Detection of acute effects of cigarette smoking on airway dynamics: A critical and comparative study of pulmonary function tests.

In an effort to determine which measure of airway dynamics was the most sensitive to airway obstruction, comparisons were made between a variety of tests. Twenty cigarette smokers were studied both before and immediately after smoking a cigarette. The maximum midexpiratory flow (FEV25-75) and the FEV1/FVC per cent were abnormal in the largest number of cases. Closing volume was abnormal in only one case. Significant worsening in function after smoking a cigarette occurred in airway resistance and specific conductance. A lesser degree of impairment in airway dynamics was evident from FEV25-75 and first-second expired volume. The closing volume showed no change.