Hopkins Research May Bring "Sigh" Of Relief To Asthmatics

"Understanding the protective effects of sighing may give us therapeutic options for asthmatics in the future," says Alkis Togias, M.D., an associate professor of clinical immunology and principal investigator of the study, which appears in the August issue of the Journal of Applied Physiology.

For years, scientists have used the drug methacholine to study asthma because it narrows airways and causes wheezing in asthmatics, but not in healthy people. Then, in 1995, Hopkins researchers discovered that if people with healthy lung function took only shallow breaths before inhaling the drug, their lungs behaved more like those belonging to asthmatics, and breathing was difficult. With further study, the researchers found that deep breaths help open airways after they close.

To investigate whether deep breathing might bestow other protective effects, Togias and his colleagues exposed nine healthy volunteers and eight asthmatics to methacholine. At first, the volunteers were asked not to inhale deeply for 20 minutes before taking the drug. Then, the investigators gauged airway openness by having the volunteers breathe into a tube and measuring the speed and quantity of air exhaled. The test was then repeated, but this time the volunteers were instructed to take five deep breaths before inhaling the drug.

While breathing deeply did not affect airway openness in asthmatics, it reduced the adverse effects of methacholine in healthy individuals by 85 percent. "Before this study, we knew that deep breaths helped open airways after they closed," says Togias. "Now we know that deep breaths protect the airways from closing in the first place."

The scientists speculate that deep breaths may stretch lung tissue, which then causes the release of a protective chemical that keeps airways open. "If we could figure out what that substance was, perhaps we could provide it to asthmatics via a drug," says Togias.