The effects of different body positions on pulmonary function in healthy adults

Abstract Introduction: Pulmonary function testing, or spirometry, is a validated, globally recognized test that contributes to the diagnosis, staging, and longitudinal follow-up of lung diseases. The exam is most often performed in a sitting position in clinical practice; hence, there are no predicted values for its performance in other positions, such as in different decubitus. Objective: The present study aimed to evaluate the effects of position on pulmonary function test results in healthy adults. Methods: Forty-two healthy adults of both sexes, divided into male (MG) and female groups (FG), were provided respiratory questionnaires. Subsequently, the pulmonary function test was conducted to evaluate the ventilatory parameters of forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and FEV1/FVC ratio in the sitting (S), dorsal decubitus (DD), right lateral decubitus (RLD), and left lateral decubitus (LLD) positions. A comparison of the parametric data was performed via one-way analysis of variance followed by Tukey post-hoc tests. Correlations between the S position variables along with the other positions were evaluated using the Pearson test. Results: The mean and standard error for the FVC values of the MG at positions DD (4.3 ± 0.7/L), RLD (4.1 ± 0.6/L) and LLD (4.1 ± 0.6/L) were lower when compared to S (5.05 ± 0.6 L). There was a strong positive correlation between the values of FVC, FEV1, and FEV1/FVC in the S position compared to other positions analyzed in both groups. Conclusion: Body positioning altered the parameters of the pulmonary function test in healthy adults.