Presentation Details
| iCoagLab Permits Comprehensive Coagulation Profiling in Patients on Percutaneous Cardiac Pump Support Eli J Foster, Nathaniel Hai, Ziqian Zeng, Seemantini K Nadkarni. Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA |
Abstract
Background Rapidly changing coagulation status is a major challenge in managing and preventing bleeding in patients on mechanical circulatory support. While having positive implications on patients’ long-term outcomes, percutaneous left ventricular assist devices (p-LVADs) have notoriously been associated with severe bleeding in 15-30% of patients during in-hospital treatment [1][2]. Conventional plasma tests that measure activated partial thromboplastin time (aPTT) and anti-Xa often are imprecise in the context of rapidly changing coagulation conditions in these patients and fail to accurately predict major bleeding events. These factors highlight a critical barrier to the wide-spread clinical adoption of implantable cardiac pumps: the ability to predict hemorrhage is restricted by the absence of tools to evaluate the coagulation system rapidly and comprehensively at the point-of-care. Objective Here, we present iCoagLab, a hand-held coagulation profiling instrument, as a method for timely and comprehensive blood coagulation assessment in patients with p-LVADs. The iCoagLab system is shown in figure 1. We aim to assess the accuracy of iCoagLab for comprehensive coagulation profiling in whole blood samples by comparing against Thromboelastography (TEG 6s) and standard clinical coagulation tests. Methodology iCoagLab quantifies the viscoelastic properties of clotting blood by measuring displacements of endogenous light scattering centers within the sample, through time-varying laser speckle intensity fluctuations of back-scattered light [3]-[7]. We test the accuracy of performing comprehensive coagulation tests using iCoagLab in patients (N=15) with implanted cardiac pumps (Impella 5.5 and CP pumps, Abiomed, Danvers, MA). For this study, we collected discarded blood samples from the hematology core lab at Massachusetts General Hospital. We initiate coagulation intrinsically using kaolin assays and extrinsically using recombinant human tissue factor assays. We use iCoagLab to extract intrinsic coagulation parameters relating to the rate (reaction time, R; activated clotting time, ACT; and clot rate, angle) and mechanical strength (maximum amplitude, MA) of clot formation, as well as extrinsic coagulation parameters prothrombin time, PT, and fibrinogen, QFA. The iCoagLab characterizes intrinsic parameters within 15 minutes while it characterizes extrinsically initiated clots in under 1 minute using 25uL of whole blood. Sample coagulation curves with labeled parameters in shown in figure 2. The iCoagLab values are then compared with corresponding Thromboelastography TEG 6S parameters and with fibrinogen levels, aPTT, PT, and anti-Xa, as measured by a Werfen ACL Top 350, using linear regression analysis. Results Statistically significant correlations were observed between iCoagLab and TEG 6s for R time (r=0.56, p<0.001, N=35), angle (r=0.38, p<0.05), ACT (r=0.64, p<0.001, N=36) and MA (r=0.70, p<0.001, N=45). Strong correlations were further observed between iCoagLab ACT and Werfen anti-Xa (r=0.57, p<0.001, N=72), iCoaglab angle and Werfen aPTT( r=-0.74, p<0.001, N=72), iCoagLab PT and Werfen PT (r=0.61, p<0.001, N=66), and iCoagLab MA and Werfen QFA (r=0.66, p<0.001, N=66). Conclusions Our results confirm the high accuracy of iCoagLab in quantifying actionable clotting parameters within 15 minutes in patients with p-LVADs using a small volume of whole blood. These studies will help pave the way towards addressing life-threatening bleeding complications swiftly at the point of care.
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