Heart Failure Patients with Sleep Apnea Benefit by Drug Acetazolamide

January 16th 2006

Heart

Researchers have found that heart failure patients with sleep apnea who take a single dose of acetazolamide before going to bed exhibit less sleep apnea, improved blood oxygen levels and fewer daytime symptoms of sleepiness. Acetazolamide is a mild diuretic and respiratory stimulant.

This is important because many heart failure patients suffer from sleep apnea or have been diagnosed with sleep apnea. Earlier studies have shown a link between the two. Sleep apnea is a condition where the sleeper stops breathing several times an hour while asleep.

There are two types of sleep apnea; central and obstructive. Younger patients usually suffer from obstructive sleep apnea (OSA) while central sleep apnea (CSA) usually occurs as we age. Recent research indicates CSA is caused by loss of brain stem cells. Almost all people with sleep apnea are unaware that they have the condition because it occurs while they are asleep.

Shahrokh Javaheri, M.D., of the Pulmonary Service in the Department of Veterans Affairs Medical Center and Department of Medicine, at the University of Cincinnati College of Medicine in Cincinnati, Ohio, conducted double blind placebo studies on 12 male patients with stable heart failure who had more than 15 episodes per hour each night of sleep apnea. The average age was 66.

In heart failure, the quantity of blood pumped each minute by the heart is insufficient to meet the body’s requirements for oxygen and nutrients. In the past, acetazolamide was use principally to help treat breathing irregularities and sleep apneas occurring at high altitude.

The participants either took acetazolamide or the placebo for 6 nights. There was a two-week washout period between treatments before the patients switched regimens.

Each patient underwent a sleep test, an analysis of blood gases as well as a pH study (a test of acidity or alkalinity in the blood), a measurement of serum electrolytes, a pulmonary function test, plus other measurements at the start of the study and at the completion of each arm (acetazolamide and placebo).

Dr. Javaheri said "An important finding of the double-blind study was the significant improvement in patient perception of improved sleep quality, waking up more refreshed, with less daytime fatigue and sleepiness while taking acetazolamide, compared with placebo."

"We hypothesize that with long-term drug therapy, as sleep-related breathing disorders improve, it may be reflected in an improvement in cardiac function that will further improve periodic breathing, resulting in a positive feedback cycle," said Dr. Javaheri. "Improvement in sleep apnea may assist cardiac function by a variety of mechanisms such as improved oxygenation."

Further long term tests are needed to measure patient cardiac function, quality of life and the levels of norepinephrine in the plasma and urine. Norepinephrine is a hormone used to maintain blood pressure and to treat cardiac arrest.

The research appears in the second issue for January 2006 of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.