Effects of spontaneous breathing with different PEEP levels on ventilator-induced lung injury in mild ARDS

Abstract

Background: The beneficial effects of assisted mechanical ventilation have been put on hold, mainly because of recent evidences showing that spontaneous breathing may exacerbate lung injury by large changes in transpulmonary pressure in severe acute respiratory distress syndrome (ARDS). However, so far, no study has evaluated the effects of spontaneous breathing with different levels of PEEP on ventilator-induced lung injury (VILI) in mild ARDS, which is the main clinical indication for spontaneous breathing. Aim: To compare pressure-support ventilation (PSV) and pressure-controlled ventilation (PCV) with two PEEP levels in mild ARDS. Methods: Twenty-eight Wistar rats (weight 310±19g) received E. coli lipopolysaccharide. After 24 hours, animals were anesthetized and randomly allocated to either PCV (n=14) or PSV (n=14), and latter assigned to 2cmH2O, and 5cmH2O PEEP levels. Lung mechanics, mechanical power of breathing (POB), inflammation [cytokine-induced neutrophil chemoattractant (CINC-1)] and epithelial integrity measured by E-cadherin expression were evaluated. Results: At PEEP 2cmH2O, although Ppeak, L and Pmean, L were similar in both PCV and PSV, POB was higher in PCV compared to PSV (92 ± 32 vs 54 ± 11, p Conclusions: In PSV, the level of PEEP should be carefully adjusted in mild ARDS, so as to mitigate ventilator induced lung injury.