Respiratory electrodialysis : a novel, highly efficient, extracorporeal CO2 removal technique

We developed an innovative, minimally invasive, highly efficient, extracorporeal CO2 removal (ECCO2R) technique called Respiratory Electrodialysis (R-ED). OBJECTIVES: To evaluate the efficacy of R-ED in controlling ventilation compared to conventional ECCO2R-technology. METHODS: Five mechanically ventilated swine were connected to a custom-made circuit optimized for R-ED, consisting of a hemofilter, a membrane lung, and an electrodialysis cell. Electrodialysis regionally modulates blood electrolyte concentration to convert bicarbonate to CO2 prior to entering the membrane lung, enhancing membrane lung CO2 extraction. All animals underwent 3 repeated experimental sequences, consisting of 4 steps: Baseline (1 h), conventional ECCO2R (2 h), R-ED (2 h), and Final NO-ECCO2R (1 h). Blood and gas flow were 250 mL/min and 10 L/min, respectively. Tidal volume was set at 8 mL/kg and respiratory rate was adjusted to maintain arterial pCO2 at 50 mmHg. MEASUREMENTS AND MAIN RESULTS: During R-ED, chloride and H+ concentration increased in blood entering the membrane lung, almost doubling CO2 extraction compared to ECCO2R (112 ± 6 vs. 64 ± 5 mL/min, p < 0.001). Compared to baseline, R-ED and ECCO2R reduced minute ventilation by 50% and 27%, respectively. Systemic arterial gas analyses remained stable during the experimental phases. No major complication occurred, but an increase in creatinine level. CONCLUSIONS: In this first in-vivo application, we proved electrodialysis feasible and effective in increasing membrane lung CO2 extraction. R-ED was more effective than conventional ECCO2R-technology in controlling ventilation. Further studies are warranted to assess safety profile of R-ED, especially as regards to kidney function.