Effect of PEEP-Induced Alveolar Recruitment on Lung Injury during Extracorporeal Membrane Oxygenation for ARDS

Abstract

Purpose Extracorporeal membrane oxygenation, veno-venous configuration (VV-ECMO) is an effective intervention to improve gas exchange in patients with severe respiratory failure, refractory to conventional treatments, or as a bridge to lung transplantation. However, optimal mechanical ventilation (MV) strategies during VV-ECMO to minimize ventilator-induced lung injury are undetermined. While there is general consensus in minimizing tidal ventilation, the potential benefit of high positive end-expiratory pressure (PEEP) strategies in optimizing cardiopulmonary interaction and reducing the severity of lung injury remains unclear.We hypothesize that PEEP-induced alveolar recruitment will reduce lung injury during VV-ECMO for ARDS, in comparison to atelectatic lungs. Methods Yorkshire pigs weresedated, paralyzed, mechanically ventilated,and cannulated for VV-ECMO support. Lung injury was done by two serial bronchoscopic instillations of gastric juice to achieve a P/F ratio Results During VV-ECMO, gas exchange and hemodynamic parameters remained stable and comparable in the two groups, despite the very low tidal volume delivered (HP 54 ml ±; LP 41 ml ±11). Lung volume was higher in the HP compared with the LP group, and remained unchanged during the 5 hours of VV-ECMO support. At the end of the 5 hours of ECMO support, in the dependent lung areas the W/D was significantly higher in the HP compared to LP group (HP 11.1, 95% CI: 10.5-11.7; LP 9.2, 95% CI: 8.2-10.3); in the non-dependent areas the W/D was significantly higher in the LP compared to HP group (LP 6.3, 95% CI: 5.6-6.9; HP 5.3, 95% CI: 4.9-5.8). Conclusion VV-ECMO for severe acute respiratory failure MV with very low tidal volume and LP reduces regional lung edema in the dependent areas, while HP reduces edema.More studies are required to characterize the mechanisms of these findings.