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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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2
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Highton D, Caldwell M, Tachtsidis I, Elwell CE, Smith M, Cooper CE. The influence of carbon dioxide on cerebral metabolism and oxygen consumption: combining multimodal monitoring with dynamic systems modelling. Biol Open 2024; 13:bio060087. [PMID: 38180242 PMCID: PMC10810564 DOI: 10.1242/bio.060087] [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: 07/24/2023] [Accepted: 11/22/2023] [Indexed: 01/06/2024] Open
Abstract
Hypercapnia increases cerebral blood flow. The effects on cerebral metabolism remain incompletely understood although studies show an oxidation of cytochrome c oxidase, Complex IV of the mitochondrial respiratory chain. Systems modelling was combined with previously published non-invasive measurements of cerebral tissue oxygenation, cerebral blood flow, and cytochrome c oxidase redox state to evaluate any metabolic effects of hypercapnia. Cerebral tissue oxygen saturation and cytochrome oxidase redox state were measured with broadband near infrared spectroscopy and cerebral blood flow velocity with transcranial Doppler ultrasound. Data collected during 5-min hypercapnia in awake human volunteers were analysed using a Fick model to determine changes in brain oxygen consumption and a mathematical model of cerebral hemodynamics and metabolism (BrainSignals) to inform on mechanisms. Either a decrease in metabolic substrate supply or an increase in metabolic demand modelled the cytochrome oxidation in hypercapnia. However, only the decrease in substrate supply explained both the enzyme redox state changes and the Fick-calculated drop in brain oxygen consumption. These modelled outputs are consistent with previous reports of CO2 inhibition of mitochondrial succinate dehydrogenase and isocitrate dehydrogenase. Hypercapnia may have physiologically significant effects suppressing oxidative metabolism in humans and perturbing mitochondrial signalling pathways in health and disease.
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Affiliation(s)
- David Highton
- Neurocritical Care Unit, University College London Hospitals, National Hospital for Neurology & Neurosurgery, London WC1N 3BG, UK
- Princess Alexandra Hospital Southside Clinical Unit, University of Queensland, Brisbane QLD 4102, Australia
| | - Matthew Caldwell
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
| | - Ilias Tachtsidis
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
| | - Clare E. Elwell
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
| | - Martin Smith
- Neurocritical Care Unit, University College London Hospitals, National Hospital for Neurology & Neurosurgery, London WC1N 3BG, UK
- Department of Medical Physics and Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, UK
| | - Chris E. Cooper
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
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3
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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: 0] [Impact Index Per Article: 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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Gangaram-Panday NH, van Essen T, van Weteringen W, Dremmen MHG, Goos TG, de Jonge RCJ, Reiss IKM. Transcutaneous carbon dioxide monitoring during therapeutic hypothermia for neonatal encephalopathy. Pediatr Res 2022; 92:1724-1730. [PMID: 35352004 DOI: 10.1038/s41390-022-02035-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 03/07/2022] [Accepted: 03/11/2022] [Indexed: 12/30/2022]
Abstract
BACKGROUND In neonates with post-asphyxial neonatal encephalopathy, further neuronal damage is prevented with therapeutic hypothermia (TH). In addition, fluctuations in carbon dioxide levels have been associated with poor neurodevelopmental outcome, demanding close monitoring. This study investigated the accuracy and clinical value of transcutaneous carbon dioxide (tcPCO2) monitoring during TH. METHODS In this retrospective cohort study in neonates, agreement between arterial carbon dioxide (PaCO2) values and tcPCO2 measurements during TH was determined. TcPCO2 levels during the first 24 h of hypothermia were tested for an association with ischemic brain injury on magnetic resonance imaging (MRI). RESULTS Thirty-four neonates were included. Agreement (bias (95% limits of agreement)) between tcPCO2 and PaCO2 levels was 3.9 (-12.4-20.2) mm Hg. No relation was found between the body temperature and tcPCO2 levels. TcPCO2 levels differed significantly between patients with considerable and minimal damage on MRI; after 6 h (P = 0.02) and 9 h (P = 0.04). CONCLUSIONS Although tcPCO2 provided a limited estimation of PaCO2, it can be used for trend monitoring during TH. TcPCO2 levels after birth could provide an early indicator of ischemic brain injury. This relation should be investigated in large prospective studies, in which adjustments for confounders can be made. IMPACT Transcutaneous carbon dioxide measurements during therapeutic hypothermia in neonates show limited accuracy similar to measurements reported in normothermic neonates and can be used for trend monitoring. Low transcutaneous carbon dioxide levels during the first 24 h were associated with considerable ischemic brain injury on MRI. The value of transcutaneous carbon dioxide measurements during the first 24 h as an indicator of considerable ischemic brain injury on MRI should be investigated in future studies, adjusting for confounders. Transcutaneous oxygen measurements during therapeutic hypothermia showed an inaccuracy that could not be related to a low body temperature.
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Affiliation(s)
- Norani H Gangaram-Panday
- Department of Pediatrics, Division of Neonatology, Erasmus MC Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands.
| | - Tanja van Essen
- Department of Pediatrics, Division of Neonatology, Erasmus MC Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Willem van Weteringen
- Department of Pediatrics, Division of Neonatology, Erasmus MC Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands.,Department of Pediatric Surgery, Erasmus MC Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Marjolein H G Dremmen
- Department of Radiology and Nuclear Medicine, Erasmus MC Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Tom G Goos
- Department of Pediatrics, Division of Neonatology, Erasmus MC Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands.,Department of Biomechanical Engineering, Faculty of Mechanical Engineering, Delft University of Technology, Delft, The Netherlands
| | - Rogier C J de Jonge
- Pediatric Intensive Care Unit, Departments of Pediatrics and Pediatric Surgery, Erasmus MC Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Irwin K M Reiss
- Department of Pediatrics, Division of Neonatology, Erasmus MC Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Wijdicks EFM. Corroborating the Monro-Kellie Principles. Neurocrit Care 2022:10.1007/s12028-022-01624-x. [PMID: 36316567 DOI: 10.1007/s12028-022-01624-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 09/30/2022] [Indexed: 06/16/2023]
Affiliation(s)
- Eelco F M Wijdicks
- Neurocritical Care Services, Saint Marys Hospital, Mayo Clinic, Rochester, MN, USA.
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6
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Cunningham NR, Nahman-Averbuch H, Lee GR, King CD, Coghill RC. Amygdalar functional connectivity during resting and evoked pain in youth with functional abdominal pain disorders. Pain 2022; 163:2031-2043. [PMID: 35472070 PMCID: PMC9329503 DOI: 10.1097/j.pain.0000000000002601] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 12/17/2021] [Indexed: 02/04/2023]
Abstract
ABSTRACT Pediatric functional abdominal pain disorders (FAPD) are highly prevalent, difficult to diagnose, and challenging to treat. The brain systems supporting FAPD remain poorly understood. This investigation examined the neuromechanisms of FAPD during a well-tolerated visceral pain induction task, the water load symptom provocation task (WL-SPT). Youth between the ages of 11 and 17 years participated. Functional connectivity (FC) was examined through the blood oxygenation level-dependent effect using the left and right amygdala (AMY) as seed regions. Relationships of the time courses within these seeds with voxels across the whole brain were evaluated. Arterial spin labeling was used to assess regional brain activation by examining cerebral blood flow. Increased FC between the left AMY with regions associated with nociceptive processing (eg, thalamus) and right AMY FC changes with areas associated with cognitive functioning (dorsolateral prefrontal cortex) and the default mode network (DMN; parietal lobe) were observed in youth with FAPD after the WL-SPT. These changes were related to changes in pain unpleasantness. Amygdala FC changes post-WL-SPT were also related to changes in pain intensity. Amygdala FC with the DMN in youth with FAPD also differed from healthy controls. Global cerebral blood flow changes were also noted between FAPD and healthy controls, but no significant differences in grey matter were detected either between groups or during the WL-SPT in youth with FAPD. Findings confirm youth with FAPD undergo changes in brain systems that could support the development of biomarkers to enhance understanding of the mechanisms of pain and treatment response.
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Affiliation(s)
- Natoshia R Cunningham
- Department of Family Medicine, Michigan State University, Grand Rapids, MI, United States
| | - Hadas Nahman-Averbuch
- Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
- Pediatric Pain Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
- Department of Anesthesiology, Washington University Pain Center and Division of Clinical and Translational Research, Washington University in St Louis School of Medicine, St Louis, MO, United States
| | - Gregory R Lee
- Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
- Department of Radiology, University of Cincinnati, Cincinnati, OH, United States
| | - Christopher D King
- Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
- Pediatric Pain Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Robert C Coghill
- Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
- Pediatric Pain Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
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7
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Yang J, Jing J, Chen S, Liu X, Tang Y, Pan C, Tang Z. Changes in Cerebral Blood Flow and Diffusion-Weighted Imaging Lesions After Intracerebral Hemorrhage. Transl Stroke Res 2022; 13:686-706. [PMID: 35305264 DOI: 10.1007/s12975-022-00998-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 11/25/2022]
Abstract
Intracerebral hemorrhage (ICH) is a common subtype of stroke and places a great burden on the family and society with a high mortality and disability rate and a poor prognosis. Many findings from imaging and pathologic studies have suggested that cerebral ischemic lesions visualized on diffusion-weighted imaging (DWI) in patients with ICH are not rare and are generally considered to be associated with poor outcome, increased risk of recurrent (ischemic and hemorrhagic) stroke, cognitive impairment, and death. In this review, we describe the changes in cerebral blood flow (CBF) and DWI lesions after ICH and discuss the risk factors and possible mechanisms related to the occurrence of DWI lesions, such as cerebral microangiopathy, cerebral atherosclerosis, aggressive early blood pressure lowering, hyperglycemia, and inflammatory response. We also point out that a better understanding of cerebral DWI lesions will be a key step toward potential therapeutic interventions to improve long-term recovery for patients with ICH.
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Affiliation(s)
- Jingfei Yang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, 430030, NO, China
| | - Jie Jing
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, 430030, NO, China
| | - Shiling Chen
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, 430030, NO, China
| | - Xia Liu
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, 430030, NO, China
| | - Yingxin Tang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, 430030, NO, China
| | - Chao Pan
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, 430030, NO, China.
| | - Zhouping Tang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan, 430030, NO, China.
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Miao Z, Wang H, Cai Z, Lei J, Wan X, Li Y, Wang J, Zhao K, Niu H, Lei T. Spontaneous Hyperventilation Is Common in Patients with Spontaneous Cerebellar Hemorrhage, and Its Severity Is Associated with Outcome. J Clin Med 2022; 11:jcm11195564. [PMID: 36233445 PMCID: PMC9572038 DOI: 10.3390/jcm11195564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 09/17/2022] [Accepted: 09/19/2022] [Indexed: 11/16/2022] Open
Abstract
Background: The spontaneous hyperventilation (SHV) accompanying spontaneous cerebellar hemorrhage has yet to attract a sufficient amount of attention. This study aimed to analyze the incidence of SHV in spontaneous cerebellar hemorrhage patients and its risk factors as well as its association with the outcome. Methods: We retrospectively reviewed the medical records of all spontaneous cerebellar hemorrhage patients who underwent surgical treatment at Tongji Hospital from July 2018 to December 2020. Arterial blood gas (ABG) test results and clinical characteristics, including demographics, comorbidities, imaging features, laboratory tests, and therapy choices, were collected. The Glasgow Outcome Scale was used to assess the outcome at two weeks and six months after admission. Results: A total of 147 patients were included, and of these patients 44.9% had spontaneous hyperventilation. Hypertension (OR, 3.175; CI, 1.332–7.569), usage of sedation drugs (OR, 3.693; CI, 1.0563–8.724), and hypernatremia (OR, 2.803; CI, 1.070–7.340) seemed to positively correlate to SHV occurrence. Hematoma removal had an inverse association with SHV (OR, 0.176; CI, 0.068–0.460). Patients with poor and good outcomes had significant differences in pH, PaCO2, and HCO3− values, and the severity of SHV was associated with the PaCO2 level. Conclusions: Spontaneous hyperventilation is common in patients with spontaneous cerebellar hemorrhage, and its severity is associated with the outcome.
