OBJECTIVE: To evaluate the effects of the progressive increase in body weight on lung function by oxygen peripheral saturation, spirometry and maximal respiratory pressures in different degrees of obesity. METHODS: Cross-sectional study including 140 patients in clinical and surgical evaluation for obesity treatment. The selected patients were divided into six groups of body mass index (BMI), including a control group of non-obese and a subdivision for the morbidly obese into three subgroups. RESULTS: Significant differences were demonstrated between the groups regarding oxygen peripheral saturation (SpO2) (p < 0.001), forced vital capacity (FVC) (p < 0.002, p < 0.02) and forced expiratory volume in one second (FEV1) (p < 0.001, p < 0.03) in relative and absolute values, respectively. Group VI (BMI > 50.9 kg/m²) showed significant differences (SpO2, FVC and FEV1) when compared with the other groups (except group V) and group V (BMI > 45 to 49.9 kg/m²) with the group control. The other variables (FEV1/FVC ratio, forced expiratory flow 25-75 [FEF25-75] and maximal respiratory pressure) did not show any statistical differences. CONCLUSION: Lung function is influen- ced by the progressive increase in BMI, with changes in lung function better demonstrated when BMI > 45 kg/m²; these changes are more evident when BMI > 50.9 kg/m².
Spirometry; respiratory function tests; obesity; morbid obesity; cross-sectional studies; body mass index
