O027 Patterns of nocturnal swallow frequency and related tachycardia with sleep stages and obstructive sleep apnoea severity

BACKGROUND: Swallowing is a complex activity associated with cortical arousal and tachycardia in sleep(1). Obstructive sleep apnoea (OSA) has been associated with dysfunction and altered biomechanics of swallow (2-3). This study seeks to investigate patterns of swallow frequency and associated tachycardia in relation to OSA severity. METHODS: Anthropometric and polysomnographic data for 70 subjects were analysed. Swallow index (SI; swallows per hour) and average heart rate changes from 30 seconds pre- to 10 seconds post-swallow were derived from epiglottic pressure and electrocardiogram signals respectively. This study had approval from the local district ethics committee. PROGRESS TO DATE: Analysis has been completed for 34 subjects (median age 47.5, range 24-64; 24 males), most with at least moderate OSA (n=20/26). Mean SI was 3.2 in subjects without OSA (n=2), 8 in mild OSA (n=4), 5.8 in moderate OSA (n=10) and 9 in severe OSA (n=10). Mean swallow-related tachycardia was 24.3bpm in subjects without OSA, compared to 14.0bpm in those with severe OSA. Mean swallow-related tachycardia increased with progressive sleep stages (14.8bpm in wakefulness; 16.8bpm Stage 1; 16.8bpm Stage 2; 19.0bpm Stage 3; 19.4bpm in REM). A negative correlation was observed between sleep SI and magnitude of associated tachycardia (Pearson correlation r=-0.387, p=0.026). INTENDED OUTCOME AND IMPACT: Our results support existing observations that swallow-associated tachycardia is reliably conserved in sleep, and suggest possible new relationships between swallow frequency and associated tachycardia with OSA severity and sleep stage. We intend with further dataset analyses to explore relationships between sleep swallow physiology and OSA pathophysiology.