal Medicine, and
- Biomedical Engineering, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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10
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Strapazzon G, Taboni A, Dietrichs ES, Luks AM, Brugger H. Avalanche burial pathophysiology - a unique combination of hypoxia, hypercapnia and hypothermia. J Physiol 2024. [PMID: 39073871 DOI: 10.1113/jp284607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 06/17/2024] [Indexed: 07/30/2024] Open
Abstract
For often unclear reasons, the survival times of critically buried avalanche victims vary widely from minutes to hours. Individuals can survive and sustain organ function if they can breathe under the snow and maintain sufficient delivery of oxygen and efflux of carbon dioxide. We review the physiological responses of humans to critical avalanche burial, a model which shares similarities and differences with apnoea and accidental hypothermia. Within a few minutes of burial, an avalanche victim is exposed to hypoxaemia and hypercapnia, which have important effects on the respiratory and cardiovascular systems and pose a major threat to the central nervous system. As burial time increases, an avalanche victim also develops hypothermia. Despite progressively reduced metabolism, reduced oxygen and increased carbon dioxide tensions may exacerbate the pathophysiological consequences of hypothermia. Hypercapnia seems to be the main cause of cardiovascular instability, which, in turn, is the major reason for reduced cerebral oxygenation despite reductions in cerebral metabolic activity caused by hypothermia. 'Triple H syndrome' refers to the interaction of hypoxia, hypercapnia and hypothermia in a buried avalanche victim. Future studies should investigate how the respiratory gases entrapped in the porous snow structure influence the physiological responses of buried individuals and how haemoconcentration, blood viscosity and cell deformability affect blood flow and oxygen delivery. Attention should also be devoted to identifying strategies to prolong avalanche survival by either mitigating hypoxia and hypercapnia or reducing core temperature so that neuroprotection occurs before the onset of cerebral hypoxia.
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Affiliation(s)
- Giacomo Strapazzon
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
- Department of Medicine - DIMEM, University of Padova, Padova, Italy
| | - Anna Taboni
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | | | - Andrew M Luks
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of Washington, Seattle, WA, USA
| | - Hermann Brugger
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
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11
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Kish B, Jean Chen J, Tong Y. Effects of clamping end-tidal CO 2 on neurofluidic low-frequency oscillations. NMR IN BIOMEDICINE 2024; 37:e5084. [PMID: 38104563 PMCID: PMC11162899 DOI: 10.1002/nbm.5084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/17/2023] [Accepted: 11/11/2023] [Indexed: 12/19/2023]
Abstract
In recent years, low-frequency oscillations (LFOs) (0.01-0.1 Hz) have been a subject of interest in resting-state functional magnetic resonance imaging research. They are believed to have many possible driving mechanisms, from both regional and global sources. Internal fluctuations in the partial pressure of CO2 (PCO2) has long been thought of as one of these major driving forces, but its exact contributions compared with other mechanisms have yet to be fully understood. This study examined the effects of end-tidal PCO2 (PetCO2) oscillations on LF cerebral hemodynamics and cerebrospinal fluid (CSF) dynamics under "clamped PetCO2" and "free-breathing" conditions. Under clamped PetCO2, a participant's PetCO2 levels were fixed to their baseline average, whereas PetCO2 was not controlled in free breathing. Under clamped PetCO2, the fractional amplitude of hemodynamic LFOs in the occipital and sensorimotor cortex and temporal lobes were found to be significantly reduced. Additionally, the fractional amplitude of CSF LFOs, measured at the fourth ventricle, was found to be reduced by almost one-half. However, the spatiotemporal distributions of blood and CSF delay times, as measured by cross-correlation in the LF domain, were not significantly altered between conditions. This study demonstrates that, while PCO2 oscillations significantly mediate LFOs, especially those observed in the CSF, other mechanisms are able to maintain LFOs, with high correlation, even in their absence.
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Affiliation(s)
- Brianna Kish
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - J. Jean Chen
- Rotman Research Institute, Baycrest Health Sciences, Toronto, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
- Institute of Biomedical Engineering, University of Toronto, Toronto, Canada
| | - Yunjie Tong
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
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12
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Toader AE, Fukuda M, Vazquez AL. Evaluation of calibrated and uncalibrated optical imaging approaches for relative cerebral oxygen metabolism measurements in awake mice. Physiol Meas 2024; 45:045007. [PMID: 38569522 DOI: 10.1088/1361-6579/ad3a2d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 04/03/2024] [Indexed: 04/05/2024]
Abstract
Objective. The continuous delivery of oxygen is critical to sustain brain function, and therefore, measuring brain oxygen consumption can provide vital physiological insight. In this work, we examine the impact of calibration and cerebral blood flow (CBF) measurements on the computation of the relative changes in the cerebral metabolic rate of oxygen consumption (rCMRO2) from hemoglobin-sensitive intrinsic optical imaging data. Using these data, we calculate rCMRO2, and calibrate the model using an isometabolic stimulus.Approach. We used awake head-fixed rodents to obtain hemoglobin-sensitive optical imaging data to test different calibrated and uncalibrated rCMRO2models. Hypercapnia was used for calibration and whisker stimulation was used to test the impact of calibration.Main results. We found that typical uncalibrated models can provide reasonable estimates of rCMRO2with differences as small as 7%-9% compared to their calibrated models. However, calibrated models showed lower variability and less dependence on baseline hemoglobin concentrations. Lastly, we found that supplying the model with measurements of CBF significantly reduced error and variability in rCMRO2change calculations.Significance. The effect of calibration on rCMRO2calculations remains understudied, and we systematically evaluated different rCMRO2calculation scenarios that consider including different measurement combinations. This study provides a quantitative comparison of these scenarios to evaluate trade-offs that can be vital to the design of blood oxygenation sensitive imaging experiments for rCMRO2calculation.
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Affiliation(s)
- A E Toader
- Departments of Radiology, University of Pittsburgh, Pittsburgh PA 15217, United States of America
| | - M Fukuda
- Departments of Radiology, University of Pittsburgh, Pittsburgh PA 15217, United States of America
| | - A L Vazquez
- Departments of Radiology, University of Pittsburgh, Pittsburgh PA 15217, United States of America
- Bioengineering, University of Pittsburgh, Pittsburgh PA 15217, United States of America
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13
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Chakravartula S, Thrasher B, Mann J, Chaturbedi A, Han X, Dahan A, Florian J, Strauss D, Li Z. Physiologically based modeling reveals different risk of respiratory depression after fentanyl overdose between adults and children. Clin Transl Sci 2024; 17:e13780. [PMID: 38618722 PMCID: PMC11017203 DOI: 10.1111/cts.13780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 03/01/2024] [Accepted: 03/14/2024] [Indexed: 04/16/2024] Open
Abstract
Despite a rapid increase in pediatric mortality rate from prescription and illicit opioids, there is limited research on the dose-dependent impact of opioids on respiratory depression in children, the leading cause of opioid-associated death. In this article, we extend a previously developed translational model to cover pediatric populations by incorporating age-dependent pharmacokinetic, pharmacodynamic, and physiological changes compared to adults. Our model reproduced previous perioperative clinical findings that adults and children have similar risk of respiratory depression at the same plasma fentanyl concentration when specific endpoints (minute ventilation, CO2 tension in the blood) were used. However, our model points to a potential caveat that, in a perioperative setting, routine use of mechanical ventilation and supplemental oxygen maintained the blood and tissue oxygen partial pressures in patients and prevented the use of oxygen-related endpoints to evaluate the consequences of respiratory depression. In a community setting when such oxygenation procedures are not immediately available, our model suggests that the higher oxygen demand and reduced cerebrovascular reactivity could make children more susceptible to severe hypoxemia and brain hypoxia, even with the same plasma fentanyl concentration as adults. Our work indicates that when developing intervention strategies to protect children from opioid overdose in a community setting, these pediatric-specific factors may need to be considered.
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Affiliation(s)
- Shilpa Chakravartula
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational SciencesCenter for Drug Evaluation and Research, Food and Drug AdministrationSilver SpringMarylandUSA
| | - Bradlee Thrasher
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational SciencesCenter for Drug Evaluation and Research, Food and Drug AdministrationSilver SpringMarylandUSA
| | - John Mann
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational SciencesCenter for Drug Evaluation and Research, Food and Drug AdministrationSilver SpringMarylandUSA
| | - Anik Chaturbedi
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational SciencesCenter for Drug Evaluation and Research, Food and Drug AdministrationSilver SpringMarylandUSA
| | - Xiaomei Han
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational SciencesCenter for Drug Evaluation and Research, Food and Drug AdministrationSilver SpringMarylandUSA
| | - Albert Dahan
- Leiden University Medical CenterLeidenThe Netherlands
| | - Jeffry Florian
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational SciencesCenter for Drug Evaluation and Research, Food and Drug AdministrationSilver SpringMarylandUSA
| | - David Strauss
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational SciencesCenter for Drug Evaluation and Research, Food and Drug AdministrationSilver SpringMarylandUSA
| | - Zhihua Li
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational SciencesCenter for Drug Evaluation and Research, Food and Drug AdministrationSilver SpringMarylandUSA
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14
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Møller K. Hypoxic cerebrovascular oxidative-nitrosative stress: Take my breath away. J Physiol 2024. [PMID: 38466023 DOI: 10.1113/jp286304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Accepted: 02/29/2024] [Indexed: 03/12/2024] Open
Affiliation(s)
- Kirsten Møller
- Department of Neuroanaesthesiology, Neuroscience Centre, Copenhagen University Hospital - Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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15
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Daher A, Payne S. The conducted vascular response as a mediator of hypercapnic cerebrovascular reactivity: A modelling study. Comput Biol Med 2024; 170:107985. [PMID: 38245966 DOI: 10.1016/j.compbiomed.2024.107985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/29/2023] [Accepted: 01/13/2024] [Indexed: 01/23/2024]
Abstract
It is well established that the cerebral blood flow (CBF) shows exquisite sensitivity to changes in the arterial blood partial pressure of CO2 ( [Formula: see text] ), which is reflected by an index termed cerebrovascular reactivity. In response to elevations in [Formula: see text] (hypercapnia), the vessels of the cerebral microvasculature dilate, thereby decreasing the vascular resistance and increasing CBF. Due to the challenges of access, scale and complexity encountered when studying the microvasculature, however, the mechanisms behind cerebrovascular reactivity are not fully understood. Experiments have previously established that the cholinergic release of the Acetylcholine (ACh) neurotransmitter in the cortex is a prerequisite for the hypercapnic response. It is also known that ACh functions as an endothelial-dependent agonist, in which the local administration of ACh elicits local hyperpolarization in the vascular wall; this hyperpolarization signal is then propagated upstream the vascular network through the endothelial layer and is coupled to a vasodilatory response in the vascular smooth muscle (VSM) layer in what is known as the conducted vascular response (CVR). Finally, experimental data indicate that the hypercapnic response is more strongly correlated with the CO2 levels in the tissue than in the arterioles. Accordingly, we hypothesize that the CVR, evoked by increases in local tissue CO2 levels and a subsequent local release of ACh, is responsible for the CBF increase observed in response to elevations in [Formula: see text] . By constructing physiologically grounded dynamic models of CBF and control in the cerebral vasculature, ones that integrate the available knowledge and experimental data, we build a new model of the series of signalling events and pathways underpinning the hypercapnic response, and use the model to provide compelling evidence that corroborates the aforementioned hypothesis. If the CVR indeed acts as a mediator of the hypercapnic response, the proposed mechanism would provide an important addition to our understanding of the repertoire of metabolic feedback mechanisms possessed by the brain and would motivate further in-vivo investigation. We also model the interaction of the hypercapnic response with dynamic cerebral autoregulation (dCA), the collection of mechanisms that the brain possesses to maintain near constant CBF despite perturbations in pressure, and show how the dCA mechanisms, which otherwise tend to be overlooked when analysing experimental results of cerebrovascular reactivity, could play a significant role in shaping the CBF response to elevations in [Formula: see text] . Such in-silico models can be used in tandem with in-vivo experiments to expand our understanding of cerebrovascular diseases, which continue to be among the leading causes of morbidity and mortality in humans.
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Affiliation(s)
- Ali Daher
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, United Kingdom.
| | - Stephen Payne
- Institute of Applied Mechanics, National Taiwan University, Taiwan
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16
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Le TT, Im GH, Lee CH, Choi SH, Kim SG. Mapping cerebral perfusion in mice under various anesthesia levels using highly sensitive BOLD MRI with transient hypoxia. SCIENCE ADVANCES 2024; 10:eadm7605. [PMID: 38416820 PMCID: PMC10901365 DOI: 10.1126/sciadv.adm7605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Accepted: 01/24/2024] [Indexed: 03/01/2024]
Abstract
Cerebral perfusion is critical for the early detection of neurological diseases and for effectively monitoring disease progression and treatment responses. Mouse models are widely used in brain research, often under anesthesia, which can affect vascular physiology. However, the impact of anesthesia on regional cerebral blood volume and flow in mice has not been thoroughly investigated. In this study, we have developed a whole-brain perfusion MRI approach by using a 5-second nitrogen gas stimulus under inhalational anesthetics to induce transient BOLD dynamic susceptibility contrast (DSC). This method proved to be highly sensitive, repeatable within each imaging session, and across four weekly sessions. Relative cerebral blood volumes measured by BOLD DSC agree well with those by contrast agents. Quantitative cerebral blood volume and flow metrics were successfully measured in mice under dexmedetomidine and various isoflurane doses using both total vasculature-sensitive gradient-echo and microvasculature-sensitive spin-echo BOLD MRI. Dexmedetomidine reduces cerebral perfusion, while isoflurane increases cerebral perfusion in a dose-dependent manner.
