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Abstract
Cardiac surgical patients are administered large heparin doses to prevent thrombosis during surgery. Activated clotting time (ACT), traditionally used to assess anticoagulation correlates poorly with heparin concentration and lacks information on key coagulation metrics such as fibrin polymerization (α-angle) and clot strength (MA). Here we assess the accuracy of our novel bedside optical sensor, iCoagLab, in measuring several coagulation parameters including ACT, α-angle and MA and evaluate its capability to monitor anticoagulation during cardiac surgery. iCoagLab measures anticoagulation by assessing changes in blood viscosity from intensity fluctuations of laser speckle patterns measured from a 25µL blood drop. In this study, blood samples from 18 volunteers spiked with increased concentrations of heparin (0.2-5USP/mL) and from 30 patients undergoing cardiac surgery were assessed using iCoagLab. Coagulation metrics, including, ACT, α-angle and MA, were derived and compared with corresponding results obtained from thromboelastography (TEG), ISTAT-kaolin-ACT and Hepcon-HMS-Plus-instruments. In volunteer samples, heparin dose significantly prolonged the ACT values measured by iCoagLab which correlated closely with TEG (r=0.95, p<0.0001) and ISTAT-ACT (r=0.87, p<0.0001). Both the iCoagLab and TEG showed a decrease in MA at high heparin concentration (p<0.01). Similarly, in cardiac surgical patients, iCoagLab-ACT correlated strongly with Hepcon (r=0.76 p<0.0001) and TEG-ACT (r=0.89, p<0.0001). The MA and α-angle were also significantly modulated throughout surgery (p<0.05-0.0001) similar to TEG. These studies showed that iCoagLab rapidly and accurately measured anticoagulation and global hemostasis using just a 25µL blood drop, likely opening the powerful opportunity for multifunctional coagulation monitoring at the bedside during surgery.
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