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Bellomo J, Sebök M, van Niftrik CH, Stumpo V, Schubert T, Madjidyar J, Thurner P, Globas C, Wegener S, Luft AR, Kulcsár Z, Regli L, Fierstra J. The volume of steal phenomenon is associated with neurological deterioration in patients with large-vessel occlusion minor stroke not eligible for thrombectomy. Eur Stroke J 2024:23969873241251718. [PMID: 38742386 DOI: 10.1177/23969873241251718] [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: 05/16/2024] Open
Abstract
INTRODUCTION A significant number of patients who present with mild symptoms following large-vessel occlusion acute ischemic stroke (LVO-AIS) are currently considered ineligible for EVT. However, they frequently experience neurological deterioration during hospitalization. This study aimed to investigate the association between neurological deterioration and hemodynamic impairment by assessing steal phenomenon derived from blood oxygenation-level dependent cerebrovascular reactivity (BOLD-CVR) in this specific patient cohort. PATIENTS AND METHODS From the database of our single-center BOLD-CVR observational cohort study (June 2015-October 2023) we retrospectively identified acute ischemic stroke patients with admission NIHSS < 6, a newly detected large vessel occlusion of the anterior circulation and ineligible for EVT. Neurological deterioration during hospitalization as well as outcome at hospital discharge were rated with NIHSS score. We analyzed the association between these two outcomes and BOLD-CVR-derived steal phenomenon volume through regression analysis. Additionally, we investigated the discriminatory accuracy of steal phenomenon volume for predicting neurological deterioration. RESULTS Forty patients were included in the final analysis. Neurological deterioration occurred in 35% of patients. In the regression analysis, a strong association between steal phenomenon volume and neurological deterioration (OR 4.80, 95% CI 1.32-31.04, p = 0.04) as well as poorer NIHSS score at hospital discharge (OR 3.73, 95% CI 1.52-10.78, p = 0.007) was found. The discriminatory accuracy of steal phenomenon for neurological deterioration prediction had an AUC of 0.791 (95% CI 0.653-0.930). DISCUSSION Based on our results we may distinguish two groups of patients with minor stroke currently ineligible for EVT, however, showing hemodynamic impairment and exhibiting neurological deterioration during hospitalization: (1) patients exhibiting steal phenomenon on BOLD-CVR imaging as well as hemodynamic impairment on resting perfusion imaging; (2) patients exhibiting steal phenomenon on BOLD-CVR imaging, however, no relevant hemodynamic impairment on resting perfusion imaging. CONCLUSION The presence of BOLD-CVR derived steal phenomenon may aid to further study hemodynamic impairment in patients with minor LVO-AIS not eligible for EVT.
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Affiliation(s)
- Jacopo Bellomo
- Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
| | - Martina Sebök
- Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
| | - Christiaan Hb van Niftrik
- Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
| | - Vittorio Stumpo
- Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
| | - Tilman Schubert
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
- Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
| | - Jawid Madjidyar
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
- Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
| | - Patrick Thurner
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
- Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
| | - Christoph Globas
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
| | - Susanne Wegener
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
| | - Andreas R Luft
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
- Department of Neurology, University Hospital Zurich, Zurich, Switzerland
- Cereneo Center for Neurology and Rehabilitation, Vitznau, Switzerland
| | - Zsolt Kulcsár
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
- Department of Neuroradiology, University Hospital Zurich, Zurich, Switzerland
| | - Luca Regli
- Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
| | - Jorn Fierstra
- Department of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
- Clinical Neuroscience Center (KNZ), Neuroscience Center (ZNZ), University of Zurich, Switzerland
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Yang L, Du H, Zhang X, Zhang D, Su X, Qiao Z, Gao B. Evaluation of the correlation between cerebral hemodynamics and blood pressure by comparative analysis of variation in cerebral blood flow in hypertensive versus normotensive individuals: A systematic review and meta-analysis. BIOMOLECULES & BIOMEDICINE 2024; 24:775-786. [PMID: 38709773 PMCID: PMC11293236 DOI: 10.17305/bb.2024.10230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 04/20/2024] [Accepted: 04/20/2024] [Indexed: 05/08/2024]
Abstract
Current understanding of the cerebral vascular response to variations in blood pressure (BP) among individuals with hypertension is limited. The aim of this meta-analysis was to determine the correlation between hypertension, risk of stroke, and cerebral blood flow (CBF). We reviewed studies published between 2000 and 2023 from PubMed, Google Scholar, and Science Direct that compared mean CBF in normotensive (NTN) and hypertensive (HTN) patients. A random effects model was used to construct the risk ratio (RR), 95% confidence interval (CI), forest plot, and inverse variance weighting. Additionally, a mixed-effects meta-regression was employed to examine the impact of study-specific patient variables. This meta-analysis included eight prospective cross-sectional studies published from 2002 to 2023. It revealed a significant average difference in the standard mean CBF of -0.45 (95% CI -0.60 to -0.30, I2 = 69%, P < 0.00001), distinguishing NTN from HTN subjects. A RR of 0.90 (95% CI 0.63 to 1.30, I2 = 89%, P = 0.04) indicated a significant decrease in CBF among individuals with hypertension. We found a statistically significant relationship between changes in diastolic and systolic BPs and the mean CBF (R -0.81, P = 0.001 and R = -0.90, P = 0.005, respectively). Our research demonstrates a strong relationship between elevated BP and reduced CBF, with hypertension reducing CBF compared to NTN individuals, by increasing cerebrovascular resistance.
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Affiliation(s)
- Lei Yang
- Department of Neurosurgery, Shijiazhuang People’s Hospital, Shijiazhuang, China
| | - Hong Du
- Department of Cardiology, Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Xuejing Zhang
- Center of Medical Research, Shijiazhuang People’s Hospital, Shijiazhuang, China
| | - Dongliang Zhang
- Department of Neurosurgery, Shijiazhuang People’s Hospital, Shijiazhuang, China
| | - Xianhui Su
- Department of Neurosurgery, Shijiazhuang People’s Hospital, Shijiazhuang, China
| | - Zongrong Qiao
- Department of Neurosurgery, Shijiazhuang People’s Hospital, Shijiazhuang, China
| | - Bulang Gao
- Center of Medical Research, Shijiazhuang People’s Hospital, Shijiazhuang, China
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3
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McIntyre CW. Update on Hemodialysis-Induced Multiorgan Ischemia: Brains and Beyond. J Am Soc Nephrol 2024; 35:653-664. [PMID: 38273436 PMCID: PMC11149050 DOI: 10.1681/asn.0000000000000299] [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: 06/30/2023] [Accepted: 12/17/2023] [Indexed: 01/27/2024] Open
Abstract
Hemodialysis is a life-saving treatment for patients with kidney failure. However, patients requiring hemodialysis have a 10-20 times higher risk of cardiovascular morbidity and mortality than that of the general population. Patients encounter complications such as episodic intradialytic hypotension, abnormal perfusion to critical organs (heart, brain, liver, and kidney), and damage to vulnerable vascular beds. Recurrent conventional hemodialysis exposes patients to multiple episodes of circulatory stress, exacerbating and being aggravated by microvascular endothelial dysfunction. This promulgates progressive injury that leads to irreversible multiorgan injury and the well-documented higher incidence of cardiovascular disease and premature death. This review aims to examine the underlying pathophysiology of hemodialysis-related vascular injury and consider a range of therapeutic approaches to improving outcomes set within this evolved rubric..
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Affiliation(s)
- Christopher W McIntyre
- Lilibeth Caberto Kidney Clinical Research Unit, Lawson Health Research Institute, London, Ontario, Canada, and Departments of Medicine, Medical Biophysics and Pediatrics, Western University, London, Ontario, Canada
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Sayin ES, Duffin J, Poublanc J, Venkatraghavan L, Mikulis DJ, Fisher JA, Sobczyk O. Determining the effects of elevated partial pressure of oxygen on hypercapnia-induced cerebrovascular reactivity. J Cereb Blood Flow Metab 2023; 43:2085-2095. [PMID: 37632334 PMCID: PMC10925865 DOI: 10.1177/0271678x231197000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 08/28/2023]
Abstract
Evaluation of cerebrovascular reactivity (CVR) to hypo- and hypercapnia is a valuable test for the assessment of vasodilatory reserve. While hypercapnia-induced CVR testing is usually performed at normoxia, mild hyperoxia may increase tolerability of hypercapnia by reducing the ventilatory distress. However, the effects of mild hyperoxia on CVR was unknown. We therefore recruited 21 patients with a range of steno-occlusive diseases and 12 healthy participants who underwent a standardized 13-minute step plus ramp CVR test with a carbon dioxide gas challenge at the subject's resting end-tidal partial pressure of oxygen or at mild hyperoxia (PetO2 = 150 mmHg) depending on to which group they were assigned. In 11 patients, the second CVR test was at normoxia to examine test-retest differences. CVR was defined as % Δ Signal/ΔPetCO2. We found that there was no significant difference between CVR test results conducted at normoxia and at mild hyperoxia for participants in Groups 1 and 2 for the step and ramp portion. We also found no difference between test and retest CVR at normoxia for patients with cerebrovascular pathology (Group 3) for step and ramp portion. We concluded normoxic CVR is repeatable, and that mild hyperoxia does not affect CVR.
