Rationale: 

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 with 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 before entering the membrane lung, enhancing membrane lung CO₂ extraction. All animals underwent three repeated experimental sequences, consisting of four 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 mm Hg.

Measurements and Main Results: 

During R-ED, chloride and H⁺ concentration increased in blood entering the membrane lung, almost doubling CO₂ extraction compared with ECCO₂R (112 ± 6 vs. 64 ± 5 ml/min, P < 0.001). Compared with 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 there was 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 the safety profile of R-ED, especially regarding kidney function.