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Affiliation(s)
- Zhuangzhuang Miao
- Department of Neurosurgery, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science & Technology, Wuhan 430030, China
| | - Huajian Wang
- Department of Neurosurgery, Wuhan Fourth Hospital, Puai Hospital, Wuhan 430030, China
| | - Zhi Cai
- Department of Neurosurgery, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science & Technology, Wuhan 430030, China
| | - Jin Lei
- Department of Neurosurgery, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science & Technology, Wuhan 430030, China
| | - Xueyan Wan
- Department of Neurosurgery, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science & Technology, Wuhan 430030, China
| | - Yu Li
- Department of Neurosurgery, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science & Technology, Wuhan 430030, China
| | - Junwen Wang
- Department of Neurosurgery, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science & Technology, Wuhan 430030, China
| | - Kai Zhao
- Department of Neurosurgery, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science & Technology, Wuhan 430030, China
- Correspondence: (K.Z.); (H.N.)
| | - Hongquan Niu
- Department of Neurosurgery, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science & Technology, Wuhan 430030, China
- Correspondence: (K.Z.); (H.N.)
| | - Ting Lei
- Department of Neurosurgery, Tongji Hospital Affiliated to Tongji Medical College of Huazhong University of Science & Technology, Wuhan 430030, China
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Karalapillai D, Weinberg L, Neto AS, Peyton PJ, Ellard L, Hu R, Pearce B, Tan C, Story D, O'Donnell M, Hamilton P, Oughton C, Galtieri J, Appu S, Wilson A, Eastwood G, Bellomo R, Jones DA. Intraoperative low tidal volume ventilation and the risk of ICD-10 coded delirium and the use for antipsychotic medications. BMC Anesthesiol 2022; 22:149. [PMID: 35578170 PMCID: PMC9109306 DOI: 10.1186/s12871-022-01689-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 05/05/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Low tidal volume (VT) ventilation and its associated increase in arterial carbon dioxide (PaCO2) may affect postoperative neurologic function. We aimed to test the hypothesis that intraoperative low VT ventilation affect the incidence of postoperative ICD-10 coded delirium and/or the need for antipsychotic medications. METHODS This is a post-hoc analysis of a large randomized controlled trial evaluating low vs. conventional VT ventilation during major non-cardiothoracic, non-intracranial surgery. The primary outcome was the incidence of ICD-10 delirium and/or the use of antipsychotic medications during hospital stay, and the absolute difference with its 95% confidence interval (CI) was calculated. RESULTS We studied 1206 patients (median age of 64 [55-72] years, 59.0% males, median ARISCAT of 26 [19-37], and 47.6% of ASA 3). ICD-10 coded delirium and /or antipsychotic medication use was diagnosed in 11.2% with similar incidence between low and conventional VT ventilation (11.1% vs. 11.3%; absolute difference, -0.24 [95%CI, -3.82 to 3.32]; p = 0.894). There was no interaction between allocation group and type of surgery. CONCLUSION In adult patients undergoing major surgery, low VT ventilation was not associated with increased risk of ICD-10 delirium and/or the use of antipsychotic medications during hospital stay. TRIAL REGISTRATION ANZCTR Identifier: ACTRN12614000790640 .
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Affiliation(s)
- Dharshi Karalapillai
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia.
- Department of Intensive Care, Austin Hospital, Melbourne, VIC, Australia.
- Department of Critical Care, The University of Melbourne, Melbourne, VIC, Australia.
| | - Laurence Weinberg
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia
- Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - Ary Serpa Neto
- Department of Intensive Care, Austin Hospital, Melbourne, VIC, Australia
- Department of Critical Care, The University of Melbourne, Melbourne, VIC, Australia
- Australian and New Zealand Intensive Care Research Centre, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia
- Data Analytics Research and Evaluation (DARE) Centre, University of Melbourne, Melbourne, VIC, Australia
- Department of Critical Care Medicine, Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - Philip J Peyton
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia
- Department of Critical Care, The University of Melbourne, Melbourne, VIC, Australia
| | - Louise Ellard
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia
- Department of Critical Care, The University of Melbourne, Melbourne, VIC, Australia
- Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - Raymond Hu
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia
- Department of Critical Care, The University of Melbourne, Melbourne, VIC, Australia
- Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - Brett Pearce
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia
- Department of Critical Care, The University of Melbourne, Melbourne, VIC, Australia
- Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - Chong Tan
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia
- Department of Critical Care, The University of Melbourne, Melbourne, VIC, Australia
- Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
| | - David Story
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia
- Department of Critical Care, The University of Melbourne, Melbourne, VIC, Australia
| | - Mark O'Donnell
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia
| | - Patrick Hamilton
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia
| | - Chad Oughton
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia
| | - Jonathan Galtieri
- Department of Anaesthesia, Austin Hospital, Melbourne, VIC, Australia
| | - Sree Appu
- Department of Surgery, Austin Hospital, Melbourne, VIC, Australia
| | - Anthony Wilson
- Department of Intensive Care, Austin Hospital, Melbourne, VIC, Australia
| | - Glenn Eastwood
- Department of Intensive Care, Austin Hospital, Melbourne, VIC, Australia
| | - Rinaldo Bellomo
- Department of Intensive Care, Austin Hospital, Melbourne, VIC, Australia
- Department of Critical Care, The University of Melbourne, Melbourne, VIC, Australia
- Australian and New Zealand Intensive Care Research Centre, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia
- Data Analytics Research and Evaluation (DARE) Centre, University of Melbourne, Melbourne, VIC, Australia
| | - Daryl A Jones
- Department of Intensive Care, Austin Hospital, Melbourne, VIC, Australia
- Department of Surgery, University of Melbourne, Melbourne, VIC, Australia
- Australian and New Zealand Intensive Care Research Centre, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia
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10
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Petran J, Ansems K, Rossaint R, Marx G, Kalvelage C, Kopp R, Benstoem C, Brülls C. Effects of hypercapnia versus normocapnia during general anesthesia on outcomes: a systematic review and meta-analysis. BRAZILIAN JOURNAL OF ANESTHESIOLOGY (ELSEVIER) 2022; 72:398-406. [PMID: 35644204 PMCID: PMC9373272 DOI: 10.1016/j.bjane.2020.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/24/2020] [Accepted: 11/29/2020] [Indexed: 11/25/2022]
Abstract
BACKGROUND The effect of mild changes in CO2 levels to organ perfusion and tissue inflammation are well known, whereas an influence of hypercapnia under general anesthesia on adverse events as nausea and vomiting, or length of hospital stay is barely examined. The goal of our meta-analysis was to identify possibly positive effects of hypercapnia versus normocapnia in general anesthesia in adult patients. METHODS We conducted a systematic review of parallel-arm randomised controlled trials comparing hypercapnia versus normocapnia in adult patients undergoing general anesthesia. In July 2018 and September 2019 we searched "CENTRAL‿, "MEDLINE‿, and "Embase‿, checked reference lists of all included studies and relevant systematic reviews for additional references to trials. Two review authors independently assessed trials for inclusion, extracted data, and completed a "Risk of bias‿ assessment for all included studies. RESULTS Our search identified 297 records after abstract screening 30 full-text papers remained for further examination. Ten publications met our inclusion criteria and were used for narrative description of this systematic review. Three studies were eligible for the meta-analysis normocapnia versus hypercapnia with the outcomes: time to extubation and adverse events. On average, time to extubation was significantly reduced in the hypercapnia group with a mean difference 3.78 (95% CI 0.85 to 6.71). No difference was found regarding adverse events. CONCLUSIONS The findings of our study do not enable us to produce evidence of a positive influence of increased CO2 partial pressure levels during general anesthesia. A well-planned, adequately powered randomized controlled trial would be desirable in the future.
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Affiliation(s)
- Jan Petran
- RWTH Aachen University, Medical Faculty, Department of Anaesthesiology, Aachen, Germany; RWTH Aachen University, Medical Faculty, Department of Intensive Care Medicine and Intermediate Care, Aachen, Germany.
| | - Kelly Ansems
- RWTH Aachen University, Medical Faculty, Department of Intensive Care Medicine and Intermediate Care, Aachen, Germany
| | - Rolf Rossaint
- RWTH Aachen University, Medical Faculty, Department of Anaesthesiology, Aachen, Germany
| | - Gernot Marx
- RWTH Aachen University, Medical Faculty, Department of Intensive Care Medicine and Intermediate Care, Aachen, Germany
| | - Christina Kalvelage
- RWTH Aachen University, Medical Faculty, Department of Intensive Care Medicine and Intermediate Care, Aachen, Germany
| | - Rüdger Kopp
- RWTH Aachen University, Medical Faculty, Department of Intensive Care Medicine and Intermediate Care, Aachen, Germany
| | - Carina Benstoem
- RWTH Aachen University, Medical Faculty, Department of Intensive Care Medicine and Intermediate Care, Aachen, Germany
| | - Christian Brülls
- RWTH Aachen University, Medical Faculty, Department of Anaesthesiology, Aachen, Germany
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11
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Caldwell HG, Hoiland RL, Smith KJ, Brassard P, Bain AR, Tymko MM, Howe CA, Carr JMJR, Stacey BS, Bailey DM, Drapeau A, Sekhon MS, MacLeod DB, Ainslie PN. Trans-cerebral HCO 3- and PCO 2 exchange during acute respiratory acidosis and exercise-induced metabolic acidosis in humans. J Cereb Blood Flow Metab 2022; 42:559-571. [PMID: 34904461 PMCID: PMC8943603 DOI: 10.1177/0271678x211065924] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/03/2021] [Accepted: 11/11/2021] [Indexed: 01/06/2023]
Abstract
This study investigated trans-cerebral internal jugular venous-arterial bicarbonate ([HCO3-]) and carbon dioxide tension (PCO2) exchange utilizing two separate interventions to induce acidosis: 1) acute respiratory acidosis via elevations in arterial PCO2 (PaCO2) (n = 39); and 2) metabolic acidosis via incremental cycling exercise to exhaustion (n = 24). During respiratory acidosis, arterial [HCO3-] increased by 0.15 ± 0.05 mmol ⋅ l-1 per mmHg elevation in PaCO2 across a wide physiological range (35 to 60 mmHg PaCO2; P < 0.001). The narrowing of the venous-arterial [HCO3-] and PCO2 differences with respiratory acidosis were both related to the hypercapnia-induced elevations in cerebral blood flow (CBF) (both P < 0.001; subset n = 27); thus, trans-cerebral [HCO3-] exchange (CBF × venous-arterial [HCO3-] difference) was reduced indicating a shift from net release toward net uptake of [HCO3-] (P = 0.004). Arterial [HCO3-] was reduced by -0.48 ± 0.15 mmol ⋅ l-1 per nmol ⋅ l-1 increase in arterial [H+] with exercise-induced acidosis (P < 0.001). There was no relationship between the venous-arterial [HCO3-] difference and arterial [H+] with exercise-induced acidosis or CBF; therefore, trans-cerebral [HCO3-] exchange was unaltered throughout exercise when indexed against arterial [H+] or pH (P = 0.933 and P = 0.896, respectively). These results indicate that increases and decreases in systemic [HCO3-] - during acute respiratory/exercise-induced metabolic acidosis, respectively - differentially affect cerebrovascular acid-base balance (via trans-cerebral [HCO3-] exchange).
