PEEP titration in moderate to severe ARDS: plateau versus transpulmonary pressure

BackgroundAlthough lung protection with low tidal volume and limited plateau pressure (P-plat) improves survival in acute respiratory distress syndrome patients (ARDS), the best way to set positive end-expiratory pressure (PEEP) is still debated.MethodsThis study aimed to compare two strategies using individual PEEP based on a maximum P-plat (28-30 cmH(2)O, the Express group) or on keeping end-expiratory transpulmonary pressure positive (0-5 cmH(2)O, P-Lexpi group). We estimated alveolar recruitment (Vrec), end-expiratory lung volume and alveolar distension based on elastance-related end-inspiratory transpulmonary pressure (P-L,P-EL).ResultsNineteen patients with moderate to severe ARDS (PaO2/FiO(2)<150mmHg) were included with a baseline PEEP of 7.01.8 cmH(2)O and a PaO2/FiO(2) of 91.2 +/- 31.2mmHg. PEEP and oxygenation increased significantly from baseline with both protocols; PEEP Express group was 14.2 +/- 3.6 cmH(2)O versus 16.7 +/- 5.9 cmH(2)O in P-Lexpi group. No patient had the same PEEP with the two protocols. Vrec was higher with the latter protocol (299 [0 to 875] vs. 222 [47 to 483] ml, p=0.049) and correlated with improved oxygenation (R-2=0.45, p=0.002). Two and seven patients in the Express and P(L,expi)There is a great heterogeneity of P-Lexpi when P-plat is used to titrate PEEP but with limited risk of over-distension. A PEEP titration for a moderate positive level of P-Lexpi might slightly improve alveolar recruitment and oxygenation but increases the risk of over-distension in one-third of patients.