The effect of massive weight loss on pulmonary function of morbid obese patients

To test if morbid obesity causes pulmonary function changes and if massive weight loss have effect on pulmonary function (especially in subjects with BMI>or=60 kg/m(2)).

Thirty-nine morbid obese subjects before and after massive weight loss.

Patients had baseline BMI>or=40 kg/m(2), pulmonary function test (PFT) before and after surgery for gastric volume reduction and massive weight loss, and presented no complaints unrelated to obesity. Based on initial BMI, the patients were divided in groups A (BMI 40-59.9 kg/m(2)) and B (BMI>or=60 kg/m(2)). Initially, group A (n=28) had normal PFT, however group B (n=11) presented FVC and FEV(1) measurements in the lowest limit of normality (with normal FEV(1)/FVC), significantly different from group A. After massive weight loss, the group B compared to A had a significant improvement in FVC (23.7% vs. 9.7%, P=0.012) and FEV(1) (25.6% vs. 9.1%, P=0.006); thus the initial difference in FVC and FEV(1) between groups no longer existed after weight loss.

These results point out that the severe morbid obesity (BMI>or=60 kg/m(2)) may lead to pulmonary function impairment and presents more prominent pulmonary function gain after massive weight reduction. The possible clinical implications of these results are that PFT abnormalities in subjects with BMI<60 kg/m(2) should probably be interpreted as consequence of intrinsic respiratory disease and that severe morbid obese patients may be encouraged to lose weight to improve their pulmonary function, especially those with concomitant pulmonary disorders.