“Non-dipping” blood pressure and excessive daytime sleepiness in severe obstructive sleep apnea

Abstract

Background: Non-dipping blood pressure and obstructive sleep apnea both carry an increased risk of cardiovascular events and mortality. The relationship between non-dipping blood pressure and obstructive sleep apnea has been noted. However, data on the prevalence of sleep apnea with non-dipping hypertension and the relationship with excessive daytime sleepiness are limited. Objective: The purpose of the present study was to determine the prevalence of nondipping blood pressure and evaluate the relationship with excessive daytime sleepiness. Patients and Methods: We prospectively enrolled adult patients with habitual snoring who visited our sleep clinics from November 2010 to May 2013. Polysomnography and 24-hour ambulatory blood pressure monitoring (ABPM) were used. Excessive daytime sleepiness was evaluated. The prevalence of non-dipping blood pressure and the relationship with excessive daytime sleepiness were evaluated. Results: Thirty patients were dippers (57%) and 23 (43%) were non-dippers. Nondippers had lower nighttime blood pressure and more excessive daytime sleepiness (Epworth sleepiness scale (ESS) ≥10) than dippers (p=0.045). ESS was significantly negatively correlated with dipping of systolic and diastolic blood pressure and mean arterial pressure, R=-0.313, -0.304, -0.302, respectively (p ＜ 0.05). Multivariate linear regression models for associations involving systolic blood pressure dipping showed that ESS was the only independent predictor of systolic blood pressure dipping [β=-0.005, p=0.022, R^2=0.099, 95% confidence interval (CI) of β=-0.009-0.000] in stepwise linear regression analyses. Conclusions: High prevalence of non-dippers was noted in severe obstructive sleep apnea patients. Non-dippers experienced more excessive daytime sleepiness. ESS was an independent predictor of dipping values. ABPM may play an important role in these high cardiovascular risk groups.