Enhanced Lung Protective Ventilation With ECCO2R During ARDS

Acute Respiratory Distress Syndrome (ARDS) is associated with a mortality rate of 30 - 45 % and required invasive mechanical ventilation (MV) in almost 85 % of patients\[1\]. During controlled MV, driving pressure (i.e., the difference between end-inspiratory and end-expiratory airway pressure) depends of both tidal volume and respiratory system compliance. Either excessive tidal volume or reduced lung aeration may increase the driving pressure. ARDS patients receiving tidal volume of 6 ml/kg predicted body weight (PBW) and having a day-1 driving pressure ≥ 14 cmH2O have an increased risk of death in the hospital\[2\]. Seemly, in the LUNG SAFE observational cohort, ARDS patients having a day-1 driving pressure \< 11 cmH2O had the lowest risk of death in the hospital\[1\]. Hence, driving pressure acts as a major contributor of mortality in ARDS, and probably reflects excessive regional lung distension resulting in pro-inflammatory and fibrotic biological processes. Whether decreasing the driving pressure by an intervention change mortality remains an hypothesis; but one of means is to decrease the tidal volume from 6 to 4 ml/ kg predicted body weight (PBW). However, this strategy promotes hypercarbia, at constant respiratory rate, by decreasing the alveolar ventilation. In this setting, implementing an extracorporeal CO2 removal (ECCO2R) therapy prevents from hypercarbia. A number of low-flow ECCO2R devices are now available and some of those use renal replacement therapy (RRT) platform. The investigators previously reported that combining a membrane oxygenator (0.65 m²) within a hemofiltration circuit provides efficacious low flow ECCO2R and blood purification in patients presenting with both ARDS and Acute Kidney injury\[3\]. This study aims to investigate the efficacy of an original ECCO2R system combining a 0.67 m² membrane oxygenator (Lilliput 2, SORIN) inserted within a specific circuit (HP-X, BAXTER) and mounted on a RRT monitor (PrismafleX, BAXTER). Such a t