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Affiliation(s)
- Ece Su Sayin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Lashmikumar Venkatraghavan
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - David John Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Joseph Arnold Fisher
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Olivia Sobczyk
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
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Brasil S, de Carvalho Nogueira R, Salinet ÂSM, Yoshikawa MH, Teixeira MJ, Paiva W, Malbouisson LMS, Bor-Seng-Shu E, Panerai RB. Critical Closing Pressure and Cerebrovascular Resistance Responses to Intracranial Pressure Variations in Neurocritical Patients. Neurocrit Care 2023; 39:399-410. [PMID: 36869208 PMCID: PMC10541829 DOI: 10.1007/s12028-023-01691-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 01/31/2023] [Indexed: 03/05/2023]
Abstract
BACKGROUND Critical closing pressure (CrCP) and resistance-area product (RAP) have been conceived as compasses to optimize cerebral perfusion pressure (CPP) and monitor cerebrovascular resistance, respectively. However, for patients with acute brain injury (ABI), the impact of intracranial pressure (ICP) variability on these variables is poorly understood. The present study evaluates the effects of a controlled ICP variation on CrCP and RAP among patients with ABI. METHODS Consecutive neurocritical patients with ICP monitoring were included along with transcranial Doppler and invasive arterial blood pressure monitoring. Internal jugular veins compression was performed for 60 s for the elevation of intracranial blood volume and ICP. Patients were separated in groups according to previous intracranial hypertension severity, with either no skull opening (Sk1), neurosurgical mass lesions evacuation, or decompressive craniectomy (DC) (patients with DC [Sk3]). RESULTS Among 98 included patients, the correlation between change (Δ) in ICP and the corresponding ΔCrCP was strong (group Sk1 r = 0.643 [p = 0.0007], group with neurosurgical mass lesions evacuation r = 0.732 [p < 0.0001], and group Sk3 r = 0.580 [p = 0.003], respectively). Patients from group Sk3 presented a significantly higher ΔRAP (p = 0.005); however, for this group, a higher response in mean arterial pressure (change in mean arterial pressure p = 0.034) was observed. Exclusively, group Sk1 disclosed reduction in ICP before internal jugular veins compression withholding. CONCLUSIONS This study elucidates that CrCP reliably changes in accordance with ICP, being useful to indicate ideal CPP in neurocritical settings. In the early days after DC, cerebrovascular resistance seems to remain elevated, despite exacerbated arterial blood pressure responses in efforts to maintain CPP stable. Patients with ABI with no need of surgical procedures appear to remain with more effective ICP compensatory mechanisms when compared with those who underwent neurosurgical interventions.
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Affiliation(s)
- Sérgio Brasil
- Division of Neurosurgery, Department of Neurology, School of Medicine, University of São Paulo, Av. Dr. Eneas de Carvalho Aguiar 255, São Paulo, Brazil.
| | - Ricardo de Carvalho Nogueira
- Division of Neurosurgery, Department of Neurology, School of Medicine, University of São Paulo, Av. Dr. Eneas de Carvalho Aguiar 255, São Paulo, Brazil
| | - Ângela Salomão Macedo Salinet
- Division of Neurosurgery, Department of Neurology, School of Medicine, University of São Paulo, Av. Dr. Eneas de Carvalho Aguiar 255, São Paulo, Brazil
| | - Márcia Harumy Yoshikawa
- Division of Neurosurgery, Department of Neurology, School of Medicine, University of São Paulo, Av. Dr. Eneas de Carvalho Aguiar 255, São Paulo, Brazil
| | - Manoel Jacobsen Teixeira
- Division of Neurosurgery, Department of Neurology, School of Medicine, University of São Paulo, Av. Dr. Eneas de Carvalho Aguiar 255, São Paulo, Brazil
| | - Wellingson Paiva
- Division of Neurosurgery, Department of Neurology, School of Medicine, University of São Paulo, Av. Dr. Eneas de Carvalho Aguiar 255, São Paulo, Brazil
| | | | - Edson Bor-Seng-Shu
- Division of Neurosurgery, Department of Neurology, School of Medicine, University of São Paulo, Av. Dr. Eneas de Carvalho Aguiar 255, São Paulo, Brazil
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, School of Life Sciences, University of Leicester, Leicester, UK
- National Institute for Health and Care Research, Cardiovascular Research Centre, Glenfield Hospital, University of Leicester, Leicester, UK
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Lee CH, Chung JW, Guk HS, Hong JM, Rosenson RS, Jeong SK. Cerebral artery signal intensity gradient from Time-of-Flight Magnetic Resonance Angiography and clinical outcome in lenticulostriate infarction: a retrospective cohort study. Front Neurol 2023; 14:1220840. [PMID: 37799283 PMCID: PMC10547899 DOI: 10.3389/fneur.2023.1220840] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 08/30/2023] [Indexed: 10/07/2023] Open
Abstract
Purpose Lenticulostriate infarction requires further research of arterial hemodynamic factors, as the disease is diagnosed in the absence of major arterial stenosis or cardioembolism. Methods In this multicenter retrospective cohort study, we included patients who were hospitalized for lenticulostriate infarction from January 2015 to March 2021 at three stroke centers in South Korea. We obtained hemodynamic information on cerebral arteries using signal intensity gradient (SIG), an in-vivo approximated wall shear stress (WSS) derived from Time-of-Flight Magnetic Resonance Angiography (TOF-MRA). A favorable outcome was defined as a modified Rankin Scale of 0 to 2 at hospital discharge. Results A total of 294 patients were included, of whom 146 (49.7%) had an unfavorable outcome. The unfavorable outcome group showed significantly lower SIG in both middle cerebral arteries (MCAs) than the favorable group (5.2 ± 1.2 SI/mm vs. 5.9 ± 1.2, p < 0.001), and similar findings were observed in other cerebral arteries. The SIGs in both MCAs were independently associated with favorable outcome, with an odds ratio of 1.42 (95% confidence interval, 1.11-1.80; p = 0.005) for the right MCA and 1.49 (95% CI, 1.15-1.93; p = 0.003) for the left MCA, after adjusting for potential confounders. Similar findings were observed in other cerebral artery SIGs. Conclusion Cerebral artery SIG from TOF-MRA was significantly associated with short-term functional outcomes in patients with lenticulostriate infarction. Further studies are needed to investigate the temporal relationships of SIG in patients with cerebral infarction.
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Affiliation(s)
- Chan-Hyuk Lee
- Department of Neurology, Asan Medical Center, Seoul, Republic of Korea
- Department of Neurology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Republic of Korea
| | - Jong-Won Chung
- Department of Neurology, Samsung Medical Center, Seoul, Republic of Korea
| | - Hyung Seok Guk
- Department of Neurology, Gunsan Medical Center, Gunsan, Republic of Korea
| | - Ji Man Hong
- Department of Neurology, Ajou University School of Medicine, Suwon, Republic of Korea
| | - Robert S. Rosenson
- Mount Sinai Heart, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Seul-Ki Jeong
- Seul-Ki Jeong Neurology Clinic, Seoul, Republic of Korea
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Singh MV, Uddin MN, Singh VB, Peterson AN, Murray KD, Zhuang Y, Tyrell A, Wang L, Tivarus ME, Zhong J, Qiu X, Schifitto G. Initiation of combined antiretroviral therapy confers suboptimal beneficial effects on neurovascular function in people with HIV. Front Neurol 2023; 14:1240300. [PMID: 37719766 PMCID: PMC10500594 DOI: 10.3389/fneur.2023.1240300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 08/14/2023] [Indexed: 09/19/2023] Open
Abstract
Introduction Due to advances in combined anti-retroviral treatment (cART), there is an increased burden of age-related cerebrovascular disease (CBVD), in people living with HIV (PWH). The underlying CNS injury can be assessed by measuring cerebral blood flow (CBF) and cerebrovascular reactivity (CVR). Methods 35 treatment-naïve PWH and 53 HIV negative controls (HC) were enrolled in this study. Study participants underwent T1-weighted anatomical, pseudo-continuous arterial spin labeling, and resting-state functional MRI to obtain measures of CBF and CVR prior to starting cART treatment and at two-time points (12 weeks and 2 years) post-cART initiation. Controls were scanned at the baseline and 2-year visits. We also measured plasma levels of microparticles of endothelial and glial origin and well-known endothelial inflammation markers, ICAM-1 and VCAM-1, to assess HIV-associated endothelial inflammation and the interaction of these peripheral markers with brain neurovascular function. Results HIV infection was found to be associated with reduced CVR and increased levels of endothelial and glial microparticles (MPs) prior to initiation of cART. Further, CVR correlated negatively with peripheral MP levels in PWH. Discussion Our results suggest that while cART treatment has a beneficial effect on the neurovascular function after initiation, these benefits are suboptimal over time.
