Regional blood acidification inhibits coagulation during extracorporeal carbon dioxide removal (ECCO₂R)

Abstract

Background: Consumption of platelets and coagulation factors during extracorporeal carbon dioxide removal (ECCO 2 R) increases bleeding complications and associated mortality. Regional infusion of lactic acid enhances ECCO 2 R by shifting the chemical equilibrium from bicarbonate to carbon dioxide. Our goal was to test if regional blood acidification during ECCO 2 R inhibits platelet function and coagulation.Methods: An ECCO 2 R system containing a hemofilter circulated blood at 0.25 L/min in eight healthy ewes (Ovis aries) for 36 h. Three of the sheep received ECCO 2 R with no recirculation compared to five sheep that received ECCO 2 R plus 12 h of regional blood acidification via the hemofilter, placed upstream from the oxygenator, into which 4.4 M lactic acid was infused. Blood gases, platelet count and function, thromboelastography, coagulation-factor activity, and von Willebrand factor activity (vWF:Ag) were measured at baseline, at start of lactic acid infusion, and after 36 h of extracorporeal circulation.Results: Twelve hours of regional acid infusion significantly inhibited platelet aggregation response to adenosine diphosphate; vWF; and platelet expression of P-selectin compared to control. It also significantly reduced consumption of fibrinogen and of coagulation factors V, VII, IX, compared to control. Conclusions: Regional acidification reduces platelet activation and vitamin-Kdependent coagulation-factor consumption during ECCO 2 R. This is the first report of a simple method that may enhance effective anticoagulation for ECCO 2 R.