[Lung scintigraphy and ergospirometry in prediction of postoperative course in lung resection candidates with increased risk of postoperative complications].
Patients with impaired pulmonary function are at increased risk for the development of postoperative complications. We therefore analyzed the value of preoperative lung scanning and exercise testing for the prediction of postoperative complications and of the short- as well as long-term performance in lung resection candidates at increased risk for complications. Twenty-five (mean age 63 y; 17 m) out of 84 consecutive lung resection candidates were considered at increased risk for postoperative complications due to impaired pulmonary function (FEV1 < 2L or diffusion for carbon monoxide (DLCO) < 50% predicted, or FEV1 and DLCO < or = 80% predicted combined with New York Heart Association dyspnea index > or = 2). Candidates underwent radionuclide perfusion scans and exercise testing to predict postoperative ( = ppo) values for FEV1, DLCO and maximal O2-uptake (VO2max). They all underwent thoracotomy for neoplastic lesions; 7 had pneumonectomies, 18 lobectomies. Six had postoperative complications (within 30 days), of whom three died. Three and 6 months postoperatively, pulmonary function tests and VO2max were repeated. In the 22 survivors, the observed values were then compared with the predicted values. At 3 months, there were excellent correlations (absolute/predicted values): for FEV1r = 0.78 and 0.81; for DLCOr = 0.77 and 0.74; and for VO2max r = 0.71 and 0.83. The means of FEV1 and VO2max did not differ from the predicted values, whereas the predicted DLCO was lower than the observed value (ml/min/mmHg: 15.1 vs 17.9; percent predicted: 59.6 vs 70.9) (p < 0.05). At 6 months, correlations remained very good for FEV1 (r = 0.81 and 0.84) and for DLCO (r = 0.76 and 0.74), but had decreased for VO2max to 0.56 and 0.65, respectively. All means were higher than predicted (p < 0.05) owing to recovery in the lobectomy group. Patients with postoperative complications (group B) had a lower preoperative VO2max in percent predicted (62.8 +/- 7.5% vs 84.6 +/- 19.7%) (p < 0.01) and also a lower VO2max-ppo (10.6 +/- 3.6 vs 14.8 +/- 3.5 ml/kg/min and 44.3 +/- 13.5 vs 68.0 +/- 20.7 percent predicted) (p < 0.05) than patients without complication (group A). AVO2max-ppo < 10/ml/kg/min was associated with a 100% mortality. Although FEV1-ppo and DLco-ppo were lower in group B the difference did not reach significance. We conclude that radionuclide-based calculations of postoperative VO2max are predictive of perioperative morbidity and mortality: a VO2max-ppo of < 10 ml/kg/min may indicate inoperability. Further, short-term postoperative performance is accurately predicted by FEV1-ppo and VO2max-ppo, but long-term function is underestimated after lobectomy.