The first study, on the use of continuous positive airway pressure (CPAP) for patients with central sleep apnea and heart failure, was led by T. Douglas Bradley, M.D., of Toronto General Hospital. The other study on obstructive sleep apnea as a risk factor for stroke and death was led by H. Klar Yaggi, M.D., of Yale Center for Sleep Medicine.
In his editorial, Dr. Somers notes that central sleep apnea is characterized by intermittent loss of respiratory drive, while obstructive sleep apnea results in a narrowing or collapse of the airway. While they differ, both sleep apneas are "linked to the modern-day epidemics of obesity, cardiovascular disease, and heart failure," he says.
The results of the first study -- also referred to as the Canadian Positive Airway Pressure trial -- were disappointing because, even though the treatment was carefully applied, it was not sufficiently effective, Dr. Somers says. Patients with both heart failure and central sleep apnea received either CPAP -- a mask worn during sleep that delivers air through the airway -- or no treatment to see if CPAP improved survival.
In the end, mortality was similar in both groups. "Unfortunately, the study doesn't tell us for certain whether or not we should treat central sleep apnea in our heart failure patients," Dr. Somers says.
Because of limited effectiveness of the treatment, the study points to a need to "rethink what we are treating and how we are treating it," he says, adding that the CPAP device was intended to treat obstructive sleep apnea, not central sleep apnea. "This suggests we need to find better treat