Regional blood acidification inhibits coagulation during extracorporeal carbon dioxide removal (ECCO2 R).

Abstract

Consumption of platelets and coagulation factors during extracorporeal carbon dioxide removal (ECCO2 R) increases bleeding complications and associated mortality. Regional infusion of lactic acid enhances ECCO2 R by shifting the chemical equilibrium from bicarbonate to carbon dioxide. Our goal was to test if regional blood acidification during ECCO2 R inhibits platelet function and coagulation. An ECCO2 R system containing a hemofilter circulated blood at 0.25L/min in eight healthy ewes (Ovis aries) for 36h. Three of the sheep received ECCO2 R with no recirculation compared to five sheep that received ECCO2 R plus 12h 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 36h of extracorporeal circulation. 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. Regional acidification reduces platelet activation and vitamin-K-dependent coagulation-factor consumption during ECCO2 R. This is the first report of a simple method that may enhance effective anticoagulation for ECCO2 R.