Influence of excessive weight loss after gastroplasty for morbid obesity on respiratory muscle performance

• Published in: Thorax Vol. 53; no. 1; pp. 39 - 42
• Main Authors: Weiner, P, Waizman, J, Weiner, M, Rabner, M, Magadle, R, Zamir, D
• Format: Journal Article
• Language: English
• Published: London BMJ 01.01.1998; BMJ Publishing Group LTD; BMJ Group
• Subjects: Adult; Biological and medical sciences; Gastroplasty; Humans; Lung Volume Measurements; Medical sciences; Middle Aged; Obesity, Morbid - physiopathology; Obesity, Morbid - surgery; Original; Postoperative Period; Respiratory Muscles - physiopathology; Stomach, duodenum, intestine, rectum, anus; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Surgery of the digestive system; Tropical medicine; Weight Loss; Human; Postoperative; Stomach; Obesity; Respiratory disease; Treatment efficiency; Nutrition disorder; Weight loss; Exploration; Surgical resection; Lung function; Treatment; Respiratory muscle; Surgery; Complication; Preoperative; Nutritional status
• ISSN: 0040-6376; 1468-3296
• DOI: 10.1136/thx.53.1.39

BACKGROUND: Morbidly obese subjects are known to have impaired respiratory function and inefficient respiratory muscles. A study was undertaken to investigate the influence of excessive weight loss on pulmonary and respiratory muscle function in morbidly obese individuals who underwent gastroplasty to induce weight loss. METHODS: Twenty one obese individuals with mean (SE) body mass index (BMI) 41.5 (4.5) kg/m2 without overt obstructive airways disease (FEV1/FVC ratio > 80%) were studied before and six months after vertical banded gastroplasty. Only patients who had lost at least 20% of baseline BMI were included in the study. Standard pulmonary function tests and respiratory muscle strength and endurance were measured. RESULTS: Before operation the predominant abnormalities in respiratory function were significant reductions in lung volumes and respiratory muscle endurance and, to a lesser degree, reductions in respiratory muscle strength. All parameters increased towards normal values after weight loss with significant increases in functional residual capacity (FRC) from 84.0 (2.2) to 91.3 (2.5)% of predicted normal values (mean difference 7.3, 95% confidence interval of difference (CI) 4.2 to 10.5), total lung capacity (TLC) from 85.6 (3.0) to 93.5 (3.7)% of predicted normal values (mean difference 7.9, 95% CI 4.5 to 11.5), residual volume (RV) from 86.7 (3.1) to 96.4 (3.0) of predicted normal values (mean difference 9.7, 95% CI 5.2 to 14.1), expiratory reserve volume (ERV) from 76.6 (3.0) to 89.0 (3.4)% of predicted normal values (mean difference 12.4, 95%, CI 6.3 to 18.9), respiratory muscle strength: PImax from 92 (4.4) to 113 (4.6) cm H2O (mean difference 21, 95% CI 12.2 to 31.6), PEmax from 144 (5.6) to 166 (4.3) cm H2O (mean difference 22, 95% CI 12.9 to 32.0), and endurance: PmPeak/PImax from 56 (1.4) to 69 (2.0)% (mean difference 13, 95% CI 9.7 to 16.9). The strongest correlation was between weight loss and the improvement in respiratory muscle endurance. CONCLUSIONS: Lung volumes and respiratory muscle performance are decreased in obese individuals. Weight loss following gastroplasty is associated with improvement in lung volumes and respiratory muscle function.