Weight Gain After Lung Volume Reduction Surgery Is Not Correlated With Improvement in Pulmonary Mechanics

22 Sep

Weight Gain After Lung Volume Reduction Surgery Is Not Correlated With Improvement in Pulmonary MechanicsIt alnutrition and low body weight are common in patients with COPD, particularly in the subset of patients with emphysema. Patients tend to lose weight as the disease progresses, and several studies have demonstrated correlations between severity of airflow obstruction and body weight. This suggests that worsening pulmonary mechanics may affect a patient’s metabolism and lead to weight loss. Despite this association, the degree of airflow obstruction and low body weight have been shown to be independent predictors of mortality in patients with COPD. my canadian pharmacy

Lung volume reduction surgery (LVRS) is a recent advance in the treatment of selected patients with severe emphysema. Initial reports have shown increased exercise tolerance, decreased sensation of breathlessness, and improved pulmonary function in patients who have undergone this procedure. The improvement in pulmonary function in most patients is modest. However, because body weight is correlated with measures of airflow obstruction, this improvement could result in body weight gain, particularly in the subset of malnourished patients with emphysema. We therefore formed the hypothesis that improved lung mechanics after LVRS would result in body weight gain. To test this hypothesis we measured body weight and pulmonary function pre-operatively and at 3, 6, and 12 months postoperatively for all patients who underwent bilateral LVRS at the University of Michigan between January 1995 and April 1996. We sought to correlate the changes in body weight with changes in pulmonary function.
Materials and Methods
Patient Selection

All patients who underwent bilateral LVRS for severe emphysema at the University of Michigan from January 1995 to April 1996 were eligible for the study. Selection criteria for surgery at our institution have been described previously. To be considered for LVRS, patients needed clinical and CT scan evidence of emphysema with severely affected areas that could be targeted for resection, physiologic evidence of severe airflow obstruction (FEV1 11 to 40% predicted) and hyperinflation (residual volume [RV] > 180% predicted; total lung capacity [TLC] > 105% predicted). Patients eligible for surgery also underwent cardiac testing as defined below. Patients were excluded from surgery if any of the following criteria were met: (1) age > 75 years; (2) Paco2 > 50 mm Hg; (3) active severe cardiac disease; (4) diffusion of carbon monoxide (Dlco)< 20% predicted; (5) inability to participate in pulmonary rehabilitation; (6) bronchiectasis; (7) prior sternotomy, lung resection, or significant pleural abnormalities; (8) supplemental oxygen requirements of > 6 L/min via nasal cannulae to maintain oxygen saturation > 87%; (9) active substance abuse; (10) ventilator dependence; (11) cigarette smoking within the last 6 months; (12) severe kyphosis; (13) 6-min walk < 250 feet (after rehabilitation); (14) recurrent pulmonary infections or > 1 cup sputum/d; (15) other systemic disease likely to limit survival to < 5 years; (16) pulmonary hypertension with mean pulmonary artery pressure > 35 mm Hg or systolic > 50 mm Hg; or (17) mental incompetence/active psychiatric illness.