0529 Reduced Forearm Skin Conductance Responses During Obstructive Apnea Event in Patients with OSA

Abstract Introduction Electrodermal activity (EDA) measured on the palm has been used as a physiological indicator of sympathetic nervous activity. Previous studies in healthy individuals have reported that skin conductance responses (SCRs), a phasic component of EDA, occur most frequently during deep sleep (N3), although evidence in Obstructive Sleep Apnea (OSA) patients remains limited. We hypothesized that similar patterns would appear in OSA. This study aimed to characterize forearm SCR patterns in OSA patients and to evaluate their utility as markers of sleep stages and respiratory events, including obstructive apneas and hypopneas. Methods Nine OSA patients underwent simultaneous polysomnography and skin conductance monitoring. Skin conductance was recorded with a wearable device using a nano-mesh dry electrode, providing breathability and flexibility. SCR counts were defined as the number of times that skin conductance derivative exceeds a predefined threshold per 30-s epoch. A relative threshold (median + 3×MAD) was used for within-subject analysis and an absolute threshold (0.01 μS/s) for between-subject comparisons. Results In the pooled within-subject analysis across all patients, SCR counts (mean ± SE) increased with sleep stage, following Wake < N1 < REM < N2 < N3 (0.85 ± 0.15 < 1.25 ± 0.22 < 1.32 ± 0.33 < 2.00 ± 0.35 < 3.18 ± 0.77; Friedman χ2 = 13.30, p < 0.05). SCR counts also varied across respiratory conditions, following obstructive apneas < hypopneas < normal breathing (1.02 ± 0.60 < 1.58 ± 0.30 < 2.11 ± 0.31), and obstructive apneas consistently yielded the lowest SCR counts across sleep stages (N1, N2, N3, REM). In the between-subject analysis, the nightly mean SCR counts calculated for each participant showed a strong negative correlation with the proportion of abnormal breathing time (r = −0.70, p < 0.05). Conclusion This study provides the first evidence that SCRs decrease during obstructive apnea events in OSA patients and that individuals with more frequent apnea/hypopnea events show fewer SCRs across the night. Given its compatibility with wearable devices, forearm EDA during sleep may serve as a useful indicator of sleep quality, reflecting deeper sleep and reduced abnormal respiratory time, for future high-accuracy, home-based sleep monitoring. Support (if any)