Effects of Five Body Positions on the Regional Ventilation Distribution Assessed Using Electrical Impedance Tomography

Background: Electrical impedance tomography (EIT) is a noninvasive method for visualization and quantification of regional ventilation. The objective of this study was to assess regional variations in ventilation across different positions in healthy subjects. Methods: Regional differences in ventilation were compared between the right and left lateral decubitus positions, as well as between the supine, semi-sitting, and prone positions. EIT was performed using a PulmoVista 500 (Dräger Medical, Lübeck, Germany). Results: During lateral decubitus, ventilation significantly increased in the dependent lung. In the right lung, ventilation was 42.5 ± 11.4% in the left lateral decubitus compared with 65.2 ± 12.8% in the right lateral decubitus (P < .001). In the left lung, ventilation was 56.6 ± 11.6% in left lateral decubitus versus 34.4 ± 13.0% in right lateral decubitus (P < .001). These changes were mainly observed in the ventral dependent quadrants. In the supine, semi-sitting, and prone positions, no global differences in ventilation distribution were observed. However, ventilation slightly increased in the left ventral quadrant (supine < prone, P = .03) and decreased in the right dorsal quadrant (supine > prone, P = .03). These subtle variations likely reflect the physiological characteristics of healthy individuals. Conclusions: EIT demonstrated a clear redistribution of ventilation toward the dependent lung in lateral decubitus positions. In contrast, only minimal regional ventilation changes were observed among supine, semi-sitting, and prone positions in healthy subjects. These findings support the utility of EIT in assessing position-related ventilation shifts and underscore the need for further research in patients with impaired pulmonary function.