Blood Pressure May Be Lowered with CPAP

Treatment of obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP) may also lower blood pressure (BP) among hypertensive adults, according to a new study.

Researchers at University Hospital Arnau de Vilanova (Lleida, Spain) included 394 consecutive patients with high BP and non-sleepy OSA (OSA mild enough so that their daytime alertness was unaffected). The patients were randomized to receive either CPAP or no treatment. Blood pressure was measured at 3-, 6-, and 12-month follow-ups after their baseline evaluation.

The researchers found that, on average, patients who used the CPAP machine experienced an average 2 mm Hg drop in both systolic and diastolic blood pressure at the end of the year when compared to patients who did not use the CPAP machine. The patients for whom the effect was most pronounced used the CPAP machine for more than five hours a night. The study was presented at the American Thoracic Society's international conference, held during May 2008 in Toronto (Canada).

"The mechanism by which CPAP is able to effect a drop in blood pressure is complex and it is mainly related to a reduction in sympathetic tone, oxidative stress,” said Ferran E. Barbé, M.D. "This suggests that CPAP can not only be used to treat the symptoms of sleep apnea (daytime sleepiness), but also to reduce cardiovascular risk in apneic patients.”

Although the researchers do not yet know whether CPAP should be recommended for all OSA patients with high blood pressure and without daytime sleepiness, barring contraindications, the results point to the need for further study of the cardiovascular benefits of CPAP in OSA patients, as well as the effects of CPAP treatment on other cardiovascular outcomes such as stroke, myocardial infarction (MI), or heart failure.