Abstract
Background: The strong association between obstructive sleep apnea syndrome (OSAS) and systemic hypertension is well recognized in some epidemiological researches.
Objective: To analyze the relationship between hypertension and obstructive sleep apnea.
Methods: All hypertensive patients (n=25) who were BMI>25kg/m2 or had heavy snoring or excessive daytime sleepiness were examined with polysomnography (PSG). These subjects were classified according to data of apnea and hypopnea index (AHI). AHI was calculated as the total number of episodes of apnea and hypopnea per hour of sleep. An AHI≥5 to<20 indicated mild OSAS, 20≤to<40 indicated moderate OSAS, and≥40 indicated severe OSAS. These groups were then compared in terms of age, BMI, number of antihypertensive drugs used, blood pressure (BP) at out-patient clinic, lowest SaO2, mean SaO2, creatinine, uric acid, and lipids. PSG revealed all hypertensive patients (malel5, female10) to be OSAS patients (AHI>5). Patients (n=13) with moderate to severe OSAS (AHI>30/hr) were treated with nCPAP. 4 weeks after nCPAP was begun, blood pressure was measured between 10:00-12:00a.m. at our outpatient clinic.
Results: AHI was strongly associated with mean SaO2 and systolic BP. There was a significant positive relationship between medications for hypertension and AHI (r=0.46, P<0.05). After nCPAP treatment for 4 weeks, systolic BP was significantly reduced from 139.4±18.3mmHg to 120.9±7.7mmHg (P<0.05). Our results demonstrate that nCPAP is useful for lowering blood pressure in such patients with drug-resistant hypertension and OSAS.
