P. J. Lawson1, H. B. Moore1, G. R. Stettler1, T. J. Pshak1, T. L. Nydam1 1University Of Colorado Denver,Aurora, CO, USA
Introduction:
Pre-operative laboratory values to assess liver transplant patients coagulation status is based off of plasma based assays, such as INR. These assays partition coagulation and violate the current understanding of cell the based hemostasis. Whole blood viscoelastic assays such as thrombelastography (TEG) have been used for decades in liver transplant surgery but have not been utilized for perioperative coagulation assessment. We hypothesize that TEG is a superior predictor of perioperative blood products transfused during liver transplant surgery than INR.
Methods:
Liver transplant had blood drawn prior to surgical incision and assayed with citrated native TEG. Pre-operative labs including liver function test, coagulation assays, and complete blood counts were collected as part of the standard of care. Initial blood samples were collected on patients before surgical incision. TEG variables including R-Time, Angle, MA, and LY30 were correlated to red blood cell (RBC), plasma (FFP), cryoprecipitate (Cryo), and platelets (Plts) during the intra operative period in addition to INR, platelet count, and MELD score. Massive transfusion (MT) was defined as >10 units of RBC during surgery. A receiver operator curve (ROC) was generated to identify which pre-operative value had the greatest predictability of identifying a patient requiring a MT during surgery.
Results:
Eighteen patients were included in the analysis. The median MELD score was 29.0 (20.5-37.0). The median INR was 1.4 (1.3-2.8). The median RBC transfused was 3.5 (0.8-11.3). The median Platelet Count was 91 (50-111). Pre-Op TEG values were: R-Time (12.3 min, 7.4-12.3), Angle (52.2 degrees, 38.6-56.9), MA (51.8 mm, 36.5-60.8), and LY30 (0.1 %, 0.0-1.3). 33% of patients required a massive transfusion. Spearman’s Rho correlations for RBC transfusion and variables of interest included: R-Time (0.1583, p=0.530), Angle (-0.4623, p=0.534), MA (-0.6268, p=0.005), LY30 (0.1184, p=0.640), INR (0.5013, p=0.422), Plts (0.5053, p=0.040), MELD (0.4974, p=0.036). Correlation to FFP utilization was significant for MA (p=0.0081), INR (p=0.006), and Plts (p=0.044), but not other variables. This correlation persisted for MA for Cryo (p=0.003) and Plts (p<0.001), but not INR. Pre-Op lab and TEG variable correlation to RBC use were ROC curve with AUC (p=0.013). When performing a ROC curve, MA had an AUC of 0.941 (p<0.001) superior to INR AUC of 0.618 (p=0.235).
Conclusion:
Preoperative assessment of predicted blood product utilization in liver transplant surgery remains poorly defined. The INR which drives preemptive plasma transfusion before surgery was not a good predictor of massive transfusion. The maximum clot strength measured by TEG has superior predictability and may help guide more cost effective blood bank preparation for this procedure as only a third of patients required a massive transfusion.