Chest
Original Research: ObesityThe Effects of Body Mass Index on Lung Volumes
Section snippets
MATERIALS AND METHODS
This was a retrospective study conducted between October 2004 and March 2005, and ethics approval was previously obtained to review the results of lung function. Data were collected from two laboratories with identical body plethysmograph systems. Three hundred seventy-three PFT results were selected for both male and female patients > 18 years old with normal forced expired flow rates and a smoking history of < 10 pack-years. The majority of the patient results that were reviewed but not
RESULTS
The numbers of female and male patients in each BMI group are shown in Table 1. There were fewer men in both the lowest and the two highest BMI groups. However, there were no significant differences in the best-fit regression lines between men and women for the effects of BMI on TLC, VC, RV, FRC, ERV, or Dlco. Therefore, we grouped the data from men and women together.
Figure 1shows the effects of BMI on TLC, VC, and RV. The 20 to 25 kg/m2 BMI group was not significantly different from the 25 to
DISCUSSION
Our results confirm the findings of many others14, 15, 17, 20, 22 who have shown that lung volumes, especially FRC and ERV, decrease as body weight increases. However, our study is unique in that it clearly shows the effects of BMI on lung volumes. This information is not available from other studies7, 10, 13, 14, 15, 16, 20 that included small numbers or limited BMI groups. An interesting finding from the regression analyses is that FRC decreased from 112% of predicted at a BMI of 20 kg/m2 to
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Dr. Jones and Ms. Nzekwu did not receive financial support for this study, nor do they have a financial interest in the research subject area.
Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml)