Respiratory Electrodialysis. A Novel, Highly Efficient Extracorporeal CO₂ Removal Technique

Abstract

Rationale: We developed an innovative, minimally invasive, highly efficient extracorporeal CO 2 removal (ECCO 2 R) technique called respiratory electrodialysis (R-ED).Objectives: To evaluate the efficacy of R-ED in controlling ventilation compared with conventional ECCO 2 R 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 CO 2 before entering the membrane lung, enhancing membrane lung CO 2 extraction. All animals underwent three repeated experimental sequences, consisting of four steps: baseline (1 h), conventional ECCO 2 R (2 h), R-ED (2 h), and final NO-ECCO 2 R (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 PCO 2 at 50 mm Hg.Measurements and Main Results: During R-ED, chloride and H 1 concentration increased in blood entering the membrane lung, almost doubling CO 2 extraction compared with ECCO 2 R (112 6 6 vs. 64 6 5 ml/min, P , 0.001). Compared with baseline, R-ED and ECCO 2 R 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 CO 2 extraction. R-ED was more effective than conventional ECCO 2 R technology in controlling ventilation. Further studies are warranted to assess the safety profile of R-ED, especially regarding kidney function.Keywords: extracorporeal circulation; carbon dioxide; respiratory insufficiency; hypercapnia At a Glance CommentaryScientific Knowledge on the Subject: Extracorporeal CO 2 removal (ECCO 2 R) has been suggested for the treatment of patients with acute and chronic respiratory failure. The current ECCO 2 R technology, although perfected compared to the past, still has room for improvement.What This Study Adds to the Field: We developed respiratory electrodialysis, an innovative extracorporeal CO 2 removal technique that selectively modulates pH and electrolyte concentration and highly enhances CO 2 removal by applying an electrical field to blood. Respiratory electrodialysis, requiring a minimally invasive approach, could greatly affect the way we treat patients suffering from respiratory failure and other conditions.

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