Impact of Surgically-Induced Weight Loss on Respiratory Function: A Prospective Analysis

Background: Morbid obesity (MO) causes several degrees of respiratory impairment that may resolve after weight reduction. The aims of the present study were to investigate the frequency of respiratory impairment in a selected cohort of morbidly obese patients with BMI 40-50 kg/m² with no respiratory symptoms and to evaluate the impact of surgically-induced weight loss on respiratory function. Methods: Prospective analysis of respiratory impairment was conducted before surgery and 1 year after surgery in a cohort of patients with MO who underwent vertical banded gastroplasty (VBG). 30 consecutive patients with MO who underwent VBG (14 open and 16 laparoscopic) in a 1-year period were studied. Respiratory function tests, arterial blood gases and hemoglobin were obtained in all patients before and 1 year after VBG. Results: Results were analyzed using the Wilcoxon signed-rank test and Spearman for variables without normal distribution. Mean age was 35±8 years; there were 3 males and 27 females. BMI was 44±4 kg/m² before surgery and 32±4 kg/m² at 1-year follow-up. By respiratory function tests, the diagnosis of obstructive disease was made before surgery in 4 patients and a restrictive disorder was identified in 4 additional patients. Evidence of pulmonary disease was absent in all patients 1 year after surgery. Forced vital capacity, inspiratory and expiratory forces, tidal volume, SaO₂, and PaCO₂ significantly improved after weight reduction. Conclusion: Surgically-induced weight loss significantly improves pulmonary function.