A 58-year-old man requires a right pneumonectomy for a central squamous cell carcinoma of the lung. He has a preoperative forced expiratory volume in one second (FEV1) of 1.6 liters. A quantitative ventilation/perfusion scan demonstrates that the right lung receives 60% of all ventilation and 40% of total perfusion. The predicted postoperative FEV1 is 

A. 0.6 liter.
B. 0.8 liter.
C. 1.0 liter.
D. 1.2 liters.
E. impossible to estimate with the given data.

Answer C

The predicted postoperative forced expiratory volume in one second (FEV1) is the most commonly used predictor of postoperative pulmonary morbidity after lung resection. Patients with a preoperative FEV1 less than 2.0 liters who may require pneumonectomy should usually have a quantitative ventilation/perfusion scan to further quantitate the predicted postoperative FEV1. This is particularly true when central tumors result in asymmetric lung function due to post-obstructive pneumonia, atelectasis, or direct involvement of the pulmonary vessels. Preoperative fractional ventilation is not used for this determination. The perfusion portion of the scan provides the most accurate measure of regional lung function. The predicted postoperative FEV1 is calculated by multiplying the perfusion fraction of the retained lung and the preoperative FEV1: 

Predicted postoperative FEV1= (preoperative FEV1) x (perfusion fraction of retained lung)

In this case, the calculation is: (1.6) x (0.60) = 0.96 ~ 1.0 liter



Corris PA, Ellis DA, Hawkins T, et al. Use of radionuclide scanning in the preoperative estimation of pulmonary function after pneumonectomy. Thorax 1987;42:284-91
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 < 0.001). There were mean decreases in FEV1of 22% and in vital capacity (VC) of 28.7% predicted. Estimation of postoperative FEV1from 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 (VO2 max) after pneumonectomy and percentage preoperative perfusion to the resected lung (p < 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.