Presentation Details
| Drop-of-blood coagulation analysis by i-QATTTM Huy Q Pham1, Collette Barnor1, Daishen Luo1, Elizabeth M Cummins1, Nithya Kasireddy1, Daniel Arango2, Shaun Yockelson3, Damir B Khismatullin1. 1Department of Biomedical Engineering, Tulane University, New Orleans, LA, USA.2The University of Texas Medical Branch, Galveston, TX, USA.3Department of Anesthesiology and Perioperative Medicine, Ochsner Medical Center, New Orleans, LA, USA |
Abstract
Background: Blood coagulation testing is important for assessing bleeding/thrombotic risks in critical care patients and patients with coagulation disorders. Integrated quasi-static acoustic tweezing thromboelastometry (i-QATTTM) provides both viscoelastic and turbidimetric measurements of blood coagulation using a small drop of blood (4-6 μ L). Objectives: We aim to (1) establish the clinical validity of i-QATTTM by correlation analysis with gold-standard tests (INR/aPTT and TEG) and reference range measurements of coagulation parameters, and (2) investigate its capability to diagnose hypo- and hyper-coagulable states caused by abnormal fibrinogen, heparin, and coagulopathy. Methods: Citrated whole blood (WB) samples were collected from 16 healthy volunteers using IRB-approved protocols No. 520566 and 944474, and from 8 liver transplant recipients using IRB-approved protocol No. 2020.245. Platelet poor plasma (PPP) samples were isolated from WB samples. Commercial PPP samples, including normal control, low and high fibrinogen, and factor-deficient, were obtained from Fisher Scientific (Hampton, NH) and Affinity Biologicals (Ontario, Canada). For blood samples obtained from healthy volunteers, aPTT/INR and fibrinogen tests were performed by Tulane Coagulation Laboratory, in parallel with i-QATTTM measurements. The first ~500 microliters from each WB sample from liver transplant patients were used for standard-of-care TEG testing at each timepoint of the liver transplant procedure, and the remainder of the sample was used for i-QATTTM analysis. INR values were also obtained for these samples at each timepoint. The linear correlation between the parameters of i-QATTTM and those of gold-standard tests was assessed using either the Pearson correlation coefficient (rp) or the Spearman rank correlation coefficient (rs). Reference ranges for i-QATTTM coagulation parameters were calculated using the established protocol. The i-QATTTM diagnostic capability was assessed by abnormal blood sample analysis. Here, we report the data on the following i-QATTTM parameters: clot initiation time (CIT), reaction time (RT), maximum clot firmness (MCF), and maximum fibrin level (MFL). Results: Statistically significant differences in clot firmness, measured by relative angle ∆θ , between normal and abnormal blood samples were observed at 6 min (p<0.05) (Fig. 1). As shown in Figure 2(a), CIT and RT were strongly correlated with aPTT (rp ≥ 0.83) and INR (rs ≥ 0.67) for PPP samples. CIT and MCF were strongly correlated with TEG R-time and MA (rp ≥ 0.64) for WB samples. Reference ranges for PPP CIT (2.65-4.72 for intrinsic or 0.63-2.04 for extrinsic pathway) established based on normal blood analysis ruled out abnormal coagulation caused by single factor deficiency (FVII, FIX, FX) or anticoagulant therapy (heparin) (Fig. 2b). PPP MCF had abnormal values corresponding to high and low fibrinogen levels outside the established reference range (3.76-9.53). Abnormal CIT and reduced MCF values were seen for WB samples from liver transplant patients with elevated INR (INR = 2.4) and from normal WB samples with platelet function reduced by Cytochalasin-D, respectively. Conclusions: i-QATTTM strongly correlates with gold-standard techniques, and reference ranges of its parameters accurately describe normal coagulation and rule out abnormal cases. Furthermore, i-QATTTM can rapidly detect hypo- and hyper-coagulable states.
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