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Affiliation(s)
- Thuy Thi Le
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Republic of Korea
| | - Geun Ho Im
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea
| | - Chan Hee Lee
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea
| | - Sang Han Choi
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea
| | - Seong-Gi Kim
- Center for Neuroscience Imaging Research (CNIR), Institute for Basic Science (IBS), Suwon, Republic of Korea
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
- Department of Intelligent Precision Healthcare Convergence, Sungkyunkwan University, Suwon, Republic of Korea
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17
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Kaiser HA, Bauer T, Riva T, Greif R, Riedel T, Theiler L, Nabecker S. Carbon dioxide and cardiac output as major contributors to cerebral oxygenation during apnoeic oxygenation. Sci Rep 2024; 14:3617. [PMID: 38351038 PMCID: PMC10864331 DOI: 10.1038/s41598-023-49238-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 12/06/2023] [Indexed: 02/16/2024] Open
Abstract
Apnoeic oxygenation has experienced a resurgence in interest in critical care and perioperative medicine. However, its effect on cerebral oxygenation and factors influencing it, have not yet been investigated in detail. By using near-infrared spectroscopy, we intended to provide further evidence for the safety of apnoeic oxygenation and to increase our understanding of the association between cerebral perfusion, haemodynamic, respiratory and demographic factors. In this secondary analysis of a prospective randomized controlled noninferiority trial, we recruited 125 patients, who underwent surgery under general anaesthesia with neuromuscular blockade. Arterial blood samples were taken every 2 min for a total of 15 min under apnoeic oxygenation with 100% oxygen. Near-infrared spectroscopy and cardiac output were continuously measured. Statistical analysis was performed using uni- and multivariable statistics. Ninety-one complete data sets were analysed. In six patients the SpO2 fell below 92% (predefined study termination criterion). The significant average increase of cerebral oxygenation was 0.5%/min and 2.1 mmHg/min for the arterial pressure of carbon dioxide (paCO2). The median cardiac output increased significantly from 5.0 l/min (IQR 4.5-6.0) to 6.5 l/min (IQR 5.7-7.5). The most significant effect on cerebral oxygenation was exhibited by the variable paCO2 and non-specific patient factors, followed by cardiac output and paO2. Apnoeic oxygenation proves to have a high safety profile while significantly increasing cerebral oxygenation, paCO2 and cardiac output. In reverse, NIRS might act as a reliable clinical surrogate of paCO2 and cardiac output during stable arterial oxygenation.
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Grants
- no ID The study was supported by a departmental research grant of the Department of Anaesthesiology and Pain Medicine, University Hospital of Bern, Bern, Switzerland.
- no ID The study was supported by a departmental research grant of the Department of Anaesthesiology and Pain Medicine, University Hospital of Bern, Bern, Switzerland.
- no ID The study was supported by a departmental research grant of the Department of Anaesthesiology and Pain Medicine, University Hospital of Bern, Bern, Switzerland.
- no ID The study was supported by a departmental research grant of the Department of Anaesthesiology and Pain Medicine, University Hospital of Bern, Bern, Switzerland.
- no ID The study was supported by a departmental research grant of the Department of Anaesthesiology and Pain Medicine, University Hospital of Bern, Bern, Switzerland.
- no ID The study was supported by a departmental research grant of the Department of Anaesthesiology and Pain Medicine, University Hospital of Bern, Bern, Switzerland.
- no ID The study was supported by a departmental research grant of the Department of Anaesthesiology and Pain Medicine, University Hospital of Bern, Bern, Switzerland.
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Affiliation(s)
- Heiko Andreas Kaiser
- Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Thomas Bauer
- Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Thomas Riva
- Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Unit for Research and Innovation, Department of Paediatric Anaesthesia, Istituto Giannina Gaslini, Genova, Italy
| | - Robert Greif
- University of Bern, Bern, Switzerland
- School of Medicine, Sigmund Freud University Vienna, Vienna, Austria
| | - Thomas Riedel
- Department of Paediatrics, Cantonal Hospital Graubünden, Chur, Switzerland
- Division of Respiratory Medicine, Department of Paediatrics, Inselspital, University Children's Hospital, University of Bern, Bern, Switzerland
| | - Lorenz Theiler
- Department of Anaesthesia, Cantonal Hospital Aarau, Aarau, Switzerland
| | - Sabine Nabecker
- Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
- Department of Anaesthesiology and Pain Management, Sinai Health System, University of Toronto, Toronto, Canada.
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18
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Young MJ, Fecchio M, Bodien YG, Edlow BL. Covert cortical processing: a diagnosis in search of a definition. Neurosci Conscious 2024; 2024:niad026. [PMID: 38327828 PMCID: PMC10849751 DOI: 10.1093/nc/niad026] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 10/22/2023] [Accepted: 12/10/2023] [Indexed: 02/09/2024] Open
Abstract
Historically, clinical evaluation of unresponsive patients following brain injury has relied principally on serial behavioral examination to search for emerging signs of consciousness and track recovery. Advances in neuroimaging and electrophysiologic techniques now enable clinicians to peer into residual brain functions even in the absence of overt behavioral signs. These advances have expanded clinicians' ability to sub-stratify behaviorally unresponsive and seemingly unaware patients following brain injury by querying and classifying covert brain activity made evident through active or passive neuroimaging or electrophysiologic techniques, including functional MRI, electroencephalography (EEG), transcranial magnetic stimulation-EEG, and positron emission tomography. Clinical research has thus reciprocally influenced clinical practice, giving rise to new diagnostic categories including cognitive-motor dissociation (i.e. 'covert consciousness') and covert cortical processing (CCP). While covert consciousness has received extensive attention and study, CCP is relatively less understood. We describe that CCP is an emerging and clinically relevant state of consciousness marked by the presence of intact association cortex responses to environmental stimuli in the absence of behavioral evidence of stimulus processing. CCP is not a monotonic state but rather encapsulates a spectrum of possible association cortex responses from rudimentary to complex and to a range of possible stimuli. In constructing a roadmap for this evolving field, we emphasize that efforts to inform clinicians, philosophers, and researchers of this condition are crucial. Along with strategies to sensitize diagnostic criteria and disorders of consciousness nosology to these vital discoveries, democratizing access to the resources necessary for clinical identification of CCP is an emerging clinical and ethical imperative.
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Affiliation(s)
- Michael J Young
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA 02114, USA
| | - Matteo Fecchio
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA 02114, USA
| | - Yelena G Bodien
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA 02114, USA
- Department of Physical Medicine and Rehabilitation, Spaulding Rehabilitation Hospital, Harvard Medical School, 300 1st Ave, Charlestown, Boston, MA 02129, USA
| | - Brian L Edlow
- Center for Neurotechnology and Neurorecovery, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 101 Merrimac Street, Suite 310, Boston, MA 02114, USA
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, 149 13th St, Charlestown, Charlestown, MA 02129, USA
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19
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Mikulis DJ. Cerebrovascular Reserve Imaging: Problems and Solutions. Magn Reson Imaging Clin N Am 2024; 32:93-109. [PMID: 38007286 DOI: 10.1016/j.mric.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2023]
Abstract
The current standard of practice for assessing patients with cerebrovascular steno-occlusive disease is based on measuring resting blood flow metrics using MR imaging and CT perfusion imaging. However, the reliability of these methods decreases as the degree and number of stenoses increase. The reason for this is that measures of adequate baseline blood flow in highly collateralized circulations do not account for possible shortfalls in recruitable blood flow or increased metabolic demand. The following offers a clinically tested solution for this purpose using cerebrovascular reactivity methodology that applies a quantifiable vasodilatory stimulus improving reproducibility and repeatability essential for optimizing patient management.
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Affiliation(s)
- David J Mikulis
- The Krembil Brain Institute, Institute of Medcial Science, Department of Medical Imaging, The University of Toronto, The University Health Network, The Toronto Western Hospital, 399 Bathurst Street, Room 3MC-431, Toronto, ON M5T 2S8, Canada.
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20
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Battaglini D, Delpiano L, Masuello D, Leme Silva P, Rocco PRM, Matta B, Pelosi P, Robba C. Effects of positive end-expiratory pressure on brain oxygenation, systemic oxygen cascade and metabolism in acute brain injured patients: a pilot physiological cross-sectional study. J Clin Monit Comput 2024; 38:165-175. [PMID: 37453007 DOI: 10.1007/s10877-023-01042-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 06/02/2023] [Indexed: 07/18/2023]
Abstract
Patients with acute brain injury (ABI) often require the application of positive end-expiratory pressure (PEEP) to optimize mechanical ventilation and systemic oxygenation. However, the effect of PEEP on cerebral function and metabolism is unclear. The primary aim of this study was to evaluate the effects of PEEP augmentation test (from 5 to 15 cmH2O) on brain oxygenation, systemic oxygen cascade and metabolism in ABI patients. Secondary aims include to determine whether changes in regional cerebral oxygenation are reflected by changes in oxygenation cascade and metabolism, and to assess the correlation between brain oxygenation and mechanical ventilation settings. Single center, pilot cross-sectional observational study in an Academic Hospital. Inclusion criteria were: adult (> 18 y/o) patients with ABI and stable intracranial pressure, available gas exchange and indirect calorimetry (IC) monitoring. Cerebral oxygenation was monitored with near-infrared spectroscopy (NIRS) and different derived parameters were collected: variation (Δ) in oxy (O2)-hemoglobin (Hb) (ΔO2Hbi), deoxy-Hb(ΔHHbi), total-Hb(ΔcHbi), and total regional oxygenation (ΔrSO2). Oxygen cascade and metabolism were monitored with arterial/venous blood gas analysis [arterial partial pressure of oxygen (PaO2), arterial saturation of oxygen (SaO2), oxygen delivery (DO2), and lactate], and IC [energy expenditure (REE), respiratory quotient (RQ), oxygen consumption (VO2), and carbon dioxide production (VCO2)]. Data were measured at PEEP 5 cmH2O and 15 cmH2O and expressed as delta (Δ) values. Ten patients with ABI [median age 70 (IQR 62-75) years, 6 (60%) were male, median Glasgow Coma Scale at ICU admission 5.5 (IQR 3-8)] were included. PEEP augmentation from 5 to 15 cmH2O did not affect cerebral oxygenation, systemic oxygen cascade parameters, and metabolism. The arterial component of cerebral oxygenation was significantly correlated with DO2 (ΔO2HBi, rho = 0.717, p = 0.037). ΔrSO2 (rho = 0.727, p = 0.032), ΔcHbi (rho = 0.797, p = 0.013), and ΔHHBi (rho = 0.816, p = 0.009) were significantly correlated with SaO2, but not ΔO2Hbi. ΔrSO2 was significantly correlated with VCO2 (rho = 0.681, p = 0.049). No correlation between brain oxygenation and ventilatory parameters was found. PEEP augmentation test did not affect cerebral and systemic oxygenation or metabolism. Changes in cerebral oxygenation significantly correlated with DO2, SaO2, and VCO2. Cerebral oxygen monitoring could be considered for individualization of mechanical ventilation setting in ABI patients without high or instable intracranial pressure.
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Affiliation(s)
| | - Lara Delpiano
- IRCCS Ospedale Policlinico San Martino, Genoa, Italy
- Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Università degli Studi di Genova, Genoa, Italy
| | - Denise Masuello
- Hospital Donaciòn Francisco Santojanni, Buenos Aires, Argentina
| | - Pedro Leme Silva
- Laboratory of Pulmonary Investigation, Centro de Ciências da Saúde, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Patricia R M Rocco
- Laboratory of Pulmonary Investigation, Centro de Ciências da Saúde, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Rio de Janeiro Network on Neuroinflammation, Carlos Chagas Filho Foundation for Supporting Research in the State of Rio de Janeiro (FAPERJ), Rio de Janeiro, Brazil
| | - Basil Matta
- Neurocritical Care Unit, Addenbrooke's Hospital, Cambridge University Hospital NHS Foundation Trust, Cambridge, UK
| | - Paolo Pelosi
- IRCCS Ospedale Policlinico San Martino, Genoa, Italy
- Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Università degli Studi di Genova, Genoa, Italy
| | - Chiara Robba
- IRCCS Ospedale Policlinico San Martino, Genoa, Italy
- Dipartimento di Scienze Chirurgiche e Diagnostiche Integrate, Università degli Studi di Genova, Genoa, Italy
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21
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Fettahoglu A, Zhao M, Khalighi M, Vossler H, Jovin M, Davidzon G, Zeineh M, Boada F, Mormino E, Henderson VW, Moseley M, Chen KT, Zaharchuk G. Early-Frame [ 18F]Florbetaben PET/MRI for Cerebral Blood Flow Quantification in Patients with Cognitive Impairment: Comparison to an [ 15O]Water Gold Standard. J Nucl Med 2024; 65:306-312. [PMID: 38071587 PMCID: PMC10858379 DOI: 10.2967/jnumed.123.266273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 10/24/2023] [Indexed: 02/03/2024] Open
Abstract
Cerebral blood flow (CBF) may be estimated from early-frame PET imaging of lipophilic tracers, such as amyloid agents, enabling measurement of this important biomarker in participants with dementia and memory decline. Although previous methods could map relative CBF, quantitative measurement in absolute units (mL/100 g/min) remained challenging and has not been evaluated against the gold standard method of [15O]water PET. The purpose of this study was to develop and validate a minimally invasive quantitative CBF imaging method combining early [18F]florbetaben (eFBB) with phase-contrast MRI using simultaneous PET/MRI. Methods: Twenty participants (11 men and 9 women; 8 cognitively normal, 9 with mild cognitive impairment, and 3 with dementia; 10 β-amyloid negative and 10 β-amyloid positive; 69 ± 9 y old) underwent [15O]water PET, phase-contract MRI, and eFBB imaging in a single session on a 3-T PET/MRI scanner. Quantitative CBF images were created from the first 2 min of brain activity after [18F]florbetaben injection combined with phase-contrast MRI measurement of total brain blood flow. These maps were compared with [15O]water CBF using concordance correlation (CC) and Bland-Altman statistics for gray matter, white matter, and individual regions derived from the automated anatomic labeling (AAL) atlas. Results: The 2 methods showed similar results in gray matter ([15O]water, 55.2 ± 14.7 mL/100 g/min; eFBB, 55.9 ± 14.2 mL/100 g/min; difference, 0.7 ± 2.4 mL/100 g/min; P = 0.2) and white matter ([15O]water, 21.4 ± 5.6 mL/100 g/min; eFBB, 21.2 ± 5.3 mL/100 g/min; difference, -0.2 ± 1.0 mL/100 g/min; P = 0.4). The intrasubject CC for AAL-derived regions was high (0.91 ± 0.04). Intersubject CC in different AAL-derived regions was similarly high, ranging from 0.86 for midfrontal regions to 0.98 for temporal regions. There were no significant differences in performance between the methods in the amyloid-positive and amyloid-negative groups as well as participants with different cognitive statuses. Conclusion: We conclude that eFBB PET/MRI can provide robust CBF measurements, highlighting the capability of simultaneous PET/MRI to provide measurements of both CBF and amyloid burden in a single imaging session in participants with memory disorders.
