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 CO_2 removal (ECCO_2R) 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 ECCO_2R 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 m^2) in a conventional renal replacement circuit. After changes in blood gases under ECCO_2R 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 ECCO_2R at rate of 43.4 ± 14.1 ml/min, PaCO_2 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 cmH_2O ( p  < 0.05) and a decrease in driving pressure from 18.3 ± 4.3 to 15.6 ± 3.9 cmH_2O ( p  < 0.05), indicating reduced pulmonary stress and strain. No complications related to the procedure were observed

Conclusions

The investigated low-flow ECCO_2R 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.