SPIROMETRIC VALUES IN OBESE INDIVIDUALS - EFFECTS OF BODY POSITION

Obesity is increasingly prevalent. Earlier studies indicated that ther e was a significant but small difference in spirometric values between sitting and standing position in the normal population. It is not kno wn if this is true for obese individuals. The recommendations of the A merican Thoracic Society (ATS) are to document if a spirometry is done in a sitting or standing position. We performed a study in which we c ompared sitting and standing spirometric values in obese individuals. Patients with a body mass index (BMI) greater than or equal to 30 kg/m (2) who were referred for spirometry were invited to participate. All tests were done according to American Thoracic Society recommendations . We studied 50 subjects (32 females and 18 males; mean age 45 yr [SD +/- 14.4]). Age range was 20-71 years. Average BMI was 39 (SD +/- 7, r ange 30 to 65). Twenty-two did the first testing in the sitting positi on and 28 standing. There was a small but statistically significant di fference between forced vital capacity (FVC) in the standing versus si tting position (Wilcoxen test, p less than or equal to 0.05). There wa s no significant difference in FEV1 between sitting and standing. Our conclusion is that body position is not important when performing spir ometry in persons with BMI greater than or equal to 30 kg/m(2).