Improvement in upright and supine lung mechanics with bariatric surgery affects bronchodilator responsiveness and sleep quality

摘要

Obesity and weight loss have complex effects on respiratory physiology, but these have been insufficiently studied, particularly at early time points following weight loss surgery and in the supine position. We evaluated 15 female participants with severe obesity before and 5 wk and 6 mo after bariatric surgery using the Pittsburgh Sleep Quality Index (PSQI), spirometry, plethysmography, and oscillometry to measure respiratory system mechanics. Oscillometry and spirometry were conducted in the upright and supine position and before and after bronchodilation with 200 mu g of salbutamol. At 5 wk postsurgery, weight loss was 11.9 kg (SD 2.7) with no effect on spirometric outcomes and a slight effect on oscillometric outcomes. However, at 6 mo weight loss was 21.4 kg (SD 7.1) with a 14.1% (SD 6.1) and 17.8 (5.4)% reduction in upright and supine respiratory system resistance (Rrs), 6, respectively. Respiratory system elastance also decreased by 25.7% (SD 9.4) and 20.2 (SD 7.2)% in the upright and supine positions. No changes were observed in spirometry, but sleep quality improved from PSQI of 8.4 (SD 3.5) to 4.1 (SD 2.9). Bronchodilator responsiveness was low at baseline but increased significantly after surgery, and this response was comparable to the improvement in Rrs produced by weight loss. Modeling the impedance spectra with a two-compartment model demonstrated that improvements in lung mechanics with weight loss begin in the upper or central compartment of the lungs and progress to include the peripheral compartment. Respiratory mechanics are impaired in individuals with severe obesity and is associated with poor sleep quality, but these improved substantially with weight loss. Our data provide new evidence that individuals with severe obesity may have poor sleep quality because of abnormal respiratory mechanics that weight loss improves.