Abstract 2991: Immediate Effect of CPAP on Morning Hypertension in Patients with Obstructive Sleep Apnea
BACKGROUND: Early morning blood pressure is generally recognized as an important therapeutic target and morning surge in blood pressure may lead to increase cardiovascular events in hypertensive patients. It is known that obstructive sleep apnea (OSA) very often associated with blood pressure surge. Because treatment of OSA may improve morning hypertension, we investigated the immediate effect of continuous positive airway pressure (CPAP).
METHODS: We screened 431 patients who took overnight polysomnography in our institute from January to December, 2005. All the subjects were in good general status and were not treated by antihypertensive agent. Blood pressures were obtained in the morning and in the evening before polysomnography. Diagnosis of polysomnography and CPAP treatment were done for two consecutive nights. Morning hypertension was defined as average BP ((morning BP + evening BP)/2) ≥ 135/85mmHg with blood pressure surge (morning BP-evening BP) ≥ 15/10mmHg.
RESULTS: Sixty two patients (14.3%) had morning hypertension. This group had higher BMI, apnea-hypopnea index and arousal index compared with normotensive group. With a single night CPAP treatment, both average BP (mean SBP: from 153.7 ± 10.8 to 141.4 ± 16.1mmHg, P < 0.01, mean DBP: 96.2 ± 8.8 to 87.6 ± 10.8mmHg, P < 0.01) and blood pressure surge (from 17.6 ± 11.6/15.5 ± 5.3 to 2.2 ± 23.6/6.5 ± 10.4mmHg, P < 0.01) were significantly decreased.
CONCLUSIONS: The rate of morning hypertension in patients with OSA was high, and it might relate to the etiology of cerebral vascular accident which risk is high in OSA patients. The observed improvement of morning hypertension by CPAP, especially the decrease of blood pressure surge, indicates that CPAP may reduce vascular events caused by morning hypertension in OSA patients.