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Affiliation(s)
- Ates Fettahoglu
- Department of Radiology, Stanford University, Stanford, California
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut
| | - Moss Zhao
- Department of Radiology, Stanford University, Stanford, California
- Stanford Cardiovascular Institute, Stanford University, Stanford, California
| | - Mehdi Khalighi
- Department of Radiology, Stanford University, Stanford, California
| | - Hillary Vossler
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California; and
| | - Maria Jovin
- Department of Radiology, Stanford University, Stanford, California
| | - Guido Davidzon
- Department of Radiology, Stanford University, Stanford, California
| | - Michael Zeineh
- Department of Radiology, Stanford University, Stanford, California
| | - Fernando Boada
- Department of Radiology, Stanford University, Stanford, California
| | - Elizabeth Mormino
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California; and
| | - Victor W Henderson
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, California; and
| | - Michael Moseley
- Department of Radiology, Stanford University, Stanford, California
| | - Kevin T Chen
- Department of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Greg Zaharchuk
- Department of Radiology, Stanford University, Stanford, California
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22
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Deshpande RS, Langham MC, Susztak K, Wehrli FW. MRI-based quantification of whole-organ renal metabolic rate of oxygen. NMR IN BIOMEDICINE 2024; 37:e5036. [PMID: 37750009 PMCID: PMC10841084 DOI: 10.1002/nbm.5036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/02/2023] [Accepted: 08/21/2023] [Indexed: 09/27/2023]
Abstract
During the early stages of diabetes, kidney oxygen utilization increases. The mismatch between oxygen demand and supply contributes to tissue hypoxia, a key driver of chronic kidney disease. Thus, whole-organ renal metabolic rate of oxygen (rMRO2 ) is a potentially valuable biomarker of kidney function. The key parameters required to determine rMRO2 include the renal blood flow rate (RBF) in the feeding artery and oxygen saturation in the draining renal vein (SvO2 ). However, there is currently no noninvasive method to quantify rMRO2 in absolute physiologic units. Here, a new MRI pulse sequence, Kidney Metabolism of Oxygen via T2 and Interleaved Velocity Encoding (K-MOTIVE), is described, along with evaluation of its performance in the human kidney in vivo. K-MOTIVE interleaves a phase-contrast module before a background-suppressed T2 -prepared balanced steady-state-free-precession (bSSFP) readout to measure RBF and SvO2 in a single breath-hold period of 22 s, yielding rMRO2 via Fick's principle. Variants of K-MOTIVE to evaluate alternative bSSFP readout strategies were studied. Kidney mass was manually determined from multislice gradient recalled echo images. Healthy subjects were recruited to quantify rMRO2 of the left kidney at 3-T field strength (N = 15). Assessments of repeat reproducibility and comparisons with individual measurements of RBF and SvO2 were performed, and the method's sensitivity was evaluated with a high-protein meal challenge (N = 8). K-MOTIVE yielded the following metabolic parameters: T2 = 157 ± 19 ms; SvO2 = 92% ± 6%; RBF = 400 ± 110 mL/min; and rMRO2 = 114 ± 117(μmol O2 /min)/100 g tissue. Reproducibility studies of T2 and RBF (parameters directly measured by K-MOTIVE) resulted in coefficients of variation less than 10% and intraclass correlation coefficients more than 0.75. The high-protein meal elicited an increase in rMRO2 , which was corroborated by serum biomarkers. The K-MOTIVE sequence measures SvO2 and RBF, the parameters necessary to quantify whole-organ rMRO2 , in a single breath-hold. The present work demonstrates that rMRO2 quantification is feasible with good reproducibility. rMRO2 is a potentially valuable physiological biomarker.
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Affiliation(s)
- Rajiv S. Deshpande
- Laboratory for Structural Physiologic and Functional Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, PA, USA
| | - Michael C. Langham
- Laboratory for Structural Physiologic and Functional Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, PA, USA
| | - Katalin Susztak
- Department of Nephrology and Hypertension, Perelman School of Medicine, University of Pennsylvania, PA, USA
- Department of Medicine and Genetics, Perelman School of Medicine, University of Pennsylvania, PA, USA
| | - Felix W. Wehrli
- Laboratory for Structural Physiologic and Functional Imaging, Department of Radiology, Perelman School of Medicine, University of Pennsylvania, PA, USA
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23
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Chen DY, Di X, Biswal B. Cerebrovascular reactivity increases across development in multiple networks as revealed by a breath-holding task: A longitudinal fMRI study. Hum Brain Mapp 2024; 45:e26515. [PMID: 38183372 PMCID: PMC10789211 DOI: 10.1002/hbm.26515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/15/2023] [Accepted: 09/29/2023] [Indexed: 01/08/2024] Open
Abstract
Functional magnetic resonance imaging (fMRI) has been widely used to understand the neurodevelopmental changes that occur in cognition and behavior across childhood. The blood-oxygen-level-dependent (BOLD) signal obtained from fMRI is understood to be comprised of both neuronal and vascular information. However, it is unclear whether the vascular response is altered across age in studies investigating development in children. Since the breath-hold (BH) task is commonly used to understand cerebrovascular reactivity (CVR) in fMRI studies, it can be used to account for developmental differences in vascular response. This study examines how the cerebrovascular response changes over age in a longitudinal children's BH data set from the Nathan Kline Institute (NKI) Rockland Sample (aged 6-18 years old at enrollment). A general linear model approach was applied to derive CVR from BH data. To model both the longitudinal and cross-sectional effects of age on BH response, we used mixed-effects modeling with the following terms: linear, quadratic, logarithmic, and quadratic-logarithmic, to find the best-fitting model. We observed increased BH BOLD signals in multiple networks across age, in which linear and logarithmic mixed-effects models provided the best fit with the lowest Akaike information criterion scores. This shows that the cerebrovascular response increases across development in a brain network-specific manner. Therefore, fMRI studies investigating the developmental period should account for cerebrovascular changes that occur with age.
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Affiliation(s)
- Donna Y. Chen
- Department of Biomedical EngineeringNew Jersey Institute of TechnologyNewarkNew JerseyUSA
- Rutgers Biomedical and Health SciencesRutgers School of Graduate StudiesNewarkNew JerseyUSA
| | - Xin Di
- Department of Biomedical EngineeringNew Jersey Institute of TechnologyNewarkNew JerseyUSA
| | - Bharat Biswal
- Department of Biomedical EngineeringNew Jersey Institute of TechnologyNewarkNew JerseyUSA
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24
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Wang CH, Chang WT, Huang CH, Tsai MS, Wang CC, Liu SH, Chen WJ. Optimal inhaled oxygen and carbon dioxide concentrations for post-cardiac arrest cerebral reoxygenation and neurological recovery. iScience 2023; 26:108476. [PMID: 38187189 PMCID: PMC10767205 DOI: 10.1016/j.isci.2023.108476] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/17/2023] [Accepted: 11/14/2023] [Indexed: 01/09/2024] Open
Abstract
Prolonged cerebral hypoperfusion after the return of spontaneous circulation (ROSC) from cardiac arrest (CA) may lead to poor neurological recovery. In a 7-min asphyxia-induced CA rat model, four combinations of inhaled oxygen (iO2) and carbon dioxide (iCO2) were administered for 150 min post-ROSC and compared in a randomized animal trial. At the end of administration, the partial pressure of brain tissue oxygenation (PbtO2) monitored in the hippocampal CA1 region returned to the baseline for the 88% iO2 [ΔPbtO2, median: -0.39 (interquartile range: 5.6) mmHg] and 50% iO2 [ΔpbtO2, -2.25 (10.9) mmHg] groups; in contrast, PbtO2 increased substantially in the 88% iO2+12% iCO2 [ΔpbtO2, 35.05 (16.0) mmHg] and 50% iO2+12% iCO2 [ΔpbtO2, 42.03 (31.7) mmHg] groups. Pairwise comparisons (post hoc Dunn's test) indicated the significant role of 12% iCO2 in augmenting PbtO2 during the intervention and improving neurological recovery at 24 h post-ROSC. Facilitating brain reoxygenation may improve post-CA neurological outcomes.
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Affiliation(s)
- Chih-Hung Wang
- Department of Emergency Medicine, National Taiwan University Hospital, Taipei, Taiwan
- Department of Emergency Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wei-Tien Chang
- Department of Emergency Medicine, National Taiwan University Hospital, Taipei, Taiwan
- Department of Emergency Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chien-Hua Huang
- Department of Emergency Medicine, National Taiwan University Hospital, Taipei, Taiwan
- Department of Emergency Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Min-Shan Tsai
- Department of Emergency Medicine, National Taiwan University Hospital, Taipei, Taiwan
- Department of Emergency Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chan-Chi Wang
- Department of Emergency Medicine, National Taiwan University Hospital, Taipei, Taiwan
- Department of Emergency Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shing-Hwa Liu
- Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
- Department of Pediatrics, National Taiwan University Hospital, Taipei, Taiwan
| | - Wen-Jone Chen
- Department of Emergency Medicine, National Taiwan University Hospital, Taipei, Taiwan
- Department of Emergency Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
- Department of Internal Medicine, Min-Sheng General Hospital, Taoyuan, Taiwan
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25
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Andersen L, Appelblad M, Wiklund U, Sundström N, Svenmarker S. Our initial experience of monitoring the autoregulation of cerebral blood flow during cardiopulmonary bypass. THE JOURNAL OF EXTRA-CORPOREAL TECHNOLOGY 2023; 55:209-217. [PMID: 38099638 PMCID: PMC10723576 DOI: 10.1051/ject/2023032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 07/05/2023] [Indexed: 12/17/2023]
Abstract
BACKGROUND Cerebral blood flow (CBF) is believed to be relatively constant within an upper and lower blood pressure limit. Different methods are available to monitor CBF autoregulation during surgery. This study aims to critically analyze the application of the cerebral oxygenation index (COx), one of the commonly used techniques, using a reference to data from a series of clinical registrations. METHOD CBF was monitored using near-infrared spectroscopy, while cerebral blood pressure was estimated by recordings obtained from either the radial or femoral artery in 10 patients undergoing cardiopulmonary bypass. The association between CBF and blood pressure was calculated as a moving continuous correlation coefficient. A COx index > 0.4 was regarded as a sign of abnormal cerebral autoregulation (CA). Recordings were examined to discuss reliability measures and clinical feasibility of the measurements, followed by interpretation of individual results, identification of possible pitfalls, and suggestions of alternative methods. RESULTS AND CONCLUSION Monitoring of CA during cardiopulmonary bypass is intriguing and complex. A series of challenges and limitations should be considered before introducing this method into clinical practice.
