Chest
Clinical InvestigationsChanging Patterns of Aerosol Deposition During Methacholine Bronchoprovocation
Section snippets
Subjects
Sixteen subjects were recruited by advertisement. Nine had a history of being treated for asthma, and seven had no history of asthma. All subjects had been free of symptoms of upper respiratory tract infection for at least four weeks. All subjects abstained from taking bronchodilators for 12 h prior to the study, and none had taken corticosteroids or cromolyn sodium for at least 8 weeks. The study was confined to subjects with a baseline FEV1 percent predicted of greater than 75 percent. The
RESULTS
Clinical and spirometric details and the responsiveness expressed as PC20 are shown in Table 1. Of the nine subjects who gave a history of asthma, two did not have a significant response to methacholine. By contrast, two of the seven without a history of asthma were hyperresponsive. The subjects are grouped into methacholine responsive (MR) and nonmethacholine responsive (NMR). The age distribution of the two groups is similar. The baseline FEV1 percent predicted (FEV1 percent) for both groups
DISCUSSION
This study demonstrates that the pattern of aerosol deposition changes significantly during typical methacholine bronchoprovocation in subjects with and without hyperresponsiveness. The finding that changes occur in the MR subjects is consistent with the work of Pavia et al14 in stable subjects with airways obstruction, with a study by Clague et al8 in subjects who were hyperresponsive to histamine, and with a study by Richards et al9 who induced a 20 percent decrease in FEV1 in normal subjects
ACKNOWLEDGMENTS
The authors would like to thank Mr. Robert Perry for technical assistance in performing the deposition studies and Roger Grimson, Ph.D., Department of Community Medicine, SUNY at Stony Brook, for statistical advice.
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Cited by (0)
Supported by grant AI 16337 from the National Institutes of Health, Bethesda, Md.
Manuscript received May 14; revision accepted August 7.