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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, BC, Canada
| | - Ryan L Hoiland
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Kurt J Smith
- Department of Exercise Science, Physical and Health Education, Faculty of Education, University of Victoria, Victoria, British Columbia, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada
| | - Anthony R Bain
- Faculty of Human Kinetics, Department of Kinesiology, University of Windsor, Windsor, ON, Canada
| | - Michael M Tymko
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Jay MJR Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, 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
| | - Audrey Drapeau
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada
| | - Mypinder S Sekhon
- Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
| | - David B MacLeod
- Human Pharmacology and Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
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12
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Hoffman GM, Scott JP, Stuth EA. Effects of Arterial Carbon Dioxide Tension on Cerebral and Somatic Regional Tissue Oxygenation and Blood Flow in Neonates After the Norwood Procedure With Deep Hypothermic Cardiopulmonary Bypass. Front Pediatr 2022; 10:762739. [PMID: 35223690 PMCID: PMC8873518 DOI: 10.3389/fped.2022.762739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 01/04/2022] [Indexed: 11/13/2022] Open
Abstract
Neonates undergoing the Norwood procedure for hypoplastic left heart syndrome are at higher risk of impaired systemic oxygen delivery with resultant brain, kidney, and intestinal ischemic injury, shock, and death. Complex developmental, anatomic, and treatment-related influences on cerebral and renal-somatic circulations make individualized treatment strategies physiologically attractive. Monitoring cerebral and renal circulations with near infrared spectroscopy can help drive rational therapeutic interventions. The primary aim of this study was to describe the differential effects of carbon dioxide tension on cerebral and renal circulations in neonates after the Norwood procedure. Using a prospectively-maintained database of postoperative physiologic and hemodynamic parameters, we analyzed the relationship between postoperative arterial carbon dioxide tension and tissue oxygen saturation and arteriovenous saturation difference in cerebral and renal regions, applying univariate and multivariate multilevel mixed regression techniques. Results were available from 7,644 h of data in 178 patients. Increases in arterial carbon dioxide tension were associated with increased cerebral and decreased renal oxygen saturation. Differential changes in arteriovenous saturation difference explained these effects. The cerebral circulation showed more carbon dioxide sensitivity in the early postoperative period, while sensitivity in the renal circulation increased over time. Multivariate models supported the univariate findings and defined complex time-dependent interactions presented graphically. The cerebral and renal circulations may compete for blood flow with critical limitations of cardiac output. The cerebral and renal-somatic beds have different circulatory control mechanisms that can be manipulated to change the distribution of cardiac output by altering the arterial carbon dioxide tension. Monitoring cerebral and renal circulations with near infrared spectroscopy can provide rational physiologic targets for individualized treatment.
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Affiliation(s)
- George M. Hoffman
- Division of Pediatric Cardiac Anesthesia, Children's Hospital of Wisconsin Herma Heart Institute, Milwaukee, WI, United States
- Division of Pediatric Cardiac Critical Care, Children's Hospital of Wisconsin Herma Heart Institute, Milwaukee, WI, United States
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
| | - John P. Scott
- Division of Pediatric Cardiac Anesthesia, Children's Hospital of Wisconsin Herma Heart Institute, Milwaukee, WI, United States
- Division of Pediatric Cardiac Critical Care, Children's Hospital of Wisconsin Herma Heart Institute, Milwaukee, WI, United States
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Eckehard A. Stuth
- Division of Pediatric Cardiac Anesthesia, Children's Hospital of Wisconsin Herma Heart Institute, Milwaukee, WI, United States
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI, United States
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13
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Powers WJ, An H, Diringer MN. Cerebral Blood Flow and Metabolism. Stroke 2022. [DOI: 10.1016/b978-0-323-69424-7.00003-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Katagiri A, Kitadai Y, Miura A, Fukuba Y, Fujii N, Nishiyasu T, Tsuji B. Sodium bicarbonate ingestion mitigates the heat-induced hyperventilation and reduction in cerebral blood velocity during exercise in the heat. J Appl Physiol (1985) 2021; 131:1617-1628. [PMID: 34590911 DOI: 10.1152/japplphysiol.00261.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hyperthermia during exercise in the heat causes minute ventilation ([Formula: see text]) to increase, which leads to reductions in arterial CO2 partial pressure ([Formula: see text]) and cerebral blood flow. On the other hand, sodium bicarbonate ingestion reportedly results in metabolic alkalosis, leading to decreased [Formula: see text] and increased [Formula: see text] during prolonged exercise in a thermoneutral environment. Here, we investigated whether sodium bicarbonate ingestion suppresses heat-induced hyperventilation and the resultant hypocapnia and cerebral hypoperfusion during prolonged exercise in the heat. Eleven healthy men ingested a solution of sodium bicarbonate (0.3 g/kg body wt) (NaHCO3 trial) or sodium chloride (0.208 g/kg) (NaCl trial). Ninety minutes after the ingestion, the subjects performed a cycle exercise for 60 min at 50% of peak oxygen uptake in the heat (35°C and 40% relative humidity). Esophageal temperature did not differ between the trials throughout (P = 0.56, main effect of trial). [Formula: see text] gradually increased with exercise duration in the NaCl trial, but the increases in [Formula: see text] were attenuated in the NaHCO3 trial (P = 0.01, main effect of trial). Correspondingly, estimated [Formula: see text] and middle cerebral artery blood velocity (an index of anterior cerebral blood flow) were higher in the NaHCO3 than the NaCl trial (P = 0.002 and 0.04, main effects of trial). Ratings of perceived exertion were lower in the NaHCO3 than the NaCl trial (P = 0.02, main effect of trial). These results indicate that sodium bicarbonate ingestion mitigates heat-induced hyperventilation and reductions in [Formula: see text] and cerebral blood velocity during prolonged exercise in the heat.NEW & NOTEWORTHY Hyperthermia causes hyperventilation and concomitant hypocapnia and cerebral hypoperfusion. The cerebral hypoperfusion may underlie central fatigue. We demonstrate that sodium bicarbonate ingestion reduces heat-induced hyperventilation and attenuates hypocapnia-related cerebral hypoperfusion during prolonged exercise in the heat. In addition, we show that sodium bicarbonate ingestion reduces ratings of perceived exertion during the exercise. This study provides new insight into the development of effective strategies for preventing central fatigue during exercise in the heat.
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Affiliation(s)
- Akira Katagiri
- Department of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan.,Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Yasuhiko Kitadai
- Department of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Akira Miura
- Department of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Yoshiyuki Fukuba
- Department of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan
| | - Bun Tsuji
- Department of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
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15
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Caldwell HG, Carr JMJR, Minhas JS, Swenson ER, Ainslie PN. Acid-base balance and cerebrovascular regulation. J Physiol 2021; 599:5337-5359. [PMID: 34705265 DOI: 10.1113/jp281517] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 10/19/2021] [Indexed: 12/22/2022] Open
Abstract
The regulation and defence of intracellular pH is essential for homeostasis. Indeed, alterations in cerebrovascular acid-base balance directly affect cerebral blood flow (CBF) which has implications for human health and disease. For example, changes in CBF regulation during acid-base disturbances are evident in conditions such as chronic obstructive pulmonary disease and diabetic ketoacidosis. The classic experimental studies from the past 75+ years are utilized to describe the integrative relationships between CBF, carbon dioxide tension (PCO2 ), bicarbonate (HCO3 - ) and pH. These factors interact to influence (1) the time course of acid-base compensatory changes and the respective cerebrovascular responses (due to rapid exchange kinetics between arterial blood, extracellular fluid and intracellular brain tissue). We propose that alterations in arterial [HCO3 - ] during acute respiratory acidosis/alkalosis contribute to cerebrovascular acid-base regulation; and (2) the regulation of CBF by direct changes in arterial vs. extravascular/interstitial PCO2 and pH - the latter recognized as the proximal compartment which alters vascular smooth muscle cell regulation of CBF. Taken together, these results substantiate two key ideas: first, that the regulation of CBF is affected by the severity of metabolic/respiratory disturbances, including the extent of partial/full acid-base compensation; and second, that the regulation of CBF is independent of arterial pH and that diffusion of CO2 across the blood-brain barrier is integral to altering perivascular extracellular pH. Overall, by realizing the integrative relationships between CBF, PCO2 , HCO3 - and pH, experimental studies may provide insights to improve CBF regulation in clinical practice with treatment of systemic acid-base disorders.
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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, 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, Canada
| | - Jatinder S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, NIHR Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Erik R Swenson
- Pulmonary, Critical Care and Sleep Medicine Division, University of Washington, and VA Puget Sound Healthcare System, Seattle, WA, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan, Kelowna, Canada
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16
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Jin S, Yang Q, Chen X, Zhan Y. Etiologies and Mechanisms of Ischemic Stroke Associated with Sexual Intercourse: A Literature Review. Cerebrovasc Dis 2021; 51:273-281. [PMID: 34649242 DOI: 10.1159/000519262] [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: 06/20/2021] [Accepted: 08/22/2021] [Indexed: 12/08/2022] Open
Abstract
BACKGROUND Exposure to some special events, also called stroke triggers, can precipitate the onset of ischemic stroke (IS). Previous studies have presented preliminary hypotheses about sexual intercourse as a trigger of IS in predisposed individuals, but the mechanisms of IS associated with sexual intercourse are still not well defined. This literature review summarizes the etiologies and mechanisms of IS associated with sexual intercourse. Further studies on stroke triggers are warranted, and early recognition and appropriate preventive strategies directed against the short-term risks posed by stroke triggers may complement the long-term risk factor reduction approach. METHODS Articles were selected from PubMed (1946-2021) and Web of Science Core Collection (1990-2021) using the following search terms: ischemic stroke, ischaemic stroke, stroke, cerebral infarction, cerebral ischemia, cerebral embolism, embolism, sexual intercourse, sexual activity, intercourse, coitus, coition, and coital. RESULTS A total of 20 studies, which included 26 patients with IS associated with sexual intercourse, were included. This literature review found that IS associated with sexual intercourse is not rare but has not received enough attention, and paradoxical embolization and postcoital arterial dissection are common etiologies. Other etiologies include drug usage (such as sexual adjuvant drugs and illicit drugs), paroxysmal sympathetic hyperactivity, and reversible cerebral vasoconstriction syndrome. DISCUSSION/CONCLUSION Sexual intercourse should be considered an important trigger for IS. Clinicians should be aware that IS associated with sexual intercourse is not subjective but may be a warning sign of multiple etiologies and mechanisms.
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Affiliation(s)
- Shouyue Jin
- Department of Neurology, Zhongshan Hospital Xiamen University, Xiamen, China,
| | - Qingwei Yang
- Department of Neurology, Zhongshan Hospital Xiamen University, Xiamen, China
| | - Xingyu Chen
- Department of Neurology, Zhongshan Hospital Xiamen University, Xiamen, China
| | - Yajing Zhan
- Department of Neurology, The Second Xiangya Hospital of Central South University, Changsha, China
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17
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Vu C, Bush A, Choi S, Borzage M, Miao X, Nederveen AJ, Coates TD, Wood JC. Reduced global cerebral oxygen metabolic rate in sickle cell disease and chronic anemias. Am J Hematol 2021; 96:901-913. [PMID: 33891719 PMCID: PMC8273150 DOI: 10.1002/ajh.26203] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 04/19/2021] [Accepted: 04/21/2021] [Indexed: 12/18/2022]
Abstract
Anemia is the most common blood disorder in the world. In patients with chronic anemia, such as sickle cell disease or major thalassemia, cerebral blood flow increases to compensate for decreased oxygen content. However, the effects of chronic anemia on oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2 ) are less well understood. In this study, we examined 47 sickle-cell anemia subjects (age 21.7 ± 7.1, female 45%), 27 non-sickle anemic subjects (age 25.0 ± 10.4, female 52%) and 44 healthy controls (age 26.4 ± 10.6, female 71%) using MRI metrics of brain oxygenation and flow. Phase contrast MRI was used to measure resting cerebral blood flow, while T2 -relaxation-under-spin-tagging (TRUST) MRI with disease appropriate calibrations were used to measure OEF and CMRO2 . We observed that patients with sickle cell disease and other chronic anemias have decreased OEF and CMRO2 (respectively 27.4 ± 4.1% and 3.39 ± 0.71 ml O2 /100 g/min in sickle cell disease, 30.8 ± 5.2% and 3.53 ± 0.64 ml O2 /100 g/min in other anemias) compared to controls (36.7 ± 6.0% and 4.00 ± 0.65 ml O2 /100 g/min). Impaired CMRO2 was proportional to the degree of anemia severity. We further demonstrate striking concordance of the present work with pooled historical data from patients having broad etiologies for their anemia. The reduced cerebral oxygen extraction and metabolism are consistent with emerging data demonstrating increased non-nutritive flow, or physiological shunting, in sickle cell disease patients.
