Viscoelastic Assay-Guided Hemostatic Therapy in Perioperative and Critical Care

Abstract

Hemorrhage is a major contributor to morbidity and mortality during surgery and in the intensive care unit. Viscoelastic assays are point-of-care tests that depict the hemostatic process on whole blood enabling timely and individualized administration of blood products (or lack thereof). Their use has increased exponentially in the last decades and many guidelines advocate their implementation in different scenarios, spanning from cardiac surgery to obstetrics and from liver transplants to severe trauma. Indeed, viscoelastic-based transfusion algorithms have been shown to be effective in reducing bleeding, transfusion requirements, complication rates, and health care costs. Despite the clear advantages compared to standard coagulation tests, viscoelastic assays require training of the users and pipetting skills. The new generation devices have tackled these issues and are now based on user-friendly cartridges which reduce pre-analytical manipulation and, therefore, errors. One other aspect of viscoelastic-based transfusion algorithms that limits generalizability of the results of published studies and meta-analysis is the wide variability of transfusion thresholds adopted in each algorithm. The lack of evidence-based transfusion thresholds for most parameters of the viscoelastic readout theoretically exposes patients to the risk of under- or over-transfusion. Viscoelastic tests are surely a valuable aid in the identification of coagulation deficits and individualization of therapy in bleeding patients, but more high-quality research on this topic is warranted to optimize patient safety.