Neurosurgical applications of viscoelastic hemostatic assays

Abstract

Patients taking antithrombotic agents are very common in neurosurgical practice. The perioperative management of these patients can be extremely challenging especially as newer agents, with poorly defined laboratory monitoring and reversal strategies, become more prevalent. This is especially true with emergent cases in which rapid reversal of anticoagulation is required and the patient's exact medical history is not available. With an aging patient population and the associated increase in diseases such as atrial fibrillation, it is expected that the use of these agents will continue to rise in coming years. Furthermore, thromboembolic complications such as deep venous thrombosis, pulmonary embolism, and myocardial infarction are common complications of major surgery. These trends, in conjunction with a growing understanding of the hemostatic process and its contribution to the pathophysiology of disease, stress the importance of the complete evaluation of a patient's hemostatic profile in guiding management decisions. Viscoelastic hemostatic assays (VHAs), such as thromboelastography and rotational thromboelastometry, are global assessments of coagulation that account for the cellular and plasma components of coagulation. This FDA-approved technology has been available for decades and has been widely used in cardiac surgery and liver transplantation. Although VHAs were cumbersome in the past, advances in software and design have made them more accurate, reliable, and accessible to the neurosurgeon. VHAs have demonstrated utility in guiding intraoperative blood product transfusion, identifying coagulopathy in trauma, and managing postoperative thromboprophylaxis. The first half of this review aims to evaluate and assess VHAs, while the latter half seeks to appraise the evidence supporting their use in neurosurgical populations.

Keywords: AA = arachidonic acid; ADP = adenosine diphosphate; APTEM = aprotinin effect as measured by ROTEM; CCT = conventional coagulation test; CFT = clot formation time; CI = confidence interval; DAT = dual antiplatelet therapy; DCI = delayed cerebral ischemia; DOAC = direct oral anticoagulant; EPL = estimated percentage lysis; FF = functional fibrinogen; FFP = fresh frozen plasma; FIBTEM = fibrinogen component of ROTEM; HEPTEM = heparin effect as measured by ROTEM; ICH = intracerebral hemorrhage; INTEM = intrinsic pathway measured by ROTEM; LY30 = lysis at 30 minutes; MA = maximum amplitude; MCF = maximal clot firmness; ML = maximum lysis; MRTG = maximum rate of thrombus generation; PED = Pipeline embolization device; PT = prothrombin time; PTT = partial thromboplastin time; RBC = red blood cell; ROTEM = rotational thromboelastometry; RR = relative risk; SAH = subarachnoid hemorrhage; TBI = traumatic brain injury; TEG = thromboelastography; TMRTG = time to maximum rate of thrombus generation; TTG = total thrombus generation; TXA = tranexamic acid; VHA = viscoelastic hemostatic assay; assays; coagulation; hemostasis; hemostatic; rotational thromboelastometry; thromboelastography; viscoelastic.