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Affiliation(s)
- Meera V. Singh
- Department of Neurology, University of Rochester, Rochester, NY, United States
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY, United States
| | - Md Nasir Uddin
- Department of Neurology, University of Rochester, Rochester, NY, United States
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, United States
| | - Vir B. Singh
- Albany College of Pharmacy and Health Sciences, Albany, NY, United States
| | | | - Kyle D. Murray
- Department of Physics and Astronomy, University of Rochester, Rochester, NY, United States
| | - Yuchuan Zhuang
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, United States
| | - Alicia Tyrell
- Clinical and Translational Science Institute, University of Rochester, Rochester, NY, United States
| | - Lu Wang
- Department of Biostatistics and Computational Biology, University of Rochester, Rochester, NY, United States
| | - Madalina E. Tivarus
- Department of Imaging Sciences, University of Rochester, Rochester, NY, United States
- Department of Neuroscience, University of Rochester, Rochester, NY, United States
| | - Jianhui Zhong
- Department of Biomedical Engineering, University of Rochester, Rochester, NY, United States
- Department of Imaging Sciences, University of Rochester, Rochester, NY, United States
- Department of Neuroscience, University of Rochester, Rochester, NY, United States
| | - Xing Qiu
- Department of Biostatistics and Computational Biology, University of Rochester, Rochester, NY, United States
| | - Giovanni Schifitto
- Department of Neurology, University of Rochester, Rochester, NY, United States
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, United States
- Department of Imaging Sciences, University of Rochester, Rochester, NY, United States
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Wang C, Reid G, Mackay CE, Hayes G, Bulte DP, Suri S. A Systematic Review of the Association Between Dementia Risk Factors and Cerebrovascular Reactivity. Neurosci Biobehav Rev 2023; 148:105140. [PMID: 36944391 DOI: 10.1016/j.neubiorev.2023.105140] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 02/15/2023] [Accepted: 03/15/2023] [Indexed: 03/23/2023]
Abstract
Cumulative evidence suggests that impaired cerebrovascular reactivity (CVR), a regulatory response critical for maintaining neuronal health, is amongst the earliest pathological changes in dementia. However, we know little about how CVR is affected by dementia risk, prior to disease onset. Understanding this relationship would improve our knowledge of disease pathways and help inform preventative interventions. This systematic review investigates 59 studies examining how CVR (measured by magnetic resonance imaging) is affected by modifiable, non-modifiable, and clinical risk factors for dementia. We report that non-modifiable risk (older age and apolipoprotein ε4), some modifiable factors (diabetes, traumatic brain injury, hypertension) and some clinical factors (stroke, carotid artery occlusion, stenosis) were consistently associated with reduced CVR. We also note a lack of conclusive evidence on how other behavioural factors such as physical inactivity, obesity, or depression, affect CVR. This review explores the biological mechanisms underpinning these brain- behaviour associations, highlights evident gaps in the literature, and identifies the risk factors that could be managed to preserve CVR in an effort to prevent dementia.
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Affiliation(s)
- Congxiyu Wang
- Department of Psychiatry, University of Oxford, UK; Wellcome Centre for Integrative Neuroimaging, University of Oxford, UK
| | - Graham Reid
- Department of Psychiatry, University of Oxford, UK; Department of Experimental Psychology, University of Oxford, UK
| | - Clare E Mackay
- Department of Psychiatry, University of Oxford, UK; Wellcome Centre for Integrative Neuroimaging, University of Oxford, UK
| | - Genevieve Hayes
- Institute of Biomedical Engineering, University of Oxford, UK
| | - Daniel P Bulte
- Institute of Biomedical Engineering, University of Oxford, UK
| | - Sana Suri
- Department of Psychiatry, University of Oxford, UK; Wellcome Centre for Integrative Neuroimaging, University of Oxford, UK.
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Arora Y, Dutta A. Human-in-the-Loop Optimization of Transcranial Electrical Stimulation at the Point of Care: A Computational Perspective. Brain Sci 2022; 12:1294. [PMID: 36291228 PMCID: PMC9599464 DOI: 10.3390/brainsci12101294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/05/2022] [Accepted: 09/18/2022] [Indexed: 11/17/2022] Open
Abstract
Individual differences in the responsiveness of the brain to transcranial electrical stimulation (tES) are increasingly demonstrated by the large variability in the effects of tES. Anatomically detailed computational brain models have been developed to address this variability; however, static brain models are not “realistic” in accounting for the dynamic state of the brain. Therefore, human-in-the-loop optimization at the point of care is proposed in this perspective article based on systems analysis of the neurovascular effects of tES. First, modal analysis was conducted using a physiologically detailed neurovascular model that found stable modes in the 0 Hz to 0.05 Hz range for the pathway for vessel response through the smooth muscle cells, measured with functional near-infrared spectroscopy (fNIRS). During tES, the transient sensations can have arousal effects on the hemodynamics, so we present a healthy case series for black-box modeling of fNIRS−pupillometry of short-duration tDCS effects. The block exogeneity test rejected the claim that tDCS is not a one-step Granger cause of the fNIRS total hemoglobin changes (HbT) and pupil dilation changes (p < 0.05). Moreover, grey-box modeling using fNIRS of the tDCS effects in chronic stroke showed the HbT response to be significantly different (paired-samples t-test, p < 0.05) between the ipsilesional and contralesional hemispheres for primary motor cortex tDCS and cerebellar tDCS, which was subserved by the smooth muscle cells. Here, our opinion is that various physiological pathways subserving the effects of tES can lead to state−trait variability, which can be challenging for clinical translation. Therefore, we conducted a case study on human-in-the-loop optimization using our reduced-dimensions model and a stochastic, derivative-free covariance matrix adaptation evolution strategy. We conclude from our computational analysis that human-in-the-loop optimization of the effects of tES at the point of care merits investigation in future studies for reducing inter-subject and intra-subject variability in neuromodulation.
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Affiliation(s)
- Yashika Arora
- Neuroimaging and Neurospectroscopy Lab, National Brain Research Centre, Gurgaon 122052, India
| | - Anirban Dutta
- Neuroengineering and Informatics for Rehabilitation and Simulation-Based Learning (NIRSlearn), University of Lincoln, Lincoln LN6 7TS, UK
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Differential regional cerebrovascular reactivity to end-tidal gas combinations commonly seen during anaesthesia: A blood oxygenation level-dependent MRI observational study in awake adult subjects. Ugeskr Laeger 2022; 39:774-784. [PMID: 35852545 DOI: 10.1097/eja.0000000000001716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Regional cerebrovascular reactivity (rCVR) is highly variable in the human brain as measured by blood oxygenation level-dependent (BOLD) MRI to changes in both end-tidal CO 2 and O 2 . OBJECTIVES We examined awake participants under carefully controlled end-tidal gas concentrations to assess how regional CVR changes may present with end-tidal gas changes seen commonly with anaesthesia. DESIGN Observational study. SETTING Tertiary care centre, Winnipeg, Canada. The imaging for the study occurred in 2019. SUBJECTS Twelve healthy adult subjects. INTERVENTIONS Cerebral BOLD response was studied under two end-tidal gas paradigms. First end-tidal oxygen (ETO 2 ) maintained stable whereas ETCO 2 increased incrementally from hypocapnia to hypercapnia (CO 2 ramp); second ETCO 2 maintained stable whereas ETO 2 increased from normoxia to hyperoxia (O 2 ramp). BOLD images were modeled with end-tidal gas sequences split into two equal segments to examine regional CVR. MAIN OUTCOME MEASURES The voxel distribution comparing hypocapnia to mild hypercapnia and mild hyperoxia (mean F I O 2 = 0.3) to marked hyperoxia (mean F I O 2 = 0.7) were compared in a paired fashion ( P < 0.005 to reach threshold for voxel display). Additionally, type analysis was conducted on CO 2 ramp data. This stratifies the BOLD response to the CO 2 ramp into four categories of CVR slope based on segmentation (type A; +/+slope: normal response, type B +/-, type C -/-: intracranial steal, type D -/+.) Types B to D represent altered responses to the CO 2 stimulus. RESULTS Differential regional responsiveness was seen for both end-tidal gases. Hypocapnic regional CVR was more marked than hypercapnic CVR in 0.3% of voxels examined ( P < 0.005, paired comparison); the converse occurred in 2.3% of voxels. For O 2 , mild hyperoxia had more marked CVR in 0.2% of voxels compared with greater hyperoxia; the converse occurred in 0.5% of voxels. All subjects had altered regional CO 2 response based on Type Analysis ranging from 4 ± 2 to 7 ± 3% of voxels. CONCLUSION In awake subjects, regional differences and abnormalities in CVR were observed with changes in end-tidal gases common during the conduct of anaesthesia. On the basis of these findings, consideration could be given to minimising regional CVR fluctuations in patients-at-risk of neurological complications by tighter control of end-tidal gases near the individual's resting values.
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11
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Deckers PT, Bhogal AA, Dijsselhof MB, Faraco CC, Liu P, Lu H, Donahue MJ, Siero JC. Hemodynamic and metabolic changes during hypercapnia with normoxia and hyperoxia using pCASL and TRUST MRI in healthy adults. J Cereb Blood Flow Metab 2022; 42:861-875. [PMID: 34851757 PMCID: PMC9014679 DOI: 10.1177/0271678x211064572] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Blood oxygenation level-dependent (BOLD) or arterial spin labeling (ASL) MRI with hypercapnic stimuli allow for measuring cerebrovascular reactivity (CVR). Hypercapnic stimuli are also employed in calibrated BOLD functional MRI for quantifying neuronally-evoked changes in cerebral oxygen metabolism (CMRO2). It is often assumed that hypercapnic stimuli (with or without hyperoxia) are iso-metabolic; increasing arterial CO2 or O2 does not affect CMRO2. We evaluated the null hypothesis that two common hypercapnic stimuli, 'CO2 in air' and carbogen, are iso-metabolic. TRUST and ASL MRI were used to measure the cerebral venous oxygenation and cerebral blood flow (CBF), from which the oxygen extraction fraction (OEF) and CMRO2 were calculated for room-air, 'CO2 in air' and carbogen. As expected, CBF significantly increased (9.9% ± 9.3% and 12.1% ± 8.8% for 'CO2 in air' and carbogen, respectively). CMRO2 decreased for 'CO2 in air' (-13.4% ± 13.0%, p < 0.01) compared to room-air, while the CMRO2 during carbogen did not significantly change. Our findings indicate that 'CO2 in air' is not iso-metabolic, while carbogen appears to elicit a mixed effect; the CMRO2 reduction during hypercapnia is mitigated when including hyperoxia. These findings can be important for interpreting measurements using hypercapnic or hypercapnic-hyperoxic (carbogen) stimuli.
