Breathing disorders during sleep are common among asthmatics

When asthmatics are awake, they can turn to their inhalers to open their airways. But when they sleep, many of them continue to struggle with breathing - and an understanding of their sleep-related problems may help doctors better diagnose and treat their patients' asthma, according to new University of Michigan Health System research.

Symptoms of sleep apnea and other breathing problems during sleep are common among people with asthma, according to the research, which is being presented today at the American Thoracic Society's 2005 International Conference in San Diego.

Given this preliminary finding from an ongoing study, researchers say doctors should examine their asthma patients' sleep patterns more often, especially when the patients continue to have trouble even with regular use of inhalers and other common asthma treatments.

"The more you look for sleep apnea in patients with asthma, the more you find it," says William F. Bria II, M.D., medical co-director of the UMHS Asthma Airways Program and associate professor of internal medicine in the U-M Medical School.

"This tells us that a lot more people with asthma need to have sleep studies," Bria says. "When patients are having problems with asthma, their doctors need to look at more than whether they are taking enough puffs from their inhalers."

Researchers examined the connection between sleep-related breathing disorders by giving questionnaires to patients with asthma. Of the 115 subjects included in the study so far, most were in one of the most severe stages of asthma.

Most participants were being treated for asthma with inhalers and other medications, but they were still symptomatic, says Mihaela Teodorescu, M.D., a pulmonary medicine specialist, research fellow in sleep medicine and a lecturer at UMHS, who is presenting the findings at the ATS meeting and who is leading the study.

Large percentages of the people included in the study - 33 percent of men and 49 percent of women - were found to be at risk for obstructive sleep apnea, a condition in which people stop breathing for periods of time during sleep.

Those numbers are based on the symptoms of sleep apnea reported by the subjects,

including 86 percent who said they snored with any frequency, 38 percent who snored regularly and 31 percent who said a family member had witnessed their pauses in breathing during sleep. The symptoms of sleep apnea were related to the severity of asthma, independent of other conditions that could influence asthma. In addition, 55 percent of these people said they experienced excessive daytime sleepiness.

Although the study is still ongoing, Teodorescu says the early findings should encourage doctors to consider sleep apnea as a possible aggravating condition in their asthma patients.

"We hope that eventually, by addressing this earlier, we'll be able to help sooner with patients' asthma control," Teodorescu says.

These early findings offer one more reason people should be tested for sleep disorders, a vast majority of which are under-diagnosed, says Ronald Chervin, M.D., M.S., director of the Sleep Disorders Center and Michael S. Aldrich Sleep Disorders Laboratory at UMHS. Some 80 percent of men and 90 percent of women who have sleep apnea don't know it, he says.

"We might be able to control some of these patients' asthma better if we could identify and treat their apnea," says Chervin, associate professor of neurology at the U-M Medical School.

He also notes that many asthmatics complain of daytime sleepiness, which is often assumed to be a result of the asthma itself. Instead, the study is finding that apnea symptoms rather than asthma severity best predict daytime sleepiness. The investigators hope that attention to the overlap of sleep apnea and asthma might one day lead to better nighttime sleep and daytime alertness for asthmatics.

In addition to Teodorescu, Bria and Chervin, the authors are Flavia Consens, M.D., clinical assistant professor of neurology; Michael Coffey, M.D., associate professor of internal medicine; Ann Durance, R.N., a clinical nurse at UMHS; Kevin Weatherwax, a project associate in the Department of Neurology; John Palmisano, clinical coordinator in the Department of Neurology; Peter Mancuso, Ph.D., assistant professor at the School of Public Health; and Jesica Pedroza, all from the University of Michigan; and Srinivas Bhadriraju, M.D., of Emory University and formerly of the University of Michigan.