Diagnosis of Upper Airway Stenosis by Pulmonary Function Examination

Abstract

Twenty four cases of upper airway stenosis were examined and the following findings were obtained, based on the results of pulmonary function in these cases. 1) Convexity of the descending curve was observed on the maximum expiratory flow volume loop due to a flow plateau phenomenon and reduction of the peak expiratory flow rate. 2) In case with a peak expiratory flow rate of less than 6.4 1/sec airway stenosis or obstruction should be suspected, although it is impossible to state whether upper or lower airways are imvolved. 3) Upper airway stenosis should be strongly suspected in cases with a peak expiratory flow rate less than 6.4 1/sex. and an S index of the descending curve below zero. 4) The O.I. index is useful as a more convenient parameter than the S index.