Extracorporeal Chloride Removal by Electrodialysis (CRe-ED): A Novel Approach to Correct Acidemia.

RATIONALE Acidemia is a severe condition among critically ill patients. Despite lack of evidence, sodium bicarbonate is frequently used to correct pH. However, its administration is burdened by several side effects. We hypothesized that the reduction of plasma chloride concentration could be an alternative strategy to correct acidemia. OBJECTIVES To evaluate feasibility, safety, and effectiveness of a novel strategy to correct acidemia through Extracorporeal Chloride Removal by Electrodialysis (CRe-ED). METHODS Ten swine (6 treatments, 4 controls) were sedated, mechanically ventilated and connected to an electrodialysis extracorporeal device capable of removing selectively chloride. In random order, an arterial pH of 7.15 was induced either through reduction of ventilation (respiratory acidosis) or through lactic acid infusion (metabolic acidosis). Acidosis was subsequently sustained for 12-14 hours. In treatment pigs, soon after reaching target acidemia, electrodialysis was started in order to restore pH. MEASUREMENTS AND MAIN RESULTS During respiratory acidosis, electrodialysis reduced plasma chloride concentration by 26±5 mEq/L within 6 hours (final pH=7.36±0.04). Control animals exhibited incomplete and slower compensatory response to respiratory acidosis (final pH=7.29±0.03, p<0.001). During metabolic acidosis, electrodialysis reduced plasma chloride concentration by 15±3 mEq/L within 4 hours (final pH=7.34±0.07). No effective compensatory response occurred in controls (final pH=7.11±0.08; p<0.001). No complications occurred. CONCLUSIONS We described the first in-vivo application of an extracorporeal system targeted to correct severe acidemia by lowering plasma chloride concentration. The CRe-ED proved to be feasible, safe, and effective. Further studies are warranted to assess its performance in presence of impaired respiratory and renal functions.