Feasibility and safety of low-flow extracorporeal CO2 removal managed with a renal replacement platform to enhance lung-protective ventilation of patients with mild-to-moderate ARDS

Background: Extracorporeal carbon-dioxide removal (ECCO2R) might allow ultraprotective mechanical ventilation with lower tidal volume (VT) (< 6 ml/kg predicted body weight), plateau pressure (P-plat) (< 30 cmH(2)O), and driving pressure to limit ventilator-induced lung injury. This study was undertaken to assess the feasibility and safety of ECCO2R managed with a renal replacement therapy (RRT) platform to enable very low tidal volume ventilation of patients with mild-to-moderate acute respiratory distress syndrome (ARDS). Methods: Twenty patients with mild (n = 8) or moderate (n = 12) ARDS were included. VT was gradually lowered from 6 to 5, 4.5, and 4 ml/kg, and PEEP adjusted to reach 23 = Pplat = 25 cmH(2)O. Standalone ECCO2R (no hemofilter associated with the RRT platform) was initiated when arterial PaCO2 increased by > 20% from its initial value. Ventilation parameters (VT, respiratory rate, PEEP), respiratory system compliance, Pplat and driving pressure, arterial blood gases, and ECCO2R-system operational characteristics were collected during at least 24 h of very low tidal volume ventilation. Complications, day-28 mortality, need for adjuvant therapies, and data on weaning off ECCO2R and mechanical ventilation were also recorded. Results: While VT was reduced from 6 to 4 ml/kg and Pplat kept < 25 cmH(2)O, PEEP was significantly increased from 13.4 +/- 3.6 cmH(2)O at baseline to 15.0 +/- 3.4 cmH(2)O, and the driving pressure was significantly reduced from 13.0 +/- 4.8 to 7.9 +/- 3.2 cmH(2)O (both p < 0.05). The PaO2/FiO(2) ratio and respiratory-system compliance were not modified after VT reduction. Mild respiratory acidosis occurred, with mean PaCO2 increasing from 43 +/- 8 to 53 +/- 9 mmHg and mean pH decreasing from 7.39 +/- 0.1 to 7.32 +/- 0.10 from baseline to 4 ml/kg VT, while the respiratory rate was not altered. Mean extracorporeal blood flow, sweep-gas flow, and CO2 removal were 421 +/- 40 ml/min, 10 +/- 0.3 L/min, and 51 +/- 26 ml/min, respectively. Mean treatment duration was 31 +/- 22 h. Day-28 mortality was 15%. Conclusions: A low-flow ECCO2R device managed with an RRT platform easily and safely enabled very low tidal volume ventilation with moderate increase in PaCO2 in patients with mild-to-moderate ARDS.