Sleep Apnea: Treatment May Help Keep BP Low
CPAP Linked to Lower Hypertension Risk, but Questions Remain
May 22, 2012 -- People with obstructive sleep apnea have an increased risk for high blood pressure and heart disease, and now two new studies suggest that treating the disorder may lower this risk.
In one study, patients with obstructive sleep apnea who slept with continuous positive airway pressure (CPAP) treatment appeared to have a reduced risk for developing high blood pressure.
Another study that included patients who used a CPAP machine for more than four hours a night, but not less, appeared to have a lower high blood pressure risk.
Obstructive sleep apnea occurs when the airways become narrowed or blocked during sleep, leading to pauses in breathing from a few times a night to hundreds of times.
CPAP opens airways by forcing air into the nostrils through a mask worn while sleeping.
The studies, published today in the Journal of the American Medical Association, add to the evidence that positive air pressure treatment lowers heart risk in patients with obstructive sleep apnea -- but important questions remain, experts say.
"We know that obstructive sleep apnea is a potential cause of high blood pressure, and we know that CPAP use is associated with reductions in blood pressure in people with hypertension," says sleep specialist Vishesh K. Kapur, MD, of the University of Washington, Seattle. "And now there is reasonable evidence that this treatment can prevent high blood pressure in patients who don't already have it."
Sleep Apnea Often Not Diagnosed
Almost 1 in 5 adults in the United States has mild to severe sleep apnea, but only about 10% have been diagnosed with the disorder.
CPAP has been shown to improve quality of life and daytime sleepiness, but adherence is an issue because many patients find the masks too uncomfortable to wear.
While studies strongly suggest a causal role for obstructive sleep apnea in high blood pressure, confirming the association has been difficult because the disorder is common in people with other risk factors for high blood pressure, such as obesity.
In one of the newly published studies, researchers from Lleida, Spain's, Institut de Recerca Biomedica recruited around 700 sleep apnea patients and treated half with CPAP.
At a follow-up of around four years, patients treated with CPAP had a slightly lower incidence of high blood pressure, heart attack, stroke, and other heart-related events than patients not treated with CPAP, but the difference was not found to be significant -- a finding the researchers themselves admitted, though, might have had a more positive outcome if the study had been longer or had more participants.
Use of CPAP for more than four hours per night did however appear to lower high blood pressure risk, suggesting that adherence with treatment may be critical in this group of patients.