March 26 (HealthDay News) -- A disrupted breathing-swallowing pattern may explain why people with moderate to severe chronic obstructive pulmonary disease (COPD) are at increased risk for aspiration pneumonia, researchers report.
Patients with moderate to severe COPD show alterations between normal breathing and swallowing patterns (during eating) even when they're not experiencing exacerbations, according to the study by Roxann Diez Gross and colleagues at the University of Pittsburgh.
"In healthy subjects, the usual pattern is to time swallows to occur during early to mid exhalation. Healthy individuals also nearly exclusively follow each swallow with exhalation. This pattern assures that there is sufficient air pressure below the vocal folds during a swallow and prevents inhalation of food residue after swallowing," Gross said in the news release.
"In contrast, in COPD patients, we saw that several aspects of their swallowing and breathing timing were disrupted such that swallows were occurring during inhalation or were followed by inhalation," she said. "COPD patients also swallowed more often at the end of exhalation at lower lung volumes."
COPD is a progressive, destructive disease of the lungs, usually brought on by smoking. There is no known cure. Symptoms include restricted breathing, secretion of mucus, oxidative stress and airway inflammation.
It had been known that COPD patients "exhibited decoupling of the breathing-swallowing pattern of saliva during exacerbations," according to a news release about the study. But this is the first study to detail to what extent, if any, disruptions in breathing and swallowing coordination occur during normal eating in COPD patients even when they're not experiencing exacerbations.
The study included 25 patients with moderate to severe COPD and 25 healthy people. All the participants ate nine wafer cookies and 10 teaspoons of pudding to determine how well they swallowed sold and semi-solid food. There was a marked difference between the two groups, the researchers found.
The respiratory tract may be thrown out of balance by the respiratory burden imposed by COPD, Gross explained.
"Because breathing and eating share the structures of the upper airway, precise coordination is needed to prevent food material from entering the airway while eating," she said. "In patients with COPD, the competition for the upper airway may cause the respiratory drive to override swallowing function and disrupt the normal patterning. The lungs of COPD patients have less elasticity than those of healthy individuals and this may also play a role in swallowing safety."
The study appears in the first April issue of the American Journal of Respiratory and Critical Care Medicine.
SOURCE: American Thoracic Society, news release, March 26, 2009