ABSTRACT
Morbidly obese individuals may have altered pulmonary diffusion during exercise. The purpose of this study was to examine pulmonary diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) during exercise in these subjects. Ten morbidly obese subjects (age = 38 +/- 9 years, BMI = 47 +/- 7 kg/m(2), peak oxygen consumption or VO(2peak) = 2.4 +/- 0.4 l/min) and nine nonobese controls (age = 41 +/- 9 years, BMI = 23 +/- 2 kg/m(2), VO(2peak) = 2.6 +/- 0.9 l/min) participated in two sessions: the first measured resting O(2) and VO(2peak) for determination of wattage equating to 40, 75, and 90% oxygen uptake reserve (VO(2)R). The second session measured pulmonary diffusion from single-breath maneuvers of 5 s each, as well as heart rate (HR) and VO(2) over three workloads. DLNO, DLCO, and pulmonary capillary blood volume were larger in obese compared to nonobese groups (P