Masked Hypertension and Morning Blood Pressure Surge in Patients with Obstructive Sleep Apnea Syndrome

Objective: Frequent hypoxic episodes and arousal during sleep in obstructive sleep apnea syndrome (OSAS) result in increased nocturnal blood pressure, which in turn may lead to sustained hypertension. Patients with severe OSAS exhibit attenuated nocturnal blood pressure (BP) dipping, as well as marked and rapid BP elevation in the morning shortly after waking. We examined the prevalence of masked hypertension and morning BP surge in patients with OSAS, and the relationship between the severity of OSAS and abnormal circadian BP patterns.
Methods: We performed 24-hour ambulatory BP monitoring in the absence of antihypertensive medication on 26 patients with OSAS (49.3 ± 8.4 yrs) to investigate masked hypertension and morning BP surge.
Results: Results of the 26 patients, three (11.7%) were normotensive, six (23.0%) exhibited masked hypertension, and 17 (65.3%) were hypertensive. The apnea/hypopnea index was significantly correlated with 24-hour mean, daytime, and night time systolic and diastolic BP. 24-hour mean, daytime, and night time BPs in the severe OSAS group were significantly higher than in the mild to moderate OSAS group. We observed morning BP surge in 16 patients (61.5%). There were no significant differences in the prevalence of morning BP surge and masked hypertension between the mild to moderate and the severe OSAS groups.
Conclusion: Mild to moderate OSAS may play an important role in masked hypertension and morning BP surge.