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Affiliation(s)
- Leon Andersen
- Heart Centre, Department of Public Health and Clinical Medicine, Umeå University 901 87 Umeå Sweden
| | - Micael Appelblad
- Heart Centre, Department of Public Health and Clinical Medicine, Umeå University 901 87 Umeå Sweden
| | - Urban Wiklund
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University 901 87 Umeå Sweden
| | - Nina Sundström
- Department of Radiation Sciences, Radiation Physics, Biomedical Engineering, Umeå University 901 87 Umeå Sweden
| | - Staffan Svenmarker
- Heart Centre, Department of Public Health and Clinical Medicine, Umeå University 901 87 Umeå Sweden
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26
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Sayin ES, Duffin J, Poublanc J, Venkatraghavan L, Mikulis DJ, Fisher JA, Sobczyk O. Determining the effects of elevated partial pressure of oxygen on hypercapnia-induced cerebrovascular reactivity. J Cereb Blood Flow Metab 2023; 43:2085-2095. [PMID: 37632334 PMCID: PMC10925865 DOI: 10.1177/0271678x231197000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 08/28/2023]
Abstract
Evaluation of cerebrovascular reactivity (CVR) to hypo- and hypercapnia is a valuable test for the assessment of vasodilatory reserve. While hypercapnia-induced CVR testing is usually performed at normoxia, mild hyperoxia may increase tolerability of hypercapnia by reducing the ventilatory distress. However, the effects of mild hyperoxia on CVR was unknown. We therefore recruited 21 patients with a range of steno-occlusive diseases and 12 healthy participants who underwent a standardized 13-minute step plus ramp CVR test with a carbon dioxide gas challenge at the subject's resting end-tidal partial pressure of oxygen or at mild hyperoxia (PetO2 = 150 mmHg) depending on to which group they were assigned. In 11 patients, the second CVR test was at normoxia to examine test-retest differences. CVR was defined as % Δ Signal/ΔPetCO2. We found that there was no significant difference between CVR test results conducted at normoxia and at mild hyperoxia for participants in Groups 1 and 2 for the step and ramp portion. We also found no difference between test and retest CVR at normoxia for patients with cerebrovascular pathology (Group 3) for step and ramp portion. We concluded normoxic CVR is repeatable, and that mild hyperoxia does not affect CVR.
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Affiliation(s)
- Ece Su Sayin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Lashmikumar Venkatraghavan
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - David John Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Joseph Arnold Fisher
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Olivia Sobczyk
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
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27
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Singh N, MacNicol E, DiPasquale O, Randall K, Lythgoe D, Mazibuko N, Simmons C, Selvaggi P, Stephenson S, Turkheimer FE, Cash D, Zelaya F, Colasanti A. The effects of acute Methylene Blue administration on cerebral blood flow and metabolism in humans and rats. J Cereb Blood Flow Metab 2023; 43:95-105. [PMID: 36803299 PMCID: PMC10638993 DOI: 10.1177/0271678x231157958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 11/09/2022] [Accepted: 12/26/2022] [Indexed: 02/23/2023]
Abstract
Methylene Blue (MB) is a brain-penetrating drug with putative neuroprotective, antioxidant and metabolic enhancing effects. In vitro studies suggest that MB enhances mitochondrial complexes activity. However, no study has directly assessed the metabolic effects of MB in the human brain. We used in vivo neuroimaging to measure the effect of MB on cerebral blood flow (CBF) and brain metabolism in humans and in rats. Two doses of MB (0.5 and 1 mg/kg in humans; 2 and 4 mg/kg in rats; iv) induced reductions in global cerebral blood flow (CBF) in humans (F(1.74, 12.17)5.82, p = 0.02) and rats (F(1,5)26.04, p = 0.0038). Human cerebral metabolic rate of oxygen (CMRO2) was also significantly reduced (F(1.26, 8.84)8.01, p = 0.016), as was the rat cerebral metabolic rate of glucose (CMRglu) (t = 2.6(16) p = 0.018). This was contrary to our hypothesis that MB will increase CBF and energy metrics. Nevertheless, our results were reproducible across species and dose dependent. One possible explanation is that the concentrations used, although clinically relevant, reflect MB's hormetic effects, i.e., higher concentrations produce inhibitory rather than augmentation effects on metabolism. Additionally, here we used healthy volunteers and healthy rats with normal cerebral metabolism where MB's ability to enhance cerebral metabolism might be limited.
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Affiliation(s)
- Nisha Singh
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Eilidh MacNicol
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Ottavia DiPasquale
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Karen Randall
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - David Lythgoe
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Ndabezinhle Mazibuko
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Camilla Simmons
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Pierluigi Selvaggi
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Stephanie Stephenson
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Federico E Turkheimer
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Diana Cash
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Fernando Zelaya
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Alessandro Colasanti
- Department of Clinical Neuroscience and Neuroimaging, Brighton and Sussex Medical School, University of Sussex, Brighton, UK
- Centre for Affective Disorders, Department of Psychological Medicine, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
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28
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Yeom R, Gorgone M, Malinovic M, Panzica P, Maslow A, Augoustides JG, Marchant BE, Fernando RJ, Nampi RG, Pospishil L, Neuburger PJ. Surgical Aortic Valve Replacement in a Patient with Very Severe Chronic Obstructive Pulmonary Disease. J Cardiothorac Vasc Anesth 2023; 37:2335-2349. [PMID: 37657996 DOI: 10.1053/j.jvca.2023.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 08/06/2023] [Indexed: 09/03/2023]
Affiliation(s)
- Richard Yeom
- Department of Anesthesiology, Westchester Medical Center, Valhalla, NY
| | - Michelle Gorgone
- Department of Anesthesiology, Rhode Island Hospital, Providence, RI
| | - Matea Malinovic
- Department of Anesthesiology, Westchester Medical Center, Valhalla, NY
| | - Peter Panzica
- Department of Anesthesiology, Westchester Medical Center, Valhalla, NY
| | - Andrew Maslow
- Department of Anesthesiology, Rhode Island Hospital, Providence, RI
| | - John G Augoustides
- Department of Anesthesiology and Critical Care, Hospital of the University of Pennsylvania, Philadelphia, PA
| | - Bryan E Marchant
- Department of Anesthesiology, Cardiothoracic and Critical Care Sections, Wake Forest University School of Medicine, Winston Salem, NC
| | - Rohesh J Fernando
- Department of Anesthesiology, Cardiothoracic Section, Wake Forest University School of Medicine, Medical Center Boulevard, Winston Salem, NC.
| | - Robert G Nampi
- Department of Anesthesiology, Perioperative Care, and Pain Medicine, NYU Grossman School of Medicine, New York, NY
| | - Liliya Pospishil
- Department of Anesthesiology, Perioperative Care, and Pain Medicine, NYU Grossman School of Medicine, New York, NY
| | - Peter J Neuburger
- Department of Anesthesiology, Perioperative Care, and Pain Medicine, NYU Grossman School of Medicine, New York, NY
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29
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Vestergaard MB, Laursen JC, Heinrich NS, Rossing P, Hansen TW, Larsson HBW. Patients with type 1 diabetes and albuminuria have a reduced brain glycolytic capability that is correlated with brain atrophy. Front Neurosci 2023; 17:1229509. [PMID: 37869511 PMCID: PMC10585154 DOI: 10.3389/fnins.2023.1229509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 09/14/2023] [Indexed: 10/24/2023] Open
Abstract
Introduction Patients with type 1 diabetes (T1D) demonstrate brain alterations, including white matter lesions and cerebral atrophy. In this case-control study, we investigated if a reason for this atrophy could be because of diabetes-related complications affecting cerebrovascular or cerebral glycolytic functions. Cerebral physiological dysfunction can lead to energy deficiencies and, consequently, neurodegeneration. Methods We examined 33 patients with T1D [18 females, mean age: 50.8 years (range: 26-72)] and 19 matched healthy controls [7 females, mean age: 45.0 years (range: 24-64)]. Eleven (33%) of the patients had albuminuria. Total brain volume, brain parenchymal fraction, gray matter volume and white matter volume were measured by anatomical MRI. Cerebral vascular and glycolytic functions were investigated by measuring global cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2) and cerebral lactate concentration in response to the inhalation of hypoxic air (12-14% fractional oxygen) using phase-contrast MRI and magnetic resonance spectroscopy (MRS) techniques. The inspiration of hypoxic air challenges both cerebrovascular and cerebral glycolytic physiology, and an impaired response will reveal a physiologic dysfunction. Results Patients with T1D and albuminuria had lower total brain volume, brain parenchymal fraction, and gray matter volume than healthy controls and patients without albuminuria. The inhalation of hypoxic air increased CBF and lactate in all groups. Patients with albuminuria had a significantly (p = 0.032) lower lactate response compared to healthy controls. The CBF response was lower in patients with albuminuria compared to healthy controls, however not significantly (p = 0.24) different. CMRO2 was unaffected by the hypoxic challenge in all groups (p > 0.16). A low lactate response was associated with brain atrophy, characterized by reduced total brain volume (p = 0.003) and reduced gray matter volume (p = 0.013). Discussion We observed a reduced response of the lactate concentration as an indication of impaired glycolytic activity, which correlated with brain atrophy. Inadequacies in upregulating cerebral glycolytic activity, perhaps from reduced glucose transporters in the brain or hypoxia-inducible factor 1 pathway dysfunction, could be a complication in diabetes contributing to the development of neurodegeneration and declining brain health.
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Affiliation(s)
- Mark B. Vestergaard
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital – Rigshospitalet, Glostrup, Denmark
| | | | | | - Peter Rossing
- Steno Diabetes Center Copenhagen, Gentofte, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
| | | | - Henrik B. W. Larsson
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital – Rigshospitalet, Glostrup, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, Denmark
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Sarwal A, Robba C, Venegas C, Ziai W, Czosnyka M, Sharma D. Are We Ready for Clinical Therapy based on Cerebral Autoregulation? A Pro-con Debate. Neurocrit Care 2023; 39:269-283. [PMID: 37165296 DOI: 10.1007/s12028-023-01741-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 04/19/2023] [Indexed: 05/12/2023]
Abstract
Cerebral autoregulation (CA) is a physiological mechanism that maintains constant cerebral blood flow regardless of changes in cerebral perfusion pressure and prevents brain damage caused by hypoperfusion or hyperperfusion. In recent decades, researchers have investigated the range of systemic blood pressures and clinical management strategies over which cerebral vasculature modifies intracranial hemodynamics to maintain cerebral perfusion. However, proposed clinical interventions to optimize autoregulation status have not demonstrated clear clinical benefit. As future trials are designed, it is crucial to comprehend the underlying cause of our inability to produce robust clinical evidence supporting the concept of CA-targeted management. This article examines the technological advances in monitoring techniques and the accuracy of continuous assessment of autoregulation techniques used in intraoperative and intensive care settings today. It also examines how increasing knowledge of CA from recent clinical trials contributes to a greater understanding of secondary brain injury in many disease processes, despite the fact that the lack of robust evidence influencing outcomes has prevented the translation of CA-guided algorithms into clinical practice.
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Affiliation(s)
- Aarti Sarwal
- Atrium Wake Forest School of Medicine, Winston-Salem, NC, USA.
| | | | - Carla Venegas
- Mayo Clinic School of Medicine, Jacksonville, FL, USA
| | - Wendy Ziai
- Johns Hopkins University School of Medicine and Johns Hopkins Bayview Medical Center, Baltimore, MD, USA
| | - Marek Czosnyka
- Division of Neurosurgery, Cambridge University Hospital, Cambridge, UK
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Carr JMJR, Day TA, Ainslie PN, Hoiland RL. The jugular venous-to-arterial P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ difference during rebreathing and end-tidal forcing: Relationship with cerebral perfusion. J Physiol 2023; 601:4251-4262. [PMID: 37635691 DOI: 10.1113/jp284449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 08/11/2023] [Indexed: 08/29/2023] Open
Abstract
We examined two assumptions of the modified rebreathing technique for the assessment of the ventilatory central chemoreflex (CCR) and cerebrovascular CO2 reactivity (CVR), hypothesizing: (1) that rebreathing abolishes the gradient between the partial pressures of arterial and brain tissue CO2 [measured via the surrogate jugular venousP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ and arterialP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ difference (Pjv-a CO2 )] and (2) rebreathing eliminates the capacity of CVR to influence the Pjv-a CO2 difference, and thus affect CCR sensitivity. We also evaluated these variables during two separate dynamic end-tidal forcing (ETF) protocols (termed: ETF-1 and ETF-2), another method of assessing CCR sensitivity and CVR. Healthy participants were included in the rebreathing (n = 9), ETF-1 (n = 11) and ETF-2 (n = 10) protocols and underwent radial artery and internal jugular vein (advanced to jugular bulb) catheterization to collect blood samples. Transcranial Doppler ultrasound was used to measure middle cerebral artery blood velocity (MCAv). The Pjv-a CO2 difference was not abolished during rebreathing (6.2 ± 2.6 mmHg; P < 0.001), ETF-1 (9.3 ± 1.5 mmHg; P < 0.001) or ETF-2 (8.6 ± 1.4 mmHg; P < 0.001). The Pjv-a CO2 difference did not change during the rebreathing protocol (-0.1 ± 1.2 mmHg; P = 0.83), but was reduced during the ETF-1 (-3.9 ± 1.1 mmHg; P < 0.001) and ETF-2 (-3.4 ± 1.2 mmHg; P = 0.001) protocols. Overall, increases in MCAv were associated with reductions in the Pjv-a CO2 difference during ETF (-0.095 ± 0.089 mmHg cm-1 s-1 ; P = 0.001) but not during rebreathing (-0.028 ± 0.045 mmHg · cm-1 · s-1 ; P = 0.067). These findings suggest that, although the Pjv-a CO2 is not abolished during any chemoreflex assessment technique, hyperoxic hypercapnic rebreathing is probably more appropriate to assess CCR sensitivity independent of cerebrovascular reactivity to CO2 . KEY POINTS: Modified rebreathing is a technique used to assess the ventilatory central chemoreflex and is based on the premise that the rebreathing method eliminates the difference between arterial and brain tissueP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Therefore, rebreathing is assumed to isolate the ventilatory response to central chemoreflex stimulation from the influence of cerebral blood flow. We assessed these assumptions by measuring arterial and jugular venous bulbP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ and middle cerebral artery blood velocity during modified rebreathing and compared these data against data from another test of the ventilatory central chemoreflex using hypercapnic dynamic end-tidal forcing. The difference between arterial and jugular venous bulbP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ remained present during both rebreathing and end-tidal forcing tests, whereas middle cerebral artery blood velocity was associated with theP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ difference during end-tidal forcing but not rebreathing. These findings offer substantiating evidence that clarifies and refines the assumptions of modified rebreathing tests, enhancing interpretation of future findings.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, AB, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, BC, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
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Hencz A, Magony A, Thomas C, Kovacs K, Szilagyi G, Pal J, Sik A. Mild hypoxia-induced structural and functional changes of the hippocampal network. Front Cell Neurosci 2023; 17:1277375. [PMID: 37841285 PMCID: PMC10576450 DOI: 10.3389/fncel.2023.1277375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 09/15/2023] [Indexed: 10/17/2023] Open
Abstract
Hypoxia causes structural and functional changes in several brain regions, including the oxygen-concentration-sensitive hippocampus. We investigated the consequences of mild short-term hypoxia on rat hippocampus in vivo. The hypoxic group was treated with 16% O2 for 1 h, and the control group with 21% O2. Using a combination of Gallyas silver impregnation histochemistry revealing damaged neurons and interneuron-specific immunohistochemistry, we found that somatostatin-expressing inhibitory neurons in the hilus were injured. We used 32-channel silicon probe arrays to record network oscillations and unit activity from the hippocampal layers under anaesthesia. There were no changes in the frequency power of slow, theta, beta, or gamma bands, but we found a significant increase in the frequency of slow oscillation (2.1-2.2 Hz) at 16% O2 compared to 21% O2. In the hilus region, the firing frequency of unidentified interneurons decreased. In the CA3 region, the firing frequency of some unidentified interneurons decreased while the activity of other interneurons increased. The activity of pyramidal cells increased both in the CA1 and CA3 regions. In addition, the regularity of CA1, CA3 pyramidal cells' and CA3 type II and hilar interneuron activity has significantly changed in hypoxic conditions. In summary, a low O2 environment caused profound changes in the state of hippocampal excitatory and inhibitory neurons and network activity, indicating potential changes in information processing caused by mild short-term hypoxia.
