EVALUATION OF ASYMPTOMATIC SUBJECTS WITH LOW FORCED EXPIRATORY RATIOS(FEV(1) VC)/

Background - Heightened bronchial hyperreactivity is frequently associ ated with airflow limitation, atopy, or cigarette smoking. The purpose of this study was to evaluate healthy subjects with significantly low values of forced expiratory volume in one second/vital capacity % (FE V(1)/VC%) by measuring their airway response to exercise and methachol ine challenge, compared with a control group with normal spirometric v alues. Methods - Eighty four healthy subjects with significantly low f low rates (group A, FEV(1)/VC% <2 SD% predicted) were evaluated and co mpared with 37 subjects with normal flow rates (group B). Static lung volumes, spirometric tests, exercise, and methacholine challenges were performed. Results - Lung volumes were normal for both groups. Mean F EV(1)/VC% was 69% for group A and 82% for the control group. Salbutamo l improved baseline FEV, in eight subjects in group A (mean 15%), whil e methacholine induced a drop in FEV(1) in 12 subjects. The dose-respo nse curve to methacholine reached a plateau in all the responders. Non e of the subjects in the control group improved their baseline FEV(1)/ VC% to salbutamol, but three showed bronchial hyperreactivity similar to those in group A. Conclusions - Bronchial hyperreactivity does not occur more often in asymptomatic subjects with mildly low FEV(1)/ VC% so these subjects do not require special investigations for airway dis ease.