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The influence of gender and upper airway resistance on the ventilatory response to arousal in obstructive sleep apnoea in humans
Author(s) -
Jordan Amy S.,
McEvoy R. Doug,
Edwards Jill K.,
Schory Karen,
Yang ChangKook,
Catcheside Peter G.,
Fogel Robert B.,
Malhotra Atul,
White David P.
Publication year - 2004
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2004.064238
Subject(s) - non rapid eye movement sleep , anesthesia , medicine , arousal , continuous positive airway pressure , sleep and breathing , hyperventilation , sleep stages , airway resistance , sleep (system call) , obstructive sleep apnea , airway , apnea , polysomnography , psychology , electroencephalography , neuroscience , psychiatry , computer science , operating system
The termination of obstructive respiratory events is typically associated with arousal from sleep. The ventilatory response to arousal may be an important determinant of subsequent respiratory stability/instability and therefore may be involved in perpetuating obstructive respiratory events. In healthy subjects arousal is associated with brief hyperventilation followed by more prolonged hypoventilation on return to sleep. This study was designed to assess whether elevated sleeping upper airway resistance ( R UA ) alters the ventilatory response to arousal and subsequent breathing on return to sleep in patients with obstructive sleep apnoea (OSA). Inspired minute ventilation ( V I ), R UA and end‐tidal CO 2 pressure ( P ET,CO2 ) were measured in 22 patients (11 men, 11 women) with OSA (mean ± s.e.m. , apnoea–hypopnoea index (AHI) 48.9 ± 5.9 events h −1 ) during non‐rapid eye movement (NREM) sleep with low R UA (2.8 ± 0.3 cmH 2 O l −1 s; optimal continuous positive airway pressure (CPAP) = 11.3 ± 0.7 cmH 2 O) and with elevated R UA (17.6 ± 2.8 cmH 2 O l −1 s; sub‐optimal CPAP = 8.4 ± 0.8 cmH 2 O). A single observer, unaware of respiratory data, identified spontaneous and tone‐induced arousals of 3–15 s duration preceded and followed by stable NREM sleep. V I was compared between CPAP levels before and after spontaneous arousal in 16 subjects with tone‐induced arousals in both conditions. During stable NREM sleep at sub‐optimal CPAP, P ET,CO2 was mildly elevated (43.5 ± 0.8 versus 42.5 ± 0.8 Torr). However, baseline V I (7.8 ± 0.3 versus 8.0 ± 0.3 l min −1 ) was unchanged between CPAP conditions. For the first three breaths following arousal, V I was higher for sub‐optimal than optimal CPAP (first breath: 11.2 ± 0.9 versus 9.3 ± 0.6 l min −1 ). The magnitude of hypoventilation on return to sleep was not affected by the level of CPAP and both obstructive and central respiratory events were rare following arousal. Similar results occurred after tone‐induced arousals which led to larger responses than spontaneous arousals. V I for the first breath following arousal under optimal CPAP was greater in men than women (11.0 ± 0.4 versus 7.6 ± 0.6 l min −1 ). These results demonstrate that the ventilatory response to arousal is influenced by pre‐arousal airway resistance and gender. Whether this contributes to the perpetuation of respiratory events and the pathogenesis of OSA is unclear.