|
1
|
Sayin ES, Davidian A, Levine H, Venkatraghavan L, Mikulis DJ, Fisher JA, Sobczyk O, Duffin J. Does breathing pattern affect cerebrovascular reactivity? Exp Physiol 2021; 107:183-191. [PMID: 34961983 DOI: 10.1113/ep090122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 12/22/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Is cerebrovascular reactivity affected by isocapnic changes in breathing pattern? What is the main finding and its importance? The main finding is that cerebrovascular reactivity does not change with isocapnic variations in tidal volume and frequency. ABSTRACT Deviations of arterial carbon dioxide tension from resting values affect cerebral blood vessel tone and thereby cerebral blood flow. Arterial carbon dioxide tension also affects central respiratory chemoreceptors, adjusting respiratory drive. This coincidence raises the question whether respiratory drive also affects the cerebral blood flow response to carbon dioxide. A change in cerebral blood flow for a given change in the arterial carbon dioxide tension is defined as cerebrovascular reactivity. Two studies have reached conflicting conclusions on this question, using voluntary control of breathing as a disturbing factor during measurements of cerebrovascular reactivity. Here we address some of the methodological limitations of both studies by using sequential gas delivery and targeted control of carbon dioxide and oxygen to enable a separation of the effects of carbon dioxide on cerebrovascular reactivity from breathing vigor. We confirm there is no detectable superimposed effect of breathing efforts on cerebrovascular reactivity. This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Ece Su Sayin
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, Canada.,Department of Physiology, University of Toronto, Toronto, Canada
| | - Anahis Davidian
- Department of Physiology, University of Toronto, Toronto, Canada
| | - Harrison Levine
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, Canada.,Department of Physiology, University of Toronto, Toronto, Canada
| | - Lashmi Venkatraghavan
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, Canada.,Department of Physiology, University of Toronto, Toronto, Canada
| | - David J Mikulis
- Institute of Medical Sciences, University of Toronto, Toronto, Canada.,Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, Canada
| | - Joseph A Fisher
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, Canada.,Department of Physiology, University of Toronto, Toronto, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, Canada
| | - Olivia Sobczyk
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, Canada.,Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory, University Health Network, Toronto, Canada
| | - James Duffin
- Department of Anaesthesia and Pain Management, University Health Network, Toronto, Canada.,Department of Physiology, University of Toronto, Toronto, Canada
| |
Collapse
|