Safety and Efficacy of Combined Extracorporeal Co2 Removal and Renal Replacement Therapy in Patients With Acute Respiratory Distress Syndrome and Acute Kidney Injury: The Pulmonary and Renal Support in Acute Respiratory Distress Syndrome Study

Objective: To assess the safety and efficacy of combining extracorporeal Co-2 removal with continuous renal replacement therapy in patients presenting with acute respiratory distress syndrome and acute kidney injury. Design: Prospective human observational study. Settings: Patients received volume-controlled mechanical ventilation according to the acute respiratory distress syndrome net protocol. Continuous venovenous hemofiltration therapy was titrated to maintain maximum blood flow and an effluent flow of 45 mL/kg/h with 33% predilution. Patients: Eleven patients presenting with both acute respiratory distress syndrome and acute kidney injury required renal replacement therapy. Interventions: A membrane oxygenator (0.65 m(2)) was inserted within the hemofiltration circuit, either upstream (n = 7) or downstream (n = 5) of the hemofilter. Baseline corresponded to tidal volume 6 mL/kg of predicted body weight without extracorporeal Co-2 removal. The primary endpoint was 20% reduction in Paco(2) at 20 minutes after extracorporeal Co-2 removal initiation. Tidal volume was subsequently reduced to 4 mL/kg for the remaining 72 hours. Measurements and Main Results: Twelve combined therapies were conducted in the 11 patients. Age was 70 9 years, Simplified Acute Physiology Score II was 69 +/- 13, Sequential Organ Failure Assessment score was 14 +/- 4, lung injury score was 3 +/- 0.5, and Pao(2)/Fio(2) was 135 +/- 41. Adding extracorporeal Co-2 removal at tidal volume 6 mL/kg decreased Paco(2) by 21% (95% CI, 17-25%), from 47 +/- 11 to 37 +/- 8 Torr (p < 0.001). Lowering tidal volume to 4 mL/kg reduced minute ventilation from 7.8 +/- 1.5 to 5.2 +/- 1.1 L/min and plateau pressure from 25 +/- 4 to 21 +/- 3 cm H2O and raised Paco(2) from 37 +/- 8 to 48 +/- 10 Torr (all p < 0.001). On an average of both positions, the oxygenator's blood flow was 410 +/- 30 mL/min and the Co-2 removal rate was 83 +/- 20 mL/min. The oxygenator blood flow (p <0.001) and the Co-2 removal rate (p = 0.083) were higher when the membrane oxygenator was placed upstream of the hemofilter. There was no safety concern. Conclusions: Combining extracorporeal Co-2 removal and continuous venovenous hemofiltration in patients with acute respiratory distress syndrome and acute kidney injury is safe and allows efficient blood purification together with enhanced lung protective ventilation.