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Affiliation(s)
- Chau Vu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA
| | - Adam Bush
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA
- Department of Radiology, Stanford University, Stanford, CA
| | - Soyoung Choi
- Neuroscience Graduate Program, University of Southern California, Los Angeles, CA
| | - Matthew Borzage
- Division of Neonatology, Fetal and Neonatal Institute, Children’s Hospital Los Angeles, Los Angeles, CA
- Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Xin Miao
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA
| | - Aart J. Nederveen
- University of Amsterdam, Amsterdam UMC, Radiology and Nuclear Medicine, the Netherlands
| | - Thomas D. Coates
- Division of Hematology-Oncology, Department of Pediatrics, Children’s Hospital Los Angeles, Los Angeles, CA
- Departments of Pediatrics and Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - John C. Wood
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA
- Division of Cardiology, Departments of Pediatrics and Radiology, Children’s Hospital Los Angeles, Los Angeles, CA
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18
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Johnson MA, Sharpe GR, Needham RS, Williams NC. Effects of Prior Voluntary Hyperventilation on the 3-min All-Out Cycling Test in Men. Med Sci Sports Exerc 2021; 53:1482-1494. [PMID: 33481485 DOI: 10.1249/mss.0000000000002608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION The ergogenic effects of respiratory alkalosis induced by prior voluntary hyperventilation (VH) are controversial. This study examined the effects of prior VH on derived parameters from the 3-min all-out cycling test (3MT). METHODS Eleven men ( = 46 ± 8 mL·kg-1·min-1) performed a 3MT preceded by 15 min of rest (CONT) or VH ( = 38 ± 5 L·min-1) with PETCO2 reduced to 21 ± 1 mm Hg (HYP). End-test power (EP; synonymous with critical power) was calculated as the mean power output over the last 30 s of the 3MT, and the work done above EP (WEP; synonymous with W') was calculated as the power-time integral above EP. RESULTS At the start of the 3MT, capillary blood PCO2 and [H+] were lower in HYP (25.2 ± 3.0 mm Hg, 27.1 ± 2.6 nmol·L-1) than CONT (43.2 ± 2.0 mm Hg, 40.0 ± 1.5 nmol·L-1) (P < 0.001). At the end of the 3MT, blood PCO2 was still lower in HYP (35.7 ± 5.4 mm Hg) than CONT (40.6 ± 5.0 mm Hg) (P < 0.001). WEP was 10% higher in HYP (19.4 ± 7.0 kJ) than CONT (17.6 ± 6.4 kJ) (P = 0.006), whereas EP was 5% lower in HYP (246 ± 69 W) than CONT (260 ± 74 W) (P = 0.007). The ΔWEP (J·kg-1) between CONT and HYP correlated positively with the PCO2 immediately before the 3MT in HYP (r = 0.77, P = 0.006). CONCLUSION These findings suggest that acid-base changes elicited by prior VH increase WEP but decrease EP during the all-out 3MT.
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Affiliation(s)
- Michael A Johnson
- Exercise and Health Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and Technology, Nottingham Trent University, Nottingham, UNITED KINGDOM
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Perry BG, Lucas SJE. The Acute Cardiorespiratory and Cerebrovascular Response to Resistance Exercise. SPORTS MEDICINE-OPEN 2021; 7:36. [PMID: 34046740 PMCID: PMC8160070 DOI: 10.1186/s40798-021-00314-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/07/2021] [Indexed: 12/18/2022]
Abstract
Resistance exercise (RE) is a popular modality for the general population and athletes alike, due to the numerous benefits of regular participation. The acute response to dynamic RE is characterised by temporary and bidirectional physiological extremes, not typically seen in continuous aerobic exercise (e.g. cycling) and headlined by phasic perturbations in blood pressure that challenge cerebral blood flow (CBF) regulation. Cerebral autoregulation has been heavily scrutinised over the last decade with new data challenging the effectiveness of this intrinsic flow regulating mechanism, particularly to abrupt changes in blood pressure over the course of seconds (i.e. dynamic cerebral autoregulation), like those observed during RE. Acutely, RE can challenge CBF regulation, resulting in adverse responses (e.g. syncope). Compared with aerobic exercise, RE is relatively understudied, particularly high-intensity dynamic RE with a concurrent Valsalva manoeuvre (VM). However, the VM alone challenges CBF regulation and generates additional complexity when trying to dissociate the mechanisms underpinning the circulatory response to RE. Given the disparate circulatory response between aerobic and RE, primarily the blood pressure profiles, regulation of CBF is ostensibly different. In this review, we summarise current literature and highlight the acute physiological responses to RE, with a focus on the cerebral circulation.
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Affiliation(s)
- Blake G Perry
- School of Health Sciences, Massey University, Wellington, New Zealand.
| | - Samuel J E Lucas
- School of Sport, Exercise and Rehabilitation Sciences & Centre for Human Brain Health, College of Life and Environmental Sciences, University of Birmingham, Birmingham, UK
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Carr JMJR, Caldwell HG, Ainslie PN. Cerebral blood flow, cerebrovascular reactivity and their influence on ventilatory sensitivity. Exp Physiol 2021; 106:1425-1448. [PMID: 33932955 DOI: 10.1113/ep089446] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 04/26/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the topic of this review? Cerebrovascular reactivity to CO2 , which is a principal factor in determining ventilatory responses to CO2 through the role reactivity plays in determining cerebral extra- and intracellular pH. What advances does it highlight? Recent animal evidence suggests central chemoreceptor vasculature may demonstrate regionally heterogeneous cerebrovascular reactivity to CO2 , potentially as a protective mechanism against excessive CO2 washout from the central chemoreceptors, thereby allowing ventilation to reflect the systemic acid-base balance needs (respiratory changes in P aC O 2 ) rather than solely the cerebral needs. Ventilation per se does not influence cerebrovascular reactivity independent of changes in P aC O 2 . ABSTRACT Alveolar ventilation and cerebral blood flow are both predominantly regulated by arterial blood gases, especially arterial P C O 2 , and so are intricately entwined. In this review, the fundamental mechanisms underlying cerebrovascular reactivity and central chemoreceptor control of breathing are covered. We discuss the interaction of cerebral blood flow and its reactivity with the control of ventilation and ventilatory responsiveness to changes in P C O 2 , as well as the lack of influence of ventilation itself on cerebrovascular reactivity. We briefly summarize the effects of arterial hypoxaemia on the relationship between ventilatory and cerebrovascular response to both P C O 2 and P O 2 . We then highlight key methodological considerations regarding the interaction of reactivity and ventilatory sensitivity, including the following: regional heterogeneity of cerebrovascular reactivity; a pharmacological approach for the reduction of cerebral blood flow; reactivity assessment techniques; the influence of mean arterial blood pressure; and sex-related differences. Finally, we discuss ventilatory and cerebrovascular control in the context of high altitude and congestive heart failure. Future research directions and pertinent questions of interest are highlighted throughout.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
| | - Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
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21
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Roberts DR, Collins HR, Lee JK, Taylor JA, Turner M, Zaharchuk G, Wintermark M, Antonucci MU, Mulder ER, Gerlach DA, Asemani D, McGregor HR, Seidler RD. Altered cerebral perfusion in response to chronic mild hypercapnia and head-down tilt Bed rest as an analog for Spaceflight. Neuroradiology 2021; 63:1271-1281. [PMID: 33587162 DOI: 10.1007/s00234-021-02660-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 01/26/2021] [Indexed: 01/01/2023]
Abstract
PURPOSE Following prolonged stays on the International Space Station (ISS), some astronauts exhibit visual acuity changes, ophthalmological findings, and mildly elevated intracranial pressures as part of a novel process called spaceflight-associated neuro-ocular syndrome (SANS). To determine the pathophysiology of SANS, NASA conducted a multi-investigator study in which 11 healthy participants underwent head-down tilt bed rest, mimicking microgravity-induced cephalad fluid shifts, combined with elevated ambient CO2 levels similar to those on the ISS (HDT+CO2). As part of that study, we examined the effects of HDT+CO2 on cerebral perfusion. METHODS Using arterial spin labeling, we compared cerebral perfusion before, during, and after HDT+CO2 in participants who developed SANS (n = 5) with those who did not (n = 6). RESULTS All participants demonstrated a decrease in perfusion during HDT+CO2 (mean decrease of 25.1% at HDT7 and 16.2% at HDT29); however, the timing and degree of change varied between the groups. At day 7 of HDT+CO2, the SANS group experienced a greater reduction in perfusion than the non-SANS group (p =.05, 95% CI:-0.19 to 16.11, d=.94, large effect). Conversely, by day 29 of HDT+CO2, the SANS group had significantly higher perfusion (approaching their baseline) than the non-SANS group (p = .04, 95% CI:0.33 to 13.07, d=1.01, large effect). CONCLUSION Compared with baseline and recovery, HDT+CO2 resulted in reduced cerebral perfusion which varied based on SANS status. Further studies are needed to unravel the relative role of HDT vs hypercapnia, to determine if these perfusion changes are clinically relevant, and whether perfusion changes contribute to the development of SANS during spaceflight.
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Affiliation(s)
- Donna R Roberts
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA. .,Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
| | - Heather R Collins
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
| | - Jessica K Lee
- German Aerospace Center (DLR, Institute of Aerospace Medicine), Cologne, Germany.,Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, USA
| | - James A Taylor
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
| | - Matthew Turner
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
| | - Greg Zaharchuk
- Department of Radiology, Division of Neuroradiology, Stanford University, Stanford, CA, USA
| | - Max Wintermark
- Department of Radiology, Division of Neuroradiology, Stanford University, Stanford, CA, USA
| | - Michael U Antonucci
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
| | - Edwin R Mulder
- German Aerospace Center (DLR, Institute of Aerospace Medicine), Cologne, Germany
| | - Darius A Gerlach
- German Aerospace Center (DLR, Institute of Aerospace Medicine), Cologne, Germany
| | - Davud Asemani
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
| | - Heather R McGregor
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, USA
| | - Rachael D Seidler
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, USA.,Norman Fixel Institute for Neurological Diseases, College of Health and Human Performance, University of Florida, Gainesville, FL, USA
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22
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Junejo RT, Lip GYH, Fisher JP. Cerebrovascular Dysfunction in Atrial Fibrillation. Front Physiol 2020; 11:1066. [PMID: 33013456 PMCID: PMC7509200 DOI: 10.3389/fphys.2020.01066] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 08/04/2020] [Indexed: 01/13/2023] Open
Abstract
It is now well established that besides being the most common sustained arrhythmia, atrial fibrillation (AF) is a major healthcare burden. Risk of debilitating stroke is increased in AF patients, but even in the absence of stroke, this population is at heightened risk of cognitive decline, depression, and dementia. The reasons for this are complex, multifactorial, and incompletely understood. One potential contributing mechanism is cerebrovascular dysfunction. Cerebral blood flow is regulated by chemical, metabolic, autoregulatory, neurogenic, and systemic factors. The dysfunction in one or more of these mechanisms may contribute to the elevated risk of cognitive decline and cerebrovascular events in AF. This short review presents the evidence for diminished cerebral blood flow, cerebrovascular carbon dioxide reactivity (i.e., cerebrovascular vasodilatory reserve), cerebral autoregulation, and neurovascular coupling in AF patients when compared to control participants in sinus rhythm. Further work is needed to understand the physiological mechanisms underpinning these observations and their clinical significance in atrial fibrillation patients.
