Therapeutic body positioning has often been used in the hospital to improve oxygenation. Among the different positions, lateralization therapy is suggested to improve local pulmonary function by positioning the region of interest in the chest upwards to reduce the effect of gravity. However, there is still a gap in describing the physiological effects of lateralization between gravity-dependent and gravity-independent lung regions.

To analyze the acute effects of body lateralization on aeration and distribution of regional pulmonary ventilation in healthy individuals breathing spontaneously.

A cohort of 10 healthy volunteers was evaluated in the supine position and a lateral decubitus position with a 30º inclination and the right hemithorax positioned upwards. The change in body position was automatically performed using the Multicare bed (Linet, Prague). Pulmonary ventilation and aeration were evaluated with the electrical impedance tomography (EIT) Enlight 1800 (Timpel, São Paulo). EIT images were segmented into four regions (ROIs: anterior right [AR], left [PL], posterior right [PR], and left [AL]). Data collection was performed at the Hospital das Clínicas of UFPE. The effect of body lateralization on regional pulmonary aeration was evaluated using the One-Way ANOVA test and Tukey's post hoc test. The interaction between regional ventilation distribution and body position was evaluated using the Two-Way ANOVA test. Differences were considered significant when the P value < 0.05.

From supine to lateral decubitus position, pulmonary aeration in the AR and PR regions increased by an average of 197 mL and 130 mL, respectively. Only the AL region showed a systematic reduction in aeration, with an average of -155 mL compared to AR, PR, and PL (p<0.05). The distribution of ventilation in ROIs was modified with body position (p = 0.004 for interaction between ROIs and position). In the supine position, the AR, AL, PR, and PL regions received, respectively, an average of 23±8%, 20±12%, 23±5% and 32±17% of the inspired tidal volume (p=0.27 for ROI comparison). In lateral decubitus position, the distribution of ventilation in the AR, AL, PR, and PL regions was 12±5%, 25±11%, 13±8%, and 48±12%, respectively (p<0.001 for ROI comparison).

This study found that body lateralization increased lung aeration in non-gravity-dependent regions (AR and PR) and decreased it in the most gravity-dependent region (AL), suggesting that the change in gravitational axis may have altered the transpulmonary pressure. Lateralization also modulated the regional distribution of ventilation, decreasing it in non-gravity-dependent regions due to the decrease in lung compliance induced by increased aeration and greater diaphragmatic mobility in the dependent region.

The analysis of the results obtained in this case series has direct and comprehensive implications for the fields of technology and health. This therapy promoted favorable results in aeration and regional distribution of ventilation, thus contributing for fundamentals in theory and practice for assessment methods employed and the reproducibility in further new studies.