Improvements of lung volumes and respiratory symptoms after weight loss through laparoscopic sleeve gastrectomy

Purpose This study evaluated the improvement of respiratory function and airway volumes using spirometry and computed tomography (CT) in severely obese Japanese patients undergoing laparoscopic sleeve gastrectomy (LSG). We also evaluated the quality of life (QOL) of enrolled patients using questionnaires. Methods A total of 71 patients who underwent LSG at Iwate Medical University Hospital between October 2013 and September 2020 were enrolled. The changes and relationships between respiratory parameters including CT volumetry and weight-loss effects were evaluated. Improvements to QOL and bronchial asthma (BA) were also assessed before LSG and 1 year after LSG. Results The mean excess weight loss percentage (%EWL) and total weight loss percentage (%TWL) were measured at 55.1% and 26.1%, respectively. The attack frequency of BA significantly decreased (6.1/month vs. 1.5/month; P < 0.001), and the disease severity decreased according to severity classification (P = 0.032). Almost spirometric parameters, lung volume (LV) (4905.0 mL vs. 5490.3 mL; P < 0.001), and airway volume (AV) (108.6 mL vs. 119.3 mL; P = 0.022) significantly improved. The change of functional residual capacity (FRC) was correlated with both %EWL (rho = 0.69, P < 0.001) and %TWL (rho = 0.62, P < 0.001). The increase of LV (rho = 0.79, P < 0.001) and AV (rho = 0.69, P < 0.001) were correlated with the increase of FRC. Scores of QOL questionnaires dramatically became better owing to improvements in dyspnea. Conclusion Weight loss effects and the reduction of body fat mass correlated significantly with increase in LV and AV. Improvements of respiratory functions after LSG contributes to QOL and BA symptoms.