EFFECT OF WEIGHT-LOSS AND BODY POSITION ON PULMONARY-FUNCTION AND GAS-EXCHANGE ABNORMALITIES IN MORBID-OBESITY

OBJECTIVE: To determine, whether behavioral management of obesity incl uding very-low-calorie-diet would produce weight loss enough to improv e pulmonary mechanics and gas exchange in morbid obesity. DESIGN: Pulm onary function and arterial oxygenation were studied before and after weight loss in 11 patients attending a group therapy with the program of VLCD for 6 weeks and 16 weeks' behavioral intervention. MEASUREMENT S: Spirometry, diffusing capacity, body plethysmograph, closing volume and arterial blood gas analyses. RESULTS: The mean initial BMI was 45 .4 kg/m(2) (range 39.8-58.7 kg/m(2)) and decreased to 39.4 kg/m(2) (ra nge 31-49.8 kg/m(2)) (P < 0.01). Expiratory reserve volume (ERV) and f unctional residual capacity (FRC) improved significantly with weight l oss, Closing capacity (CC) exceeded FRC in 10 cases of 11 at the initi al stage, but after weight loss only in three patients, The mean arter ial oxygen tension with the patients in supine position did not change after weight loss, but standing up improved PaO2 significantly before and after weight loss. CONCLUSION: The dietary treatment of morbid ob esity was sufficient to induce improvement in lung volumes, but not en ough to improve arterial oxygenation, although ventilatory mechanics w as improved significantly and the tendency to early small airway closu re was decreased. Hypoxemia was significantly relieved by standing up both before and after weight loss.