Impact of intermittent hypoxia on human vascular responses during sleep

Andrew E Beaudin; Patrick J Hanly; Jill K Raneri; Magdy Younes; Matiram Pun; Todd J Anderson; Marc J Poulin

doi:10.1016/j.expneurol.2021.113897

Impact of intermittent hypoxia on human vascular responses during sleep

Exp Neurol. 2022 Jan:347:113897. doi: 10.1016/j.expneurol.2021.113897. Epub 2021 Oct 13.

Authors

Andrew E Beaudin¹, Patrick J Hanly², Jill K Raneri³, Magdy Younes⁴, Matiram Pun¹, Todd J Anderson⁵, Marc J Poulin⁶

Affiliations

¹ University of Calgary, Cumming School of Medicine, Department of Physiology and Pharmacology, 3330 Hospital Drive N.W., Calgary, Alberta T2N 4N1, Canada; Hotchkiss Brain Institute, University of Calgary, Cumming School of Medicine, 3330 Hospital Drive N.W., Calgary, Alberta T2N 4N1, Canada.
² Hotchkiss Brain Institute, University of Calgary, Cumming School of Medicine, 3330 Hospital Drive N.W., Calgary, Alberta T2N 4N1, Canada; University of Calgary, Cumming School of Medicine, Department of Medicine, 3330 Hospital Drive N.W., Calgary, Alberta T2N 4N1, Canada; Sleep Centre, Foothills Medical Centre, 1403 29 St NW, Calgary, Alberta T2N 2T9, Canada.
³ Sleep Centre, Foothills Medical Centre, 1403 29 St NW, Calgary, Alberta T2N 2T9, Canada.
⁴ University of Manitoba, Department of Medicine, 1105-255 Wellington Crescent, Winnipeg, Manitoba R3M 3V4, Canada.
⁵ University of Calgary, Cumming School of Medicine, Department of Cardiac Science, 3330 Hospital Drive N.W., Calgary, Alberta T2N 4N1, Canada; Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
⁶ University of Calgary, Cumming School of Medicine, Department of Physiology and Pharmacology, 3330 Hospital Drive N.W., Calgary, Alberta T2N 4N1, Canada; Hotchkiss Brain Institute, University of Calgary, Cumming School of Medicine, 3330 Hospital Drive N.W., Calgary, Alberta T2N 4N1, Canada; Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada. Electronic address: poulin@ucalgary.ca.

PMID: 34655575
DOI: 10.1016/j.expneurol.2021.113897

Abstract

Exposure to intermittent hypoxia (IH) ≥15 times per hour is believed to be the primary mechanism for the increased risk of cerebrovascular and cardiovascular disease in patients with moderate to severe sleep apnea. Human experimental models of IH used to investigate this link have been predominantly employed during wakefulness, which limits extrapolation of findings to sleep apnea where IH occurs during sleep. Moreover, how IH impacts vascular regulation during sleep has not been measured quantitatively. Therefore, the objective of this study was to assess the impact sleep accompanied by IH on vascular responses to hypoxia and hypercapnia during sleep. Ten males performed two randomly scheduled 6-h overnight sleep studies. One sleep study was performed in room air (normoxia) and the other sleep study was performed during isocapnic IH (60 s hypoxia-60 s normoxia). On each night, cerebrovascular (peak blood velocity through the middle cerebral artery (V¯_P); transcranial Doppler ultrasound) and cardiovascular (blood pressure, heart rate) responses to hypoxia and hypercapnia were measured before sleep onset (PM-Awake), within the first 2 h of sleep (PM-Asleep), in the 5th (out of 6) hours of sleep (AM-Asleep) and after being awoken in the morning (AM-Awake). Sleep accompanied by IH had no impact on the V¯_P and blood pressure responses to hypoxia and hypercapnic at any timepoint (p ≥ 0.103 for all responses). However, the AM-Awake heart rate response to hypoxia was greater following sleep in IH compared to sleep in normoxia. Independent of the sleep environment, the V¯_P response to hypoxia and hypercapnia were reduced during sleep. In conclusion, cerebral blood flow responses are reduced during sleep compared to wakefulness, but 6 h of sleep accompanied by IH does not alter cerebrovascular and cardiovascular response to hypoxia and hypercapnia during wakefulness or sleep in healthy young humans. However, it is likely that longer exposure to IH during sleep (i.e., days-to-weeks) is required to better elucidate IH's impact on vascular regulation in humans.

Keywords: Blood pressure; Cardiovascular; Cerebral blood flow; Cerebrovascular; Heart rate; Hypercapnia; Intermittent hypoxia; Sleep; Sleep apnea.

Publication types

Research Support, Non-U.S. Gov't
Review

MeSH terms

Adult
Blood Pressure / physiology*
Cerebrovascular Circulation / physiology*
Cohort Studies
Continuous Positive Airway Pressure / methods*
Humans
Hypoxia / diagnosis
Hypoxia / physiopathology*
Male
Polysomnography / methods
Sleep / physiology*
Sleep Apnea Syndromes / diagnosis
Sleep Apnea Syndromes / physiopathology
Young Adult

Grants and funding

CIHR/Canada