A patient is bleeding profusely and needs blood. Do you measure hematocrit and conduct viscoelastic tests, e.g., thromboelastography, to determine which blood products are needed? Alternatively, do you give a fixed ratio of blood to fresh frozen plasma? No matter which approach is used, quick decision-making skills and therapy are required.
Drs. Herbert Schöchl and Christoph J. Schlimp, Department of Anaesthesiology and Intensive Care, AUVA Trauma Hospital, Salzburg, Austria, and Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, Austria, compared these two methods of therapy for just such a scenario. Their work will be published in a future issue of Anesthesia & Analgesia in the review article “Trauma Bleeding Management: The Concept of Goal-Directed Primary Care.”
Tests such as prothrombin time (PT), prothrombin index, International Normalized Ratio (INR), and/or activated partial thromboplastin time (aPTT) can be used, but processing the results can take an hour. The bleeding patient might die if therapy is delayed awaiting laboratory studies. Viscoelastic measurements such as rotational thromboelastometry (ROTEM®) and thromboelastography (TEG®) can provide real-time assessment of coagulation status.
Earlier work showed that use of a ratio of FFP:RBC of 2:3 would correct coagulation when treating major bleeding. In a study of major bleeding at a combat support hospital, mortality was less when a FFP:RBC ratio of 1:1.4 was used. All studies of this type have been retrospective. Such observational studies can have survivor bias: patients with a worse prognosis might have been given more blood compared to FFP and patients could have died after receiving blood but before they received FFP, particularly since blood can be given immediately while FFP takes time to thaw.
When viscoelastic monitors are used, hemostatic therapy can be goal directed. Hyperfibrinolysis can be detected using such monitors. Objective evidence of hyperfibrinolysis can be specifically treated, tranexamic acid (TXA), which inhibits fibrinolysis. Similarly, inadequate clot strength can be treated with fibrinogen supplementation to improve clot strength. Fibrinogen can be quickly reconstituted without having to thaw or cross-match. Similarly, the use of cryoprecipitate can be goal directed, if cryoprecipitate is available (it has been withdrawn in many European countries due to safety concerns).
No study of outcome has been performed that has compared the use of goal-directed coagulation management to using fixed PC:FFP ratios. Nevertheless, guided use of fibrinogen supplements is faster since the time required to allow FFP to thaw is avoided. Prospective studies comparing the two techniques are needed.