Prevalence of masked and nocturnal hypertension in patients with obstructive sleep apnea syndrome

Introduction: Obstructive sleep apnea (OSA) is considered as a risk factor for the development and worsening of compensation of arterial hypertension and other cardiovascular diseases. Prevalence of masked and nocturnal hypertension can have a significant negative impact on these patients and these prevalences are not well known. Aim: To evaluate the prevalence of masked and nocturnal hypertension in patients with OSA. Materials and methods: In this study, 97 (88 men) patients were enrolled, average age 53.9 +/- 9.7 years. OSA was diagnosed with polysomnography and the continuous positive airway pressure therapy has been indicated according to current guidelines. Then were evaluated parameters of OSA (apnea-hypopnea index (AHI), oxygen desaturation index (ODI), % of sleep time <90% SpO(2), average night SpO(2)). Patients also underwent physical examination including office blood pressure measurement, 24 h blood pressure monitoring (ABPM) and measurement of anthropometric parameters. Results: Following average values were present in OSA patients (mean value and standard deviation): AHI 54.6 +/- 22.7,ODI 58.3 +/- 24, % of sleep time <90% SpO(2) 35.4 +/- 25.1, average night SpO(2) 88.8 +/- 5. Masked hypertension was present in 55 (56.7%) patients, nocturnal hypertension in 79 (81.4%) patients. Arterial hypertension was appropriately compensated in only 15 (15.5%) patients. Results have not shown any statistically significant correlation between prevalence of nocturnal hypertension and AHI (p = 0.059), % of sleep time <90% SpO2 (p = 0.516), average night SpO(2) (p = 0.167). ODI was significantly higher in patients with nocturnal hypertension (p = 0.002). No correlation between prevalence of masked hypertension and AHI (p = 0.841), ODI (p = 0.137), average night SpO(2) (p = 0.991) and % of sleep time <90% SpO(2) (p = 0.896) has been present. Conclusion: This study has demonstrated high prevalence of masked and nocturnal hypertension in patients with OSA, which can considerably increase risks of cardiovascular diseases in these patients. (C) 2014 The Czech Society of Cardiology. Published by Elsevier Urban & Partner Sp.z.o.o. All rights reserved.