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Affiliation(s)
- Alexandra Hencz
- Institute of Physiology, Medical School, University of Pecs, Pecs, Hungary
| | - Andor Magony
- Institute of Physiology, Medical School, University of Pecs, Pecs, Hungary
- Institute of Transdisciplinary Discoveries, Medical School, University of Pecs, Pecs, Hungary
| | - Chloe Thomas
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Krisztina Kovacs
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Gabor Szilagyi
- Institute of Biochemistry and Medical Chemistry, Medical School, University of Pecs, Pecs, Hungary
| | - Jozsef Pal
- Institute of Physiology, Medical School, University of Pecs, Pecs, Hungary
| | - Attila Sik
- Institute of Physiology, Medical School, University of Pecs, Pecs, Hungary
- Institute of Transdisciplinary Discoveries, Medical School, University of Pecs, Pecs, Hungary
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
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Madsen SS, Lindberg U, Asghar S, Olsen KS, Møller K, Larsson HBW, Vestergaard MB. Reproducibility of cerebral blood flow, oxygen metabolism, and lactate and N-acetyl-aspartate concentrations measured using magnetic resonance imaging and spectroscopy. Front Physiol 2023; 14:1213352. [PMID: 37731542 PMCID: PMC10508186 DOI: 10.3389/fphys.2023.1213352] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 08/21/2023] [Indexed: 09/22/2023] Open
Abstract
In humans, resting cerebral perfusion, oxygen consumption and energy metabolism demonstrate large intersubject variation regardless of methodology. Whether a similar large variation is also present longitudinally in individual subjects is much less studied, but knowing the time variance in reproducibility is important when designing and interpreting longitudinal follow-up studies examining brain physiology. Therefore, we examined the reproducibility of cerebral blood flow (CBF), global cerebral metabolic rate of oxygen (CMRO2), global arteriovenous oxygen saturation difference (A-V.O2), and cerebral lactate and N-acetyl-aspartate (NAA) concentrations measured using magnetic resonance imaging (MRI) and spectroscopy (MRS) techniques through repeated measurements at 6 h, 24 h, 7 days and several weeks after initial baseline measurements in young healthy adults (N = 26, 13 females, age range 18-35 years). Using this setup, we calculated the correlation, limit of agreement (LoA) and within-subject coefficient of variation (CoVWS) between baseline values and the subsequent repeated measurements to examine the longitudinal variation in individual cerebral physiology. CBF and CMRO2 correlated significantly between baseline and all subsequent measurements. The strength of the correlations (R2) and reproducibility metrics (LoA and CoVWS) demonstrated the best reproducibility for the within-day measurements and generally declined with longer time between measurements. Cerebral lactate and NAA concentrations also correlated significantly for all measurements, except between baseline and the 7-day measurement for lactate. Similar to CBF and CMRO2, lactate and NAA demonstrated the best reproducibility for within-day repeated measurements. The gradual decline in reproducibility over time should be considered when designing and interpreting studies on brain physiology, for example, in the evaluation of treatment efficacy.
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Affiliation(s)
- Signe Sloth Madsen
- Department of Anaesthesiology, Pain and Respiratory Support, Neuroscience Centre, Copenhagen University Hospital–Rigshospitalet, Glostrup, Denmark
| | - Ulrich Lindberg
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital—Rigshospitalet, Copenhagen, Denmark
| | - Sohail Asghar
- Anesthesiology and Intensive Care, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
| | - Karsten Skovgaard Olsen
- Department of Anaesthesiology, Pain and Respiratory Support, Neuroscience Centre, Copenhagen University Hospital–Rigshospitalet, Glostrup, Denmark
| | - Kirsten Møller
- Department of Neuroanaesthesiology, Neuroscience Centre, Copenhagen University Hospital–Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Henrik Bo Wiberg Larsson
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital—Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mark Bitsch Vestergaard
- Functional Imaging Unit, Department of Clinical Physiology and Nuclear Medicine, Copenhagen University Hospital—Rigshospitalet, Copenhagen, Denmark
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Carr JMJR, Hoiland RL, Fernandes IA, Schrage WG, Ainslie PN. Recent insights into mechanisms of hypoxia-induced vasodilatation in the human brain. J Physiol 2023. [PMID: 37655827 DOI: 10.1113/jp284608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 08/07/2023] [Indexed: 09/02/2023] Open
Abstract
The cerebral vasculature manages oxygen delivery by adjusting arterial blood in-flow in the face of reductions in oxygen availability. Hypoxic cerebral vasodilatation, and the associated hypoxic cerebral blood flow reactivity, involve many vascular, erythrocytic and cerebral tissue mechanisms that mediate elevations in cerebral blood flow via micro- and macrovascular dilatation. This contemporary review focuses on in vivo human work - with reference to seminal preclinical work where necessary - on hypoxic cerebrovascular reactivity, particularly where recent advancements have been made. We provide updates with the following information: in humans, hypoxic cerebral vasodilatation is partially mediated via a - likely non-obligatory - combination of: (1) nitric oxide synthases, (2) deoxygenation-coupled S-nitrosothiols, (3) potassium channel-related vascular smooth muscle hyperpolarization, and (4) prostaglandin mechanisms with some contribution from an interrelationship with reactive oxygen species. And finally, we discuss the fact that, due to the engagement of deoxyhaemoglobin-related mechanisms, reductions in O2 content via haemoglobin per se seem to account for ∼50% of that seen with hypoxic cerebral vasodilatation during hypoxaemia. We further highlight the issue that methodological impediments challenge the complete elucidation of hypoxic cerebral reactivity mechanisms in vivo in healthy humans. Future research is needed to confirm recent advancements and to reconcile human and animal findings. Further investigations are also required to extend these findings to address questions of sex-, heredity-, age-, and disease-related differences. The final step is to then ultimately translate understanding of these mechanisms into actionable, targetable pathways for the prevention and treatment of cerebral vascular dysfunction and cerebral hypoxic brain injury.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Ryan L Hoiland
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Collaborative Entity for Researching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, British Columbia, Canada
| | - Igor A Fernandes
- Department of Health and Kinesiology, Purdue University, Indiana, USA
| | - William G Schrage
- Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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Hoiland RL, Robba C, Menon DK, Citerio G, Sandroni C, Sekhon MS. Clinical targeting of the cerebral oxygen cascade to improve brain oxygenation in patients with hypoxic-ischaemic brain injury after cardiac arrest. Intensive Care Med 2023; 49:1062-1078. [PMID: 37507572 PMCID: PMC10499700 DOI: 10.1007/s00134-023-07165-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023]
Abstract
The cerebral oxygen cascade includes three key stages: (a) convective oxygen delivery representing the bulk flow of oxygen to the cerebral vascular bed; (b) diffusion of oxygen from the blood into brain tissue; and (c) cellular utilisation of oxygen for aerobic metabolism. All three stages may become dysfunctional after resuscitation from cardiac arrest and contribute to hypoxic-ischaemic brain injury (HIBI). Improving convective cerebral oxygen delivery by optimising cerebral blood flow has been widely investigated as a strategy to mitigate HIBI. However, clinical trials aimed at optimising convective oxygen delivery have yielded neutral results. Advances in the understanding of HIBI pathophysiology suggest that impairments in the stages of the oxygen cascade pertaining to oxygen diffusion and cellular utilisation of oxygen should also be considered in identifying therapeutic strategies for the clinical management of HIBI patients. Culprit mechanisms for these impairments may include a widening of the diffusion barrier due to peri-vascular oedema and mitochondrial dysfunction. An integrated approach encompassing both intra-parenchymal and non-invasive neuromonitoring techniques may aid in detecting pathophysiologic changes in the oxygen cascade and enable patient-specific management aimed at reducing the severity of HIBI.
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Affiliation(s)
- Ryan L Hoiland
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.
- Division of Neurosurgery, Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, BC, Canada.
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada.
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, BC, Canada.
| | - Chiara Robba
- Anesthesia and Intensive Care, San Martino Policlinico Hospital, IRCCS for Oncology and Neurosciences, Genoa, Italy
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy
| | - David K Menon
- Department of Medicine, University Division of Anaesthesia, University of Cambridge, Cambridge, UK
| | - Giuseppe Citerio
- School of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy
| | - Claudio Sandroni
- Department of Intensive Care, Emergency Medicine and Anaesthesiology, Fondazione Policlinico Universitario "Agostino Gemelli", IRCCS, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Mypinder S Sekhon
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, BC, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC, Canada
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van Campen C(LMC, Rowe PC, Verheugt FWA, Visser FC. Influence of end-tidal CO 2 on cerebral blood flow during orthostatic stress in controls and adults with myalgic encephalomyelitis/chronic fatigue syndrome. Physiol Rep 2023; 11:e15639. [PMID: 37688420 PMCID: PMC10492011 DOI: 10.14814/phy2.15639] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 02/15/2023] [Accepted: 02/22/2023] [Indexed: 09/10/2023] Open
Abstract
Brain perfusion is sensitive to changes in CO2 levels (CO2 reactivity). Previously, we showed a pathological cerebral blood flow (CBF) reduction in the majority of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients during orthostatic stress. Limited data are available on the relation between CO2 and CBF changes in ME/CFS patients. Therefore, we studied this relation between ME/CFS patients and healthy controls (HC) during tilt testing. In this retrospective study, supine and end-tilt CBF, as measured by extracranial Doppler flow, were compared with PET CO2 data in female patients either with a normal heart rate and blood pressure (HR/BP) response or with postural orthostatic tachycardia syndrome (POTS), and in HC. Five hundred thirty-five female ME/CFS patients and 34 HC were included. Both in supine position and at end-tilt, there was a significant relation between CBF and PET CO2 in patients (p < 0.0001), without differences between patients with a normal HR/BP response and with POTS. The relations between the %CBF change and the PET CO2 reduction were both significant in patients and HC (p < 0.0001 and p = 0.0012, respectively). In a multiple regression analysis, the patient/HC status and PET CO2 predicted CBF. The contribution of the PET CO2 to CBF changes was limited, with low adjusted R2 values. In female ME/CFS patients, CO2 reactivity, as measured during orthostatic stress testing, is similar to that of HC and is independent of the type of hemodynamic abnormality. However, the influence of CO2 changes on CBF changes is modest in female ME/CFS patients.