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Affiliation(s)
- Pieter T Deckers
- Department of Neurosurgery, University Medical Center Utrecht, Utrecht, Netherlands
| | - Alex A Bhogal
- Department of Radiology, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands
| | - Mathijs Bj Dijsselhof
- Department of Radiology, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands.,Department of Radiology and Nuclear Medicine, Amsterdam Neuroscience, Amsterdam UMC (location VUmc), Amsterdam, Netherlands
| | - Carlos C Faraco
- Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Peiying Liu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Hanzhang Lu
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Manus J Donahue
- Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jeroen Cw Siero
- Department of Radiology, Center for Image Sciences, University Medical Center Utrecht, Utrecht, Netherlands.,Spinoza Centre for Neuroimaging, Amsterdam, Netherlands
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12
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Sayin ES, Sobczyk O, Poublanc J, Mikulis DJ, Fisher JA, Kuo KHM, Duffin J. Assessing Cerebrovascular Resistance in Patients With Sickle Cell Disease. Front Physiol 2022; 13:847969. [PMID: 35422710 PMCID: PMC9002264 DOI: 10.3389/fphys.2022.847969] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/08/2022] [Indexed: 02/05/2023] Open
Abstract
In patients with sickle cell disease (SCD) the delivery of oxygen to the brain is compromised by anemia, abnormal rheology, and steno-occlusive vascular disease. Meeting demands for oxygen delivery requires compensatory features of brain perfusion. The cerebral vasculature’s regulatory function and reserves can be assessed by observing the flow response to a vasoactive stimulus. In a traditional approach we measured voxel-wise change in Blood Oxygen-Level Dependent (BOLD) MRI signal as a surrogate of cerebral blood flow (CBF) in response to a linear progressive ramping of end-tidal partial pressure of carbon dioxide (PETCO2). Cerebrovascular reactivity (CVR) was defined as ΔBOLD/ΔPETCO2. We used a computer model to fit a virtual sigmoid resistance curve to the progressive CBF response to the stimulus, enabling the calculation of resistance parameters: amplitude, midpoint, range response, resistance sensitivity and vasodilatory reserve. The quality of the resistance sigmoid fit was expressed as the r2 of the fit. We tested 35 patients with SCD, as well as 24 healthy subjects to provide an indication of the normal ranges of the resistance parameters. We found that gray matter CVR and resistance amplitude, range, reserve, and sensitivity are reduced in patients with SCD compared to healthy controls, while resistance midpoint was increased. This study is the first to document resistance measures in adult patients with SCD. It is also the first to score these vascular resistance measures in comparison to the normal range. We anticipate these data will complement the current understanding of the cerebral vascular pathophysiology of SCD, identify paths for therapeutic interventions, and provide biomarkers for monitoring the progress of the disease.
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Affiliation(s)
- Ece Su Sayin
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
| | - Olivia Sobczyk
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - David J. Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Joseph A. Fisher
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
- Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Kevin H. M. Kuo
- Division of Hematology, Department of Medicine, University of Toronto, Toronto, ON, Canada
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
- *Correspondence: James Duffin,
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13
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Grey-box modeling and hypothesis testing of functional near-infrared spectroscopy-based cerebrovascular reactivity to anodal high-definition tDCS in healthy humans. PLoS Comput Biol 2021; 17:e1009386. [PMID: 34613970 PMCID: PMC8494321 DOI: 10.1371/journal.pcbi.1009386] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 08/28/2021] [Indexed: 12/12/2022] Open
Abstract
Transcranial direct current stimulation (tDCS) has been shown to evoke hemodynamics response; however, the mechanisms have not been investigated systematically using systems biology approaches. Our study presents a grey-box linear model that was developed from a physiologically detailed multi-compartmental neurovascular unit model consisting of the vascular smooth muscle, perivascular space, synaptic space, and astrocyte glial cell. Then, model linearization was performed on the physiologically detailed nonlinear model to find appropriate complexity (Akaike information criterion) to fit functional near-infrared spectroscopy (fNIRS) based measure of blood volume changes, called cerebrovascular reactivity (CVR), to high-definition (HD) tDCS. The grey-box linear model was applied on the fNIRS-based CVR during the first 150 seconds of anodal HD-tDCS in eleven healthy humans. The grey-box linear models for each of the four nested pathways starting from tDCS scalp current density that perturbed synaptic potassium released from active neurons for Pathway 1, astrocytic transmembrane current for Pathway 2, perivascular potassium concentration for Pathway 3, and voltage-gated ion channel current on the smooth muscle cell for Pathway 4 were fitted to the total hemoglobin concentration (tHb) changes from optodes in the vicinity of 4x1 HD-tDCS electrodes as well as on the contralateral sensorimotor cortex. We found that the tDCS perturbation Pathway 3 presented the least mean square error (MSE, median <2.5%) and the lowest Akaike information criterion (AIC, median -1.726) from the individual grey-box linear model fitting at the targeted-region. Then, minimal realization transfer function with reduced-order approximations of the grey-box model pathways was fitted to the ensemble average tHb time series. Again, Pathway 3 with nine poles and two zeros (all free parameters), provided the best Goodness of Fit of 0.0078 for Chi-Square difference test of nested pathways. Therefore, our study provided a systems biology approach to investigate the initial transient hemodynamic response to tDCS based on fNIRS tHb data. Future studies need to investigate the steady-state responses, including steady-state oscillations found to be driven by calcium dynamics, where transcranial alternating current stimulation may provide frequency-dependent physiological entrainment for system identification. We postulate that such a mechanistic understanding from system identification of the hemodynamics response to transcranial electrical stimulation can facilitate adequate delivery of the current density to the neurovascular tissue under simultaneous portable imaging in various cerebrovascular diseases.
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14
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Hemodynamic evaluation of patients with Moyamoya Angiopathy: comparison of resting-state fMRI to breath-hold fMRI and [ 15O]water PET. Neuroradiology 2021; 64:553-563. [PMID: 34570251 PMCID: PMC8850258 DOI: 10.1007/s00234-021-02814-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 09/09/2021] [Indexed: 11/27/2022]
Abstract
Purpose Patients with Moyamoya Angiopathy (MMA) require hemodynamic evaluation to assess the risk of stroke. Assessment of cerebral blood flow with [15O]water PET and acetazolamide challenge is the diagnostic standard for the evaluation of the cerebral perfusion reserve (CPR). Estimation of the cerebrovascular reactivity (CVR) by use of breath-hold-triggered fMRI (bh-fMRI) as an index of CPR has been proposed as a reliable and more readily available approach. Recent findings suggest the use of resting-state fMRI (rs-fMRI) which requires minimum patient compliance. The aim of this study was to compare rs-fMRI to bh-fMRI and [15O]water PET in patients with MMA. Methods Patients with MMA underwent rs-fMRI and bh-fMRI in the same MRI session. Maps of the CVR gained by both modalities were compared retrospectively by calculating the correlation between the mean CVR of 12 volumes of interest. Additionally, the rs-maps of a subgroup of patients were compared to CPR-maps gained by [15O]water PET. Results The comparison of the rs-maps and the bh-maps of 24 patients revealed a good correlation (Pearson’s r = 0.71 ± 0.13; preoperative patients: Pearson’s r = 0.71 ± 0.17; postoperative patients: Pearson’s r = 0.71 ± 0.11). The comparison of 7 rs-fMRI data sets to the corresponding [15O]water PET data sets also revealed a high level of agreement (Pearson’s r = 0.80 ± 0.19). Conclusion The present analysis indicates that rs-fMRI might be a promising non-invasive method with almost no patient cooperation needed to evaluate the CVR. Further prospective studies are required.
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15
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Keough JRG, Cates VC, Tymko MM, Boulet LM, Jamieson AN, Foster GE, Day TA. Regional differences in cerebrovascular reactivity in response to acute isocapnic hypoxia in healthy humans: Methodological considerations. Respir Physiol Neurobiol 2021; 294:103770. [PMID: 34343693 DOI: 10.1016/j.resp.2021.103770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/15/2021] [Accepted: 07/29/2021] [Indexed: 11/30/2022]
Abstract
The cerebrovasculature responds to blood gas challenges. Regional differences (anterior vs. posterior) in cerebrovascular responses to increases in CO2 have been extensively studied. However, regional cerebrovascular reactivity (CVR) responses to low O2 (hypoxia) are equivocal, likely due to differences in analysis. We assessed the effects of acute isocapnic hypoxia on regional CVR comparing absolute and relative (%-change) responses in the middle cerebral artery (MCA) and posterior cerebral artery (PCA). We instrumented 14 healthy participants with a transcranial Doppler ultrasound (cerebral blood velocity), finometer (beat-by-beat blood pressure), dual gas analyzer (end-tidal CO2 and O2), and utilized a dynamic end-tidal forcing system to elicit a single 5-min bout of isocapnic hypoxia (∼45 Torr PETO2, ∼80 % SpO2). During exposure to acute hypoxia, absolute responses were larger in the anterior compared to posterior cerebral circulation (P < 0.001), but were not different when comparing relative responses (P = 0.45). Consistent reporting of CVR to hypoxia will aid understanding normative responses, particularly in assessing populations with impaired cerebrovascular function.
