The influence of posture on spirometric values in grade III obese patients.

BACKGROUND AND OBJECTIVES The change from the sitting position to supine position, general anesthesia, and surgical procedure reduce lung volumes and this effect can be greater in obese patients. The objective of the present study was to evaluate the influence of the sitting position, 30 dorsal inclination, and horizontal dorsal decubitus on spirometry of grade III obese patients. METHODS Twenty-six adult patients in the preoperatory period were selected according to the following criteria: BMI>40kg.m(-2), age between 18 years and 60 years, and female gender. Variables analyzed included: age, weight, height, BMI, percentage of predictive values of FVC, FEV(1), and VEF(1)/FVC in the sitting position (90°), 30° dorsal elevation, and horizontal dorsal decubitus (0°). ANOVA, followed or not by Tukey test were used to compare mean predicted values on the different positions, considering significant a p value lower than 0.05. RESULTS Percentage values of FVC, FEV(1), and FEV(1)/FVC ratio regarding predicted values in the sitting position (90°), 30° dorsal elevation, and horizontal dorsal decubitus (0°), and p value of the corresponding statistical analysis were, respectively: FVC=92.8%, 88.2%, and 86.5%, p=0.301 (ANOVA); FEV(1): 93.1%, 83.8%, and 83.3%, p=0.023 (ANOVA), p=0.038 (Tukey test - 90°×0°); FEV(1)/FVC: 100,8%, 95.5%, and 96.8%, p=0.035 (ANOVA), p=0.035 (Tukey test - 90°×30°). CONCLUSIONS Changes in position produced changes in spirometry results of patients with grade III obesity.