Hypertension and obstructive sleep apnea - Ambulatory blood pressure monitoring before and with nCPAP-therapy

We studied 24-h blood pressure (BP) in 17 hypertensive patients with polysomnographic verified moderate to severe obstructive sleep apnea (OSA) before, after 1-3 days and after 4-6 months of treatment with nasal continuous positive airway pressure (nCPAP). BP was recorded using an ambulatory blood pressure monitoring (ABPM) device with oscillometric measurement method (SpaceLabs 90207) over a period of 24 h with intervals of 15 min in daytime and nighttime. Hypertension was defined as mean BP in the daytime period > 135/85 mm Hg; OSA was diagnosed when a full night polysomnography indicated an apnea hypopnea index (AHI) > 10/h. Hypertensive systolic/diastolic daytime BP values decreased significantly from 144.8/94.4 mm Hg at baseline to 138.9/89.4 mm Hg after short-term, and to 136.4/86.9 mm Hg after long-term nCPAP-therapy. Nighttime BP values, too, were reduced significantly from 137.6/87.1 mm Hg at baseline to 129.9/82.3 mm Hg after short-term, and to 128.6/79.8 mm Hg after long-term therapy. In addition to these data the heart rate fell significantly from 82.5 b/min to 74.8 b/min after 4-6 months in daytime, and from 70.9 b/min to 63.6 b/min in night-time. The beneficial effect on diurnal and nocturnal hypertension in patients with nCPAP-therapy of OSA suggests a causal relationship between systemic hypertension and obstructive sleep apnea.