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Affiliation(s)
- Joanna R G Keough
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Valerie C Cates
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Michael M Tymko
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada; Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada; Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Lindsey M Boulet
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada; Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Alenna N Jamieson
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Glen E Foster
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada.
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16
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Sobczyk O, Fierstra J, Venkatraghavan L, Poublanc J, Duffin J, Fisher JA, Mikulis DJ. Measuring Cerebrovascular Reactivity: Sixteen Avoidable Pitfalls. Front Physiol 2021; 12:665049. [PMID: 34305634 PMCID: PMC8294324 DOI: 10.3389/fphys.2021.665049] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 06/07/2021] [Indexed: 12/04/2022] Open
Abstract
An increase in arterial PCO2 is the most common stressor used to increase cerebral blood flow for assessing cerebral vascular reactivity (CVR). That CO2 is readily obtained, inexpensive, easy to administer, and safe to inhale belies the difficulties in extracting scientifically and clinically relevant information from the resulting flow responses. Over the past two decades, we have studied more than 2,000 individuals, most with cervical and cerebral vascular pathology using CO2 as the vasoactive agent and blood oxygen-level-dependent magnetic resonance imaging signal as the flow surrogate. The ability to deliver different forms of precise hypercapnic stimuli enabled systematic exploration of the blood flow-related signal changes. We learned the effect on CVR of particular aspects of the stimulus such as the arterial partial pressure of oxygen, the baseline PCO2, and the magnitude, rate, and pattern of its change. Similarly, we learned to interpret aspects of the flow response such as its magnitude, and the speed and direction of change. Finally, we were able to test whether the response falls into a normal range. Here, we present a review of our accumulated insight as 16 “lessons learned.” We hope many of these insights are sufficiently general to apply to a range of types of CO2-based vasoactive stimuli and perfusion metrics used for CVR.
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Affiliation(s)
- Olivia Sobczyk
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada.,Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - Jorn Fierstra
- Department of Neurosurgery, University Hospital Zurich, Zürich, Switzerland
| | - Lakshmikumar Venkatraghavan
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - James Duffin
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Joseph A Fisher
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
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17
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Poublanc J, Shafi R, Sobczyk O, Sam K, Mandell DM, Venkatraghavan L, Duffin J, Fisher JA, Mikulis DJ. Normal BOLD Response to a Step CO 2 Stimulus After Correction for Partial Volume Averaging. Front Physiol 2021; 12:639360. [PMID: 34194335 PMCID: PMC8236700 DOI: 10.3389/fphys.2021.639360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/26/2021] [Indexed: 11/26/2022] Open
Abstract
Cerebrovascular reactivity (CVR) is defined as the change in cerebral blood flow induced by a change in a vasoactive stimulus. CVR using BOLD MRI in combination with changes in end-tidal CO2 is a very useful method for assessing vascular performance. In recent years, this technique has benefited from an advanced gas delivery method where end-tidal CO2 can be targeted, measured very precisely, and validated against arterial blood gas sampling (Ito et al., 2008). This has enabled more precise comparison of an individual patient against a normative atlas of healthy subjects. However, expected control ranges for CVR metrics have not been reported in the literature. In this work, we calculate and report the range of control values for the magnitude (mCVR), the steady state amplitude (ssCVR), and the speed (TAU) of the BOLD response to a standard step stimulus, as well as the time delay (TD) as observed in a cohort of 45 healthy controls. These CVR metrics maps were corrected for partial volume averaging for brain tissue types using a linear regression method to enable more accurate quantitation of CVR metrics. In brief, this method uses adjacent voxel CVR metrics in combination with their tissue composition to write the corresponding set of linear equations for estimating CVR metrics of gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF). After partial volume correction, mCVR and ssCVR increase as expected in gray matter, respectively, by 25 and 19%, and decrease as expected in white matter by 33 and 13%. In contrast, TAU and TD decrease in gray matter by 33 and 13%. TAU increase in white matter by 24%, but TD surprisingly decreased by 9%. This correction enables more accurate voxel-wise tissue composition providing greater precision when reporting gray and white matter CVR values.
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Affiliation(s)
- Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - Reema Shafi
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - Olivia Sobczyk
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada.,Department of Anesthesia and Pain Management, University Health Network, Toronto, ON, Canada
| | - Kevin Sam
- Department of Radiology and Radiological Sciences, Johns Hopkins University, United States
| | - Daniel M Mandell
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | | | - James Duffin
- Department of Anesthesia and Pain Management, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Joseph A Fisher
- Department of Anesthesia and Pain Management, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
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18
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Differential regional cerebral blood flow reactivity to alterations in end-tidal gases in healthy volunteers. Can J Anaesth 2021; 68:1497-1506. [PMID: 34105067 DOI: 10.1007/s12630-021-02042-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 04/05/2021] [Accepted: 04/09/2021] [Indexed: 12/19/2022] Open
Abstract
PURPOSE Anesthesia is associated with alterations in end-tidal (ET) respiratory gases from the awake state. These alterations result in marked vasoactive changes in regional cerebral blood flow (rCBF). Altered regional cerebrovascular reactivity (rCVR) is linked to neurologic dysfunction. We examined these differences in reactivity from prior work by focusing on the ratio of vasoconstriction with hyperoxia/hypocapnia (HO/hc):vasodilation with hypercapnia (HC) using magnetic resonance imaging pseudo-continuous arterial spin labelling (pCASL) to measure rCBF and compare rCVR The distribution and magnitude of these ratios could provide insights into rCBF during clinical anesthesia and inform future research into the origins of postoperative delirium (POD). METHODS Ten healthy subjects underwent cerebral blood flow (CBF) studies using pCASL with computer-controlled delivery of ET gases to assess flow effects of hyperoxia, hypercapnia, and hyperoxia/hypocapnia as part of a larger study into cerebrovascular reactivity. The vasoconstrictor stimulus was compared with the vasodilator stimulus by the ratio HO/hc:HC. RESULTS Hyperoxia minimally decreased whole brain CBF by - 0.6%/100 mm Hg increase in ETO2. Hypercapnia increased CBF by +4.6%/mm Hg carbon dioxide (CO2) and with HO/hc CBF decreased by - 5.1%/mm Hg CO2. The brain exhibited markedly different rCVR-regional HO/hc:HC ratios varied from 7.2:1 (greater response to vasoconstriction) to 0.49:1 (greater response to vasodilation). Many of the ratios greater than 1, where vasoconstriction predominated, were seen in regions associated with memory, cognition, and executive function, including the entorhinal cortex, hippocampus, parahippocampus, and dorsolateral prefrontal cortex. CONCLUSIONS In awake humans, marked rCBF changes occurred with alterations in ET respiratory gases common under anesthesia. Such heterogeneous reactivity may be relevant to future studies to identify those at risk of POD.
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Sobczyk O, Sayin ES, Sam K, Poublanc J, Duffin J, Fisher JA, Mikulis DJ. The Reproducibility of Cerebrovascular Reactivity Across MRI Scanners. Front Physiol 2021; 12:668662. [PMID: 34025455 PMCID: PMC8134667 DOI: 10.3389/fphys.2021.668662] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/12/2021] [Indexed: 11/13/2022] Open
Abstract
Cerebrovascular reactivity (CVR) is defined as the ratio of the cerebral blood flow (CBF) response to an increase in a vasoactive stimulus. We used changes in blood oxygenation level-dependent (BOLD) MRI as surrogates for changes of CBF, and standardized quantitative changes in arterial partial pressure of carbon dioxide as the stimulus. Despite uniform stimulus and test conditions, differences in voxel-wise BOLD changes between testing sites may remain, attributable to physiologic and machine variability. We generated a reference atlas of normal CVR metrics (voxel-wise mean and SD) for each of two sites. We hypothesized that there would be no significant differences in CVR between the two atlases enabling each atlas to be used at any site. A total of 69 healthy subjects were tested to create site-specific atlases, with 20 of those individuals tested at both sites. 38 subjects were scanned at Site 1 (17F, 37.5 ± 16.8 y) and 51 subjects were tested at Site 2 (22F, 40.9 ± 17.4 y). MRI platforms were: Site 1, 3T Magnetom Skyra Siemens scanner with 20-channel head and neck coil; and Site 2, 3T HDx Signa GE scanner with 8-channel head coil. To construct the atlases, test results of individual subjects were co-registered into a standard space and voxel-wise mean and SD CVR metrics were calculated. Map comparisons of z scores found no significant differences between white matter or gray matter in the 20 subjects scanned at both sites when analyzed with either atlas. We conclude that individual CVR testing, and atlas generation are compatible across sites provided that standardized respiratory stimuli and BOLD MRI scan parameters are used. This enables the use of a single atlas to score the normality of CVR metrics across multiple sites.
