Short-term blood pressure variability in hypertensive patients with obstructive sleep apnea syndrome

Abstract

Short-term blood pressure (BP) variability is an important cardiovascular risk factor. Whether patients with obstructive sleep apnea syndrome (OSAS) indeed display increased short-term BP variability and, if so, what is its underlying mechanism remain unclear. We compared the short-term BP variability between hypertensive patients with OSAS (OSAS group; n= 212) and those without OSAS (control group; n = 82) by examining data of 24-h ambulatory BP monitoring (ABPM) and investigated the effects of continuous positive airway pressure (CPAP) therapy on short-term BP variability in 37 hypertensive patients with OSAS. Short-term BP variability was calculated with the average real variability (ARV) of awake and sleep BP. ARVs of sleep systolic BP (SBP) and diastolic BP (DBP) were significantly higher in the OSAS group than in the control group. There was no significant difference in ARVs of awake SBP and DBP between the two groups. In the OSAS group, multiple regression analyses revealed that the body mass index (BMI) was an independent determinant for ARV of sleep DBP and that the lowest SpO2 was an independent determinant for ARVs of sleep SBP and sleep DBP. CPAP therapy decreased ARVs of sleep SBP and DBP. These results suggested that higher short-term BP variability during sleep is a characteristic feature of hypertensive patients with OSAS and that obesity and hypoxemia play essential roles in increasing short-term BP variability during sleep. CPAP therapy may improve exaggerated short-term BP variability during sleep in patients with OSAS.