Comparison of two transpulmonary pressure-based positive end-expiratory pressure titration strategies in acute respiratory distress syndrome: a randomized crossover study

Abstract

Esophageal pressure monitoring, which enables the estimation of transpulmonary pressure, has been proposed to personalize ventilator settings, particularly positive end-expiratory pressure (PEEP), in patients with acute respiratory distress syndrome (ARDS). Two conceptually different transpulmonary pressure-based PEEP titration strategies have thus been described but have never been compared. This study aims to compare the PEEP levels obtained with these two distinct strategies and their physiological effects. This was a randomized crossover physiological study. Twenty patients with moderate to severe ARDS (PaO2/FiO2 < 150 mmHg) were included in an academic intensive care unit. The two transpulmonary pressure-based PEEP titration strategies were applied for 45 min each in a randomized order, separated by a 45-minute washout period. In the directly measured expiratory transpulmonary pressure (PL, exp) strategy, PEEP was set to target a PL, exp using a PL, exp/FiO2 table. In the calculated inspiratory transpulmonary pressure (PL, insp) strategy, PEEP was set to maintain PL, insp estimated using the lung/respiratory system elastance ratio between 20 and 22 cmH2O. Gas exchange, hemodynamics and partitioned respiratory mechanics were assessed at the end of each PEEP application period. Median PEEP levels determined by the two strategies were not different; however, individual values were uncorrelated, with a difference of at least 3 cmH2O in 14 (70%) patients. The PL, insp strategy resulted in higher PEEP levels than the PL, exp strategy in the non-obese patients but not in the obese patients. The effects on gas exchange, hemodynamics, and respiratory mechanics did not differ between the two strategies considering the entire study population or the obese and non-obese patients separately. Recruitment with PEEP (assessed by the recruited lung volume from PEEP 5 cmH2O), PL, insp, transpulmonary driving pressure and lung strain did not differ between the two strategies. The two transpulmonary pressure-based titration strategies result in different PEEP levels in most patients. Neither strategy is associated with higher recruited lung volume or lower estimated Stress and Strain. #NCT03281473 Clinicaltrials.gov. Registered 12 September 2017.