Reduction of total lung capacity in obese men: comparison of total intrathoracic and gas volumes
Thomas, E. Louise
Morin, Stanislas X.
Bell, Jimmy D.
MetadataShow full item record
AbstractRestriction of total lung capacity (TLC) is found in some obese subjects, but the mechanism is unclear. Two hypotheses are as follows: 1) increased abdominal volume prevents full descent of the diaphragm; and 2) increased intrathoracic fat reduces space for full lung expansion. We have measured total intrathoracic volume at full inflation using magnetic resonance imaging (MRI) in 14 asymptomatic obese men [mean age 52 yr, body mass index (BMI) 35–45 kg/m2] and 7 control men (mean age 50 yr, BMI 22–27 kg/m2). MRI volumes were compared with gas volumes at TLC. All measurements were made with subjects supine. Obese men had smaller functional residual capacity (FRC) and FRC-to-TLC ratio than control men. There was a 12% predicted difference in mean TLC between obese (84% predicted) and control men (96% predicted). In contrast, differences in total intrathoracic volume (MRI) at full inflation were only 4% predicted TLC (obese 116% predicted TLC, control 120% predicted TLC), because mediastinal volume was larger in obese than in control [heart and major vessels (obese 1.10 liter, control 0.87 liter, P = 0.016) and intrathoracic fat (obese 0.68 liter, control 0.23 liter, P < 0.0001)]. As a consequence of increased mediastinal volume, intrathoracic volume at FRC in obese men was considerably larger than indicated by the gas volume at FRC. The difference in gas volume at TLC between the six obese men with restriction, TLC < 80% predicted (OR), and the eight obese men with TLC > 80% predicted (ON) was 26% predicted TLC. Mediastinal volume was similar in OR (1.84 liter) and ON (1.73 liter), but total intrathoracic volume was 19% predicted TLC smaller in OR than in ON. We conclude that the major factor restricting TLC in some obese men was reduced thoracic expansion at full inflation.
CitationWatson, R.A. et al (2010) 'Reduction of total lung capacity in obese men: comparison of total intrathoracic and gas volumes'. Journal of Applied Physiology 108 (6):1605
PublisherAmerican Physiological Society
JournalJournal of Applied Physiology
PubMed Central IDPMC2886677
- Relation between trunk fat volume and reduction of total lung capacity in obese men.
- Authors: Watson RA, Pride NB, Thomas EL, Ind PW, Bell JD
- Issue date: 2012 Jan
- Postural changes in lung volumes and respiratory resistance in subjects with obesity.
- Authors: Watson RA, Pride NB
- Issue date: 2005 Feb
- Observational study of the effect of obesity on lung volumes.
- Authors: Steier J, Lunt A, Hart N, Polkey MI, Moxham J
- Issue date: 2014 Aug
- Changes in lung volume and rib cage configuration with abdominal binding in quadriplegia.
- Authors: McCool FD, Pichurko BM, Slutsky AS, Sarkarati M, Rossier A, Brown R
- Issue date: 1986 Apr
- Total lung capacity by plethysmography and high-resolution computed tomography in COPD.
- Authors: Garfield JL, Marchetti N, Gaughan JP, Steiner RM, Criner GJ
- Issue date: 2012