Safety and Efficacy of Combined Extracorporeal CO2 Removal and Renal Replacement Therapy in Patients With Acute Respiratory Distress Syndrome and Acute Kidney Injury. (Betters)

Allardet-Servent J, et al. 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. Crit Care Med. 2015 Dec;43(12):2570-81.

OBJECTIVE: To assess the safety and efficacy of combining extracorporeal CO2 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) 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 CO2 removal. The primary endpoint was 20% reduction in PaCO2 at 20 minutes after extracorporeal CO2 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 PaO2/FIO2 was 135 ± 41. Adding extracorporeal CO2 removal at tidal volume 6 mL/kg decreased PaCO2 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 PaCO2 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 CO2 removal rate was 83 ± 20 mL/min. The oxygenator blood flow (p <0.001) and the CO2 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 CO2 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.

Continuous renal replacement therapy with an automated monitor is superior to a free-flow system during extracorporeal life support. (Paden)

Symons JM, McMahon MW, Karamlou T, Parrish AR, McMullan DM. Continuous Renal Replacement Therapy With an Automated Monitor Is Superior to a Free-Flow System During Extracorporeal Life Support. Pediatr Crit Care Med. 2013 Aug 20. [Epub ahead of print]

OBJECTIVES: To determine whether integrated continuous renal replacement therapy provides more accurate fluid management than IV pump free-flow ultrafiltration in pediatric patients on extracorporeal life support.

DESIGN: Retrospective study.

SETTING: PICU and neonatal ICU in a tertiary academic center.

PATIENTS: Infants and children less than 18 years old.

INTERVENTIONS: Extracorporeal membrane oxygenation and continuous renal replacement therapy.

MEASUREMENTS AND MAIN RESULTS: Clinical data collected on patients who received free-flow or integrated renal replacement therapy while on extracorporeal life support. Normalized ultrafiltration error was calculated as: (physician specified fluid loss per 24-hr period – actual fluid loss per 24-hr period) divided by patient body weight (kg). Mixed linear regression analyses were used to model longitudinal ultrafiltration error trajectories within each mode of ultrafiltration. Based on an analysis of 458 serial ultrafiltration fluid balance measurements, integrated ultrafiltration was significantly more accurate than free-flow ultrafiltration (normalized ultrafiltration error of 1.2 vs 13.1 mL; p < 0.001). After adjusting for patient factors and time, integrated ultrafiltration was associated with a significantly lower normalized ultrafiltration error (variable estimate, -24 ± 6; p < 0.001). The use of integrated ultrafiltration was associated with shorter duration of extracorporeal life support (384 vs 583 hr, p < 0.001) and renal replacement therapy (185 vs 477 hr, p < 0.001) than free-flow patients. Overall ICU and hospital length of stay and in-hospital mortality were similar between the groups.

CONCLUSIONS: While free-flow ultrafiltration has the advantages of simplicity and low cost, integrated renal replacement therapy provides more accurate fluid management during extracorporeal life support. Better fluid status management with integrated renal replacement therapy may contribute to shorter duration of extracorporeal life support.

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