Effect of Early Mobilization from Bed to Wheel Chair on Regional Ventilation Distribution Assessed by Electrical Impedance Tomography in Respiratory Failure Patients

Backgrounds: There was limited knowledge about the effect of early mobilization on regional lung ventilation in patients with respiratory failure. The aim of the study was to examine whether electrical impedance tomography (EIT) could help to predict the improvement in ventilation distribution due to mobilization.Methods: Forty-one patients with respiratory failure, who had weaned from ventilator and received early mobilization were prospectively enrolled in this study. EIT was used to assess regional lung ventilation distributions at 4 timepoints during the early mobilization from bed to wheelchair (Tbase: baseline, supine position at the bed, T30min: sitting position on the wheelchair after 30min, T60min: sitting position on the wheelchair after 60min, Treturn: return to supine position on the bed after early mobilization). The EIT-based global inhomogeneity (GI) and center of ventilation (CoV) indices were calculated. EIT images were equally divided into four ventral-to-dorsal horizontal regions of interest (ROIs 1-4). Depending on the improvement of ventilation distribution in dependent regions at T60min (threshold set to 15%), patients were divided into recruited (DR) and non-recruited (Non-DR) groups. Results: From the bed to the wheelchair, a significant and continuous increase of dependent regional ventilation distribution (ROI 3+4: baseline vs. T30min, vs. T60min: 45.9±12.1 vs. 48.7±11.6 vs. 49.9±12.6, p=0.015) and COV (COV baseline vs. T30min, vs. T60min: 48.2±10.1 vs. 50.1±9.2 vs. 50.5±9.6, p=0.003). Besides, there was a significant decrease of GI at T60min. Patients in the DR group (n=18) had significantly higher oxygenation than the Non-DR group (n=23) after early mobilization. ROI4Tbase was significantly negatively correlated to ΔSpO2 (R=0.72, p＜0.001). Using a cut-off value of 6.5%, ROI4Tbase had a 79.2% specificity and 58.8% sensitivity to predict response of dependent region recruitment due to early mobilization. The corresponding area under curve was 0.806 (95%CI, 0.677-0.936).Conclusions: EIT may be a promising tool to predict the ventilation improvement resulted from early mobilization.Trial registration: Effect of Early Mobilization on Regional Lung Ventilation Assessed by EIT, NCT04081129. Registered 9 June 2019 - Retrospectively registered, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S00096WT&selectaction=Edit&uid=U00020D9&ts=2&cx=v2cwij