High Bicarbonate Dialysis With or Without Extracorporeal Carbon Dioxide Removal for pH Control in a Swine Model of...

In acute respiratory distress syndrome (ARDS) complicated by acute kidney injury (AKI), severe acidemia may limit implementation of protective ventilation. Continuous renal replacement therapy (CRRT) may improve acid-base control either by increasing dialysate bicarbonate concentration or by combining CRRT with extracorporeal carbon dioxide removal (ECCO 2 R). We compared these strategies in a randomized experimental model. Twelve anesthetized Landrace pigs underwent surgical induction of anuric AKI followed by protocolized hypoventilation with stepwise tidal volume (Vt) reduction. Animals were assigned to CRRT with very-high bicarbonate dialysate (60 mEq/L) alone or CRRT with high bicarbonate dialysate (40 mEq/L) plus low-flow ECCO 2 R. The primary outcomes were time to vasopressor initiation and the lowest Vt achieved while maintaining arterial pH ≥7.2 during a 12 hour protocol. Both strategies corrected hypercapnic acidemia and enabled substantial Vt reduction, approximately 50% from baseline, without differences between groups at 12 hours ( p = 0.756). Time to vasopressor initiation was likewise similar (hazard ratio [HR] = 0.76, 95% confidence interval [CI] = 0.21-2.71). Cardiac output remained preserved despite increasing vasopressor requirements. In this experimental AKI model, very-high bicarbonate CRRT provided short-term pH control comparable to CRRT plus ECCO 2 R, supporting ultralow-Vt ventilation.