Apnea treatment might reduce signs of heart disease

Those suffering from Obstructive Sleep Apnea (OSA) are four times more prone to suffer from cardiovascular risk factors and metabolic syndrome (MS) such as obesity, hypertension, dyslipidaemia and insulin resistance. Delhi has 9.3% prevalence of OSA which is a highly prevalent but an under-recognized clinical problem. In an urban setting in northern India, the occurrence of OSA is 13.7% and 3.8% in men and women.


However, patients with moderate-to-severe OSA can reverse metabolic abnormalities and lower blood pressure by undergoing three months of continuous positive airway pressure (CPAP) therapy.


These are the findings of two separate studies - one published in the Indian Journal of Medical Research (IJMR) and the other in New England Journal of Medicine - carried out by Dr S K Sharma, who heads the department of medicine at AIIMS.


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.