Effect of Prone Positioning With Individualized Positive End-Expiratory Pressure in Acute Respiratory Distress Syndrome Using Electrical Impedance Tomography

Abstract

Background: Positive end-expiratory pressure (PEEP) optimization during prone positioning remains under debate in acute respiratory distress syndrome (ARDS). This study aimed to investigate the effect of prone position on the optimal PEEP guided by electrical impedance tomography (EIT).Methods: We conducted a retrospective analysis on nineteen ARDS patients in a single intensive care unit. All patients underwent PEEP titration guided by EIT in both supine and prone positions. EIT-derived parameters, including center of ventilation (CoV), regional ventilation delay (RVD), percentage of overdistension (OD) and collapse (CL) were calculated. Optimal PEEP was defined as the PEEP level with minimal sum of OD and CL. Patients were divided into two groups: 1) Lower Optimal PEEPPP (LOP), where optimal PEEP was lower in the prone than in the supine position, and 2) Not-Lower Optimal PEEPPP (NLOP), where optimal PEEP was not lower in the prone compared with the supine position.Results: Eleven patients were classified as LOP (9 [8-9] vs. 12 [10-15] cmH2O; PEEP in prone vs. supine). In the NLOP group, optimal PEEP increased after prone positioning in four patients and remained unchanged in the other four patients. Patients in the LOP group had a significantly higher body mass index (26 [25-28] vs. 22 [17-25] kg/m2; p = 0.009) and lower ICU mortality (0/11 vs. 4/8; p = 0.018) compared with the NLOP group. Besides, PaO2/FiO2 increased significantly during prone positioning in the LOP group (238 [170-291] vs. 186 [141-195] mmHg; p = 0.042). CoV and RVD were also significantly improved during prone positioning in LOP group. No such effects were found in the NLOP group.Conclusion: Broad variability in optimal PEEP between supine and prone position was observed in the studied ARDS patients. Not all patients showed decreased optimal PEEP during prone positioning. Patients with higher body mass index exhibited lower optimal PEEP in prone position, better oxygenation and ventilation homogeneity.

A novel method for diaphragm-based electrode belt position of electrical impedance tomography by ultrasound

“…(1) Since all healthy volunteers were male, the gender could cause the selection bias. (2) Since the lung image of diaphragm-based EIT-belt plane could be improved in the disagree group, other EIT-related parameters such as global inhomogeneity index, center of ventilation, regional ventilation delay and pendelluft parameters might be impacted [ 4 , 18 ]. Further study is required to validate the impact degree of diaphragm-based EIT-belt other EIT-related parameters.…”

Setting positive end-expiratory pressure by using electrical impedance tomography

“…A study in ARDS patients with individualized PEEP setting by EIT found smaller RVD values and more dorsal ventilation with higher CoV in prone compared to supine position in patients with higher body mass index [42]. A retrospective analysis of EIT data acquired during a decremental PEEP trial in obese and nonobese patients showed that PEEP derived from RVD was lower than when GI or a balanced ventral and dorsal fraction of ventilation were used to identify the optimum PEEP [43].…”