Abstract
Introduction: A linear and inverse association between the degree of obesity and the respiratory function has previously been attributed to altered respiratory system compliance and mechanics. The purpose of this study is to evaluate the impact of obesity and weight loss on the membrane and the capillary component of lung diffusion capacity.
Methods: Measurements of lung diffusing capacity (DL) for carbon monoxide (CO) and nitric oxide (NO) during a single breath in 13 obese subjects before and 6 months after bariatric surgery (Body Mass Index (BMI): 40±4 vs 31±3 kg/m2) were compared to age-, sex-, height-, and ethnic-matched healthy control subjects. Body composition was determined by dual-energy X-ray absorptiometry.
Results: Obesity was associated with decreased alveolar volume (VA), DLNO and membrane diffusion capacity (Dm) but with unaffected capillary volume (Vc), rate of uptake of NO (KNO) and CO (KCO). Bariatric surgery and 32% fat mass loss increased VA, DLNO and Dm. Visceral adipose tissue loss was correlated with post-surgery increase in DLNO/DLCO and Dm/Vc ratios (r=-0.55, p<0.05).
Conclusion: Obesity affects lung diffusion capacity by a reduced VA mainly affecting the membrane diffusion capacity, probably related to excessive thoracic and abdominal adipose tissue deposit. The observed deficits were restored 6 months after surgery induced fat mass loss.
| Controls | Obesity Pre-surgery | Post-surgery | |
| DLNO (ml.min-1.mmHg-1) | 139 ± 19 | 124 ± 29 | 138 ± 36* |
| DLCOcor (ml.min-1.mmHg-1) | 27.3 ± 3.5 | 22.7 ± 4.1°° | 24.7 ± 5.8 |
| VA (l) | 6.3 ± 0.9 | 5.5 ± 1.2 | 6.0 ± 1.2* |
| Vc (ml) | 75.1 ± 13.1 | 62 ± 10 °° | 66 ± 15 |
| Dm (ml.min-1.mmHg-1) | 173 ± 55 | 146 ± 46 |
196 ± 99* |
*p<0.05: pre- vs post-surgery, °°p<0.01: vs controls
Footnotes
Cite this article as: European Respiratory Journal 2021; 58: Suppl. 65, PA3215.
This abstract was presented at the 2021 ERS International Congress, in session “Prediction of exacerbations in patients with COPD”.
This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).
- Copyright ©the authors 2021
