This study aimed to investigate the effects of passive standing on the distribution of lung ventilation in healthy individuals using a tilt table. This study aimed to investigate the effects of passive standing on the distribution of lung ventilation in healthy individuals using a tilt table.
This study included 10 healthy adult men(age 29.0 ± 5.0 years), with no history of respiratory disease. Electrical impedance tomography (Enlight 2100, Timpel) was used to measure lung ventilation, and a measuring belt was placed around the participant’s chest. The participants initially rested in the supine position on a tilt table for 5 min, during which their local lung ventilation distribution and respiratory rates were measured. The tilt table was then gradually tilted at 30°, 45°, and 60°, with measurements taken at each angle for 5 min. The lungs were divided into four horizontal regions of interest (ROIs) from ventral to dorsal: ROI1 (ventral), ROI2 (central ventral), ROI3 (central dorsal), and ROI4 (dorsal). The ventilation rate in each region was recorded and the average of the final minute at each position was used as the representative value. Statistical analysis was performed using EZR software, with the Friedman test employed to evaluate ventilation and respiratory rates across the different tilt angles.
For ROI1, the ventilation distribution was 6.5% (2–10%) in the supine position, 4% (2–7%) at 30°, 4% (2–7%) at 45°, and 5% (3–8%) at 60° (p = 0.07). For ROI2, the distribution was 45.5% (41–50%) in the supine position, 46% (37–55%) at 30°, and 49% (36–62%) at 45° and 45% (38-52%) at 60° (p = 0.06). For ROI3, it was 44% (39–51%) in the supine position, 49% (38–51%) at 30°, 48% (30–53%) at 45°, and 46% (41–51%) at 60° (p = 0.06). For ROI4, the values were 4% (3–5%) in the supine position, 4% (2–6%) at 30°, 4% (1–6%) at 45°, and 4% (2–5%) at 60° (p = 0.06). Across all angles, no significant differences were observed in lung ventilation distribution or respiratory rate.
This study evaluated changes in regional lung ventilation distribution during passive standing using a tilt table in healthy adults. The findings demonstrated no significant differences in ventilation distribution or respiratory rate at tilt angles of 30°, 45°, or 60° compared to the supine position.
Although no significant changes were observed in healthy individuals, the data provide useful baseline information for future studies on ventilator-dependent patients. Further research is needed to assess the effects of passive standing on lung ventilation distribution in patients who may respond differently due to compromised lung function.
Ventilation distribution
Tilt table
