Impact of Intermittent Nocturnal Hypoxia on Human Cerebral Autoregulation
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2021-11-23
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Abstract
Obstructive sleep apnea (OSA) is a common sleep disorder that has been identified as an independent risk factor for the development of cardiovascular and cerebrovascular disease. OSA-induced intermittent hypoxia (IH) has been shown to be the principal mediator of vascular disease, however the specific pathophysiological mechanisms through which IH impacts human physiology is not fully understood. Individuals with OSA have been shown to have impaired cerebral autoregulation (CA), which may be a possible mechanism leading to OSA being an independent risk factor for stroke, however no studies have directly investigated how IH impacts dynamic CA. In addition, the impact of IH on human physiology has been predominately investigated during wakefulness, while individuals with OSA are exposed to IH during sleep. Therefore, the focus of the thesis was to investigate the impact of nocturnal IH on CA in healthy humans, in an effort to further understand the mechanisms by which IH disrupts physiology. The pilot study conducted in this thesis was performed as a secondary data analysis to investigate the effectiveness of the dynamic CA in healthy humans, during the transition from wakefulness to sleep, during one night of nocturnal IH exposure and during acute IH vs prolonged IH exposure, using data previously published (1). The novel findings from this study demonstrated that the dynamic CA effectiveness was similar during non-rapid eye movement (NREM) stage 2/3 sleep as compared to wakefulness; however, the reported decrease in the variability of VP and MAP oscillations during NREM stage 2/3 may help explain why the prevalence of stroke is lower during the first half of sleep. In addition, one night of nocturnal IH exposure does not impair dynamic CA and prolonged nocturnal IH exposure may not impact dynamic CA differently than acute nocturnal IH exposure.
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Prsa, A. J. (2021). Impact of Intermittent Nocturnal Hypoxia on Human Cerebral Autoregulation (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.