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Affiliation(s)
- Olivia Sobczyk
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada.,Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada
| | - Ece Su Sayin
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Kevin Sam
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada
| | - James Duffin
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Joseph A Fisher
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
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20
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Hogan WJ, Moon-Grady AJ, Zhao Y, Cresalia NM, Nawaytou H, Quezada E, Brook M, McQuillen P, Peyvandi S. Fetal cerebrovascular response to maternal hyperoxygenation in congenital heart disease: effect of cardiac physiology. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2021; 57:769-775. [PMID: 32202689 PMCID: PMC7673795 DOI: 10.1002/uog.22024] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/23/2020] [Accepted: 03/13/2020] [Indexed: 06/10/2023]
Abstract
OBJECTIVE Fetal cerebrovascular resistance is influenced by several factors in the setting of intact autoregulation to allow for normal cerebral blood flow and oxygenation. Maternal hyperoxygenation (MH) allows for acute alterations in fetal physiology and can be a tool to test cerebrovascular reactivity in late-gestation fetuses. In this study, we utilized MH to evaluate cerebrovascular reactivity in fetuses with specific congenital heart disease (CHD). METHODS This was a cross-sectional study of fetuses with complex CHD compared to controls without CHD. CHD cases were grouped according to physiology into: left-sided obstructive lesion (LSOL), right-sided obstructive lesion (RSOL) or dextro-transposition of the great arteries (d-TGA). Subjects underwent MH testing during the third-trimester fetal echocardiogram. The pulsatility index (PI) was calculated for the fetal middle cerebral artery (MCA), umbilical artery (UA) and branch pulmonary artery (PA). The change in PI from baseline to during MH was compared between each CHD group and controls. RESULTS Sixty pregnant women were enrolled (CHD, n = 43; control, n = 17). In the CHD group, there were 27 fetuses with LSOL, seven with RSOL and nine with d-TGA. Mean gestational age was 33.9 (95% CI, 33.6-34.2) weeks. At baseline, MCA-PI Z-score was lowest in the LSOL group (-1.8 (95% CI, -2.4 to -1.2)) compared with the control group (-0.8 (95% CI, -1.3 to -0.3)) (P = 0.01). In response to MH, MCA-PI Z-score increased significantly in the control and d-TGA groups but did not change significantly in the LSOL and RSOL groups. The change in MCA-PI Z-score was significantly higher in the control group than in the LSOL group (0.9 (95% CI, 0.42-1.4) vs 0.12 (95% CI, -0.21 to 0.45); P = 0.03). This difference was more pronounced in the LSOL subgroup with retrograde aortic arch flow. Branch PA-PI decreased significantly in response to MH in all groups, with no difference in the change from baseline to MH between the groups, while UA-PI was unchanged during MH compared with at baseline. CONCLUSIONS The fetal cerebrovascular response to MH varies based on the underlying CHD diagnosis, suggesting that cardiovascular physiology may influence the autoregulatory capacity of the fetal brain. Further studies are needed to determine the clinical implications of these findings on long-term neurodevelopment in these at-risk children. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.
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Affiliation(s)
- W J Hogan
- Division of Pediatric Cardiology, Department of Pediatrics, The University of California San Francisco, San Francisco, CA, USA
| | - A J Moon-Grady
- Division of Pediatric Cardiology, Department of Pediatrics, The University of California San Francisco, San Francisco, CA, USA
| | - Y Zhao
- Division of Pediatric Cardiology, Department of Pediatrics, The University of California San Francisco, San Francisco, CA, USA
| | - N M Cresalia
- Division of Pediatric Cardiology, Department of Pediatrics, The University of California San Francisco, San Francisco, CA, USA
| | - H Nawaytou
- Division of Pediatric Cardiology, Department of Pediatrics, The University of California San Francisco, San Francisco, CA, USA
| | - E Quezada
- Division of Pediatric Cardiology, Department of Pediatrics, The University of California San Francisco, San Francisco, CA, USA
| | - M Brook
- Division of Pediatric Cardiology, Department of Pediatrics, The University of California San Francisco, San Francisco, CA, USA
| | - P McQuillen
- Division of Critical Care, Department of Pediatrics, The University of California San Francisco, San Francisco, CA, USA
| | - S Peyvandi
- Division of Pediatric Cardiology, Department of Pediatrics, The University of California San Francisco, San Francisco, CA, USA
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Fisher JA, Mikulis DJ. Cerebrovascular Reactivity: Purpose, Optimizing Methods, and Limitations to Interpretation - A Personal 20-Year Odyssey of (Re)searching. Front Physiol 2021; 12:629651. [PMID: 33868001 PMCID: PMC8047146 DOI: 10.3389/fphys.2021.629651] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 03/10/2021] [Indexed: 11/18/2022] Open
Abstract
The brain is a neurovascular organ. A stimulus-response approach is effective in interrogating the physiology of its vasculature. Ideally, the stimulus is standardized across patients, and in a single patient over time. We developed a standard stimulus and attempted to measure, classify, and interpret the many forms of responses. Over the past 20 years, our work has delivered nuanced insights into normal cerebral vascular physiology, as well as adaptive physiological responses in the presence of disease. The trajectory of our understanding did not follow a logical linear progression; rather, it emerged as a coalescence of new, old, and previously dismissed, ideas that had accumulated over time. In this essay, we review what we believe were our most valuable - and sometimes controversial insights during our two decades-long journey.
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Affiliation(s)
- Joseph A. Fisher
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - David J. Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
- The Joint Department of Medical Imaging, Toronto Western Hospital, University of Toronto, Toronto, ON, Canada
- Techna Institute & Koerner Scientist in MR Imaging, University Health Network, Toronto, ON, Canada
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22
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Kosiv KA, Moon-Grady A, Hogan W, Keller R, Rapoport R, Rogers E, Feldstein VA, Lee H, Peyvandi S. Fetal cerebrovascular impedance is reduced in left congenital diaphragmatic hernia. ULTRASOUND IN OBSTETRICS & GYNECOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY OF ULTRASOUND IN OBSTETRICS AND GYNECOLOGY 2021; 57:386-391. [PMID: 32068925 PMCID: PMC7431368 DOI: 10.1002/uog.21992] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 01/31/2020] [Accepted: 02/09/2020] [Indexed: 06/10/2023]
Abstract
OBJECTIVES Congenital diaphragmatic hernia (CDH) can cause a significant mass effect in the fetal thorax, displacing the heart into the opposite hemithorax. In left-sided CDH (L-CDH), this is associated with smaller left-sided cardiac structures and reduced left-ventricular cardiac output (LVCO). The effect of these physiologic changes on cerebral blood flow is not well understood. We sought to describe the middle cerebral artery (MCA) pulsatility index (PI), a measure of cerebrovascular impedance, in fetuses with L-CDH and those with right-sided CDH (R-CDH) compared with unaffected fetuses, and the relationship between MCA-PI and LVCO. We hypothesized that MCA-PI would be lower in fetuses with L-CDH and similar in those with R-CDH compared to controls, and that MCA-PI would be correlated with LVCO. METHODS We identified all fetuses with CDH evaluated at The University of California San Francisco, San Francisco, CA, USA from 2011 to 2018. Fetal echocardiograms and ultrasound scans were reviewed. Umbilical artery and MCA Doppler examinations were assessed to calculate pulsatility indices. Ventricular outputs were calculated using Doppler-derived stroke volume and fetal heart rate. Lung-to-head ratio (LHR), estimated fetal weight, biparietal diameter (BPD) and head circumference (HC) were obtained from fetal sonograms. Measurements in fetuses with CDH, according to the side of the defect, were compared with those in unaffected, gestational age-matched controls. A subset of CDH survivors had available data on neurodevelopmental outcome, as assessed using the Bayley Scales of Infant Development, 3rd edition. RESULTS A total of 64 fetuses with CDH (L-CDH, n = 53; R-CDH, n = 11) comprised the study groups, with 27 unaffected fetuses serving as controls. Mean gestational age at evaluation was similar between the three groups. Compared to controls, fetuses with L-CDH had significantly lower LVCO expressed as a percentage of combined cardiac output (CCO) (32%; 95% CI, 29-35% vs 38%; 95% CI, 33-42%; P = 0.04) and lower MCA-PI Z-score (-1.3; 95% CI, -1.7 to -1.0 vs 0.08; 95% CI, -0.5 to 0.6; P < 0.001), while they did not differ between the R-CDH group and controls. There was a strong positive association between LVCO as a percentage of CCO and MCA-PI Z-score in the overall cohort of CDH and control fetuses (P = 0.01). BPD and HC were similar between the three groups. At neurodevelopmental follow-up, mean cognitive, motor and language scores in the CDH group were within 1 SD of those in the general population. CONCLUSION MCA-PI values are significantly lower in fetuses with L-CDH as compared to controls, and lower LVCO was correlated with lower MCA vascular impedance. The neurodevelopmental effect of changes in MCA-PI in response to decreased LVCO is unknown, although, on average, CDH survivors had neurodevelopmental scores in the normal range. This may reflect a fetal compensatory mechanism in response to diminished antegrade cerebral blood flow. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.
