Changes in respiratory function following small bowel bypass for obesity
Stalnecker, M.C.; Suratt, P.M.; Chandler, J.G.
Surgery 87(6): 645-651
1980
ISSN/ISBN: 0039-6060 PMID: 6769171 Document Number: 168076
Spirometry and arterial blood gases were estimated before and at intervals of about 6 months after operation in 11 patients weighing 137 plus or minus 22 kg (234 plus or minus 41% of actuarial ideal weight), who underwent a small-bowel bypass which left 30 cm of proximal jejunum and 20 cm of distal ileum in end-to-end continuity. The average follow-up was 20 months, during which mean weight loss was 31 plus or minus 8%. Spirometry before operation was normal, but the patients were significantly hypoxic (PaO2 75.3 plus or minus 8.5 mmHg) compared with an age-matched normal. PaCO2 and pH were normal. After operation changes in forced vital capacity (FVC) showed a significant linear correlation with the percentage of bodyweight lost: y = 1.03 X -29. Because of a significant decrease in FVC, identified in 7 patients, during the early period of rapid weight loss, the x intercept occurred at a weight loss of 27.5%. Additional weight reduction was accompanied by progressive improvement in FVC to values slightly higher than, but not significantly different from, values before operation. Forced expiratory volume at 1 s varied in accord with FVC. Hypoxia persisted after operation and was not affected by the amount of weight lost. The results suggest that loss of lean body mass, during the initial phase of rapid weight loss after intestinal bypass, may be detrimental to respiratory function, until a sufficient excess of fat also has been lost to achieve net benefit.