Low-flow CO 2 removal in combination with renal replacement therapy effectively reduces ventilation requirements in hypercapnic patients: a pilot study.

BACKGROUND: Lung-protective strategies are the cornerstone of mechanical ventilation in critically ill patients with both ARDS and other disorders. Extracorporeal CO2 removal (ECCO2 R) may enhance lung protection by allowing even further reductions in tidal volumes and is effective in low-flow settings commonly used for renal replacement therapy. In this study, we describe for the first time the effects of a labeled and certified system combining ECCO2 R and renal replacement therapy on pulmonary stress and strain in hypercapnic patients with renal failure.

METHODS: Twenty patients were treated with the combined system which incorporates a membrane lung (0.32 m2 ) in a conventional renal replacement circuit. After changes in blood gases under ECCO2 R were recorded, baseline hypercapnia was reestablished and the impact on ventilation parameters such as tidal volume and driving pressure was recorded.

RESULTS: The system delivered ECCO2 R at rate of 43.4 ± 14.1 ml/min, PaCO2 decreased from 68.3 ± 11.8 to 61.8 ± 11.5 mmHg (p < 0.05) and pH increased from 7.18 ± 0.09 to 7.22 ± 0.08 (p < 0.05). There was a significant reduction in ventilation requirements with a decrease in tidal volume from 6.2 ± 0.9 to 5.4 ± 1.1 ml/kg PBW (p < 0.05) corresponding to a decrease in plateau pressure from 30.6 ± 4.6 to 27.7 ± 4.1 cmH2 O (p < 0.05) and a decrease in driving pressure from 18.3 ± 4.3 to 15.6 ± 3.9 cmH2 O (p < 0.05), indicating reduced pulmonary stress and strain. No complications related to the procedure were observed.

CONCLUSIONS: The investigated low-flow ECCO2 R and renal replacement system can ameliorate respiratory acidosis and decrease ventilation requirements in hypercapnic patients with concomitant renal failure. Trial registration NCT02590575, registered 10/23/2015.