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Affiliation(s)
- Katherine A. Kosiv
- The University of California, San Francisco Department of Pediatrics, Division of Pediatric Cardiology, San Francisco, CA
| | - Anita Moon-Grady
- The University of California, San Francisco Department of Pediatrics, Division of Pediatric Cardiology, San Francisco, CA
| | - Whitnee Hogan
- The University of California, San Francisco Department of Pediatrics, Division of Pediatric Cardiology, San Francisco, CA
| | - Roberta Keller
- The University of California, San Francisco Department of Pediatrics, Division of Neonatology, San Francisco, CA
| | - Rebecca Rapoport
- The University of California, San Francisco Department of Pediatrics, Division of Neonatology, San Francisco, CA
| | - Elizabeth Rogers
- The University of California, San Francisco Department of Pediatrics, Division of Neonatology, San Francisco, CA
| | - Vickie A. Feldstein
- The University of California, San Francisco Department of Pediatrics, Department of Radiology & Biomedical Imaging, San Francisco, CA
| | - Hanmin Lee
- The University of California, San Francisco Department of Pediatrics, Department of Surgery, San Francisco, CA
| | - Shabnam Peyvandi
- The University of California, San Francisco Department of Pediatrics, Division of Pediatric Cardiology, San Francisco, CA
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23
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Sleight E, Stringer MS, Marshall I, Wardlaw JM, Thrippleton MJ. Cerebrovascular Reactivity Measurement Using Magnetic Resonance Imaging: A Systematic Review. Front Physiol 2021; 12:643468. [PMID: 33716793 PMCID: PMC7947694 DOI: 10.3389/fphys.2021.643468] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 02/01/2021] [Indexed: 12/27/2022] Open
Abstract
Cerebrovascular reactivity (CVR) magnetic resonance imaging (MRI) probes cerebral haemodynamic changes in response to a vasodilatory stimulus. CVR closely relates to the health of the vasculature and is therefore a key parameter for studying cerebrovascular diseases such as stroke, small vessel disease and dementias. MRI allows in vivo measurement of CVR but several different methods have been presented in the literature, differing in pulse sequence, hardware requirements, stimulus and image processing technique. We systematically reviewed publications measuring CVR using MRI up to June 2020, identifying 235 relevant papers. We summarised the acquisition methods, experimental parameters, hardware and CVR quantification approaches used, clinical populations investigated, and corresponding summary CVR measures. CVR was investigated in many pathologies such as steno-occlusive diseases, dementia and small vessel disease and is generally lower in patients than in healthy controls. Blood oxygen level dependent (BOLD) acquisitions with fixed inspired CO2 gas or end-tidal CO2 forcing stimulus are the most commonly used methods. General linear modelling of the MRI signal with end-tidal CO2 as the regressor is the most frequently used method to compute CVR. Our survey of CVR measurement approaches and applications will help researchers to identify good practice and provide objective information to inform the development of future consensus recommendations.
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Affiliation(s)
- Emilie Sleight
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
| | - Michael S. Stringer
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom,*Correspondence: Michael S. Stringer
| | - Ian Marshall
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
| | - Joanna M. Wardlaw
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
| | - Michael J. Thrippleton
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom,UK Dementia Research Institute, Edinburgh, United Kingdom
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Duffin J, Mikulis DJ, Fisher JA. Control of Cerebral Blood Flow by Blood Gases. Front Physiol 2021; 12:640075. [PMID: 33679453 PMCID: PMC7930328 DOI: 10.3389/fphys.2021.640075] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 01/25/2021] [Indexed: 12/19/2022] Open
Abstract
Cerebrovascular reactivity can be measured as the cerebrovascular flow response to a hypercapnic challenge. The many faceted responses of cerebral blood flow to combinations of blood gas challenges are mediated by its vasculature's smooth muscle and can be comprehensively described by a simple mathematical model. The model accounts for the blood flow during hypoxia, anemia, hypocapnia, and hypercapnia. The main hypothetical basis of the model is that these various challenges, singly or in combination, act via a common regulatory pathway: the regulation of intracellular hydrogen ion concentration. This regulation is achieved by membrane transport of strongly dissociated ions to control their intracellular concentrations. The model assumes that smooth muscle vasoconstriction and vasodilation and hence cerebral blood flow, are proportional to the intracellular hydrogen ion concentration. Model predictions of the cerebral blood flow responses to hypoxia, anemia, hypocapnia, and hypercapnia match the form of observed responses, providing some confidence that the theories on which the model is based have some merit.
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Affiliation(s)
- James Duffin
- Department of Anesthesia and Pain Management, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Thornhill Research Inc., Toronto, ON, Canada
- University Health Network, Toronto, ON, Canada
| | - David J. Mikulis
- Division of Neuroradiology Imaging, Joint Department of Medical Imaging, University Health Network, Toronto, ON, Canada
| | - Joseph A. Fisher
- Department of Anesthesia and Pain Management, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Thornhill Research Inc., Toronto, ON, Canada
- University Health Network, Toronto, ON, Canada
- Faculty of Medicine, Institute of Medical Science, University of Toronto, Toronto, ON, Canada
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25
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Whitaker AA, Alwatban M, Freemyer A, Perales-Puchalt J, Billinger SA. Effects of high intensity interval exercise on cerebrovascular function: A systematic review. PLoS One 2020; 15:e0241248. [PMID: 33119691 PMCID: PMC7595421 DOI: 10.1371/journal.pone.0241248] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 10/11/2020] [Indexed: 12/23/2022] Open
Abstract
High intensity interval exercise (HIIE) improves aerobic fitness with decreased exercise time compared to moderate continuous exercise. A gap in knowledge exists regarding the effects of HIIE on cerebrovascular function such as cerebral blood velocity and autoregulation. The objective of this systematic review was to ascertain the effect of HIIE on cerebrovascular function in healthy individuals. We searched PubMed and the Cumulative Index to Nursing and Allied Health Literature databases with apriori key words. We followed the Preferred Reporting Items for Systematic Reviews. Twenty articles were screened and thirteen articles were excluded due to not meeting the apriori inclusion criteria. Seven articles were reviewed via the modified Sackett’s quality evaluation. Outcomes included middle cerebral artery blood velocity (MCAv) (n = 4), dynamic cerebral autoregulation (dCA) (n = 2), cerebral de/oxygenated hemoglobin (n = 2), cerebrovascular reactivity to carbon dioxide (CO2) (n = 2) and cerebrovascular conductance/resistance index (n = 1). Quality review was moderate with 3/7 to 5/7 quality criteria met. HIIE acutely lowered exercise MCAv compared to moderate intensity. HIIE decreased dCA phase following acute and chronic exercise compared to rest. HIIE acutely increased de/oxygenated hemoglobin compared to rest. HIIE acutely decreased cerebrovascular reactivity to higher CO2 compared to rest and moderate intensity. The acute and chronic effects of HIIE on cerebrovascular function vary depending on the outcomes measured. Therefore, future research is needed to confirm the effects of HIIE on cerebrovascular function in healthy individuals and better understand the effects in individuals with chronic conditions. In order to conduct rigorous systematic reviews in the future, we recommend assessing MCAv, dCA and CO2 reactivity during and post HIIE.
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Affiliation(s)
- Alicen A. Whitaker
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Mohammed Alwatban
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Andrea Freemyer
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Jaime Perales-Puchalt
- University of Kansas Alzheimer’s Disease Center, Fairway, KS, United States of America
- Department of Neurology, University of Kansas Medical Center, Kansas City, KS, United States of America
| | - Sandra A. Billinger
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS, United States of America
- Department of Neurology, University of Kansas Medical Center, Kansas City, KS, United States of America
- Department of Physical Medicine and Rehabilitation, University of Kansas Medical Center, Kansas City, KS, United States of America
- * E-mail:
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26
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Quelhas P, Baltazar G, Cairrao E. The Neurovascular Unit: Focus on the Regulation of Arterial Smooth Muscle Cells. Curr Neurovasc Res 2020; 16:502-515. [PMID: 31738142 DOI: 10.2174/1567202616666191026122642] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 09/01/2019] [Accepted: 09/20/2019] [Indexed: 02/08/2023]
Abstract
The neurovascular unit is a physiological unit present in the brain, which is constituted by elements of the nervous system (neurons and astrocytes) and the vascular system (endothelial and mural cells). This unit is responsible for the homeostasis and regulation of cerebral blood flow. There are two major types of mural cells in the brain, pericytes and smooth muscle cells. At the arterial level, smooth muscle cells are the main components that wrap around the outside of cerebral blood vessels and the major contributors to basal tone maintenance, blood pressure and blood flow distribution. They present several mechanisms by which they regulate both vasodilation and vasoconstriction of cerebral blood vessels and their regulation becomes even more important in situations of injury or pathology. In this review, we discuss the main regulatory mechanisms of brain smooth muscle cells and their contributions to the correct brain homeostasis.
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Affiliation(s)
- Patrícia Quelhas
- CICS-UBI - Centro de Investigacao em Ciencias da Saude, University of Beira Interior, 6200-506 Covilha, Portugal
| | - Graça Baltazar
- CICS-UBI - Centro de Investigacao em Ciencias da Saude, University of Beira Interior, 6200-506 Covilha, Portugal
| | - Elisa Cairrao
- CICS-UBI - Centro de Investigacao em Ciencias da Saude, University of Beira Interior, 6200-506 Covilha, Portugal
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27
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Klein T, Bailey TG, Wollseiffen P, Schneider S, Askew CD. The effect of age on cerebral blood flow responses during repeated and sustained stand to sit transitions. Physiol Rep 2020; 8:e14421. [PMID: 32378357 PMCID: PMC7202987 DOI: 10.14814/phy2.14421] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 03/20/2020] [Accepted: 03/21/2020] [Indexed: 12/02/2022] Open
Abstract
INTRODUCTION Aging is associated with impaired cerebrovascular blood flow and function, attributed to reduced vasodilatory capacity of the cerebrovascular network. Older adults may also have an impaired relationship between changes in blood pressure and cerebral blood flow; however, previous reports conflict. This study aimed to compare the blood pressure and cerebral blood flow responses to both repeated and sustained stand-to-sit transitions in young and older adults, and to assess the relationship with cerebrovascular reactivity. METHODS In 20 young (age: 24 ± 4 years) and 20 older (age: 71 ± 7 years) adults we compared middle cerebral artery flow velocity (MCAv), end-tidal partial pressure of carbon dioxide (PET CO2 ), and blood pressure (mean arterial blood pressure [MAP]) during repeated stand-to-sit (10 s standing and 10 s sitting) and sustained stand-to-sit (3 min standing followed by 2 min sitting) transitions. Cerebrovascular reactivity to changes in carbon dioxide levels was assessed using a repeated breath-hold test. RESULTS The % change in MCAv per % change in MAP (%∆MCAv/%∆MAP) was higher in the older adults than in the young adults during repeated stand-to-sit transitions. During the sustained protocol the %∆MCAv/%∆MAP response was similar in both age groups. A high %∆MCAv/%∆MAP response during the repeated stand-to-sit protocol was associated with low cerebrovascular reactivity to CO2 (r = -.39; p < .01), which was significantly lower in the older adults. CONCLUSION These findings suggest that the higher %∆MCAv/%∆MAP during repeated stand-sit transitions was associated with impaired cerebrovascular reactivity. Impairments in endothelial function and vascular stiffness with age may contribute to the altered transient cerebral pressure-flow responses in older adults.
