The Relative Contributions of Arousal Presence and Arousal Intensity to Post-Respiratory-Event Ventilation in Obstructive Sleep Apnea.

Obstructive sleep apnea (OSA) is characterised by cyclical respiratory events followed by hyperpneic breaths that frequently coincide with cortical arousals. Whilst this post-event hyperventilation partly reflects accumulated respiratory stimuli, arousal itself appears to contribute independently through both its presence and its intensity. This study aimed to quantify the relative contributions of arousal presence and arousal intensity to post-event ventilation, independent of chemoreflex-driven responses. Two retrospective polysomnography data sets were analysed: a community-based cohort (Multi-Ethnic Study of Atherosclerosis, MESA; N = 1781 included) and a Physiological Study data set (N = 67). For every obstructive respiratory event, arousal presence (0/1), arousal intensity (range 0 to 9) and post-event ventilation were derived for each event, and mixed-effects linear models were used to examine their associations at both the inter-event and inter-participant levels. At the inter-event level, arousal presence at event termination increased ventilation by 17-30%Eupnea (increase above eupneic baseline) in both data sets, with each step increment in arousal intensity contributing an additional 1-4%Eupnea. At the inter-participant level, each step increment in overnight mean arousal intensity was associated with a 2-4%Eupnea increase in the ventilatory response to arousal in both data sets. These findings demonstrate that arousal presence plays an important role in post-event hyperventilation in OSA, with arousal intensity exerting a modest effect per increment but a substantial cumulative effect across the full 0-9 scale. Consistent across both data sets, the results suggest a mechanistic pathway to post-event hyperventilation distinct from chemoreflex stimulation.