by Anthony J. Brown, MD
Last Updated: 2009-01-22 8:00:31 -0400 (Reuters Health)

While continuous positive airway pressure (CPAP) can virtually eliminate central sleep apnea (CSA), it does not reduce sleep arousals or improve sleep quality, according to a study of heart failure patients with CSA.

This finding was surprising and runs counter to what is seen with obstructive sleep apnea, senior author Dr. T. Douglas Bradley, from Toronto General Hospital, told Reuters Health. With obstructive disease, "treatment causes a marked reduction in sleep disruption and improvement in sleep quality."

"Prior to this study, it had always been thought brief awakenings from sleep (arousals) were an important defense mechanism that terminated apneas during sleep, thus preventing asphyxia," he noted. "However, studies examining this issue were largely focused on obstructive sleep apnea."

The current results, reported in the January 1st issue of Sleep, suggest that sleep arousals are not, in fact, a defensive mechanism with central sleep apnea. Instead, these arousals may be a cause of CSA, Dr. Bradley said.

The study involved 205 heart failure patients with CSA who were randomized to receive optimized medical therapy with or without CPAP. Polysomnograms were obtained at baseline and at 3 months.

No change in the apnea-hypopnea index or in sleep arousals was seen in the control group. In the CPAP group, the apnea-hypopnea index decreased significantly, but, as noted, no change in sleep arousals or sleep quality occurred.

"Sleep disruption by frequent awakenings may have previously unrecognized harmful effects in patients with heart failure," Dr. Bradley said. Because CSA has been linked to increased mortality in heart failure patients, he added, it will be important in future studies to determine if preventing sleep arousals in these patients might alleviate CSA and also reduce mortality.

Sleep 2009.