Comparison of New Viscoelastic Coagulation Monitor with Standard of Care Thromboelastography for Anticoagulation Monitoring during 72-Hour Extracorporeal Life Support

ABSTRACT

Introduction: Management of coagulation remains the foremost challenge during extracorporeal life support (ECLS). Thromboelastography (TEG) and other viscoelastic clotting tests have shown utility for assessing coagulation status in trauma and ECLS patients and have also been utilized in COVID 19 patients. However, with few exceptions, these methods are performed in a laboratory setting, not at the bedside, and rely on cumbersome, non-portable equipment. The Viscoelastic Coagulation Monitor (VCM;Entegrion;Durham, NC) is a portable device/test developed for use at the bedside and outside hospitals to assess clot formation and lysis using a small sample of whole blood. Blood coagulation is activated by contact with the glass surface on the cartridge, and measurements are derived pertaining to clot formation, stability, and lysis - similar to metrics obtained by the TEG 5000 (Haemonetics;Boston, MA). In a recent study, the relationship of VCM results and heparin dose administered in 36 COVID-19 patients was investigated;however, use of VCM for ECLS with application of heparinase has not been reported. We investigated efficacy of the VCM for coagulation monitoring during 72 hours of continuous ECLS in swine and hypothesized that the VCM with heparinase correlates with TEG heparinase. Methods: Female Yorkshire swine (n=3, 53.4±1.6kg) were anesthetized, mechanically ventilated, and systemically heparinized. Blood samples were collected at baseline, post ECLS, 6, 24, 48, and 72-hours post ECLS initiation. For the VCM, 350μL of whole blood was added to a 0.05 IU heparinase vial, mixed, and then added to a VCM cartridge. For TEG, 340μL of citrated whole blood was added to 20μL 0.2 M CaCl2, and samples were activated with a kaolin reagent. Heparinase cups (Haemonetics;Boston, MA) were used for testing. Spearman correlation was performed to compare standard VCM metrics (clotting time [CT], clot formation time [CFT], alpha, maximum clot firmness [MCF], clot retraction/fibrinolysis [LI30]) to the respective TEG metrics (reaction time [R], clot formation time [K], alpha, maximum amplitude [MA], clot retraction/fibrinolysis [LY30]), and also to other conventional coagulation measurements such as prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen (FIB), and platelet count (PLT) for each timepoint. A p-value of 0.05 was used for significance. Results: All VCM metrics significantly correlated with the respective TEG measurements (see Table 1). Both VCM and TEG show the same positive and negative correlation relationships for clot formation time, clot kinetics, and clot retraction with conventional coagulation tests (see Table 2). Additionally, clotting time and maximum clot firmness did not show moderate or significant correlation with conventional tests. Prothrombin time did not correlate with any values. Conclusion: The VCM is comparable to TEG in assessing coagulation status in heparinized swine and can be used during austere care with ECLS application. In the next round of experiments, we will validate the VCM in clinically-relevant trauma with and without ECLS.