The Authors: Dr Littleton is an attending physician in the division of Pulmonary, Critical Care, and Sleep Medicine at Cook County Hospital in Chicago, and an assistant professor of medicine at Rush University Medical Center. His research interests include the pathophysiology of respiratory failure and hypercapnia.
Impact of obesity on respiratory function
Article first published online: 21 DEC 2011
© 2011 The Author. Respirology © 2011 Asian Pacific Society of Respirology
Volume 17, Issue 1, pages 43–49, January 2012
How to Cite
LITTLETON, S. W. (2012), Impact of obesity on respiratory function. Respirology, 17: 43–49. doi: 10.1111/j.1440-1843.2011.02096.x
SERIES EDITOR: AMANDA J PIPER
- Issue published online: 21 DEC 2011
- Article first published online: 21 DEC 2011
- Accepted manuscript online: 31 OCT 2011 11:50PM EST
- Received 15 August 2011; invited to revise: 24 August 2011; revised 29 August 2011; accepted 3 September 2011.
- lung volume;
- pulmonary function test;
- pulmonary gas exchange;
- respiratory mechanics
Obesity has long been recognized as having significant effects on respiratory function. The topic has been studied for at least the last half century, and some clear patterns have emerged. Obese patients tend to have higher respiratory rates and lower tidal volumes. Total respiratory system compliance is reduced for a variety of reasons, which will be discussed. Lung volumes tend to be decreased, especially expiratory reserve volume. Spirometry, gas exchange and airway resistance all tend to be relatively well preserved when adjusted for lung volumes. Patients may be mildly hypoxaemic, possibly due to ventilation–perfusion mismatching at the base of the lungs, where microatelectasis is likely to occur. Weight loss leads to a reversal of these changes. For all of these changes, the distribution of fat, that is, upper versus lower body, may be more important than body mass index.