In bed with a killer

Sleep apnea and congestive heart failure are closely linked. Blowing air up the nose of the afflicted may help

By Chris Williams

Sleep apnea -- a disorder in which breathing briefly stops every so often during sleep -- is a worrisome concern all on its own. But it can be a killer when combined with irregular heartbeat, high blood pressure, heart maladies like congestive heart failure (CHF), or stroke. Approximately 40% of people with CHF suffer from sleep apnea, compared to only about 6% of the general population.

Of the two types of sleep apnea, the obstructive form -- where air cannot flow in and out of a person's nose or mouth -- is by far the most common. A paper published in the February 1 issue of the American Journal of Critical Care Medicine describes how therapy for obstructive sleep apnea helps those with congestive heart failure.

A team from the Alfred Hospital in Melbourne, Australia randomly assigned 55 patients, all of whom had CHF and obstructive sleep apnea, to one of two groups. One group received a nighttime treatment for sleep apnea called continuous positive airway pressure. The other control group did not.

Continuous positive airway pressure is a breathing aid that consists of a portable low-pressure airflow generator connected by tubing to a mask that fits over the nose. The device continually supplies a low flow of air, which is especially vital during those times when breathing doesn't occur.

In 1999, a Canadian research team found that the device reduced the "breathless" episodes during sleep, and so reduced strain on the weakened heart in the three-month study. However, with only nine patients in the treatment and control groups, the significance of the results was hard to assess.

The latest study involved more patients. Of the 55 patients who started the study, 19 patients in the treatment group and 21 of those in the control group ended up completing the three-month-long Australian study, and 15 dropped out.

Compared to the control patients, those in the airway pressure treatment group displayed an improvement in the amount of blood pumped out from the left ventricle each heartbeat (the left ventricle ejection fraction). The 5% ejection fraction value observed in the treated patients was significantly greater than the 1.5% increase in the fraction in the controls.

Airway pressure treatment also reduced the activity of the sympathetic nervous system, as judged by the reduced urinary output of a hallmark compound called norepinephrine. Elevated sympathetic nervous system activity is a characteristic of CHF and obstructive sleep apnea.

Finally, the use of CHF-specific and non-specific questionnaires revealed a significant improvement in the quality of life of the airway treated patients. No changes in quality of life were evident in the control patients.

In an editorial accompanying the report, Dr Doug McEvoy of the Repatriation General Hospital in Daw Park, Australia commented that, while further studies will be needed to investigate "the place of [obstructive sleep apnea] and [continuous positive airway pressure] therapy in modern heart failure management... nonetheless, these are exciting preliminary findings."