O015 Autonomic Activations in Sleep: Tachycardic responses to nocturnal swallows and arousals in people with OSA

Abstract Introduction Nocturnal swallowing and cortical arousals from sleep both produce rapid transient heartrate increases driven by autonomic activation. Obstructive Sleep Apnoea (OSA) is associated with autonomic dysfunction and cardiovascular diseases, however, the underpinning mechanisms remain unclear. Here, we examine autonomic activation associated with swallowing and arousals during sleep in OSA. Methods Overnight sleep with epiglottic pressure data from a previous study were analyzed using custom semi-automated analysis scripts to extract variables for swallows and arousals during sleep. The following variables were extracted: average heartrate 30 seconds prior to a swallow or arousal and, peak heartrate 10 seconds afterwards, plus data on associated arousals and arousal duration, respiratory events preceding the swallow(s). Results 53 datasets were analyzed, including 6 controls, 12 mild, 17 moderate and 18 severe OSA subjects, in total: 2794 swallows and 9147 arousals. Across all samples, heartrate elevation was greater when swallows occurred in close succession (21.4bpm vs 14.7bpm, p<0.0001). Arousals with swallows produced larger heartrate elevations (17.0bpm vs 10.7bpm, p<0.0001) and prolonged duration by 6 seconds compared to arousals without swallows. Arousals during Rapid Eye Movement (REM) sleep also produced a higher heartrate increase (16.4bpm vs 12bpm, p<0.0001). Notably, the severe OSA group exhibited reduced magnitude of swallow and arousal heartrate increases (18.4bpm vs 22.3bpm and 11.9bpm vs 12.9bpm, p<0.0001). Discussion Individuals with severe OSA exhibited diminished magnitude of heartrate elevation responses to swallows and arousals. This finding potentially advances our comprehension of the underlying mechanisms of OSA with association with cardiovascular diseases.