Early EIT-Guided PEEP Titration on Pulmonary Physiology in Patients With Moderate-to-Severe ARDS Undergoing Prone Positioning (EIT-PEEP-PRONE)

Background: Electrical impedance tomography (EIT)‐guided PEEP titration has been shown toimprove regional ventilation distribution, increase respiratory system compliance, andreduce mechanical power in patients with acute respiratory distress syndrome (ARDS), butits effect on mortality remains unproven. In patients with moderate‐to‐severe ARDS, pronepositioning for 4 hours allows pulmonary ventilation and perfusion to reach a new steadystate, with optimization of ventilation‐perfusion (V/Q) matching and other pulmonaryphysiological parameters. However, whether dynamic PEEP titration guided by EIT at thistime point can further optimize V/Q matching and other pulmonary physiological parameterscompared with conventional methods has not been reported.Objective: To investigate whether EIT‐guided PEEP titration performed at 4 hours afterprone positioning initiation can further optimize V/Q matching and other pulmonaryphysiological parameters in patients with moderate‐to‐severe ARDS undergoing pronepositioning.Methods: This is a prospective, single‐center, randomized, open‐label,parallel‐controlled physiological study. A total of 40 patients with moderate‐to‐severeARDS (Berlin definition, PaO₂/FiO₂ < 150 mmHg) will be enrolled and randomized in a 1:1ratio to either the EIT‐guided group or the control group. PEEP intervention will beperformed at 4 hours after prone positioning initiation (T1) in both groups: the EITgroup receives EIT‐guided PEEP titration, while the control group receives PEEP setaccording to the ARDSNet/PEEP‐FiO₂ table. The primary outcome is V/Q matching percentageassessed by EIT at 18 hours of prone positioning (T2) and 6 hours after supinerepositioning (T3). Secondary outcomes include respiratory mechanics, EIT‐derivedparameters (regional ventilation distribution, global inhomogeneity index, center ofventilation), oxygenation indices, echocardiographic measures of cardiac function, andclinical outcomes (28‐day mortality, ventilator‐free days, ICU length of stay, etc.).Conclusion: This study will provide physiological evidence for early EIT‐guided PEEPtitration in patients with moderate‐to‐severe ARDS undergoing prone positioning, and willlay the foundation for future large‐scale clinical trials.