Fig. 2

Respiratory function. Pink lines and dots represent animals from the pneumonia-with-VILI group, and the green ones represent those animals from the pneumonia-without-VILI group. A Evolution of airway pressures in the pneumonia-with-VILI group. B Evolution of airway pressures in the pneumonia-without-VILI group. C Evolution of PaO₂/FiO₂ throughout the study with periods of moderate and severe respiratory failure in the pneumonia-with-VILI group. Note that in the group of pigs without VILI, it does not decrease below 300 mmHg. D, E PaCO₂ and exhaled minute volume were increased in the group of pneumonia with VILI after ARDS diagnosis and were stable in animals that were ventilated protectively. Note the high variability in PaCO₂ at 36 h of ARDS diagnosis is due to the death of two animals. F Higher compliance was observed in the pneumonia-with-VILI model during induction period, whereas after ARDS diagnosis, it was lower. G A significantly higher mechanical power was observed between groups and at every time point. H Extravascular lung water increased in both groups throughout the study time points, showing evidence of an increase in lung permeability. However, in the pneumonia-with-VILI group, it was significantly higher. Abbreviations: ARDS: acute respiratory distress syndrome; DP: driving pressure; PEEP: positive end-expiratory pressure; Ppeak: peak pressure; VILI: ventilator-induced lung injury. Data are reported as mean ± standard error of mean (SEM). # ARDS diagnosis time point in the pneumonia-without-VILI group corresponds to 30 h from bacterial inoculum, which is the median time from inoculum to ARDS diagnosis in the pneumonia-with-VILI group. This equivalence needed to be done for comparison reasons because the pneumonia-without-VILI group never met the Berlin criteria for ARDS diagnosis. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001