Uncertainties in the expected value for forced expiratory volume in one second after surgery.

The purpose of this study is to understand better the reasons for the frequent unreliability of the expected value for the forced expiratory volume in one second (FEV1) in predicting surgical results after pneumonectomy. Measurement of FEV1 was performed in 159 patients before and after removal of one lung. Only 41 of the postoperative values for FEV1 differed from predicted values by less than 5 percent. The reason for the discrepancy can be technical, resulting either from the method used to assess the functional pulmonary distribution (bronchospirometry or isotopic procedure) or from the data used to calculate predicted FEV1. The discrepancy can also depend on the patient himself and particularly on the possibilities of the remaining lung to expand normally after surgery. Follow-up of patients confirmed the clinical and functional effects of erroneous predicted FEV1.