Subcommittee on Biorheology: Dimensional analysis and scaling relevant to flow models of thrombus formation Flow chambers are increasingly used to model thrombus formation in (patho)physiologically inspired geometries and conditions. The flexible design enabled by microfluidics and the variety of commercially available devices makes comparisons between flow chambers challenging. There is also a need to make faithful comparisons between these in vitro models and animal models. Dimensional analysis and scaling provide a rigorous method for making these comparisons. Scaling is a mathematical tool used to simplify, characterize and design systems based on their dimensions and dynamics. Scaling arguments to describe biophysical mechanisms that regulate thrombus growth have recently appeared in hematology journals. In practise, scaling involves selecting important dimensional and dynamic parameters and forming dimensionless groups that characterize a system. These dimensionless groups determine the relative importance of geometric features, forces and rates. The purpose of this Communication is to provide a primer on scaling and provide recommendations for reporting and calculating relevant dimensionless groups in flow models of thrombus formation. Read more.
Subcommittee on Control of Anticoagulation: When and how to use antidotes for the reversal of direct oral anticoagulants The direct oral anticoagulants (DOACs), which include dabigatran, rivaroxaban, apixaban, and edoxaban, are licensed for stroke prevention in patients with atrial fibrillation and for prevention and treatment of venous thromboembolism. As a class, the DOACs are at least as effective as vitamin K antagonists (VKAs) but are associated with less life-threatening bleeding, particularly intracranial hemorrhage. Although all anticoagulants can produce bleeding, the outcomes of major bleeds with DOACs are no worse than those with VKAs even in the absence of clinically available antidotes. Nonetheless, antidotes for the DOACs would be useful as one component of strategies for management of serious bleeding, or for rapid reversal of the DOACs before urgent interventions. Read more.