Apnea Patients at Higher Risk for Cardiovascular Disease

Researchers have found that patients with obstructive sleep apnea have higher levels of apoptotic cells from the endothelium of their blood vessels circulating in their bloodstream than people who do not have obstructive sleep apnea, which may explain why those with apnea are at higher risk for cardiovascular disease. The findings appear in the June 1 issue of the American Journal of Respiratory and Critical Care Medicine.

Researchers from the Sleep Clinic at the Erie County Medical Center, a hospital affiliated with the University of Buffalo, in New York, said increased levels of circulating apoptotic endothelial cells would mean less production of nitric oxide that is crucial to artery vasodilatation. The less nitric oxide, the higher potentially is the risk of hypertension and acute heart attack. CPAP treatment would likely restore the physiologic function of the lining of the blood vessels.

Fourteen men with apnea were studied, and all were nonsmokers without any coexisting diseases, and they did not use medications. Ten healthy nonsmokers served as controls. The apnea patients were given polysomnographic testing to verify the diagnosis. Apnea patients had a higher body-mass index, though the difference was not statistically significant, but they did have more apoptotic cells circulating in their bloodstreams and had vasomotor dysfunction.

The apnea patients were given nasal CPAP treatment for eight weeks. Use of CPAP ranged from four to seven hours per night. At the end of the study, the patients' vascular reactivity and circulating endothelial apoptotic cells were reevaluated and compared with the controls. Those who received CPAP had reduced circulating endothelial apoptotic cells and had marked improvements in brachial artery vascular reactivity.