Positive end-expiratory pressure titration with electrical impedance tomography and pressure-volume curve: a randomized trial in moderate to severe ARDS

Objective. The aim of the study was to compare titration of positive end-expiratory pressure (PEEP) with electrical impedance tomography (EIT) and with ventilator-embedded pressure-volume (PV) loop in moderate to severe acute respiratory distress syndrome (ARDS). Approach. Eighty-seven moderate to severe ARDS patients (arterial oxygen partial pressure to fractional inspired oxygen ratio, PaO2/FiO2 ≤ 200 mmHg) were randomized to either EIT group (n = 42) or PV group (n = 45). All patients received identical medical care using the same general support guidelines and protective mechanical ventilation. In the EIT group, the selected PEEP equaled the airway pressure at the intercept between cumulated collapse and overdistension percentages curves and in the PV group, at the pressure where maximal hysteresis was reached. Main results. Baseline characteristics and settings were comparable between the groups. After optimization, PEEP was significantly higher in the PV group (17.4 1.7 versus 16.2 2.6 cmH2O, PV versus EIT groups, p = 0.02). After 48 h, driving pressure was significantly higher in the PV group (12.4 3.6 versus 10.9 2.5 cmH2O, p = 0.04). Lung mechanics and oxygenation were better in the EIT group but did not statistically differ between the groups. The survival rate was lower in the PV group (44.4% versus 69.0%, p = 0.02; hazard ratio 2.1, confidence interval 1 1-3.9). None of the other pre-specified exploratory clinical endpoints were significantly different. Significance. In moderate to severe ARDS, PEEP titration guided with EIT, compared with PV curve, might be associated with improved driving pressure and survival rate. Trial registration: NCT03112512, 13 April, 2017.