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Affiliation(s)
- Rehan T. Junejo
- Liverpool Centre for Cardiovascular Science, Liverpool Heart and Chest Hospital, University of Liverpool, Liverpool, United Kingdom
| | - Gregory Y. H. Lip
- Liverpool Centre for Cardiovascular Science, Liverpool Heart and Chest Hospital, University of Liverpool, Liverpool, United Kingdom
| | - James P. Fisher
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand
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23
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Baron JC. The effect of changing arterial blood pressure and carbon dioxide on cerebral blood flow. J Neurol Neurosurg Psychiatry 2020; 91:678-679. [PMID: 32213569 DOI: 10.1136/jnnp-2019-322432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 02/13/2020] [Accepted: 03/09/2020] [Indexed: 11/03/2022]
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24
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O'Dea M, Sweetman D, Bonifacio SL, El-Dib M, Austin T, Molloy EJ. Management of Multi Organ Dysfunction in Neonatal Encephalopathy. Front Pediatr 2020; 8:239. [PMID: 32500050 PMCID: PMC7243796 DOI: 10.3389/fped.2020.00239] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Accepted: 04/20/2020] [Indexed: 12/16/2022] Open
Abstract
Neonatal Encephalopathy (NE) describes neonates with disturbed neurological function in the first post-natal days of life. NE is an overall term that does not specify the etiology of the encephalopathy although it often involves hypoxia-ischaemia. In NE, although neurological dysfunction is part of the injury and is most predictive of long-term outcome, these infants may also have multiorgan injury and compromise, which further contribute to neurological impairment and long-term morbidities. Therapeutic hypothermia (TH) is the standard of care for moderate to severe NE. Infants with NE may have co-existing immune, respiratory, endocrine, renal, hepatic, and cardiac dysfunction that require individualized management and can be impacted by TH. Non-neurological organ dysfunction not only has a negative effect on long term outcome but may also influence the efficacy of treatments in the acute phase. Post resuscitative care involves stabilization and decisions regarding TH and management of multi-organ dysfunction. This management includes detailed neurological assessment, cardio-respiratory stabilization, glycaemic and fluid control, sepsis evaluation and antibiotics, seizure identification, and monitoring and responding to biochemical and coagulation derangements. The emergence of new biomarkers of specific organ injury may have predictive value and improve the definition of organ injury and prognosis. Further evidence-based research is needed to optimize management of NE, prevent further organ dysfunction and reduce neurodevelopmental impairment.
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Affiliation(s)
- Mary O'Dea
- Discipline of Paediatrics, Trinity College, The University of Dublin, Dublin, Ireland
- Paediatric Research Laboratory, Trinity Translational Institute, St. James' Hospital, Dublin, Ireland
- Neonatology, Coombe Women and Infant's University Hospital, Dublin, Ireland
- National Children's Research Centre, Dublin, Ireland
| | - Deirdre Sweetman
- National Children's Research Centre, Dublin, Ireland
- Paediatrics, National Maternity Hospital, Dublin, Ireland
| | - Sonia Lomeli Bonifacio
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, United States
| | - Mohamed El-Dib
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Topun Austin
- Neonatal Intensive Care Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom
| | - Eleanor J. Molloy
- Discipline of Paediatrics, Trinity College, The University of Dublin, Dublin, Ireland
- Paediatric Research Laboratory, Trinity Translational Institute, St. James' Hospital, Dublin, Ireland
- Neonatology, Coombe Women and Infant's University Hospital, Dublin, Ireland
- National Children's Research Centre, Dublin, Ireland
- Paediatrics, National Maternity Hospital, Dublin, Ireland
- Neonatology, Children's Hospital Ireland (CHI) at Crumlin, Dublin, Ireland
- Paediatrics, CHI at Tallaght, Tallaght University Hospital, Dublin, Ireland
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25
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Tang LY, Wang J, Alston TA. Kety-Schmidt Application of Nitrous Oxide to Determine Cerebral Blood Flow. J Anesth Hist 2020; 6:98-100. [PMID: 32593385 DOI: 10.1016/j.janh.2020.02.004] [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: 10/03/2018] [Accepted: 02/15/2020] [Indexed: 11/17/2022]
Abstract
In the 1940s, Seymour S. Kety and Carl F. Schmidt measured cerebral blood flow in awake humans by means of subanesthetic doses of inhaled nitrous oxide. The inhalation route obviated the need for an arterial injection of the indicator, and nitrous oxide had virtues of metabolic inertness, rapid diffusion through the blood-brain barrier, comparable blood and brain solubility, and ease of analytical detection. The technique was also applied to the heart. Follow-up work by Kety contributed to the development of brain scanning methods.
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Affiliation(s)
- Linda Y Tang
- Duke University Trinity College, Durham, NC 27708.
| | - Jingping Wang
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, GRJ 4-420, Boston, MA 02114
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26
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27
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Friend AT, Balanos GM, Lucas SJ. Isolating the independent effects of hypoxia and hyperventilation‐induced hypocapnia on cerebral haemodynamics and cognitive function. Exp Physiol 2019; 104:1482-1493. [DOI: 10.1113/ep087602] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 06/25/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Alexander T. Friend
- School of SportExercise and Rehabilitation SciencesUniversity of Birmingham Edgbaston UK
| | - George M. Balanos
- School of SportExercise and Rehabilitation SciencesUniversity of Birmingham Edgbaston UK
| | - Samuel J.E. Lucas
- School of SportExercise and Rehabilitation SciencesUniversity of Birmingham Edgbaston UK
- Centre for Human Brain HealthUniversity of Birmingham Edgbaston UK
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28
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Ogoh S, Suzuki K, Washio T, Tamiya K, Saito S, Bailey TG, Shibata S, Ito G, Miyamoto T. Does respiratory drive modify the cerebral vascular response to changes in end-tidal carbon dioxide? Exp Physiol 2019; 104:1363-1370. [PMID: 31264258 DOI: 10.1113/ep087744] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/28/2019] [Indexed: 12/30/2022]
Abstract
NEW FINDINGS What is the central question of this study? There is an interaction between the regulatory systems of respiration and cerebral blood flow, because the mediator (CO2 ) is the same for both physiological systems. We examined whether the traditional method for determining cerebrovascular reactivity to CO2 is modified by changes in respiration. What is the main finding and its importance? Cerebrovascular reactivity was modified by voluntary changes in respiration during hypercapnia. This finding suggests that an alteration in the respiratory system may result in under- or overestimation of cerebrovascular reactivity determined by traditional methods in healthy adults. ABSTRACT The cerebral vasculature is sensitive to changes in the arterial partial pressure of CO2 . This physiological mechanism has been well established as a cerebrovascular reactivity to CO2 (CVR). However, arterial CO2 may not be an independent variable in the traditional method for assessment of CVR, because the cerebral blood flow response is also affected by the activation of respiratory drive or higher centres in the brain. We hypothesized that CVR is modified by changes in respiration. To test our hypothesis, in the present study, 10 young, healthy subjects performed hyper- or hypoventilation to change end-tidal CO2 ( P ET , C O 2 ) with different concentrations of CO2 in the inhaled gas (0, 2.0 and 3.5%). We measured middle cerebral artery mean blood flow velocity by transcranial Doppler ultrasonography to identify the cerebral blood flow response to change in P ET , C O 2 during each set of conditions. In each set of conditions, P ET , C O 2 was significantly altered by changes in ventilation, and middle cerebral artery mean blood flow velocity changed accordingly. However, the relationship between changes in middle cerebral artery mean blood flow velocity and P ET , C O 2 as a response curve of CVR was reset upwards and downwards by hypo- and hyperventilation, respectively, compared with CVR during normal ventilation. The findings of the present study suggest the possibility that an alteration in respiration might lead to under- or overestimation of CVR determined by the traditional methods.
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Affiliation(s)
- Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Kazuya Suzuki
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Takuro Washio
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan.,Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Kazuki Tamiya
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Shotaro Saito
- Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan
| | - Tom G Bailey
- Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Shigeki Shibata
- Department of Physical Therapy, Faculty of Health Science, Kyorin University, Tokyo, Japan
| | - Go Ito
- Morinomiya University of Medical Sciences, Osaka, Japan
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29
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Stewart JM, Pianosi P, Shaban MA, Terilli C, Svistunova M, Visintainer P, Medow MS. Postural Hyperventilation as a Cause of Postural Tachycardia Syndrome: Increased Systemic Vascular Resistance and Decreased Cardiac Output When Upright in All Postural Tachycardia Syndrome Variants. J Am Heart Assoc 2018; 7:e008854. [PMID: 29960989 PMCID: PMC6064900 DOI: 10.1161/jaha.118.008854] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 06/07/2018] [Indexed: 12/15/2022]
Abstract
BACKGROUND Postural tachycardia syndrome (POTS) is a heterogeneous condition. We stratified patients previously evaluated for POTS on the basis of supine resting cardiac output (CO) or with the complaint of platypnea or "shortness of breath" during orthostasis. We hypothesize that postural hyperventilation is one cause of POTS and that hyperventilation-associated POTS occurs when initial reduction in CO is sufficiently large. We also propose that circulatory abnormalities normalize with restoration of CO2. METHODS AND RESULTS Fifty-eight enrollees with POTS were compared with 16 healthy volunteer controls. Low CO in POTS was defined by a resting supine CO <4 L/min. Patients with shortness of breath had hyperventilation with end tidal CO2 <30 Torr during head-up tilt table testing. There were no differences in height or weight between control patients and patients with POTS or differences between the POTS groups. Beat-to-beat blood pressure was measured by photoplethysmography, and CO was measured by ModelFlow. Systemic vascular resistance was defined as mean arterial blood pressure/CO. End tidal CO2 and cerebral blood flow velocity of the middle cerebral artery were only reduced during head-up tilt in the hyperventilation group, whereas blood pressure was increased compared with control. We corrected the reduced end tidal CO2 in hyperventilation by addition of exogenous CO2 into a rebreathing apparatus. With added CO2, heart rate, blood pressure, CO, and systemic vascular resistance in hyperventilation became similar to control. CONCLUSIONS We conclude that all POTS is related to decreased CO, decreased central blood volume, and increased systemic vascular resistance and that a variant of POTS is consequent to postural hyperventilation.
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Affiliation(s)
- Julian M Stewart
- Department of Pediatrics, New York Medical College, Valhalla, NY
- Department of Physiology, New York Medical College, Valhalla, NY
| | - Paul Pianosi
- Paediatric Respiratory Medicine, King's College Hospital National Health Service Foundation Trust, London, United Kingdom
| | - Mohamed A Shaban
- Department of Pediatrics, New York Medical College, Valhalla, NY
| | - Courtney Terilli
- Department of Pediatrics, New York Medical College, Valhalla, NY
| | - Maria Svistunova
- Department of Pediatrics, New York Medical College, Valhalla, NY
| | - Paul Visintainer
- Epidemiology and Biostatistics, Baystate Medical Center, University of Massachusetts School of Medicine, Worcester, MA
| | - Marvin S Medow
- Department of Pediatrics, New York Medical College, Valhalla, NY
- Department of Physiology, New York Medical College, Valhalla, NY
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30
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Metabolic regulation of synaptic activity. Rev Neurosci 2018; 29:825-835. [DOI: 10.1515/revneuro-2017-0090] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 03/16/2018] [Indexed: 12/20/2022]
Abstract
Abstract
Brain tissue is bioenergetically expensive. In humans, it composes approximately 2% of body weight and accounts for approximately 20% of calorie consumption. The brain consumes energy mostly for ion and neurotransmitter transport, a process that occurs primarily in synapses. Therefore, synapses are expensive for any living creature who has brain. In many brain diseases, synapses are damaged earlier than neurons start dying. Synapses may be considered as vulnerable sites on a neuron. Ischemic stroke, an acute disturbance of blood flow in the brain, is an example of a metabolic disease that affects synapses. The associated excessive glutamate release, called excitotoxicity, is involved in neuronal death in brain ischemia. Another example of a metabolic disease is hypoglycemia, a complication of diabetes mellitus, which leads to neuronal death and brain dysfunction. However, synapse function can be corrected with “bioenergetic medicine”. In this review, a ketogenic diet is discussed as a curative option. In support of a ketogenic diet, whereby carbohydrates are replaced for fats in daily meals, epileptic seizures can be terminated. In this review, we discuss possible metabolic sensors in synapses. These may include molecules that perceive changes in composition of extracellular space, for instance, ketone body and lactate receptors, or molecules reacting to changes in cytosol, for instance, KATP channels or AMP kinase. Inhibition of endocytosis is believed to be a universal synaptic mechanism of adaptation to metabolic changes.
