Hemorrhage remains a major contributor to morbidity and mortality during the perioperative period. The swift diagnosis and treatment of coagulopathy is critical to the care of severely bleeding patients. Current methods for diagnosing coagulopathy, however, remain limited by long laboratory runtimes, a lack of information on specific abnormalities of the coagulation cascade, minimal in vivo applicability, and little ability to guide the transfusion of blood products. Viscoelastic testing may allow providers to gather data related to bleeding and coagulopathy before a patient undergoes anesthesia and surgery.
Viscoelastic testing offers a promising solution to many of these challenges 1, helping with the care of severely bleeding patients in the context of major surgery, major trauma, or postpartum hemorrhage 2. In the perioperative period, two assays are most frequently used: kaolin thromboelastography (TEG)-based, and tissue factor–activated rotational thromboelastometry (ROTEM)-based viscoelastic monitoring. The three main goals of such viscoelastic testing assays are to predict bleeding, assess platelet function, and allow for perioperative testing to reduce transfusion 3. They thus provide a nuanced view of the elements of the coagulation system, allowing for the rapid administration of targeted therapy 3. Specifically, these assays can help guide basic decisions regarding the treatment of perioperative coagulopathy, including when the clinician should transfuse platelets, administer fibrinogen concentrate, or administer plasmatic coagulation factors 2.
However, it is critical to note that standard TEG/ROTEM assays are neither sensitive nor specific enough to adequately detect platelet inhibition, the effects of direct oral anticoagulants, or inherited bleeding disorders, such as cases of hemophilia or von Willebrand disease. Diagnoses of these specific conditions are better made preoperatively as part of a routine diagnostic workup 4.
While viscoelastic testing remains a relatively novel method to assess coagulation status, evidence for its use appears favorable in reducing blood product transfusions, especially in cardiac surgery patients 1. Indeed, reviews of the literature, which is primarily focused on cardiac surgery patients, have demonstrated that transfusions of packed red blood cells, plasma, and platelets are all decreased in patients whose transfusions were guided by viscoelastic testing rather than by clinical assessment or conventional laboratory tests. More recent research has further confirmed that implementing transfusion algorithms based on the results of viscoelastic point-of-care coagulation testing can reduce transfusions and lead to improved patient outcomes 2. Finally, meta-analytic data have corroborated that the use of viscoelastic testing in cardiac surgery patients can effectively minimize allogenic blood products exposure, dampen postoperative bleeding at 12 and 24 hours postoperatively, and reduce the need for redo surgery unrelated to surgical bleeding 5.
Overall mortality rates have also been shown to be lower in viscoelastic testing groups, while viscoelastic testing also appears to be cost-effective from a clinical standpoint 1.
However, while results are promising, there remains a dearth of systematic, larger scale trials. Viscoelastic testing remains a relatively novel method, and further improvement and clinical validation of these broadly used basic assays in different surgery contexts are needed 2.
- Shen, L., Tabaie, S. & Ivascu, N. Viscoelastic testing inside and beyond the operating room. J. Thorac. Dis. 9, S299–S308 (2017). doi: 10.21037/jtd.2017.03.85.
- Erdoes, G., Koster, A. & Levy, J. H. Viscoelastic Coagulation Testing: Use and Current Limitations in Perioperative Decision-making. Anesthesiology 135, 342–349 (2021). doi: 10.1097/ALN.0000000000003814.
- Agarwal, S. & Abdelmotieleb, M. Viscoelastic testing in cardiac surgery. Transfusion 60 Suppl 6, S52–S60 (2020). doi: 10.1111/trf.16075.
- Koscielny, J. et al. A practical concept for preoperative identification of patients with impaired primary hemostasis. Clin. Appl. Thromb. (2004). doi:10.1177/107602960401000301
- Meco, M. et al. Viscoelastic Blood Tests Use in Adult Cardiac Surgery: Meta-Analysis, Meta-Regression, and Trial Sequential Analysis. J. Cardiothorac. Vasc. Anesth. 34, 119–127 (2020). doi: 10.1053/j.jvca.2019.06.030.