Abstract
BACKGROUND: Extracorporeal carbon-dioxide removal (ECCO(2)R) 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 ECCO(2)R 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 ≤ P(plat) ≤ 25 cmH(2)O. Standalone ECCO(2)R (no hemofilter associated with the RRT platform) was initiated when arterial PaCO(2) increased by > 20% from its initial value. Ventilation parameters (VT, respiratory rate, PEEP), respiratory system compliance, P(plat) and driving pressure, arterial blood gases, and ECCO(2)R-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 ECCO(2)R and mechanical ventilation were also recorded. RESULTS: While VT was reduced from 6 to 4 ml/kg and P(plat) 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 PaO(2)/FiO(2) ratio and respiratory-system compliance were not modified after VT reduction. Mild respiratory acidosis occurred, with mean PaCO(2) 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 CO(2) 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 ECCO(2)R device managed with an RRT platform easily and safely enabled very low tidal volume ventilation with moderate increase in PaCO(2) in patients with mild-to-moderate ARDS. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02606240. Registered on 17 November 2015.