The greater a woman's BMI, the higher her FRC and the lower her IC.
"This means that among women with greater BMI, an asthma-like episode has the potential to cause greater breathing difficulties than in non-obese women. The greater dynamic hyperinflation means that obese individuals lose the ability to inhale as deeply or exhale as fully as normal weight individuals," Taylor said.
The findings suggest fundamental differences in the way that obese people with asthma may experience shortness of breath.
"We know that asthma in obese subjects is more likely to persist and is more likely to be perceived to be severe. These individuals often require more treatment to achieve asthma control. Our study provides an insight into why this might be happening -- the same asthma trigger produces a greater effect in obese individuals," Taylor said.
More research is needed to "confirm that the differences in dynamic hyperinflation between obese and non-obese asthmatics are sufficient to explain the differences in symptoms between the two groups. Our study was not large enough to do this," Taylor said.
The U.S. National Heart, Lung, and Blood Institute has more about asthma.
-- Robert Preidt
SOURCE: American Thoracic Society, news release, May 1, 2008
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