Predictability of FEV1 after pulmonary resection for bronchogenic carcinoma

The aim of this study was to review the reliability of prediction of postoperative FEV1 in patients with bronchogenic carcinoma using a Tc-99m perfusion scan and simple spirometry. Over a 27-month period, 40 patients without known recurrent disease had their FEV1 measured. One quarter of the postoperative values for FEV1 differed from predicted values by less than 5% (2/11 pneumonectomies, 5/23 lobectomies, 3/6 segmental resections) and half differed by no more than 10% of predicted FEV1 (4/11 pneumonectomies, 12/23 lobectomies, 3/6 segmentectomies). One tenth of the predicted values differed by more than 30% and up to 760 mls (1/11 pneumonectomies, 2/23 lobectomies, 1/6 segmentectomy). Disease recurrence, phrenic nerve paralysis, exacerbation of obstructive pulmonary disease and poor collaboration during spirometry explained the most severe erroneous results. Age, preoperative smoking, tumour stage and histology, absence of symptoms at the time of diagnosis and adjuvant radiotherapy showed no statistically significant effect on predictability. Twenty-one patients had a postoperative Tc-99m pulmonary scan simultaneous to the spirometric control. Overestimation of postoperative FEV1 was associated with heterogeneous distribution of ventilation and perfusion.