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Affiliation(s)
| | - Peter C. Rowe
- Department of PaediatricsJohns Hopkins University School of MedicineBaltimoreMarylandUSA
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Mason EE, Mattingly E, Herb K, Cauley SF, Śliwiak M, Drago JM, Graeser M, Mandeville ET, Mandeville JB, Wald LL. Functional magnetic particle imaging (fMPI) of cerebrovascular changes in the rat brain during hypercapnia. Phys Med Biol 2023; 68:175032. [PMID: 37531961 PMCID: PMC10461175 DOI: 10.1088/1361-6560/acecd1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 07/09/2023] [Accepted: 08/01/2023] [Indexed: 08/04/2023]
Abstract
Objective.Non-invasive functional brain imaging modalities are limited in number, each with its own complex trade-offs between sensitivity, spatial and temporal resolution, and the directness with which the measured signals reflect neuronal activation. Magnetic particle imaging (MPI) directly maps the cerebral blood volume (CBV), and its high sensitivity derives from the nonlinear magnetization of the superparamagnetic iron oxide nanoparticle (SPION) tracer confined to the blood pool. Our work evaluates functional MPI (fMPI) as a new hemodynamic functional imaging modality by mapping the CBV response in a rodent model where CBV is modulated by hypercapnic breathing manipulation.Approach.The rodent fMPI time-series data were acquired with a mechanically rotating field-free line MPI scanner capable of 5 s temporal resolution and 3 mm spatial resolution. The rat's CBV was modulated for 30 min with alternating 5 min hyper-/hypocapnic states, and processed using conventional fMRI tools. We compare our results to fMRI responses undergoing similar hypercapnia protocols found in the literature, and reinforce this comparison in a study of one rat with 9.4T BOLD fMRI using the identical protocol.Main results.The initial image in the time-series showed mean resting brain voxel SNR values, averaged across rats, of 99.9 following the first 10 mg kg-1SPION injection and 134 following the second. The time-series fit a conventional General Linear Model with a 15%-40% CBV change and a peak pixel CNR between 12 and 29, 2-6× higher than found in fMRI.Significance.This work introduces a functional modality with high sensitivity, although currently limited spatial and temporal resolution. With future clinical-scale development, a large increase in sensitivity could supplement other modalities and help transition functional brain imaging from a neuroscience tool focusing on population averages to a clinically relevant modality capable of detecting differences in individual patients.
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Affiliation(s)
- Erica E Mason
- A. A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States of America
| | - Eli Mattingly
- A. A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States of America
- Harvard-MIT Division of Health Sciences & Technology, Cambridge, MA, United States of America
- Harvard Medical School, Boston, MA, United States of America
| | - Konstantin Herb
- A. A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States of America
- ETH Zurich, Department of Physics, Zurich, Switzerland
| | - Stephen F Cauley
- A. A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States of America
- Harvard Medical School, Boston, MA, United States of America
| | - Monika Śliwiak
- A. A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States of America
| | - John M Drago
- A. A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States of America
- Harvard Medical School, Boston, MA, United States of America
- Massachusetts Institute of Technology, Department of Electrical Engineering & Computer Science, Cambridge, MA, United States of America
| | - Matthias Graeser
- Fraunhofer Research Institution for Individualized and Cell-Based Medical Engineering, IMTE, Lübeck, Germany
| | - Emiri T Mandeville
- A. A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States of America
- Harvard Medical School, Boston, MA, United States of America
| | - Joseph B Mandeville
- A. A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States of America
- Harvard Medical School, Boston, MA, United States of America
| | - Lawrence L Wald
- A. A. Martinos Center for Biomedical Imaging, Dept. of Radiology, Massachusetts General Hospital, Charlestown, MA, United States of America
- Harvard-MIT Division of Health Sciences & Technology, Cambridge, MA, United States of America
- Harvard Medical School, Boston, MA, United States of America
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Bakker ME, Djerourou I, Belanger S, Lesage F, Vanni MP. Alteration of functional connectivity despite preserved cerebral oxygenation during acute hypoxia. Sci Rep 2023; 13:13269. [PMID: 37582847 PMCID: PMC10427674 DOI: 10.1038/s41598-023-40321-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 08/08/2023] [Indexed: 08/17/2023] Open
Abstract
Resting state networks (RSN), which show the connectivity in the brain in the absence of any stimuli, are increasingly important to assess brain function. Here, we investigate the changes in RSN as well as the hemodynamic changes during acute, global hypoxia. Mice were imaged at different levels of oxygen (21, 12, 10 and 8%) over the course of 10 weeks, with hypoxia and normoxia acquisitions interspersed. Simultaneous GCaMP and intrinsic optical imaging allowed tracking of both neuronal and hemodynamic changes. During hypoxic conditions, we found a global increase of both HbO and HbR in the brain. The saturation levels of blood dropped after the onset of hypoxia, but surprisingly climbed back to levels similar to baseline within the 10-min hypoxia period. Neuronal activity also showed a peak at the onset of hypoxia, but dropped back to baseline as well. Despite regaining baseline sO2 levels, changes in neuronal RSN were observed. In particular, the connectivity as measured with GCaMP between anterior and posterior parts of the brain decreased. In contrast, when looking at these same connections with HbO measurements, an increase in connectivity in anterior-posterior brain areas was observed suggesting a potential neurovascular decoupling.
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Affiliation(s)
- Marleen E Bakker
- École d'Optométrie, Université de Montréal, 2500 Chem. De Polytechnique, Montréal, QC, H3T 1J4, Canada.
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montréal, Canada.
| | - Ismaël Djerourou
- École d'Optométrie, Université de Montréal, 2500 Chem. De Polytechnique, Montréal, QC, H3T 1J4, Canada
| | | | - Frédéric Lesage
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montréal, Canada
- Montréal Heart Institute, Montréal, Canada
| | - Matthieu P Vanni
- École d'Optométrie, Université de Montréal, 2500 Chem. De Polytechnique, Montréal, QC, H3T 1J4, Canada
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Bloomfield PM, Fisher JP, Shaw DM, Gant N. Cocoa flavanols protect cognitive function, cerebral oxygenation, and mental fatigue during severe hypoxia. J Appl Physiol (1985) 2023; 135:475-484. [PMID: 37471213 DOI: 10.1152/japplphysiol.00219.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 07/06/2023] [Accepted: 07/06/2023] [Indexed: 07/22/2023] Open
Abstract
We tested the hypothesis that ingestion of cocoa flavanols would improve cognition during acute hypoxia equivalent to 5,500 m altitude (partial pressure of end-tidal oxygen = 45 mmHg). Using placebo-controlled double-blind trials, 12 participants ingested 15 mg·kg-1 of cocoa flavanols 90 min before completing cognitive tasks during normoxia and either poikilocapnic or isocapnic hypoxia (partial pressure of end-tidal carbon dioxide uncontrolled or maintained at the baseline value, respectively). Cerebral oxygenation was measured using functional near-infrared spectroscopy. Overall cognition was impaired by poikilocapnic hypoxia (main effect of hypoxia, P = 0.008). Cocoa flavanols improved a measure of overall cognitive performance by 4% compared with placebo (effect of flavanols, P = 0.033) during hypoxia, indicating a change in performance from "low average" to "average." The hypoxia-induced decrease in cerebral oxygenation was two-fold greater with placebo than with cocoa flavanols (effect of flavanols, P = 0.005). Subjective fatigue was increased by 900% with placebo compared with flavanols during poikilocapnic hypoxia (effect of flavanols, P = 0.004). Overall cognition was impaired by isocapnic hypoxia (effect of hypoxia, P = 0.001) but was not improved by cocoa flavanols (mean improvement = 1%; effect of flavanols, P = 0.72). Reaction time was impaired by 8% with flavanols during normoxia and further impaired by 11% during isocapnic hypoxia (effect of flavanols, P = 0.01). Our findings are the first to show that flavanol-mediated improvements in cognition and mood during normoxia persist during severe oxygen deprivation, conferring a neuroprotective effect.NEW & NOTEWORTHY We show for the first time that cocoa flavanols exert a neuroprotective effect during severe hypoxia. Following acute cocoa flavanol ingestion, we observed improvements in cognition, cerebral oxygenation, and subjective fatigue during normoxia and severe poikilocapnic hypoxia. Cocoa flavanols did not improve cognition during severe isocapnic hypoxia, suggesting a possible interaction with carbon dioxide.
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Affiliation(s)
- Peter M Bloomfield
- Exercise Neurometabolism Laboratory, University of Auckland, Auckland, New Zealand
| | - James P Fisher
- Department of Physiology, Faculty of Medical & Health Sciences, Manaaki Mānawa - The Centre for Heart Research, University of Auckland, Auckland, New Zealand
| | - David M Shaw
- Aviation Medicine Unit, Royal New Zealand Air Force Base Auckland, Whenuapai, Auckland, New Zealand
| | - Nicholas Gant
- Exercise Neurometabolism Laboratory, University of Auckland, Auckland, New Zealand
- Centre for Brain Research, University of Auckland, Auckland, New Zealand
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Shen Y, Wang Q, Modi HR, Pathak AP, Geocadin RG, Thakor NV, Senarathna J. Quantification of Cerebral Vascular Autoregulation Immediately Following Resuscitation from Cardiac Arrest. Ann Biomed Eng 2023; 51:1847-1858. [PMID: 37184745 PMCID: PMC10760599 DOI: 10.1007/s10439-023-03210-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 04/06/2023] [Indexed: 05/16/2023]
Abstract
Cerebral vascular autoregulation is impaired following resuscitation from cardiac arrest (CA), and its quantification may allow assessing CA-induced brain injury. However, hyperemia occurring immediately post-resuscitation limits the application of most metrics that quantify autoregulation. Therefore, to characterize autoregulation during this critical period, we developed three novel metrics based on how the cerebrovascular resistance (CVR) covaries with changes in cerebral perfusion pressure (CPP): (i) θCVR, which quantifies the CVR vs CPP gradient, (ii) a CVR-based transfer function analysis, and (iii) CVRx, the correlation coefficient between CPP and CVR. We tested these metrics in a model of asphyxia induced CA and resuscitation using seven adult male Wistar rats. Mean arterial pressure (MAP) and cortical blood flow recorded for 30 min post-resuscitation via arterial cannulation and laser speckle contrast imaging, were used as surrogates of CPP and cerebral blood flow (CBF), while CVR was computed as the CPP/CBF ratio. Using our metrics, we found that the status of cerebral vascular autoregulation altered substantially during hyperemia, with changes spread throughout the 0-0.05 Hz frequency band. Our metrics push the boundary of how soon autoregulation can be assessed, and if validated against outcome markers, may help develop a reliable metric of brain injury post-resuscitation.
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Affiliation(s)
- Yucheng Shen
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Qihong Wang
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Hiren R Modi
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA
| | - Arvind P Pathak
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, 720 Rutland Ave, Traylor Bldg. 701, Baltimore, MD, 21205, USA
| | - Romergryko G Geocadin
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Anesthesia and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Nitish V Thakor
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Janaka Senarathna
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, 720 Rutland Ave, Traylor Bldg. 701, Baltimore, MD, 21205, USA.
- The Kavli Neuroscience Discovery Institute, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Sutin J, Vyas R, Feldman HA, Ferradal S, Hsiao CH, Zampolli L, Pierce LJ, Nelson CA, Morton SU, Hay S, El-Dib M, Soul JS, Lin PY, Grant PE. Association of cerebral metabolic rate following therapeutic hypothermia with 18-month neurodevelopmental outcomes after neonatal hypoxic ischemic encephalopathy. EBioMedicine 2023; 94:104673. [PMID: 37392599 PMCID: PMC10338207 DOI: 10.1016/j.ebiom.2023.104673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 06/02/2023] [Accepted: 06/06/2023] [Indexed: 07/03/2023] Open
Abstract
BACKGROUND Therapeutic hypothermia (TH) is standard of care for moderate to severe neonatal hypoxic ischemic encephalopathy (HIE) but many survivors still suffer lifelong disabilities and benefits of TH for mild HIE are under active debate. Development of objective diagnostics, with sensitivity to mild HIE, are needed to select, guide, and assess response to treatment. The objective of this study was to determine if cerebral oxygen metabolism (CMRO2) in the days after TH is associated with 18-month neurodevelopmental outcomes as the first step in evaluating CMRO2's potential as a diagnostic for HIE. Secondary objectives were to compare associations with clinical exams and characterise the relationship between CMRO2 and temperature during TH. METHODS This was a prospective, multicentre, observational, cohort study of neonates clinically diagnosed with HIE and treated with TH recruited from the tertiary neonatal intensive care units (NICUs) of Boston Children's Hospital, Brigham and Women's Hospital, and Beth Israel Deaconess Medical Center between December 2015 and October 2019 with follow-up to 18 months. In total, 329 neonates ≥34 weeks gestational age admitted with perinatal asphyxia and suspected HIE were identified. 179 were approached, 103 enrolled, 73 received TH, and 64 were included. CMRO2 was measured at the NICU bedside by frequency-domain near-infrared and diffuse correlation spectroscopies (FDNIRS-DCS) during the late phases of hypothermia (C), rewarming (RW) and after return to normothermia (NT). Additional variables were body temperature and clinical neonatal encephalopathy (NE) scores, as well as findings from magnetic resonance imaging (MRI) and spectroscopy (MRS). Primary outcome was the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III) at 18 months, normed (SD) to 100 (15). FINDINGS Data quality for 58 neonates was sufficient for analysis. CMRO2 changed by 14.4% per °C (95% CI, 14.2-14.6) relative to its baseline at NT while cerebral tissue oxygen extraction fraction (cFTOE) changed by only 2.2% per °C (95% CI, 2.1-2.4) for net changes from C to NT of 91% and 8%, respectively. Follow-up data for 2 were incomplete, 33 declined and 1 died, leaving 22 participants (mean [SD] postnatal age, 19.1 [1.2] month; 11 female) with mild to moderate HIE (median [IQR] NE score, 4 [3-6]) and 21 (95%) with BSID-III scores >85 at 18 months. CMRO2 at NT was positively associated with cognitive and motor composite scores (β (SE) = 4.49 (1.55) and 2.77 (1.00) BSID-III points per 10-10 moL/dl × mm2/s, P = 0.009 and P = 0.01 respectively; linear regression); none of the other measures were associated with the neurodevelopmental outcomes. INTERPRETATION Point of care measures of CMRO2 in the NICU during C and RW showed dramatic changes and potential to assess individual response to TH. CMRO2 following TH outperformed conventional clinical evaluations (NE score, cFTOE, and MRI/MRS) at predicting cognitive and motor outcomes at 18 months for mild to moderate HIE, providing a promising objective, physiologically-based diagnostic for HIE. FUNDING This clinical study was funded by an NIH grant from the Eunice Kennedy Shriver National Institute of Child Health and Human Development, United States (R01HD076258).
