P082 Neural aperiodic activity as a novel biomarker of sleepiness in patients with obstructive sleep apnoea

Abstract Background Obstructive sleep apnoea (OSA) is characterised by repetitive collapse of the upper airway causing intermittent episodes of hypoxia and apnoeas during sleep. Excessive daytime sleepiness (EDS) is the cardinal symptom of OSA and presents in between 40.5 to 58% of patients. Currently, the diagnosis of OSA requires demonstration of an elevated apnoea hypopnea index (AHI) on a polysomnogram (PSG). Higher AHI scores denote increased OSA disease severity. The correlation between objective AHI scores and subjective sleepiness reporting tools such as the Epworth Sleepiness Scale (ESS) is less clear. Electroencephalogram (EEG) readings form an important component of PSG testing. Traditionally, the periodic oscillatory waves captured on EEG are examined to accurately identify stages of sleep. EEG aperiodic activity is a measure of neural excitation/inhibition ratios and has emerged as a novel objective measure of sleepiness. Methods Intended data collection from 500 patients who have undergone ambulatory PSG testing at the Royal Adelaide Hospital between January 1st 2021 and December 31st 2022 as part of their routine care. Data collection will include patient demographics, cardiorespiratory comorbidities, medications, body mass index (BMI), Epworth Sleepiness Scale (ESS) and PSG EEG data including sleep parameters [Total sleep time (TST), stage of sleep, periodic limb movement limb index (PLMI), AHI scores]. Progress to date Research proposal is currently under review by the CALHN HREC. Intended outcome and impact In this study we will assess the utility of aperiodic neural activity as a predictor of sleepiness in patients with elevated AHI and ESS scores.