K6 - Drop-of-blood coagulation analysis with noncontact acoustic tweezing

Introduction: : Plasma and whole-blood coagulation tests are routinely performed to assess bleeding and thrombosis risks in critical care
patients, patients with coagulation disorders, and patients on anticoagulant therapy. Acoustic tweezing coagulometry is a novel sample-sparing technology that provides containerless coagulation analysis using a 4-6 microliter drop of blood. It operates in two regimes: integrated quasi-static acoustic tweezing thromboelastometry (i-QATT), which measures clot firmness and turbidity, and acoustic tweezing spectroscopy (ATS), assessing clot viscoelasticity. The objective of this study was to assess the clinical validity of these techniques through coagulation measurements of venous whole blood (WB) and platelet-poor plasma (PPP) samples from different groups of human subjects.

Materials and

Methods: : Venous WB samples were collected from healthy non-smoking adult volunteers (normal group), smoking adult volunteers (hypercoagulable group), pediatric patients with hemophilia A (hypo-coagulable group), liver transplant patients, and pediatric patients on ECMO or hemodialysis. PPP isolated from WB, commercial PPP, including normal control, low and high fibrinogen, and factor-deficient, were used in the study. The linear correlation between i-QATT/ATS coagulation parameters and standard lab test values (PT, INR, aPTT, fibrinogen, platelet count, TEG, ROTEM) was analyzed using the Pearson or Spearman rank correlation coefficient. The diagnostic capability was tested by abnormal blood sample analysis. This study was approved by Tulane University Institutional Review Board. .

Results, Conclusions, and Discussions:: The results of this study indicate that the values of i-QATT parameters MCF (maximum clot firmness), CIT (clot initiation time), and RT (reaction time) were strongly correlated with fibrinogen concentration and lab values obtained by gold-standard plasma tests (aPTT, PT) and viscoelastic hemostatic assays (TEG, ROTEM). Reference ranges for these parameters ruled out abnormal coagulation caused by factor deficiency, heparin, antiplatelet agents (Cytochalasin-D), or fibrinogen spiking (Fig. 1). The i-QATT technique was able to detect abnormal coagulation within 8 minutes in WB and 3 minutes in PPP and fibrinolysis within 15 minutes in WB. It also accurately predicted platelet hyperactivity in liver transplant patients and anticoagulant dose effects and their reversal in patients on ECMO or hemodialysis. In the ATS technique, RT measured from the WB viscosity data demonstrated a strong correlation with plasma PT/aPTT. A linear correlation was also obtained between the WB MCF output and the fibrinogen concentration. The presented data showcase the ability of acoustic tweezing coagulometry to rapidly assess coagulation status, detect factor deficiencies, measure fibrinogen level, platelet function, and fibrinolysis, diagnose consumptive coagulopathy, assess anticoagulant effects, and measure PT/INR/aPTT in WB or hemolyzed PPP samples.

Acknowledgements and/or References (Optional):: This study has been supported by grants from the National Science Foundation (2134020) and National Institutes of Health (R21EB031401, R43EB031013).