α‐angle is reduced, a normal maximum amplitude. What component replacement would aid in resuscitative efforts?CryoprecipitatePlateletsTranexamic acidFresh frozen plasma (FFP)Platelets and cryoprecipitateThrombelastography (TEG) has been used as a guide to blood product replacement for acutely bleeding patients and has been studied as an alternative to ratio‐based mass transfusion protocols. TEG offers the advantage of real‐time point of care testing of coagulation function in whole blood. A rapid TEG differs from conventional TEG because tissue factor is added to the whole blood specimen, resulting in accelerated reaction and subsequent analysis. See graphic representation and interpretation below (Figure 11.1 and Table 11.1). The R value, which is recorded as activated clotting time (ACT) in the rapid TEG specimen, reflects clotting factor activation and the time to onset of clot formation. Normal R time ranges from 5–10 minutes. A deficiency of clotting factors will result in a prolonged ACT, which can be treated by FFP transfusion. The K value is the interval from the beginning of clot formation to a fixed level of clot firmness measured at a standard 20 mm amplitude. It reflects the activity of thrombin which cleaves fibrinogen. Normal K time is 1–3 minutes. Similarly, the α angle reflects the rate of clot formation and is another measure of fibrinogen activity. Normal α angle is 53–72°. A prolonged K value and a decreased α angle represent a fibrinogen deficit which can be treated by transfusion of FFP or cryoprecipitate. The maximum amplitude (MA) measures the final clot strength, reflecting the end result of platelet–fibrin interaction. Normal MA is 50–70 mm. If the MA is decreased after transfusion of FFP, then platelet transfusion should be considered. The patient described has a prolonged ACT as well as prolonged K time and decreased α angle. This is best treated by FFP transfusion to replace both the clotting factor deficiency and fibrinogen deficiency. If the K time remains prolonged after correction of the ACT, then cryoprecipitate can be given.Figure 11.1 Normal thromboelastogram tracingTable 11.1 Normal thromboelastogram tracingThromboelastogram (TEG) InterpretationComponentsDefinitionNormal valuesProblemTreatmentR TimeTime to onset of clot formation5–10 minutesCoagulation factorsFFPK TimeTime until fixed strength is reached1–3 minutesFibrinogenCryoprecipitateAlpha angleSpeed of fibrin accumulation53–72°FibrinogenCryoprecipitateMaximum amplitudeHighest vertical amplitude of the TEG50–70 mmPlateletsPlateletsLysis at 30 minutes (LY30)Percentage of amplitude reduction 30 minutes after maximum amplitude0–8%Excess fibrinolysisTranexamic acidAnswer: DInaba, K., Rizoli, S., Veigas, P.V., et al. (2015) 2014 consensus conference on viscoelastic test‐based transfusion guidelines for early trauma resuscitation: report of the panel. J Trauma Acute Care Surg , 78 (6), 1220–1229.Gonzalez, E., Pieracci, F.M., Moore, E.E., et al. (2010) Coagulation abnormalities in the trauma patient: The role of point‐of‐care thromboelastography. Semin Thromb Hemost , 36 (7), 723–737.7 Which of the following is not an advantage of rapid thrombelastography (TEG) in the setting of trauma?Viscoelastic assays better characterize trauma‐induced coagulopathy when compared to conventional coagulation profiles.TEG can better direct massive transfusion than protocol‐driven balanced ratio component therapy allowing for reduced product administration.TEG is the only clinically available means of detecting fibrinolysis accurately and in a point‐of‐care setting.TEG results are available within minutes.TEG has demonstrated survival benefit in guiding the management of thromboembolic events in the setting of post‐injury hypercoagulability.TEG characterizes the life‐span of a clot; from initial fibrin formation, to incorporation of platelets, to fibrinolysis. With results available within 10 minutes, an initial hemostatic assessment with TEG identifies patients at risk for post‐injury coagulopathy upon arrival. The point‐of‐care variables that result enable the clinician direct management of patients in the trauma bay in real time while allowing for a data‐driven, goal‐directed hemostatic resuscitation. A recent clinical trial demonstrated that the use of TEG to guide massive transfusion in trauma patients, compared with conventional coagulation assays, resulted in a decrease in mortality while using fewer blood products. TEG is also currently used for patient‐personalized administration of antifibrinolytics (e.g., tranexamic acid) based on LY30 parameters rather than administering TXA empirically when massive transfusion is required. Additionally, because TEG characterizes dynamic hypercoagulability and simultaneously reflects the antithrombotic effect of chemoprophylaxis, it may serve as a template for designing tailored thromboprophylaxis regimens; however additional studies are needed, and survival benefit has yet to be demonstrated.Answer: EGonzalez, E., Moore, E.E., Moore, H.B., et al. (2016) Goal‐directed hemostatic resuscitation of trauma‐induced coagulopathy: A pragmatic randomized clinical trial comparing a viscoelastic assay to conventional coagulation assays. Ann Surg , 263 (6), 1051–1059.Gonzalez, E., Pieracci, F.M., Moore, E.E., et al. (2010) Coagulation abnormalities in the trauma patient: The role of point‐of‐care thromboelastography. Semin Thromb Hemost , 36 (7), 723–737.
8 A 29‐year‐old man dropped off by his friend after crashing his all‐terrain vehicle. Upon evaluation, he has altered mental status and a distended abdomen that is diffusely tender. His blood pressure is 80/60 mmHg and heart rate 140 per minute. He does not respond to initial resuscitation and massive transfusion protocol is activated. The time of his injury is unclear at this time and his initial thromboelastography (TEG) results reveal normal R time, normal k time, normal MA and LY30 greater than normal. What is the next best step in management?Give 2 units of fresh frozen plasmaAdminister 1 g of tranexamic acid (TXA)Give 1 unit of plateletsGive 10 units of cryoprecipitateGive cryoprecipitate and plateletsTEG is useful in evaluating trauma‐induced coagulopathy for goal‐directed therapy. In this instance, the patient has massive transfusion requirements and time of injury is unclear. Rather, than empirically administering TXA, the TEG is useful in quickly identifying that this patient would likely benefit from its administration. LY30 greater than 3–5% is representative of hyperfibrinolysis. It seems intuitive that an antifibrinolytic medication should only be administered to those who have demonstrable hyperfibrinolysis; however, advocates for its empiric administration to all trauma patients exist. As evident by the CRASH‐II trial, mortality benefit was seen in all trauma patients receiving TXA; however, this study also found that administration of tranexamic acid greater than 3 hours after injury was associated with increased mortality. