PP.37.01

Abstract

Objective: Sympathetic activity is suspected to be an underlying mechanism in obstructive sleep apnea (OSA) and morning blood pressure (BP) surge (MS). Few studies have evaluated the association between OSA and MS.Design and method: This study aimed to examine the association between OSA and MS in never-treated subjects with essential hypertension. This prospective study included a total of 58 patients (mean age: 51.7 years; 55.2% male) with never-treated essential hypertension. The patients were divided into non-OSA (n = 23, 49.3 ± 12.7 years) and OSA (n = 35, 53.2 ± 9.8 years) groups. The OSA group was defined as having an apnea-hypopnea index (AHI) level > 5 measured by the WATCH-PAT200. We collected the 24-hour ambulatory BP, pulse wave velocity, ankle brachial index, plasma aldosterone concentration (PAC), and plasma renin activity (PRA) from all of the patients. Results: The measured sleep-trough morning systolic blood pressure (SBP) increases were higher in the OSA group than in the non-OSA group (28.7 ± 11.8 mmHg vs. 19.6 ± 12.8 mmHg, P = 0.008). The sleep-trough morning SBP increase was inversely correlated with the lowest O2 saturation (r = −0.272, P = 0.039). The AHI was correlated with the morning SBP and DBP(r = 0.281, P = 0.032)(r = 0.319, P = 0.015). The OSA group had greater day, night, and 24-hour SBP than the non-OSA group. Additionally, there were no differences of PAC, PRA, and aldosterone-renin ratio (PAC/PRA) between groups. Conclusions: OSA known to be associated with increased daytime and nocturnal sympathetic activity was associated with significantly higher sleep-trough morning SBP levels in this study.