Abstract 520: Acoustic Tweezing Thromboelastometry

Abstract

Background: Critical care patients such as trauma and major surgery patients often develop coagulopathy due to depletion of both pro- and anti-coagulants. They are at high risk of both bleeding and thrombotic complications and require monitoring of their coagulation status. The contact of a blood sample with artificial surfaces and its exposure to clot activators, which happen in all commercially available coagulation analyzers, may lead to improper assessment of blood coagulation and thus errors in predicting bleeding/thrombosis risks. Objective: Real-time assessment of whole blood or blood plasma coagulation by novel non-contact acoustic tweezing technology. Method: 4-5 microliter drops of whole blood collected from healthy volunteers or commercial control plasma were levitated in air by acoustic radiation forces. Their coagulation kinetics including reaction time, fibrin network formation time (FNFT), clot formation time and maximum clot strength was assessed from mechanical (drop shape) and photo-optical (light intensity) data. FNFT was determined as a difference between mechanical and photo-optical reaction times. Results: Whole blood samples were exposed to pro- or anti-coagulants during levitation in the acoustic tweezing device. Changes in the coagulation status between different experimental groups were detected within 10 minutes. Similarly, less than 7 minutes was required to detect significant changes in reaction time, clot formation time and maximum clot strength between low, normal, and high fibrinogen level control plasma samples. FNFT was shown to be significantly reduced in plasma samples with a higher level of Factor XIII. Conclusions: The acoustic tweezing technology integrates photo-optical tests used in plasma coagulation assays with viscoelastic tests used in whole blood analysis. Its key disruptive features are the increased reliability and accuracy due to non-contact measurement, small sample volume requirement, relatively short procedure time (<10 minutes), and the ability to assess the level of Factor XIII function from FNFT measurements. Our technology addresses a current lack of reliable methods to measure blood coagulation in patients with coagulopathy.