Megan Brooks

June 03, 2014

MINNEAPOLIS — Continuous positive airway pressure (CPAP) therapy leads to a rapid improvement in blood pressure and arterial tone in adults with obstructive sleep apnea (OSA), results of a new study show.

The researchers found a significant reduction in systolic and diastolic blood pressure in a group of relatively young, healthy patients with OSA who were compliant with CPAP therapy for 3 months. Successful treatment of OSA was also associated with decreased vascular tone and arterial stiffness. But after 1 week off CPAP, these improvements disappeared and reverted to baseline values.

"We were surprised by the very rapid improvements in arterial tone, seen as early as 4 weeks into treatment, and how quickly they reversed after only a few days of treatment withdrawal," principal investigator Claudia Korcarz, DVM, RDCS, manager and senior scientist at the University of Wisconsin Atherosclerosis Imaging Research Program in Madison, said in a statement.

"These findings demonstrate that the vascular effects of sleep apnea are reversible if treated early in the disease process, suggesting that we might be able to mitigate the long-term risk of chronic exposure to OSA," Dr. Korcarz said.

She will present her findings here June 4 at SLEEP 2014, the 28th Annual Meeting of the Associated Professional Sleep Societies.

Adherence Matters

The study included 47 adults, mean age 40.8 years, who had recently been diagnosed with OSA. They were evaluated before and after 3 months of CPAP therapy, as well as 1 week after treatment withdrawal. Carotid to radial artery pulse-wave velocity (PWVc-r) and central aortic blood pressures (cBP) were obtained by applanation tonometry. Brachial artery (BA) size and flow-mediated dilation were measured with B-mode ultrasound.

Thirty-seven patients were highly compliant with CPAP, using it for an average of 6.1 hours per night, whereas 10 patients used CPAP for 2.4 hours nightly.

Highly compliant patients showed significant improvements in systolic (–3.2 mm Hg; P = .022) and diastolic (–4.7 mm Hg; P < .001) cBP, BA size (0.2 mm; P < .001), and PWVc-r (–0.38 m/s; P < .003), the researchers report in a meeting abstract. In contrast, no significant changes were observed in the low-compliance patients.

After 6 days of CPAP withdrawal, high-compliance patients experienced rebound increases in diastolic (1.8 mmHg; P = .057) cBP, augmentation index (2.4%; P < .009), and vasoconstriction (BA, –0.06 mm; P = .028), the researchers report.

The findings in this study reinforce that the effective treatment of OSA can have a positive effect on cardiovascular health, Dr. Korcarz said.

"The early diagnosis and treatment with well-monitored, continuous use of CPAP therapy in otherwise healthy young adults with moderate to severe obstructive sleep apnea might prevent the future development of hypertension and reduce the risk of cardiovascular complications associated with the disease," she noted in a statement.

Cardiovascular Benefits

This study supports and extends the literature on the cardiovascular benefits of CPAP adherence, Clete Kushida, MD, PhD, professor and medical director of the Stanford Sleep Medicine Center in Palo Alto, California, and past president of the American Academy of Sleep Medicine, noted in an interview with Medscape Medical News.

"If you look at the data, most of the studies indicate that there is a decrease in systolic and diastolic blood pressure with the use of CPAP and this study adds more data to that," said Dr. Kushida, who wasn't involved in the study. "The fact that they looked at arterial stiffness is interesting and begins to get into the pathogenesis of what causes the rise in blood pressure."

Dr. Kushida also noted that on average compliance with CPAP therapy "hovers between 4 and 5 hours a night and there is improvement with that level of CPAP. There is also research showing that compliance is better with an oral appliance."

Dr. Korcarz told Medscape Medical News that while compliance with CPAP therapy remains an issue "in general, compliance is much better today than what we saw 10 years ago when it was very hard for people to comply with old, bulky equipment. The machines today are more silent and the devices are getting better. Industry is now working on devices that are more flexible and allow people to not feel constrained and to be able to move during the night."

Dr. Korcarz was supported by a grant from the National Heart Lung and Blood Institute. The authors have no disclosed no relevant financial relationships.

SLEEP 2014: 28th Annual Meeting of the Associated Professional Sleep Societies. Oral Presentation 0317. To be presented June 4, 2014.  

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