The effects of weight reduction on pulmonary function and the sensitivity of the respiratory center in obesity.

Abstract

Pulmonary function and the sensitivity of the respiratory center were studied in 4 obese (weight: 251 to 424 pounds) subjects without hypoventilation before and after weight reduction of 62 to 150 pounds, which was accomplished by starvation. After weight reduction, there was an increase in expiratory reserve volume and functional residual capacity/total lung capacity ratio in all subjects. The increase in functional residual capacity/total lung capacity ratio was solely the result of an increase in expiratory reserve volume since the ratio of residual volume to total lung capacity did not change in any subject. These findings indicate that the resting end-expiratory position was lower than normal in obesity. Three subjects had abnormally high total venous admixture, which improved after weight reduction. The sensitivity of the respiratory center was determined by the ventilatory response to inhaled carbon dioxide, which, in all subjects, was significantly greater before weight reduction. It was postulate...