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31
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Fischer K, Yamaji K, Luescher S, Ueki Y, Jung B, von Tengg-Kobligk H, Windecker S, Friedrich MG, Eberle B, Guensch DP. Feasibility of cardiovascular magnetic resonance to detect oxygenation deficits in patients with multi-vessel coronary artery disease triggered by breathing maneuvers. J Cardiovasc Magn Reson 2018; 20:31. [PMID: 29730991 PMCID: PMC5937049 DOI: 10.1186/s12968-018-0446-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 03/20/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Hyperventilation with a subsequent breath-hold has been successfully used as a non-pharmacological vasoactive stimulus to induce changes in myocardial oxygenation. The purpose of this pilot study was to assess if this maneuver is feasible in patients with multi-vessel coronary artery disease (CAD), and if it is effective at detecting coronary artery stenosis > 50% determined by quantitative coronary angiography (QCA). METHODS Twenty-six patients with coronary artery stenosis (QCA > 50% diameter stenosis) underwent a contrast-free cardiovascular magnetic resonance (CMR) exam in the time interval between their primary coronary angiography and a subsequent percutaneous coronary intervention (PCI, n = 24) or coronary artery bypass (CABG, n = 2) revascularization procedure. The CMR exam involved standard function imaging, myocardial strain analysis, T2 mapping, native T1 mapping and oxygenation-sensitive CMR (OS-CMR) imaging. During OS-CMR, participants performed a paced hyperventilation for 60s followed by a breath-hold to induce a vasoactive stimulus. Ten healthy subjects underwent the CMR protocol as the control group. RESULTS All CAD patients completed the breathing maneuvers with an average breath-hold duration of 48 ± 23 s following hyperventilation and without any complications or adverse effects. In comparison to healthy subjects, CAD patients had a significantly attenuated global myocardial oxygenation response to both hyperventilation (- 9.6 ± 6.8% vs. -3.1 ± 6.5%, p = 0.012) and apnea (11.3 ± 6.1% vs. 2.1 ± 4.4%, p < 0.001). The breath-hold maneuver unmasked regional oxygenation differences in territories subtended by a stenotic coronary artery in comparison to remote territory within the same patient (0.5 ± 3.8 vs. 3.8 ± 5.3%, p = 0.011). CONCLUSION Breathing maneuvers in conjunction with OS-CMR are clinically feasible in CAD patients. Furthermore, OS-CMR demonstrates myocardial oxygenation abnormalities in regional myocardium related to CAD without the use of pharmacologic vasodilators or contrast agents. A larger trial appears warranted for a better understanding of its diagnostic utility. TRIAL REGISTRATION Clinical Trials Identifier: NCT02233634 , registered 8 September 2014.
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Affiliation(s)
- Kady Fischer
- Department of Anaesthesiology and Pain Medicine, Bern University Hospital, Inselspital, University of Bern, 3010 Bern, Switzerland
- Research Institute of the McGill University Health Centre, Montreal, QC Canada
- Institute for Diagnostic, Interventional and Paediatric Radiology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - Kyohei Yamaji
- Department of Cardiology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - Silvia Luescher
- Department of Anaesthesiology and Pain Medicine, Bern University Hospital, Inselspital, University of Bern, 3010 Bern, Switzerland
| | - Yasushi Ueki
- Department of Cardiology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - Bernd Jung
- Institute for Diagnostic, Interventional and Paediatric Radiology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - Hendrik von Tengg-Kobligk
- Institute for Diagnostic, Interventional and Paediatric Radiology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - Stephan Windecker
- Department of Cardiology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
| | - Matthias G. Friedrich
- Research Institute of the McGill University Health Centre, Montreal, QC Canada
- Department of Cardiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Balthasar Eberle
- Department of Anaesthesiology and Pain Medicine, Bern University Hospital, Inselspital, University of Bern, 3010 Bern, Switzerland
| | - Dominik P. Guensch
- Department of Anaesthesiology and Pain Medicine, Bern University Hospital, Inselspital, University of Bern, 3010 Bern, Switzerland
- Institute for Diagnostic, Interventional and Paediatric Radiology, Bern University Hospital, Inselspital, University of Bern, Bern, Switzerland
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32
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Xing CY, Tarumi T, Liu J, Zhang Y, Turner M, Riley J, Tinajero CD, Yuan LJ, Zhang R. Distribution of cardiac output to the brain across the adult lifespan. J Cereb Blood Flow Metab 2017; 37:2848-2856. [PMID: 27789785 PMCID: PMC5536794 DOI: 10.1177/0271678x16676826] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 09/23/2016] [Accepted: 10/04/2016] [Indexed: 11/16/2022]
Abstract
A widely accepted dogma is that about 15-20% of cardiac output is received by the brain in healthy adults under resting conditions. However, it is unclear if the distribution of cardiac output directed to the brain alters across the adult lifespan and is modulated by sex or other hemodynamic variables. We measured cerebral blood flow/cardiac output ratio index in 139 subjects (88 women, age 21-80 years) using phase-contrast magnetic resonance imaging and echocardiography. Body mass index, cardiac systolic function (eject fraction), central arterial stiffness (carotid-femoral pulse wave velocity), arterial pressure, heart rate, physical fitness (VO2 max), and total brain volume were measured to assess their effects on the cardiac output-cerebral blood flow relationship. Cerebral blood flow/cardiac output ratio index decreased by 1.3% per decade associated with decreases in cerebral blood flow ( P < 0.001), while cardiac output remained unchanged. Women had higher cerebral blood flow, lower cardiac output, and thus higher cerebral blood flow/cardiac output ratio index than men across the adult lifespan. Age, body mass index, carotid-femoral pulse wave velocity, and arterial pressure all had negative correlations with cerebral blood flow and cerebral blood flow/cardiac output ratio index ( P < 0.05). Multivariable analysis adjusted for sex, age showed that only body mass index was negatively associated with cerebral blood flow/cardiac output ratio index (β = -0.33, P < 0.001). These findings demonstrated that cardiac output distributed to the brain has sex differences and decreases across the adult lifespan and is inversely associated with body mass index.
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Affiliation(s)
- Chang-Yang Xing
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, USA
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi’an, China
| | - Takashi Tarumi
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, USA
| | - Jie Liu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, USA
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi’an, China
| | - Yinan Zhang
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, USA
| | - Marcel Turner
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, USA
| | - Jonathan Riley
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, USA
| | - Cynthia Duron Tinajero
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, USA
| | - Li-Jun Yuan
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi’an, China
| | - Rong Zhang
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, USA
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, USA
- Department of Neurology and Neurotherapeutics, University of Texas Southwestern Medical Center, Dallas, USA
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Morris LE, Flück D, Ainslie PN, McManus AM. Cerebrovascular and ventilatory responses to acute normobaric hypoxia in girls and women. Physiol Rep 2017; 5:e13372. [PMID: 28774953 PMCID: PMC5555897 DOI: 10.14814/phy2.13372] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 07/05/2017] [Accepted: 07/08/2017] [Indexed: 01/21/2023] Open
Abstract
Physiological responses to hypoxia in children are incompletely understood. We aimed to characterize cerebrovascular and ventilatory responses to normobaric hypoxia in girls and women. Ten healthy girls (9.9 ± 1.7 years; mean ± SD; Tanner stage 1 and 2) and their mothers (43.9 ± 3.5 years) participated. Internal carotid (ICA) and vertebral artery (VA) velocity, diameter and flow (Duplex ultrasound) was recorded pre- and post-1 h of hypoxic exposure (FIO2 = 0.126;~4000 m) in a normobaric chamber. Ventilation (V˙E) and respiratory drive (VT/TI) expressed as delta change from baseline (∆%), and end-tidal carbon-dioxide (PETCO2) were collected at baseline (BL) and 5, 30 and 60 min of hypoxia (5/30/60 HYP). Heart rate (HR) and oxygen saturation (SpO2) were also collected at these time-points. SpO2 declined similarly in girls (BL-97%; 60HYP-80%, P < 0.05) and women (BL-97%; 60HYP-83%, P < 0.05). Global cerebral blood flow (gCBF) increased in both girls (BL-687; 60HYP-912 mL·min-1, P < 0.05) and women (BL-472; 60HYP-651 mL·min-1, P < 0.01), though the ratio of ICA:VA (%) contribution to gCBF differed significantly (girls, 75:25%; women, 61:39%). The relative increase in V˙E peaked at 30HYP in both girls (27%, P < 0.05) and women (19%, P < 0.05), as did ∆%VT/TI (girls, 41%; women, 27%, P's < 0.05). Tidal volume (VT) increased in both girls and women at 5HYP, remaining elevated above baseline in girls at 30 and 60 HYP, but declined back toward baseline in women. Girls elicit similar increases in gCBF and ventilatory parameters in response to acute hypoxia as women, though the pattern and contributions mediating these responses appear developmentally divergent.
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Affiliation(s)
- Laura E Morris
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia, Kelowna, Canada
| | - Daniela Flück
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia, Kelowna, Canada
| | - Philip N Ainslie
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia, Kelowna, Canada
| | - Ali M McManus
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia, Kelowna, Canada
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Pavilla A, Gambarota G, Arrigo A, Mejdoubi M, Duvauferrier R, Saint-Jalmes H. Diffusional kurtosis imaging (DKI) incorporation into an intravoxel incoherent motion (IVIM) MR model to measure cerebral hypoperfusion induced by hyperventilation challenge in healthy subjects. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2017; 30:545-554. [PMID: 28608327 DOI: 10.1007/s10334-017-0629-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 05/18/2017] [Accepted: 05/23/2017] [Indexed: 12/11/2022]
Abstract
OBJECTIVES The objectives were to investigate the diffusional kurtosis imaging (DKI) incorporation into the intravoxel incoherent motion (IVIM) model for measurements of cerebral hypoperfusion in healthy subjects. MATERIALS AND METHODS Eight healthy subjects underwent a hyperventilation challenge with a 4-min diffusion weighted imaging protocol, using 8 b values chosen with the Cramer-Rao Lower Bound optimization approach. Four regions of interest in gray matter (GM) were analyzed with the DKI-IVIM model and the bi-exponential IVIM model, for normoventilation and hyperventilation conditions. RESULTS A significant reduction in the perfusion fraction (f) and in the product fD* of the perfusion fraction with the pseudodiffusion coefficient (D*) was found with the DKI-IVIM model, during the hyperventilation challenge. In the cerebellum GM, the percentage changes were f: -43.7 ± 40.1, p = 0.011 and fD*: -50.6 ± 32.1, p = 0.011; in thalamus GM, f: -47.7 ± 34.7, p = 0.012 and fD*: -47.2 ± 48.7, p = 0.040. In comparison, using the bi-exponential IVIM model, only a significant decrease in the parameter fD* was observed for the same regions of interest. In frontal-GM and posterior-GM, the reduction in f and fD* did not reach statistical significance, either with DKI-IVIM or the bi-exponential IVIM model. CONCLUSION When compared to the bi-exponential IVIM model, the DKI-IVIM model displays a higher sensitivity to detect changes in perfusion induced by the hyperventilation condition.
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Affiliation(s)
- Aude Pavilla
- INSERM, UMR 1099, 35000, Rennes, France. .,Université de Rennes 1, LTSI, 35000, Rennes, France. .,Department of Neuroradiology, Pierre-Zobda-Quitman Hospital, University Hospital of Martinique, Fort-de- France, Martinique, France.
| | - Giulio Gambarota
- INSERM, UMR 1099, 35000, Rennes, France.,Université de Rennes 1, LTSI, 35000, Rennes, France
| | - Alessandro Arrigo
- Department of Neuroradiology, Pierre-Zobda-Quitman Hospital, University Hospital of Martinique, Fort-de- France, Martinique, France
| | - Mehdi Mejdoubi
- Department of Neuroradiology, Pierre-Zobda-Quitman Hospital, University Hospital of Martinique, Fort-de- France, Martinique, France
| | - Régis Duvauferrier
- Department of Neuroradiology, Pierre-Zobda-Quitman Hospital, University Hospital of Martinique, Fort-de- France, Martinique, France
| | - Hervé Saint-Jalmes
- INSERM, UMR 1099, 35000, Rennes, France.,Université de Rennes 1, LTSI, 35000, Rennes, France.,CRLCC, Centre Eugène Marquis, 35000, Rennes, France
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Domi T, Vossough A, Stence NV, Felling RJ, Leung J, Krishnan P, Watson CG, Grant PE, Kassner A. The Potential for Advanced Magnetic Resonance Neuroimaging Techniques in Pediatric Stroke Research. Pediatr Neurol 2017; 69:24-36. [PMID: 28237248 DOI: 10.1016/j.pediatrneurol.2016.12.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 12/23/2016] [Accepted: 12/24/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND This article was written to provide clinicians and researchers with an overview of a number of advanced neuroimaging techniques in an effort to promote increased utility and the design of future studies using advanced neuroimaging in childhood stroke. The current capabilities of advanced magnetic resonance imaging techniques provide the opportunity to build on our knowledge of the consequences of stroke on the developing brain. These capabilities include providing information about the physiology, metabolism, structure, and function of the brain that are not routinely evaluated in the clinical setting. METHODS During the Proceedings of the Stroke Imaging Laboratory for Children Workshop in Toronto in June 2015, a subgroup of clinicians and imaging researchers discussed how the application of advanced neuroimaging techniques could further our understanding of the mechanisms of stroke injury and repair in the pediatric population. This subgroup was established based on their interest and commitment to design collaborative, advanced neuroimaging studies in the pediatric stroke population. RESULTS In working toward this goal, we first sought to describe here the magnetic resonance imaging techniques that are currently available for use, and how they have been applied in other stroke populations (e.g., adult and perinatal stroke). CONCLUSIONS With the continued improvement in advanced neuroimaging techniques, including shorter acquisition times, there is an opportunity to apply these techniques to their full potential in the research setting and learn more about the effects of stroke in the developing brain.
