RATIONALE: There are several approaches to select the optimal positive end-expiratory pressure (PEEP), resulting in different PEEP levels. The impact of different PEEP settings may extend beyond respiratory mechanics, affecting pulmonary hemodynamics. OBJECTIVES: To compare PEEP levels obtained with three titration strategies-(i) highest respiratory system compliance (C METHODS: Experimental studies in two porcine models of acute lung injury: (I) bilateral injury induced in both lungs, generating a highly recruitable model (n = 37)
(II) asymmetrical injury, generating a poorly recruitable model (n = 13). In all experiments, a decremental PEEP titration was performed monitoring P MEASUREMENTS AND MAIN RESULTS: PEEP titration methods resulted in different levels of median optimal PEEP in bilateral lung injury: 14(12-14) cmH CONCLUSIONS: In porcine models of acute lung injury with variable lung recruitability, both low and high levels of PEEP can impair pulmonary hemodynamics. Optimized ventilation and hemodynamics can be obtained simultaneously at PEEP levels individualized based on respiratory mechanics, especially by EIT and esophageal pressure.