by Michelle Rizzo

Last Updated: 2009-12-29 20:16:16 -0400 (Reuters Health)

NEW YORK (Reuters Health) – In hypertensive patients with obstructive sleep apnea (OSA), treatment with continuous positive airway pressure (CPAP) for 1 year reduces blood pressure, particularly in patients who use CPAP more than 5 hours per night, Spanish researchers have found.

"We suggest that CPAP could play a role in the management of hypertensive patients with sleep apnea," lead investigator Dr. Ferran Barbe, of Hospital University Arnau de Vilanova in Lleida told Reuters Health. "Sleep apnea is a cause of hypertension and around 40% of obese subjects with hypertension show a high number of apneas at night. By treating sleep disorders we can impact the pharmacological approach to hypertensive patients."

In a paper published online ahead of print in the American Journal of Respiratory and Critical Care Medicine, Dr. Barbe and colleagues report on a multicenter randomized controlled trial in which they assessed the long-term effects of 1 year of CPAP treatment in 359 hypertensive OSA patients. Each patient had an apnea-hypopnea index of greater than 19/h, no daytime hypersomnolence, and an Epworth Sleepiness Score <11. In addition, each was taking anti-hypertensive medication or had blood pressure above 140/90 mmHg.

One hundred seventy-eight patients were assigned to the CPAP arm. After adjustment for follow-up time, baseline blood pressure, apnea-hypopnea index, time with SaO2<90%, body mass index, and change in body mass index at follow-up, CPAP decreased systolic blood pressure by 1.89 mm Hg (p = 0.0654) and diastolic pressure by 2.19 mm Hg (p = 0.0008), the authors report.

However, they add, "This effect is only evident in patients that use CPAP more than 5.6 hours/night."

The investigators also point out that the patients in this cohort were not sleepy during the day, and among patients with OSA, those without daytime sleepiness need longer periods of CPAP to bring blood pressure down. Shorter term studies have never shown a significant effect of CPAP on blood pressure in a non-sleepy OSA cohort, they add.

"We have shown a decrease in blood pressure in non-sleepy patients after one year of treatment. These data could suggest that, in non-sleepy patients, CPAP needs more time to be effective," they write.

Am J Respir Crit Care Med 2009.