A. Kam1, H. B. Moore1, C. B. Walker1, J. L. Dexter-Meldrum1, M. Chapman1, T. Johnson1, M. A. Adams1, T. Pshak1, I. Kam1, E. Pomfret1, T. L. Nydam1 1University Of Colorado Denver,Surgery,Aurora, CO, USA
Introduction: Less than optimal outcomes following donation after cardiac death (DCD) donation are in part attributed to the development of microthrombi within the microvasculature of the graft. Using thromboelastography (TEG) during DCD recovery we have found numerous donors retain full clotting strength despite heparinization. We therefore sought to determine the effects of two commonly used preservation solutions, University of Wisconsin (UW) solution and Histidine-Tryptophan-Ketoglutarte (HTK), on clot formation and fibrinolysis. We hypothesize HTK will have a greater effect on promoting hypocoagulability due to its lower viscosity.
Methods: Coagulation was assessed by TEG using whole blood diluted to 25%, 50%, and 75% with each preservative solution including HTK, UW and normal saline (NS). NS was used as a control to adjust for dilutional effects. The following TEG parameters were recorded: clot initiation (R time), fibrin polymerization (angle), and clot strength [maximum amplitude (MA) and clot lysis 30 minutes after reaching MA (LY30)]. For each solution, the dilution concentration was correlated to TEG indices with Spearman’s Rho test. Solutions were contrasted between each other at set concentrations using a Friedman test. Data was described as the median.
Results: Eight healthy volunteers donated blood. The serial dilution of whole blood with NS correlated with a prolonged R time (0.527 p=0.008), shallow angle (-0.693 p<0.001), lower MA (-0.811 p<0.001), and lower LY30 (-0.482 p=0.017). This was similar to HTK (R time 0.564 p=0.004; angle -0.752 p<0.001; MA -0.818 P<0.001 and LY30 -0.643 p=0.001). UW dilution had similar correlations with the exception that LY30 had a positive correlation with dilution (0.410 p=0.047). When contrasting TEG indices at different dilutions, no significant differences were seen until the dilution reached 75%. Whole blood diluted with 75% HTK had significantly reduced fibrin polymerization compared to NS and UW (17° vs 32° vs 28° p=0.005 Figure). Whereas UW had significantly increased LY30 compared to NS and HTK (1.9% vs 0% vs 0% p<0.001).
Conclusion: Different preservation solutions have similar effects on coagulation as normal saline until 75% of whole blood has been replaced. However, at 75% dilution, these solutions have different contributions to disturbances in TEG indices promoting hypocoagulability. HTK promotes a weaker clot from impaired fibrin polymerization, while UW promotes fibrinolysis. These data support tailoring preservation solution to the pre-existing hypercoagulabilty seen in donors in order to optimize organ recovery.