Refractory hypertension and sleep apnoea: effect of CPAP on blood pressure and baroreflex.

This study was undertaken to determine whether abolition of obstructive sleep apnoea (OSA) by continuous positive airway pressure (CPAP) could reduce blood pressure (BP) in patients with refractory hypertension. In 11 refractory hypertensive patients with OSA, the acute effects of CPAP on nocturnal BP were studied during sleep and its longer term effects on 24-h ambulatory BP after 2 months. During a single night's application, CPAP abolished OSA and reduced systolic BP in stage 2 sleep from 138.3 +/- 6.8 to 126.0 +/- 6.3 mmHg. There was also a trend towards a reduction in average diastolic BP (from 77.7 +/- 4.5 to 72.9 +/- 4.5). CPAP usage for 2 months was accompanied by an 11.0 +/- 4.4 mmHg reduction in 24-h systolic BP. In addition, both the nocturnal and daytime components of systolic BP fell significantly by 14.4 +/- 4.4 and 9.3 +/- 3.9 mmHg, respectively. Diastolic BP was reduced significantly at night by 7.8 +/- 3.0 mmHg. In patients with refractory hypertension, acute abolition of obstructive sleep apnoea by continuous positive airway pressure reduces nocturnal blood pressure. These data also suggest that continuous positive airway pressure may reduce nocturnal and daytime systolic blood pressure chronically. Randomised trials are needed to confirm the latter results.