Weight gain after lung volume reduction surgery is not correlated with improvement in pulmonary mechanics

Study objectives: Malnutrition and low body weight are common in patients with emphysema, Previous work has demonstrated correlation between severity of airflow obstruction and body weight. Lung volume reduction surgery (LVRS) is a recent advance in the treatment of patients with severe emyhysema that results in improved pulmonary: function. We formed the hypothesis that improved lung mechanics after LVRS would result in body weight gain. Design: Retrospective chart review, Patients: All patients who underwent bilateral LVRS for severe emphysema at the University: of Michigan between January 1995 and April 1996 were eligible for the study. Measurements and results: Pulmonary function and bod! weight were measured preoperatively and at 3, 6, and 12 months postoperatively for patients who underwent bilateral LVRS between January 1995 and April 1996, The average weight gain in 38 patients returning for 12 months of follow-up was 3.8 +/- 0.9 kg, or 6.2% of the preoperative weight. Women gained significantly more weight than men (9.2 vs 2.2%, respectively) at 1 year. Interestingly, there was no correlation between change in weight and postoperative change in FEV1, FVC, residual volume (RV), total lung capacity (TLC), or RV/TLC at 12 months. However, there was a statistically significant correlation between weight gained and improvement in diffusion of carbon monoxide measured 12 months postoperatively. Conclusions: This study shows that patients with severe emphysema gain weight after LVRS, These changes were independent of changes in pulmonary mechanics but may be a result of improved gas exchange. These findings provide further information about benefits of LVRS in patients with advance emphysema that are beyond simple changes in pulmonary function.