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Am J Med Sci. 1999 Nov;318(5):293-7.

Pulmonary physiologic changes of morbid obesity.

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Department of Medicine, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, California 90048, USA.



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.


Retrospective data analysis.


Academic medical center.


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.


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.


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.

[Indexed for MEDLINE]

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