Apnea Treatment Might Reduce Signs of Heart Disease Risk

WEDNESDAY, Dec. 14, 2011 (HealthDay News) -- Along with helping people with obstructive sleep apnea get a better night's sleep, machines that help keep the airways open during sleep can also help improve the symptoms of metabolic syndrome, according to new research.

Metabolic syndrome is a group of symptoms that indicate a higher risk of heart disease. These symptoms include excess weight, especially in the abdomen, high blood pressure, abnormal cholesterol levels, higher blood sugar levels and insulin resistance. Many people with obstructive sleep apnea also have metabolic syndrome, according to the study.

After three months of continuous positive airway pressure (CPAP) treatment, study participants with obstructive sleep apnea and metabolic syndrome had improvements in their blood pressure, cholesterol, and blood sugar levels. Thirteen percent of those who received the breathing treatment had such significant reductions in their symptoms that they no longer qualified as having metabolic syndrome after three months of therapy.

"Patients with obstructive sleep apnea should be actively screened for metabolic syndrome or constituents of metabolic syndrome, and, in addition to lifestyle modification, weight reduction and dietary modification, [should be given] proper counseling for CPAP use, and a CPAP machine should be used regularly," said the study's lead author, Dr. Surendra Sharma, a professor and head of the department of internal medicine at the All India Institute of Medical Sciences in New Delhi, India.

Results of the study are published in the Dec. 15 issue of the New England Journal of Medicine. Funding for the study was provided by a grant from Pfizer. Sharma said that Pfizer does not produce CPAP machines, and they were not involved in the study's design, implementation or interpretation.

Obstructive sleep apnea occurs when the airways close during sleep, causing a lack of oxygen that startles the person awake momentarily, though they may not be aware of awakening. This can happen several times to 100 times an hour, according to the U.S. National Heart, Lung, and Blood Institute.

The current study included 86 adults between the ages of 30 and 65. All had obstructive sleep apnea, but none was being treated with CPAP. Eighty-seven percent also had metabolic syndrome.

The study volunteers were randomly assigned to receive CPAP or sham CPAP treatment for three months. CPAP treatment involves wearing a face mask during sleep that continuously delivers air into the airway so it remains open. The sham CPAP had modifications to reduce the airflow, and the mask used had tiny holes that allowed extra air to escape. The modifications were done in such a way that even the researchers couldn't tell who was receiving standard CPAP and who received the sham treatment.

After three months, the study volunteers went one month without treatment, and then switched groups for another three months of therapy with the opposite treatment.

Compared to the sham treatment, people treated with CPAP had an overall drop of 3.9 mm Hg systolic (the top number) blood pressure and 2.5 mm Hg diastolic blood pressure. Total cholesterol levels went down 13.3 milligrams per deciliter (mg/dL), and LDL cholesterol, the bad type, dropped by 9.6 mg/dL in the treatment group. Levels of triglyceride, another important and potentially harmful blood fat, went down by 18.7 mg/dL in those who received treatment, according to the study.

Blood sugar levels went down slightly, as did waist circumference, according to the study.

Eleven patients (13 percent) no longer qualified as having metabolic syndrome after receiving CPAP, compared with just 1 percent receiving sham CPAP.

Sharma said these positive effects likely come from the restoration of normal oxygen levels. When the body becomes oxygen-deprived in obstructive sleep apnea, it causes the body to become distressed, which causes the release of hormones that can cause cell damage that may lead to metabolic syndrome, according to Sharma.

"This study adds to the growing body of knowledge that obstructive sleep apnea has long-term consequences for your health, and that treatment reverses some of those consequences," said Dr. David Rapoport, an associate professor of medicine and director of the Sleep Disorders Program at NYU Langone Medical Center in New York City.

Rapoport said it wasn't clear from this study if any of the benefits seen came solely from weight loss in those on CPAP and weight gain for those on sham treatment.

"This study is thought-provoking and could be really wonderful news that using a breathing machine could have all of these beneficial effects. But, ultimately, we'd want to see clinical end points, such as the incidence of cardiovascular deaths, in order to know if an intervention is appropriate and helpful," said Dr. Tara Narula, a cardiologist at Lenox Hill Hospital in New York City.

More information

To learn more about CPAP, go to the U.S. National Heart, Lung, and Blood Institute.