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Affiliation(s)
- Timo Klein
- VasoActive Research GroupSchool of Health and Sport SciencesUniversity of the Sunshine CoastMaroochydore DCQLDAustralia
- Institute of Movement and NeuroscienceGerman Sport University CologneCologneGermany
| | - Tom G. Bailey
- VasoActive Research GroupSchool of Health and Sport SciencesUniversity of the Sunshine CoastMaroochydore DCQLDAustralia
- Centre for Research on ExercisePhysical Activity and HealthSchool of Human Movement and Nutrition SciencesThe University of QueenslandBrisbaneQLDAustralia
| | - Petra Wollseiffen
- Institute of Movement and NeuroscienceGerman Sport University CologneCologneGermany
| | - Stefan Schneider
- VasoActive Research GroupSchool of Health and Sport SciencesUniversity of the Sunshine CoastMaroochydore DCQLDAustralia
- Institute of Movement and NeuroscienceGerman Sport University CologneCologneGermany
| | - Christopher D. Askew
- VasoActive Research GroupSchool of Health and Sport SciencesUniversity of the Sunshine CoastMaroochydore DCQLDAustralia
- Sunshine Coast Health InstituteSunshine Coast Hospital and Health ServiceBirtinyaQLDAustralia
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28
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Mutch WAC, El-Gabalawy R, Ryner L, Puig J, Essig M, Kilborn K, Fidler K, Graham MR. Brain BOLD MRI O 2 and CO 2 stress testing: implications for perioperative neurocognitive disorder following surgery. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2020; 24:76. [PMID: 32131878 PMCID: PMC7057494 DOI: 10.1186/s13054-020-2800-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 02/18/2020] [Indexed: 12/17/2022]
Abstract
Background Mechanical ventilation to alter and improve respiratory gases is a fundamental feature of critical care and intraoperative anesthesia management. The range of inspired O2 and expired CO2 during patient management can significantly deviate from values in the healthy awake state. It has long been appreciated that hyperoxia can have deleterious effects on organs, especially the lung and retina. Recent work shows intraoperative end-tidal (ET) CO2 management influences the incidence of perioperative neurocognitive disorder (POND). The interaction of O2 and CO2 on cerebral blood flow (CBF) and oxygenation with alterations common in the critical care and operating room environments has not been well studied. Methods We examine the effects of controlled alterations in both ET O2 and CO2 on cerebral blood flow (CBF) in awake adults using blood oxygenation level-dependent (BOLD) and pseudo-continuous arterial spin labeling (pCASL) MRI. Twelve healthy adults had BOLD and CBF responses measured to alterations in ET CO2 and O2 in various combinations commonly observed during anesthesia. Results Dynamic alterations in regional BOLD and CBF were seen in all subjects with expected and inverse brain voxel responses to both stimuli. These effects were incremental and rapid (within seconds). The most dramatic effects were seen with combined hyperoxia and hypocapnia. Inverse responses increased with age suggesting greater risk. Conclusions Human CBF responds dramatically to alterations in ET gas tensions commonly seen during anesthesia and in critical care. Such alterations may contribute to delirium following surgery and under certain circumstances in the critical care environment. Trial registration ClincialTrials.gov NCT02126215 for some components of the study. First registered April 29, 2014.
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Affiliation(s)
- W Alan C Mutch
- Department of Anesthesiology, Perioperative and Pain Medicine, Max Rady College of Medicine, University of Manitoba, 2nd Floor, Harry Medovy House, 671 William Ave., Winnipeg, MB, R3E 0Z2, Canada. .,Canada North Concussion Network, .
| | - Renée El-Gabalawy
- Department of Anesthesiology, Perioperative and Pain Medicine, Max Rady College of Medicine, University of Manitoba, 2nd Floor, Harry Medovy House, 671 William Ave., Winnipeg, MB, R3E 0Z2, Canada.,Department of Clinical Health Psychology, University of Manitoba, Winnipeg, Canada
| | - Lawrence Ryner
- Canada North Concussion Network.,Department of Radiology, University of Manitoba, Winnipeg, Canada.,Department of Physics, University of Manitoba, Winnipeg, Canada
| | - Josep Puig
- Department of Radiology, University of Manitoba, Winnipeg, Canada
| | - Marco Essig
- Canada North Concussion Network.,Department of Radiology, University of Manitoba, Winnipeg, Canada
| | - Kayla Kilborn
- Department of Anesthesiology, Perioperative and Pain Medicine, Max Rady College of Medicine, University of Manitoba, 2nd Floor, Harry Medovy House, 671 William Ave., Winnipeg, MB, R3E 0Z2, Canada
| | - Kelsi Fidler
- Department of Anesthesiology, Perioperative and Pain Medicine, Max Rady College of Medicine, University of Manitoba, 2nd Floor, Harry Medovy House, 671 William Ave., Winnipeg, MB, R3E 0Z2, Canada
| | - M Ruth Graham
- Department of Anesthesiology, Perioperative and Pain Medicine, Max Rady College of Medicine, University of Manitoba, 2nd Floor, Harry Medovy House, 671 William Ave., Winnipeg, MB, R3E 0Z2, Canada.,Canada North Concussion Network
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Duffin J, Hare GM, Fisher JA. A mathematical model of cerebral blood flow control in anaemia and hypoxia. J Physiol 2020; 598:717-730. [DOI: 10.1113/jp279237] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 12/02/2019] [Indexed: 12/21/2022] Open
Affiliation(s)
- James Duffin
- Departments of Anaesthesia and PhysiologyUniversity of Toronto Toronto Ontario Canada
- Thornhill Research Inc. Toronto Ontario Canada
| | - Gregory M.T Hare
- Departments of Anaesthesia and PhysiologyUniversity of Toronto Toronto Ontario Canada
- Department of AnesthesiaKeenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St Michael's HospitalUnity Health Toronto Toronto Ontario Canada
| | - Joseph A. Fisher
- Departments of Anaesthesia and PhysiologyUniversity of Toronto Toronto Ontario Canada
- Thornhill Research Inc. Toronto Ontario Canada
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30
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Hoiland RL, Fisher JA, Ainslie PN. Regulation of the Cerebral Circulation by Arterial Carbon Dioxide. Compr Physiol 2019; 9:1101-1154. [DOI: 10.1002/cphy.c180021] [Citation(s) in RCA: 101] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Thiel S, Lettau F, Rejmer P, Rossi C, Haile S, Schwarz EI, Stöberl AS, Sievi NA, Boss A, Becker AS, Winklhofer S, Stradling JR, Kohler M. Effects of short-term continuous positive airway pressure withdrawal on cerebral vascular reactivity measured by blood oxygen level-dependent magnetic resonance imaging in obstructive sleep apnoea: a randomised controlled trial. Eur Respir J 2019; 53:13993003.01854-2018. [DOI: 10.1183/13993003.01854-2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/20/2018] [Indexed: 12/20/2022]
Abstract
Impaired cerebral vascular reactivity (CVR) increases long-term stroke risk. Obstructive sleep apnoea (OSA) is associated with peripheral vascular dysfunction and vascular events. The aim of this trial was to evaluate the effect of continuous positive airway pressure (CPAP) withdrawal on CVR.41 OSA patients (88% male, mean age 57±10 years) were randomised to either subtherapeutic or continuation of therapeutic CPAP. At baseline and after 2 weeks, patients underwent a sleep study and magnetic resonance imaging (MRI). CVR was estimated by quantifying the blood oxygen level-dependent (BOLD) MRI response to breathing stimuli.OSA did recur in the subtherapeutic CPAP group (mean treatment effect apnoea–hypopnoea index +38.0 events·h−1, 95% CI 24.2–52.0; p<0.001) but remained controlled in the therapeutic group. Although there was a significant increase in blood pressure upon CPAP withdrawal (mean treatment effect +9.37 mmHg, 95% CI 1.36–17.39; p=0.023), there was no significant effect of CPAP withdrawal on CVR assessedviaBOLD MRI under either hyperoxic or hypercapnic conditions.Short-term CPAP withdrawal did not result in statistically significant changes in CVR as assessed by functional MRI, despite the recurrence of OSA. We thus conclude that, unlike peripheral endothelial function, CVR is not affected by short-term CPAP withdrawal.
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