Bronchial reactivity in cystic fibrosis with normal pulmonary function
P. Van Asperen, C. M. Mellis, R. T. South and S. J. Simpson
We studied 20 children with cystic fibrosis who had relatively normal
pulmonary function (forced expiratory volume greater than or equal to 70%
of predicted) to determine whether demonstration of heightened bronchial
reactivity in this group reflects coexistent asthma. Using a standardized
histamine provocation, we found that eight (40%) had a positive response.
These responders were significantly younger than the nonresponders, had a
greater incidence of clinical asthma, and all were atopic on skin testing.
However, they had a significantly higher ratio of residual volume to total
lung capacity than the nonresponders. Although as a group they were less
sensitive to histamine than children with asthma, four of the responders
with cystic fibrosis had histamine sensitivity similar to a group of
asthmatic patients. We concluded that, in the presence of mild lung
disease, the demonstration of heightened bronchial reactivity in children
with cystic fibrosis may provide confirmatory evidence of coexistent
asthma, particularly if the children are highly sensitive to histamine.
