Background and Goal of Study: 
Abnormal fibrinolysis has been associated with increased patient mortality in major trauma and other critical care conditions. However, it is recognized that fibrinolytic defects are often underdiagnosed and that there is a lack of reliable and rapid diagnostic assays to detect and guide the appropriate therapies. The goal of this study is to present a novel fibrinolysis assay for the QuantraTM Hemostasis Analyzer.

Materials and Methods: 
The Quantra is a cartridge-based viscoelastic analyzer that measures changes in clot stiffness during coagulation and fibrinolysis using ultrasound detection of resonance. The Quantra fibrinolysis assay is based on the differential rate of reduction in clot stiffness with and without inhibition of fibrinolysis. The assay was evaluated on a research use only version of the Quantra using citrated whole blood samples from normal volunteers under an approved IRB protocol. These samples were spiked with various levels of plasminogen activators to mimic a broad range of fibrinolytic responses. For a subset of these experiments, the ROTEM (EXTEM, APTEM) and the TEG (RapidTEG) assays were performed in parallel.

Results and Discussion: 
Assay reproducibility of moderate fibrinolysis induced by 30 U/mL of t-PA was estimated in the range from 6-9%. Furthermore, titration of t-PA in the range from 0 to 100 U/mL generated a monotonic response showing a greater than 10-fold difference over that range. TEG and ROTEM assays demonstrated equal or lower response compared to the Quantra, especially in the range from 0 to 20 U/mL of tPA. Standard linear regression with RapidTEG's LY60 indicated very strong correlation with r-value greater than 0.8. Time to results with the Quantra assay depended on the degree of fibrinolysis, with runtimes ranging from 16-26 minutes in cases of pronounced fibrinolysis.

Conclusions: 
The results demonstrate the ability of the Quantra fibrinolysis assay to rapidly and precisely assess fibrinolytic activity in in vitro models. This new assay, which is implemented in a multi-test cartridge, provides additional clinical coagulation parameters and is targeted for trauma, liver disease, and peri-partum care.

07 / A Novel Differential Assay to Quantify Fibrinolytic Function in Whole Blood with the Quantra Hemostasis Analyzer