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Affiliation(s)
- Trish Domi
- Department of Physiology, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Experimental Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Arastoo Vossough
- Department of Radiology, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Nicholas V Stence
- Department of Radiology, University of Colorado School of Medicine, Aurora, Colorado
| | - Ryan J Felling
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland; Department of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jackie Leung
- Department of Physiology, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Experimental Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Pradeep Krishnan
- Department of Neuroradiology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Christopher G Watson
- Department of Computational Neuroscience, Division of Graduate Medical Sciences, Boston University School of Medicine, Boston, Massachusetts; Department of Neurology, Boston Children's Hospital, Boston, Massachusetts
| | - P Ellen Grant
- Division of Newborn Medicine, Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; Division of Newborn Medicine, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Andrea Kassner
- Department of Physiology, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Experimental Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada.
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Bierens JJLM, Lunetta P, Tipton M, Warner DS. Physiology Of Drowning: A Review. Physiology (Bethesda) 2017; 31:147-66. [PMID: 26889019 DOI: 10.1152/physiol.00002.2015] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Drowning physiology relates to two different events: immersion (upper airway above water) and submersion (upper airway under water). Immersion involves integrated cardiorespiratory responses to skin and deep body temperature, including cold shock, physical incapacitation, and hypovolemia, as precursors of collapse and submersion. The physiology of submersion includes fear of drowning, diving response, autonomic conflict, upper airway reflexes, water aspiration and swallowing, emesis, and electrolyte disorders. Submersion outcome is determined by cardiac, pulmonary, and neurological injury. Knowledge of drowning physiology is scarce. Better understanding may identify methods to improve survival, particularly related to hot-water immersion, cold shock, cold-induced physical incapacitation, and fear of drowning.
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Affiliation(s)
| | - Philippe Lunetta
- Department of Pathology and Forensic Medicine, University of Turku, Turku, Finland
| | - Mike Tipton
- Department of Sport and Exercise Science, Extreme Environments Laboratory, University of Portsmouth, Portsmouth, United Kingdom; and
| | - David S Warner
- Departments of Anesthesiology, Neurobiology and Surgery, Duke University Medical Center, Durham, North Carolina
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Hoffmann U, Sheng H, Ayata C, Warner DS. Anesthesia in Experimental Stroke Research. Transl Stroke Res 2016; 7:358-67. [PMID: 27534542 PMCID: PMC5016251 DOI: 10.1007/s12975-016-0491-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 08/03/2016] [Indexed: 10/21/2022]
Abstract
Anesthetics have enabled major advances in development of experimental models of human stroke. Yet, their profound pharmacologic effects on neural function can confound the interpretation of experimental stroke research. Anesthetics have species-, drug-, and dose-specific effects on cerebral blood flow and metabolism, neurovascular coupling, autoregulation, ischemic depolarizations, excitotoxicity, inflammation, neural networks, and numerous molecular pathways relevant for stroke outcome. Both preconditioning and postconditioning properties have been described. Anesthetics also modulate systemic arterial blood pressure, lung ventilation, and thermoregulation, all of which may interact with the ischemic insult as well as the therapeutic interventions. These confounds present a dilemma. Here, we provide an overview of the anesthetic mechanisms of action and molecular and physiologic effects on factors relevant to stroke outcomes that can guide the choice and optimization of the anesthetic regimen in experimental stroke.
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Affiliation(s)
- Ulrike Hoffmann
- Multidisciplinary Neuroprotection Laboratories, Department of Anesthesiology, Duke University Medical Center, Box 3094, Durham, NC, 27710, USA
| | - Huaxin Sheng
- Multidisciplinary Neuroprotection Laboratories, Department of Anesthesiology, Duke University Medical Center, Box 3094, Durham, NC, 27710, USA
| | - Cenk Ayata
- Neurovascular Research Laboratory, Departments of Radiology and Neurology, Massachusetts General Hospital and Harvard Medical School, 149 13th Street, Charlestown, MA, 02129, USA
| | - David S Warner
- Multidisciplinary Neuroprotection Laboratories, Department of Anesthesiology, Duke University Medical Center, Box 3094, Durham, NC, 27710, USA.
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39
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Braz ID, Fisher JP. The impact of age on cerebral perfusion, oxygenation and metabolism during exercise in humans. J Physiol 2016; 594:4471-83. [PMID: 26435295 PMCID: PMC4983626 DOI: 10.1113/jp271081] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 09/24/2015] [Indexed: 01/05/2023] Open
Abstract
Age is one of the most important risk factors for dementia and stroke. Examination of the cerebral circulatory responses to acute exercise in the elderly may help to pinpoint the mechanisms by which exercise training can reduce the risk of brain diseases, inform the optimization of exercise training programmes and assist with the identification of age-related alterations in cerebral vascular function. During low-to-moderate intensity dynamic exercise, enhanced neuronal activity is accompanied by cerebral perfusion increases of ∼10-30%. Beyond ∼60-70% maximal oxygen uptake, cerebral metabolism remains elevated but perfusion in the anterior portion of the circulation returns towards baseline, substantively because of a hyperventilation-mediated reduction in the partial pressure of arterial carbon dioxide (P aC O2) and cerebral vasoconstriction. Cerebral perfusion is lower in older individuals, both at rest and during incremental dynamic exercise. Nevertheless, the increase in the estimated cerebral metabolic rate for oxygen and the arterial-internal jugular venous differences for glucose and lactate are similar in young and older individuals exercising at the same relative exercise intensities. Correction for the age-related reduction in P aC O2 during exercise by the provision of supplementary CO2 is suggested to remove ∼50% of the difference in cerebral perfusion between young and older individuals. A multitude of candidates could account for the remaining difference, including cerebral atrophy, and enhanced vasoconstrictor and blunted vasodilatory pathways. In summary, age-related reductions in cerebral perfusion during exercise are partly associated with a lower P aC O2 in exercising older individuals; nevertheless the cerebral extraction of glucose, lactate and oxygen appear to be preserved.
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Affiliation(s)
- Igor D Braz
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
| | - James P Fisher
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
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Zhu L, Xu Z, Gong X, Zheng J, Sun Y, Liu L, Han L, Zhang H, Xu Z, Liu J, Rimensberger PC. Mechanical Ventilation After Bidirectional Superior Cavopulmonary Anastomosis for Single-Ventricle Physiology: A Comparison of Pressure Support Ventilation and Neurally Adjusted Ventilatory Assist. Pediatr Cardiol 2016; 37:1064-71. [PMID: 27090649 DOI: 10.1007/s00246-016-1392-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2015] [Accepted: 04/05/2016] [Indexed: 11/29/2022]
Abstract
We evaluated the effects of different respiratory assist modes on cerebral blood flow (CBF) and arterial oxygenation in single-ventricle patients after bidirectional superior cavopulmonary anastomosis (BCPA). We hypothesized that preserved auto-regulation of respiration during neurally adjusted ventilatory assist (NAVA) may have potential advantages for CBF and pulmonary blood flow regulation after the BCPA procedure. We enrolled 23 patients scheduled for BCPA, who underwent pressure-controlled ventilation (PCV), pressure support ventilation (PSV), and NAVA at two assist levels for all modes in a randomized order. PCV targeting large V T (15 mL × kg(-1)) resulted in lower CBF and oxygenation compared to targeting low V T (10 mL × kg(-1)). During PSV and NAVA, ventilation assist levels were titrated to reduce EAdi from baseline by 75 % (high assist) and 50 % (low assist). High assist levels during PSV (PSVhigh) were associated with lower PaCO2, PaO2, and O2SAT, lower CBF, and higher pulsatility index compared with those during NAVAhigh. There were no differences in parameters when using low assist levels, except for slightly greater oxygenation in the NAVAlow group. Modifying assist levels during NAVA did not influence hemodynamics, cerebral perfusion, or gas exchange. Targeting the larger V T during PCV resulted in hyperventilation, did not improve oxygenation, and was accompanied by reduced CBF. Similarly, high assist levels during PSV led to mild hyperventilation, resulting in reduced CBF. NAVA's results were independent of the assist level chosen, causing normalized PaCO2, improved oxygenation, and better CBF than did any other mode, with the exception of PSV at low assist levels.
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Affiliation(s)
- Limin Zhu
- Cardiac Intensive Care Unit, Department of Cardiovascular and Thoracic Surgery, Shanghai Children's Medical Center, Medical School of Shanghai Jiaotong University, Shanghai, 200127, China.
| | - Zhuoming Xu
- Cardiac Intensive Care Unit, Department of Cardiovascular and Thoracic Surgery, Shanghai Children's Medical Center, Medical School of Shanghai Jiaotong University, Shanghai, 200127, China
| | - Xiaolei Gong
- Cardiac Intensive Care Unit, Department of Cardiovascular and Thoracic Surgery, Shanghai Children's Medical Center, Medical School of Shanghai Jiaotong University, Shanghai, 200127, China
| | - Jinghao Zheng
- Cardiac Intensive Care Unit, Department of Cardiovascular and Thoracic Surgery, Shanghai Children's Medical Center, Medical School of Shanghai Jiaotong University, Shanghai, 200127, China
| | - Yanjun Sun
- Cardiac Intensive Care Unit, Department of Cardiovascular and Thoracic Surgery, Shanghai Children's Medical Center, Medical School of Shanghai Jiaotong University, Shanghai, 200127, China
| | - Liping Liu
- Cardiac Intensive Care Unit, Department of Cardiovascular and Thoracic Surgery, Shanghai Children's Medical Center, Medical School of Shanghai Jiaotong University, Shanghai, 200127, China
| | - Lu Han
- Cardiac Intensive Care Unit, Department of Cardiovascular and Thoracic Surgery, Shanghai Children's Medical Center, Medical School of Shanghai Jiaotong University, Shanghai, 200127, China
| | - Haibo Zhang
- Cardiac Intensive Care Unit, Department of Cardiovascular and Thoracic Surgery, Shanghai Children's Medical Center, Medical School of Shanghai Jiaotong University, Shanghai, 200127, China
| | - Zhiwei Xu
- Cardiac Intensive Care Unit, Department of Cardiovascular and Thoracic Surgery, Shanghai Children's Medical Center, Medical School of Shanghai Jiaotong University, Shanghai, 200127, China
| | - Jinfen Liu
- Cardiac Intensive Care Unit, Department of Cardiovascular and Thoracic Surgery, Shanghai Children's Medical Center, Medical School of Shanghai Jiaotong University, Shanghai, 200127, China
| | - Peter C Rimensberger
- Pediatric and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital of Geneva, Geneva, Switzerland
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WHITTIER JR, DHRYMIOTIS AD. Prevention of Slow Wave Response to Hyperventilation in the Human Electroencephalogram by a Vasodilator. Angiology 2016; 13:324-7. [PMID: 14006669 DOI: 10.1177/000331976201300706] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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ROSENBLUM WI. Cerebral Microcirculation: a Review Emphasizing the Interrelationship of Local Blood Flow and Neuronal Function. Angiology 2016; 16:485-507. [PMID: 14335332 DOI: 10.1177/000331976501600809] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
Ten percent to 15% of glucose used by the brain is metabolized nonoxidatively despite adequate tissue oxygenation, a process termed aerobic glycolysis (AG). Because of the known role of glycolysis in biosynthesis, we tested whether learning-induced synaptic plasticity would lead to regionally appropriate, learning-dependent changes in AG. Functional MRI (fMRI) before, during, and after performance of a visual-motor adaptation task demonstrated that left Brodmann area 44 (BA44) played a key role in adaptation, with learning-related changes to activity during the task and altered resting-state, functional connectivity after the task. PET scans before and after task performance indicated a sustained increase in AG in left BA 44 accompanied by decreased oxygen consumption. Intersubject variability in behavioral adaptation rate correlated strongly with changes in AG in this region, as well as functional connectivity, which is consistent with a role for AG in synaptic plasticity.
