Use of radionuclide scanning in the preoperative estimation of pulmonary function after pneumonectomy

Twenty eight patients with bronchial carcinoma were studied before pneumonectomy. Measurement of spirometric indices, static lung volumes, transfer factor (TLCO), and transfer coefficient (KCO) was undertaken before and four months after pneumonectomy. Fourteen of the patients also performed a symptom limited progressive exercise test on a cycle ergometer before and four months after pneumonectomy. All patients had standard xenon-133 ventilation and technetium-99m perfusion scans performed before operation. Eleven patients had krypton-81m ventilation scans in addition. Significant correlations were seen between changes in FEV1, TLCO and KCO and the preoperative function of the resected lung as determined by percentage preoperative perfusion to that lung (p less than 0.001). There were mean decreases in FEV1 of 22% and in vital capacity (VC) of 28.7% predicted. Estimation of postoperative FEV1 from the preoperative values showed equally good agreement with measured postoperative values whether 99mTc perfusion or 81mKr ventilation scans were used in the 11 patients in whom both scans were available. Significant correlations were seen between change in maximum exercise ventilation (VEmax) or maximum oxygen uptake (VO2max) after pneumonectomy and percentage preoperative perfusion to the resected lung (p less than 0.001). Estimation of postoperative maximum ventilation and maximum oxygen uptake from the postoperative values on the basis of 99mTc perfusion scans showed good agreement with observed values. Perfusion scans are useful in estimating not only the changes in spirometric indices that follow pneumonectomy for bronchial carcinoma but also changes in carbon monoxide transfer and exercise capacity.