Predicted Postoperative Product and Diffusion Heterogeneity Index in the Evaluation of Candidates for Lung Resection

Abstract

The primary objective of this retrospective study was to evaluate whether abnormal predicted postoperative variables and predicted postoperative product are useful in predicting postoperative complications. The secondary objective was to assess whether an abnormal diffusion heterogeneity index is associated with increased postoperative complications. In this retrospective study we evaluated the medical records of 57 patients who underwent lung resection for lung cancer. Calculations of the predicted postoperative variables were done using preoperative testing data, including the extent of the resected lung segments. Predicted postoperative product was obtained by multiplying the predicted postoperative percent-of-predicted FEV(1) by the predicted postoperative percent-of-predicted single-breath diffusing capacity of the lung for carbon monoxide (D(LCO)). The measured product was obtained by multiplying FEV(1) by D(LCO). We derived diffusion heterogeneity index from measurements of the single-breath D(LCO) with the 3-equation method, as a measure of the heterogeneity of the distribution of gas exchange in the lung. Patients with complications had lower predicted postoperative FEV(1) (P < .001), lower predicted postoperative D(LCO) (P < .001), lower predicted postoperative maximal oxygen uptake (P < .001), lower predicted postoperative increase in percent-of-predicted D(LCO) at 70% work load from at-rest percent-of-predicted D(LCO) (ΔD(LCO)%) (P < .001), lower predicted postoperative product (P < .001), and lower measured product (P = .004). Interestingly, diffusion heterogeneity index increased with exercise in [corrected] patients with complications but decreased with exercise in [corrected] patients without complications. The predicted postoperative variables, predicted postoperative product, measured product, and diffusion heterogeneity index are potentially useful predictors of complications in candidates for lung resection.