title: Pulmonary physiologic changes of morbid obesity.
abstract: OBJECTIVE
  Our objective was to study the effects of extreme obesity on pulmonary function tests and the effects of smoking on these variables in a population group larger than has previously been reported.
  
  
  METHODS
  Retrospective data analysis.
  
  
  METHODS
  Academic medical center.
  
  
  METHODS
  Forty-three patients with extreme obesity [ratio of weight in kilograms to height in centimeters greater than 0.9 (W/H)] who underwent pulmonary function testing at Cedars-Sinai on an out-patient or in-patient basis during the period of 1979 to 1 997.
  
  
  RESULTS
  Patients underwent standard pulmonary function testing. The patients were divided into 2 groups based on the W/H ratio: group A (0.9-0.99) and group B (greater than 1.0). Chart review was performed to identify pertinent history/co-morbidities. The independent effects of smoking between each group's patients were assessed. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), expiratory reserve volume (ERV), functional residual capacity (FRC), maximum voluntary ventilation (MVV), and forced expiratory flow during midexpiratory phase (FEF25-75%,) were significantly reduced in both groups. Single-breath diffusing capacity for carbon monoxide (DLCO) and the volume of gas into which the single-breath of carbon monoxide and helium was diluted were not elevated. Smoking did not account for the results in group A but did seem to partially explain the decrease in FVC, FEV1, and FEF25-75% in group B.
  
  
  CONCLUSIONS
  Extreme obesity is associated with a reduction in ERV, FVC, FEV1, FRC, FEF25-75%, and MVV. However, contrary to prior reports, D(LCO) is not elevated. These effects are only partially explained by smoking.
authors.affiliation: Department of Medicine, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California 90048, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Biring
authors.forename: M I
authors.initials: MI
authors.lastname: Lewis
authors.forename: J T
authors.initials: JT
authors.lastname: Liu
authors.forename: Z
authors.initials: Z
authors.lastname: Mohsenifar
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000503:physiopathology*; D011659:Pulmonary Gas Exchange; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D012907:Smoking / Q000009:adverse effects*; D013147:Spirometry