Pulmonary diffusion and aerobic capacity: is there a relation? Does obesity matter?
We sought to determine whether pulmonary diffusing capacity for nitric oxide (DLNO), carbon monoxide (DLCO) and pulmonary capillary blood volume (Vc) at rest predict peak aerobic capacity ( O2peak), and if so, to discern which measure predicts better. Methods:
Thirty-five individuals with extreme obesity (body mass index or BMI = 50 ± 8 kg m−2) and 26 fit, non-obese subjects (BMI = 23 ± 2 kg m−2) participated. DLNO and DLCO at rest were first measured. Then, subjects performed a graded exercise test on a cycle ergometer to determine O2peak. Multivariate regression was used to assess relations in the data. Results:
Findings indicate that (i) pulmonary diffusion at rest predicts O2peak in the fit and obese when measured with DLNO, but only in the fit when measured with DLCO; (ii) the observed relation between pulmonary diffusion at rest and O2peak is different in the fit and obese; (iii) DLNO explains O2peak better than DLCO or Vc. The findings imply the following reference equations for DLNO: O2peak (mL kg−1 min−1) = 6.81 + 0.27 × DLNO for fit individuals; O2peak (mL kg−1 min−1) = 6.81 + 0.06 × DLNO, for obese individuals (in both groups, adjusted R2 = 0.92; RMSE = 5.58). Conclusion:
Pulmonary diffusion at rest predicts O2peak, although a relation exists for obese subjects only when DLNO is used, and the magnitude of the relation depends on gender when either DLCO or Vc is used. We recommend DLNO as a measure of pulmonary diffusion, both for its ease of collection as well as its tighter relation with O2peak.
Document Type: Research Article
Affiliations: 1: Department of Obstetrics, Gynecology and Women’s Health & Department of Pharmacological and Physiological Science, Saint Mary’s Health Center, Saint Louis University, Saint Louis, MO, USA 2: Department of Economics, Saint Louis University, Saint Louis, MO, USA 3: Department of Community Health, Saint Louis University, Saint Louis, MO, USA 4: Department of Anesthesia, Montreal General Hospital, McGill University Health Center, Montreal, Quebec, Canada 5: Division of Clinical Epidemiology, Royal Victoria Hospital, McGill University Health Center, Montreal, Quebec, Canada
Publication date: April 1, 2010