Chest radiograph heterogeneity predicts functional improvement with volumereduction surgery

Background. Using a historical cohort study model, we tested the hypothesis that heterogeneity of emphysematous changes on the preoperative chest radi ograph correlated with favorable outcome of lung volume reduction surgery. Methods. The test population consisted of 21 patients with severe emphysema who were being treated at a 1,000-bed university-affiliated tertiary teach ing hospital. A simple but quantitative index of heterogeneity has been dev ised, whereby the preoperative posteroanterior chest radiographic lung fiel ds are divided into four geometric quadrants. Each quadrant is scored (0 to 4) for emphysematous changes by two radiologists blinded as to subsequent patient management and outcome. Criteria for determining presence of emphys ema were hyperlucency, decreased vascular markings, and parenchymal crowdin g indicating compressed lung. Heterogeneity index is the sum of the two hig hest scores minus the two lowest, with a maximum index of 8 and a minimum o f 0. Preoperative chest radiographs and postoperative changes in forced exp iratory volume in 1 second were examined. Results. The heterogeneity index was positively correlated with change in f orced expiratory volume in 1 second after operation with an r(2) of 0.31 an d an average increase of 117 mt per unit increase in heterogeneity index (p < 0.009). Conclusions. This simple index of heterogeneity may be useful as a predicto r of improved pulmonary function after lung volume reduction surgery. (C) 2 000 by The Society of Thoracic Surgeons.