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Affiliation(s)
- Jason Sutin
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA; Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA.
| | - Rutvi Vyas
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA; Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA
| | - Henry A Feldman
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA; Department of Pediatrics, Institutional Centers for Clinical and Translational Research, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA
| | - Silvina Ferradal
- Department of Intelligent Systems Engineering, Indiana University Bloomington, 107 S Indiana Ave., Bloomington, IN 47405, USA
| | - Chuan-Heng Hsiao
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA; Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA
| | - Lucca Zampolli
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA; Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA
| | - Lara J Pierce
- Department of Psychology, York University, 198 York Blvd., North York, ON M3J 2S5, Canada
| | - Charles A Nelson
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA; Division of Developmental Medicine, Department of Pediatrics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA
| | - Sarah U Morton
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA; Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA
| | - Susanne Hay
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA; Department of Neonatology, Beth Israel Deaconess Medical Center, 330 Brookline Ave., Boston, MA 02215, USA
| | - Mohamed El-Dib
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA; Division of Newborn Medicine, Department of Pediatrics, Brigham and Women's Hospital, 75 Francis St., Boston, MA 02115, USA
| | - Janet S Soul
- Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA; Department of Neurology, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA
| | - Pei-Yi Lin
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA; Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA
| | - Patricia E Grant
- Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA; Division of Newborn Medicine, Department of Pediatrics, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA; Harvard Medical School, 25 Shattuck St., Boston, MA 02115, USA; Department of Radiology, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02115, USA
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Scudellari A, Dudek P, Marino L, Badenes R, Bilotta F. Ventilation Targets for Patients Undergoing Mechanical Thrombectomy for Acute Ischemic Stroke: A Systematic Review. J Clin Med 2023; 12:4925. [PMID: 37568327 PMCID: PMC10420130 DOI: 10.3390/jcm12154925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 06/30/2023] [Accepted: 07/24/2023] [Indexed: 08/13/2023] Open
Abstract
Mechanical thrombectomy (MT) has become a standard treatment for acute ischemic stroke (AIS) caused by large vessel occlusion (LVO). Recent evidence suggests that general anesthesia (GA) and mechanical ventilation do not lead to inferior neurologic outcomes if compared to non-GA. However, the guidelines lack specific recommendations for ventilation targets during MT under GA. This systematic review aims to identify ventilation strategies correlating with better neurological outcomes in AIS patients undergoing MT, particularly focusing on oxygenation and carbon dioxide (CO2) targets. A systematic search of multiple databases was conducted to identify human studies reporting the correlation between ventilation strategies and neurological outcomes in MT for AIS. Eligible studies included clinical trials, observational studies, and case-control studies. Out of 157 studies assessed, 11 met the inclusion criteria. Five studies investigated oxygenation targets, while six studies explored CO2 targets. The published studies highlighted the controversial role of supplemental normobaric oxygen therapy and its potential association with worse outcomes. Regarding CO2 targets, the studies identified a potential association between end tidal CO2 levels and functional outcomes, with hypocapnia being unfavorable. This systematic review demonstrates that the current available evidence still lacks strength to suggest specific ventilation targets, but it highlights the potential risks of hyperoxia and hypocapnia in this specific cohort of patients.
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Affiliation(s)
| | - Paula Dudek
- 2nd Department of Anesthesiology and Intensive Care, Medical University of Warsaw, 02-097 Warsaw, Poland;
| | - Luca Marino
- Department of Mechanical and Aerospace Engineering, “Sapienza” University of Rome, 00184 Rome, Italy
| | - Rafael Badenes
- Department of Anesthesiology and Surgical-Trauma Intensive Care, Hospital Clínic Universitari de Valencia, University of Valencia, 46010 Valencia, Spain
| | - Federico Bilotta
- Department of Anesthesiology, Critical Care and Pain Medicine, Policlinico Umberto I, “Sapienza” University of Rome, 00185 Rome, Italy;
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Svedung Wettervik T, Fahlström M, Wikström J, Lewén A, Enblad P. Cerebrovascular reserve in moyamoya disease: relation to cerebral blood flow, capillary dysfunction, oxygenation, and energy metabolism. Front Neurol 2023; 14:1190309. [PMID: 37545732 PMCID: PMC10397391 DOI: 10.3389/fneur.2023.1190309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 07/04/2023] [Indexed: 08/08/2023] Open
Abstract
Background Cerebral hemodynamics in moyamoya disease (MMD) is complex and needs further elucidation. The primary aim of the study was to determine the association of the cerebrovascular reserve (CVR) with cerebral blood flow (CBF) disturbances, oxygen extraction fraction (OEFmax), and energy metabolism (CMRO 2 max ) in MMD, using arterial spin label magnetic resonance imaging (ASL-MRI) before and after acetazolamide administration. Methods Thirty-nine ASL-MRI scans with a concurrent acetazolamide challenge from 16 MMD patients at the Uppsala University Hospital, Sweden, 2016-2021, were retrospectively analyzed. CBF was assessed before and 5, 15, and 25 min after acetazolamide administration, and the maximal response CVRmax was used for further analyses. Dynamic susceptibility contrast (DSC) MRI was performed 30 min after acetazolamide injection, and the data were analyzed using the Cercare Medical Neurosuite to assess capillary transit time heterogeneity (CTTH; indicating microvascular function), OEFmax, and CMRO 2 max . Results In the ACA territory, a lower CVRmax was associated with lower baseline CBF, higher CTTH, and higher OEFmax but not with CMRO 2 max in generalized estimating equation models. In the MCA territory, lower CVRmax was associated with lower baseline CBF and higher CMRO 2 max but not with CTTH and OEFmax.. Conclusion Altogether, a compromised CVR in MMD patients reflected disturbances in macro-/microvascular blood flow, oxygenation, and CMRO2. ASL-MRI with acetazolamide challenge is a feasible and radiation-free alternative to positron emission tomography (PET) imaging in MMD.
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Affiliation(s)
| | - Markus Fahlström
- Department of Surgical Sciences, Section of Neuroradiology, Uppsala University, Uppsala, Sweden
| | - Johan Wikström
- Department of Surgical Sciences, Section of Neuroradiology, Uppsala University, Uppsala, Sweden
| | - Anders Lewén
- Department of Medical Sciences, Section of Neurosurgery, Uppsala University, Uppsala, Sweden
| | - Per Enblad
- Department of Medical Sciences, Section of Neurosurgery, Uppsala University, Uppsala, Sweden
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Chen DY, Di X, Biswal B. Cerebrovascular reactivity increases across development in multiple networks as revealed by a breath-holding task: a longitudinal fMRI study. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.05.522905. [PMID: 36712029 PMCID: PMC9881997 DOI: 10.1101/2023.01.05.522905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Functional magnetic resonance imaging (fMRI) has been widely used to understand the neurodevelopmental changes that occur in cognition and behavior across childhood. The blood-oxygen-level-dependent (BOLD) signal obtained from fMRI is understood to be comprised of both neuronal and vascular information. However, it is unclear whether the vascular response is altered across age in studies investigating development in children. Since the breath-hold task is commonly used to understand cerebrovascular reactivity in fMRI studies, it can be used to account for developmental differences in vascular response. This study examines how the cerebrovascular response changes over age in a longitudinal children's breath-hold dataset from the Nathan Kline Institute (NKI) Rockland Sample (ages 6 to 18 years old at enrollment). A general linear model (GLM) approach was applied to derive cerebrovascular reactivity from breath-hold data. To model both the longitudinal and cross-sectional effects of age on breath-hold response, we used mixed effects modeling with the following terms: linear, quadratic, logarithmic, and quadratic-logarithmic, to find the best-fitting model. We observed increased breath-hold BOLD signal in multiple networks across age, in which linear and logarithmic mixed effects models provided the best fit with the lowest Akaike Information Criterion (AIC) scores. This shows that the cerebrovascular response increases across development in a brain network-specific manner. Therefore, fMRI studies investigating the developmental period should account for cerebrovascular changes which occur with age.
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Affiliation(s)
- Donna Y. Chen
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, US
- Rutgers Biomedical and Health Sciences, Rutgers School of Graduate Studies, Newark, NJ, US
| | - Xin Di
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, US
| | - Bharat Biswal
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, US
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Bloomfield PM, Green H, Fisher JP, Gant N. Carbon dioxide protects simulated driving performance during severe hypoxia. Eur J Appl Physiol 2023; 123:1583-1593. [PMID: 36952086 PMCID: PMC10276124 DOI: 10.1007/s00421-023-05151-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 01/31/2023] [Indexed: 03/24/2023]
Abstract
PURPOSE We sought to determine the effect of acute severe hypoxia, with and without concurrent manipulation of carbon dioxide (CO2), on complex real-world psychomotor task performance. METHODS Twenty-one participants completed a 10-min simulated driving task while breathing room air (normoxia) or hypoxic air (PETO2 = 45 mmHg) under poikilocapnic, isocapnic, and hypercapnic conditions (PETCO2 = not manipulated, clamped at baseline, and clamped at baseline + 10 mmHg, respectively). Driving performance was assessed using a fixed-base motor vehicle simulator. Oxygenation in the frontal cortex was measured using functional near-infrared spectroscopy. RESULTS Speed limit exceedances were greater during the poikilocapnic than normoxic, hypercapnic, and isocapnic conditions (mean exceedances: 8, 4, 5, and 7, respectively; all p ≤ 0.05 vs poikilocapnic hypoxia). Vehicle speed was greater in the poikilocapnic than normoxic and hypercapnic conditions (mean difference: 0.35 km h-1 and 0.67 km h-1, respectively). All hypoxic conditions similarly decreased cerebral oxyhaemoglobin and increased deoxyhaemoglobin, compared to normoxic baseline, while total hemoglobin remained unchanged. CONCLUSIONS These findings demonstrate that supplemental CO2 can confer a neuroprotective effect by offsetting impairments in complex psychomotor task performance evoked by severe poikilocapnic hypoxia; however, differences in performance are unlikely to be linked to measurable differences in cerebral oxygenation.
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Affiliation(s)
- Peter Michael Bloomfield
- Exercise Neurometabolism Laboratory, University of Auckland, Building 907, 368 Khyber Pass Road, Newmarket, Auckland, 1023, New Zealand
| | - Hayden Green
- Exercise Neurometabolism Laboratory, University of Auckland, Building 907, 368 Khyber Pass Road, Newmarket, Auckland, 1023, New Zealand
| | - James P Fisher
- Department of Physiology, Faculty of Medical and Health Sciences, Manaaki Mānawa-The Centre for Heart Research, University of Auckland, Auckland, New Zealand
| | - Nicholas Gant
- Exercise Neurometabolism Laboratory, University of Auckland, Building 907, 368 Khyber Pass Road, Newmarket, Auckland, 1023, New Zealand.
- Centre for Brain Research, University of Auckland, Auckland, New Zealand.
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Kochar A, Hildebrandt K, Silverstein R, Appavu B. Approaches to neuroprotection in pediatric neurocritical care. World J Crit Care Med 2023; 12:116-129. [PMID: 37397588 PMCID: PMC10308339 DOI: 10.5492/wjccm.v12.i3.116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 03/30/2023] [Accepted: 04/12/2023] [Indexed: 06/08/2023] Open
Abstract
Acute neurologic injuries represent a common cause of morbidity and mortality in children presenting to the pediatric intensive care unit. After primary neurologic insults, there may be cerebral brain tissue that remains at risk of secondary insults, which can lead to worsening neurologic injury and unfavorable outcomes. A fundamental goal of pediatric neurocritical care is to mitigate the impact of secondary neurologic injury and improve neurologic outcomes for critically ill children. This review describes the physiologic framework by which strategies in pediatric neurocritical care are designed to reduce the impact of secondary brain injury and improve functional outcomes. Here, we present current and emerging strategies for optimizing neuroprotective strategies in critically ill children.
