Background: The Quantra® is a newly introduced cartridge-based viscoelastic testing device designed to monitor coagulation at the point-of-care (POC). The system directly measures a series of clot stiffness-based parameters which include total Clot Stiffness (CS) and the Fibrinogen Contribution (FCS) to clot stiffness. From the measurements of CS and FCS, the Platelet Contribution to stiffness (PCS) is calculated. CS and FCS represent the clot stiffness (shear modulus) measured 7 minutes after clot initiation.

Aims: To establish the relationship between the measurements of CS and FCS determined 7 minutes after clot initiation and the maximum clot stiffness values measured by the Quantra System.

Methods: The Quantra System uses multichannel cartridges with each channel containing unique combinations of lyophilized reagents. CS is measured in the presence of thromboplastin, whereas FCS is measured in the presence of thromboplastin with inhibition of platelet aggregation/contraction by abciximab. In the experiments presented here, clot stiffness vs time curves were generated for a time period of roughly 60 minutes and maximum (i.e., peak) clot stiffness values were recorded off-line using MATLAB (Mathworks Inc, Natick, MA).

Results: Data were collected using an Investigational Use Only (IUO) version of the Quantra and QStat cartridges from whole blood samples obtained from normal healthy volunteers (N = 32) and trauma patients enrolled at two sites in the United States (N = 56). The data indicated a strong correlation between FCS, CS and maximum clot stiffness measurements. The r value for the combined relationship is above 0.9 indicating that the 7 min reading used by the Quantra is directly proportional to maximum stiffness. (See Figure)

Conclusions: The relationship between maximum clot stiffness and Quantra-based stiffness parameters is highly linear indicating that reporting clot stiffness 7 min after clot initiation not only establishes physiologically based representative data but also more rapid information than max stiffness readings.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/quantra-reported-stiffness-values-have-a-strong-linear-relationship-with-clot-max-stiffness/