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44
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Zhang J, Zhou D, Nguyen TD, Spincemaille P, Gupta A, Wang Y. Cerebral metabolic rate of oxygen (CMRO2) mapping with hyperventilation challenge using quantitative susceptibility mapping (QSM). Magn Reson Med 2016; 77:1762-1773. [DOI: 10.1002/mrm.26253] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 03/06/2016] [Accepted: 03/31/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Jingwei Zhang
- Department of Biomedical EngineeringCornell University301 Weill HallIthaca New York, USA
- Department of RadiologyWeill Cornell Medical College515 East 71st St, Suite 104New York, USA
| | - Dong Zhou
- Department of RadiologyWeill Cornell Medical College515 East 71st St, Suite 104New York, USA
| | - Thanh D. Nguyen
- Department of RadiologyWeill Cornell Medical College515 East 71st St, Suite 104New York, USA
| | - Pascal Spincemaille
- Department of RadiologyWeill Cornell Medical College515 East 71st St, Suite 104New York, USA
| | - Ajay Gupta
- Department of RadiologyWeill Cornell Medical College515 East 71st St, Suite 104New York, USA
| | - Yi Wang
- Department of Biomedical EngineeringCornell University301 Weill HallIthaca New York, USA
- Department of RadiologyWeill Cornell Medical College515 East 71st St, Suite 104New York, USA
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Sun HT, Zheng M, Wang Y, Diao Y, Zhao W, Wei Z. Monitoring intracranial pressure utilizing a novel pattern of brain multiparameters in the treatment of severe traumatic brain injury. Neuropsychiatr Dis Treat 2016; 12:1517-23. [PMID: 27382294 PMCID: PMC4922802 DOI: 10.2147/ndt.s106915] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The aim of the study was to evaluate the clinical value of multiple brain parameters on monitoring intracranial pressure (ICP) procedures in the therapy of severe traumatic brain injury (sTBI) utilizing mild hypothermia treatment (MHT) alone or a combination strategy with other therapeutic techniques. A total of 62 patients with sTBI (Glasgow Coma Scale score <8) were treated using mild hypothermia alone or mild hypothermia combined with conventional ICP procedures such as dehydration using mannitol, hyperventilation, and decompressive craniectomy. The multiple brain parameters, which included ICP, cerebral perfusion pressure, transcranial Doppler, brain tissue partial pressure of oxygen, and jugular venous oxygen saturation, were detected and analyzed. All of these measures can control the ICP of sTBI patients to a certain extent, but multiparameters associated with brain environment and functions have to be critically monitored simultaneously because some procedures of reducing ICP can cause side effects for long-term recovery in sTBI patients. The result suggested that multimodality monitoring must be performed during the process of mild hypothermia combined with conventional ICP procedures in order to safely target different clinical methods to specific patients who may benefit from an individual therapy.
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Affiliation(s)
- Hong-Tao Sun
- Sixth Department of Neurosurgery, Affiliated Hospital of Logistics University of People's Armed Police Force, Tianjin
| | - Maohua Zheng
- Department of Neurosurgery, The First Hospital of Lanzhou University, Lanzhou, People's Republic of China
| | - Yanmin Wang
- Sixth Department of Neurosurgery, Affiliated Hospital of Logistics University of People's Armed Police Force, Tianjin
| | - Yunfeng Diao
- Sixth Department of Neurosurgery, Affiliated Hospital of Logistics University of People's Armed Police Force, Tianjin
| | - Wanyong Zhao
- Sixth Department of Neurosurgery, Affiliated Hospital of Logistics University of People's Armed Police Force, Tianjin
| | - Zhengjun Wei
- Sixth Department of Neurosurgery, Affiliated Hospital of Logistics University of People's Armed Police Force, Tianjin
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β-Hydroxybutyrate supports synaptic vesicle cycling but reduces endocytosis and exocytosis in rat brain synaptosomes. Neurochem Int 2016; 93:73-81. [PMID: 26748385 DOI: 10.1016/j.neuint.2015.12.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 12/28/2015] [Accepted: 12/29/2015] [Indexed: 01/04/2023]
Abstract
The ketogenic diet is used as a prophylactic treatment for different types of brain diseases, such as epilepsy or Alzheimer's disease. In such a diet, carbohydrates are replaced by fats in everyday food, resulting in an elevation of blood-borne ketone bodies levels. Despite clinical applications of this treatment, the molecular mechanisms by which the ketogenic diet exerts its beneficial effects are still uncertain. In this study, we investigated the effect of replacing glucose by the ketone body β-hydroxybutyrate as the main energy substrate on synaptic vesicle recycling in rat brain synaptosomes. First, we observed that exposing presynaptic terminals to nonglycolytic energy substrates instead of glucose did not alter the plasma membrane potential. Next, we found that synaptosomes were able to maintain the synaptic vesicle cycle monitored with the fluorescent dye acridine orange when glucose was replaced by β-hydroxybutyrate. However, in presence of β-hydroxybutyrate, synaptic vesicle recycling was modified with reduced endocytosis. Replacing glucose by pyruvate also led to a reduced endocytosis. Addition of β-hydroxybutyrate to glucose-containing incubation medium was without effect. Reduced endocytosis in presence of β-hydroxybutyrate as sole energy substrate was confirmed using the fluorescent dye FM2-10. Also we found that replacement of glucose by ketone bodies leads to inhibition of exocytosis, monitored by FM2-10. However this reduction was smaller than the effect on endocytosis under the same conditions. Using both acridine orange in synaptosomes and the genetically encoded sensor synaptopHluorin in cortical neurons, we observed that replacing glucose by β-hydroxybutyrate did not modify the pH gradient of synaptic vesicles. In conclusion, the nonglycolytic energy substrates β-hydroxybutyrate and pyruvate are able to support synaptic vesicle recycling. However, they both reduce endocytosis. Reduction of both endocytosis and exocytosis together with misbalance between endocytosis and exocytosis could be involved in the anticonvulsant activity of the ketogenic diet.
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Cerebral Blood Flow and Metabolism. Stroke 2016. [DOI: 10.1016/b978-0-323-29544-4.00003-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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48
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Perry BG, Bear TLK, Lucas SJE, Mündel T. Mild dehydration modifies the cerebrovascular response to the cold pressor test. Exp Physiol 2015; 101:135-42. [DOI: 10.1113/ep085449] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 09/11/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Blake G. Perry
- School of Sport and Exercise; Massey University; Palmerston North New Zealand
| | - Tracey L. K. Bear
- School of Sport and Exercise; Massey University; Palmerston North New Zealand
- School of Psychology; Massey University; Palmerston North New Zealand
| | - Samuel J. E. Lucas
- Department of Physiology; University of Otago; Dunedin New Zealand
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences; University of Birmingham; UK
| | - Toby Mündel
- School of Sport and Exercise; Massey University; Palmerston North New Zealand
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Abstract
Cerebral autoregulation describes a mechanism that maintains cerebral blood flow stable despite fluctuating perfusion pressure. Multiple nonperfusion pressure processes also regulate cerebral perfusion. These mechanisms are integrated. The effect of the interplay between carbon dioxide and perfusion pressure on cerebral circulation has not been specifically reviewed. On the basis of the published data and speculation on the aspects that are without supportive data, the authors offer a conceptualization delineating the regulation of cerebral autoregulation by carbon dioxide. The authors conclude that hypercapnia causes the plateau to progressively ascend, a rightward shift of the lower limit, and a leftward shift of the upper limit. Conversely, hypocapnia results in the plateau shifting to lower cerebral blood flows, unremarkable change of the lower limit, and unclear change of the upper limit. It is emphasized that a sound understanding of both the limitations and the dynamic and integrated nature of cerebral autoregulation fosters a safer clinical practice.
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Lewis NCS, Bain AR, MacLeod DB, Wildfong KW, Smith KJ, Willie CK, Sanders ML, Numan T, Morrison SA, Foster GE, Stewart JM, Ainslie PN. Impact of hypocapnia and cerebral perfusion on orthostatic tolerance. J Physiol 2014; 592:5203-19. [PMID: 25217373 PMCID: PMC4262334 DOI: 10.1113/jphysiol.2014.280586] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 09/01/2014] [Indexed: 12/25/2022] Open
Abstract
We examined two novel hypotheses: (1) that orthostatic tolerance (OT) would be prolonged when hyperventilatory-induced hypocapnia (and hence cerebral hypoperfusion) was prevented; and (2) that pharmacological reductions in cerebral blood flow (CBF) at baseline would lower the 'CBF reserve', and ultimately reduce OT. In study 1 (n = 24; aged 25 ± 4 years) participants underwent progressive lower-body negative pressure (LBNP) until pre-syncope; end-tidal carbon dioxide (P ET , CO 2) was clamped at baseline levels (isocapnic trial) or uncontrolled. In study 2 (n = 10; aged 25 ± 4 years), CBF was pharmacologically reduced by administration of indomethacin (INDO; 1.2 mg kg(-1)) or unaltered (placebo) followed by LBNP to pre-syncope. Beat-by-beat measurements of middle cerebral artery blood flow velocity (MCAv; transcranial Doppler), heart rate (ECG), blood pressure (BP; Finometer) and end-tidal gases were obtained continuously. In a subset of subjects' arterial-to-jugular venous differences were obtained to examine the independent impact of hypocapnia or cerebral hypoperfusion (following INDO) on cerebral oxygen delivery and extraction. In study 1, during the isocapnic trial, P ET , CO 2 was successfully clamped at baseline levels at pre-syncope (38.3 ± 2.7 vs. 38.5 ± 2.5 mmHg respectively; P = 0.50). In the uncontrolled trial, P ET , CO 2 at pre-syncope was reduced by 10.9 ± 3.9 mmHg (P ≤ 0.001). Compared to the isocapnic trial, the decline in mean MCAv was 15 ± 4 cm s(-1) (35%; P ≤ 0.001) greater in the uncontrolled trial, yet the time to pre-syncope was comparable between trials (544 ± 130 vs. 572 ± 180 s; P = 0.30). In study 2, compared to placebo, INDO reduced resting MCAv by 19 ± 4 cm s(-1) (31%; P ≤ 0.001), but time to pre-syncope remained similar between trials (placebo: 1123 ± 138 s vs. INDO: 1175 ± 212 s; P = 0.53). The brain extracted more oxygen in face of hypocapnia (34% to 53%) or cerebral hypoperfusion (34% to 57%) to compensate for reductions in delivery. In summary, cerebral hypoperfusion either at rest or induced by hypocapnia at pre-syncope does not impact OT, probably due to a compensatory increase in oxygen extraction.
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Affiliation(s)
- Nia C S Lewis
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Canada
| | - Anthony R Bain
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Canada
| | - David B MacLeod
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Kevin W Wildfong
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Canada
| | - Kurt J Smith
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Canada
| | - Christopher K Willie
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Canada
| | | | - Tianne Numan
- MIRA, University of Twente, Enschede, The Netherlands
| | - Shawnda A Morrison
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Canada Jozef Stefan Institute, Ljubljana, Slovenia
| | - Glen E Foster
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Canada
| | | | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Canada
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