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Affiliation(s)
- Angad Kochar
- Department of Neurosciences, Phoenix Children's Hospital, Phoenix, AZ 85213, United States
| | - Kara Hildebrandt
- Department of Neurosciences, Phoenix Children's Hospital, Phoenix, AZ 85213, United States
| | - Rebecca Silverstein
- Department of Neurosciences, Phoenix Children's Hospital, Phoenix, AZ 85213, United States
| | - Brian Appavu
- Department of Neurosciences, Phoenix Children's Hospital, Phoenix, AZ 85213, United States
- Child Health, University of Arizona College of Medicine - Phoenix, Phoenix, AZ 85016, United States
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Gee JM, Wang X, Dogra S, Veraart J, Ishida K, Dehkharghani S. White Matter Cerebrovascular Reactivity: Effects of Microangiopathy and Proximal Occlusions on the Dynamic BOLD Response. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.05.29.23290700. [PMID: 37398412 PMCID: PMC10312885 DOI: 10.1101/2023.05.29.23290700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Introduction Cerebral microangiopathy often manifests as white matter hyperintensities (WMH) on T2-weighted MR images and is associated with elevated stroke risk. Large vessel steno-occlusive disease (SOD) is also independently associated with stroke risk, however, the interaction of microangiopathy and SOD is not well understood. Cerebrovascular reactivity (CVR) describes the capacity of cerebral circulation to adapt to changes in perfusion pressure and neurovascular demand, and its impairment portends future infarctions. CVR can be measured with blood oxygen level dependent (BOLD) imaging following acetazolamide stimulus (ACZ-BOLD). We studied CVR differences between WMH and normal-appearing white matter (NAWM) in patients with chronic SOD, hypothesizing additive influences upon CVR measured by novel, fully dynamic CVR maxima ( CVR max ). Methods A cross sectional study was conducted to measure per-voxel, per-TR maximal CVR ( CVR max ) using a custom computational pipeline in 23 subjects with angiographically-proven unilateral SOD. WMH and NAWM masks were applied to CVR max maps. White matter was subclassified with respect to the SOD-affected hemisphere, including: i. contralateral NAWM; ii. contralateral WMH iii. ipsilateral NAWM; iv. ipsilateral WMH. CVR max was compared between these groups with a Kruskal-Wallis test followed by a Dunn-Sidak post-hoc test for multiple comparisons. Results 19 subjects (age 50±12 years, 53% female) undergoing 25 examinations met criteria. WMH volume was asymmetric in 16/19 subjects with 13/16 exhibiting higher volumes ipsilateral to SOD. Pairwise comparisons of CVR max between groups was significant with ipsilateral WMH CVR max lower than contralateral NAWM (p=0.015) and contralateral WMH (p=0.003) when comparing in-subject medians and lower than all groups when comparing pooled voxelwise values across all subjects (p<0.0001). No significant relationship between WMH lesion size and CVR max was detected. Conclusion Our results suggest additive effects of microvascular and macrovascular disease upon white matter CVR, but with greater overall effects relating to macrovascular SOD than to apparent microangiopathy. Dynamic ACZ-BOLD presents a promising path towards a quantitative stroke risk imaging biomarker. BACKGROUND Cerebral white matter (WM) microangiopathy manifests as sporadic or sometimes confluent high intensity lesions in MR imaging with T2-weighting, and bears known associations with stroke, cognitive disability, depression and other neurological disorders 1-5 . Deep white matter is particularly susceptible to ischemic injury owing to the deprivation of collateral flow between penetrating arterial territories, and hence deep white matter hyperintensities (WMH) may portend future infarctions 6-8 . The pathophysiology of WMH is variable but commonly includes a cascade of microvascular lipohyalinosis and atherosclerosis together with impaired vascular endothelial and neurogliovascular integrity, leading to blood brain barrier dysfunction, interstitial fluid accumulation, and eventually tissue damage 9-14 . Independent of the microcirculation, cervical and intracranial large vessel steno-occlusive disease (SOD) often results from atheromatous disease and is associated with increased risk of stroke owing to thromboembolic phenomena, hypoperfusion, or combinations thereof 15-17 . White matter disease is more common in the affected hemisphere of patients with asymmetric or unilateral SOD, producing both macroscopic WMH detectable by routine structural MRI, as well as microstructural changes and altered structural connectivity detected by advanced diffusion microstructural imaging 18, 19 . An improved understanding of the interaction of microvascular disease (i.e., WMH) and macrovascular steno-occlusion could better inform stroke risk stratification and guide treatment strategies when coexistent. Cerebrovascular reactivity (CVR) is an autoregulatory adaptation characterized by the capacity of the cerebral circulation to respond to physiological or pharmacological vasodilatory stimuli 20-22 . CVR may be heterogeneous and varies across tissue type and pathological states 1, 16 . Alterations in CVR are associated with elevated stroke risk in SOD patients, although white matter CVR, and in particular the CVR profiles of WMH, are only sparsely studied and not fully understood 1, 23-26 . We have previously employed blood oxygen level dependent (BOLD) imaging following a hemodynamic stimulus with acetazolamide (ACZ) in order to measure CVR (i.e. ACZ-BOLD) 21, 27, 28 . Despite the emergence of ACZ-BOLD as a technique for clinical and experimental use, poor signal-to-noise characteristics of the BOLD effect have generally limited its interpretation to coarse, time-averaged assessment of the terminal ACZ response at arbitrarily prescribed delays following ACZ administration (e.g. 10-20 minutes) 29 . More recently, we have introduced a dedicated computational pipeline to overcome historically intractable signal-to-noise ratio (SNR) limitations of BOLD, enabling fully dynamic characterization of the cerebrovascular response, including identification of previously unreported, unsustained or transient CVR maxima ( CVR max ) following hemodynamic provocation 27, 30 . In this study, we compared such dynamic interrogation of true CVR maxima between WMH and normal appearing white matter (NAWM) among patients with chronic, unilateral SOD in order to quantify their interaction and to assess the hypothesized additive effects of angiographically-evident macrovascular stenoses when intersecting microangiopathic WMH.
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Svedung Wettervik T, Lewén A, Enblad P. Fine tuning of neurointensive care in aneurysmal subarachnoid hemorrhage: From one-size-fits-all towards individualized care. World Neurosurg X 2023; 18:100160. [PMID: 36818739 PMCID: PMC9932216 DOI: 10.1016/j.wnsx.2023.100160] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/20/2023] [Accepted: 01/22/2023] [Indexed: 01/25/2023] Open
Abstract
Aneurysmal subarachnoid hemorrhage (aSAH) is a severe type of acute brain injury with high mortality and burden of neurological sequelae. General management aims at early aneurysm occlusion to prevent re-bleeding, cerebrospinal fluid drainage in case of increased intracranial pressure and/or acute hydrocephalus, and cerebral blood flow augmentation in case of delayed ischemic neurological deficits. In addition, the brain is vulnerable to physiological insults in the acute phase and neurointensive care (NIC) is important to optimize the cerebral physiology to avoid secondary brain injury. NIC has led to significantly better neurological recovery following aSAH, but there is still great room for further improvements. First, current aSAH NIC management protocols are to some extent extrapolated from those in traumatic brain injury, notwithstanding important disease-specific differences. Second, the same NIC management protocols are applied to all aSAH patients, despite great patient heterogeneity. Third, the main variables of interest, intracranial pressure and cerebral perfusion pressure, may be too superficial to fully detect and treat several important pathomechanisms. Fourth, there is a lack of understanding not only regarding physiological, but also cellular and molecular pathomechanisms and there is a need to better monitor and treat these processes. This narrative review aims to discuss current state-of-the-art NIC of aSAH, knowledge gaps in the field, and future directions towards a more individualized care in the future.
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Affiliation(s)
- Teodor Svedung Wettervik
- Department of Medical Sciences, Section of Neurosurgery, Uppsala University, SE-751 85, Uppsala, Sweden
| | - Anders Lewén
- Department of Medical Sciences, Section of Neurosurgery, Uppsala University, SE-751 85, Uppsala, Sweden
| | - Per Enblad
- Department of Medical Sciences, Section of Neurosurgery, Uppsala University, SE-751 85, Uppsala, Sweden
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Vu C, Xu B, González-Zacarías C, Shen J, Baas KPA, Choi S, Nederveen AJ, Wood JC. Sinusoidal CO 2 respiratory challenge for concurrent perfusion and cerebrovascular reactivity MRI. Front Physiol 2023; 14:1102983. [PMID: 36846345 PMCID: PMC9948030 DOI: 10.3389/fphys.2023.1102983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 01/30/2023] [Indexed: 02/11/2023] Open
Abstract
Introduction: Deoxygenation-based dynamic susceptibility contrast (dDSC) has previously leveraged respiratory challenges to modulate blood oxygen content as an endogenous source of contrast alternative to gadolinium injection in perfusion-weighted MRI. This work proposed the use of sinusoidal modulation of end-tidal CO2 pressures (SineCO 2 ), which has previously been used to measure cerebrovascular reactivity, to induce susceptibility-weighted gradient-echo signal loss to measure brain perfusion. Methods: SineCO 2 was performed in 10 healthy volunteers (age 37 ± 11, 60% female), and tracer kinetics model was applied in the frequency domain to calculate cerebral blood flow, cerebral blood volume, mean transit time, and temporal delay. These perfusion estimates were compared against reference techniques, including gadolinium-based DSC, arterial spin labeling, and phase contrast. Results: Our results showed regional agreement between SineCO 2 and the clinical comparators. SineCO 2 was able to generate robust CVR maps in conjunction to baseline perfusion estimates. Discussion: Overall, this work demonstrated feasibility of using sinusoidal CO2 respiratory paradigm to simultaneously acquire both cerebral perfusion and cerebrovascular reactivity maps in one imaging sequence.
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Affiliation(s)
- Chau Vu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
- Division of Cardiology, Children’s Hospital Los Angeles, University of Southern California, Los Angeles, CA, United States
| | - Botian Xu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
- Division of Cardiology, Children’s Hospital Los Angeles, University of Southern California, Los Angeles, CA, United States
| | - Clio González-Zacarías
- Division of Cardiology, Children’s Hospital Los Angeles, University of Southern California, Los Angeles, CA, United States
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, United States
- Signal and Image Processing Institute, University of Southern California, Los Angeles, CA, United States
| | - Jian Shen
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
- Division of Cardiology, Children’s Hospital Los Angeles, University of Southern California, Los Angeles, CA, United States
| | - Koen P. A. Baas
- Department of Radiology and Nuclear Medicine, Amsterdam UMC, Location AMC, Amsterdam, Netherlands
| | - Soyoung Choi
- Division of Cardiology, Children’s Hospital Los Angeles, University of Southern California, Los Angeles, CA, United States
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, United States
- Signal and Image Processing Institute, University of Southern California, Los Angeles, CA, United States
| | - Aart J. Nederveen
- Department of Radiology and Nuclear Medicine, Amsterdam UMC, Location AMC, Amsterdam, Netherlands
| | - John C. Wood
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, United States
- Division of Cardiology, Children’s Hospital Los Angeles, University of Southern California, Los Angeles, CA, United States
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Reeder EL, O'Connell CJ, Collins SM, Traubert OD, Norman SV, Cáceres RA, Sah R, Smith DW, Robson MJ. Increased Carbon Dioxide Respiration Prevents the Effects of Acceleration/Deceleration Elicited Mild Traumatic Brain Injury. Neuroscience 2023; 509:20-35. [PMID: 36332692 DOI: 10.1016/j.neuroscience.2022.10.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/30/2022] [Accepted: 10/17/2022] [Indexed: 11/07/2022]
Abstract
Acceleration/deceleration forces are a common component of various causes of mild traumatic brain injury (mTBI) and result in strain and shear forces on brain tissue. A small quantifiable volume dubbed the compensatory reserve volume (CRV) permits energy transmission to brain tissue during acceleration/deceleration events. The CRV is principally regulated by cerebral blood flow (CBF) and CBF is primarily determined by the concentration of inspired carbon dioxide (CO2). We hypothesized that experimental hypercapnia (i.e. increased inspired concentration of CO2) may act to prevent and mitigate the actions of acceleration/deceleration-induced TBI. To determine these effects C57Bl/6 mice underwent experimental hypercapnia whereby they were exposed to medical-grade atmospheric air or 5% CO2 immediately prior to an acceleration/deceleration-induced mTBI paradigm. mTBI results in significant increases in righting reflex time (RRT), reductions in core body temperature, and reductions in general locomotor activity-three hours post injury (hpi). Experimental hypercapnia immediately preceding mTBI was found to prevent mTBI-induced increases in RRT and reductions in core body temperature and general locomotor activity. Ribonucleic acid (RNA) sequencing conducted four hpi revealed that CO2 exposure prevented mTBI-induced transcriptional alterations of several targets related to oxidative stress, immune, and inflammatory signaling. Quantitative real-time PCR analysis confirmed the prevention of mTBI-induced increases in mitogen-activated protein kinase kinase kinase 6 and metallothionein-2. These initial proof of concept studies reveal that increases in inspired CO2 mitigate the detrimental contributions of acceleration/deceleration events in mTBI and may feasibly be translated in the future to humans using a medical device seeking to prevent mTBI among high-risk groups.
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Affiliation(s)
- Evan L Reeder
- University of Cincinnati James L. Winkle College of Pharmacy, Division of Pharmaceutical Sciences, Cincinnati, OH 45267, USA
| | - Christopher J O'Connell
- University of Cincinnati James L. Winkle College of Pharmacy, Division of Pharmaceutical Sciences, Cincinnati, OH 45267, USA
| | - Sean M Collins
- University of Cincinnati James L. Winkle College of Pharmacy, Division of Pharmaceutical Sciences, Cincinnati, OH 45267, USA
| | - Owen D Traubert
- University of Cincinnati College of Arts and Sciences, Department of Biological Sciences, Cincinnati, OH 45221, USA
| | - Sophia V Norman
- University of Cincinnati College of Arts and Sciences, Department of Biological Sciences, Cincinnati, OH 45221, USA
| | - Román A Cáceres
- University of Cincinnati College of Medicine, Department of Cancer and Cell Biology Cincinnati, OH 45267, USA
| | - Renu Sah
- University of Cincinnati College of Medicine, Department of Pharmacology and Systems Physiology, Cincinnati, OH 45267, USA
| | | | - Matthew J Robson
- University of Cincinnati James L. Winkle College of Pharmacy, Division of Pharmaceutical Sciences, Cincinnati, OH 45267, USA.
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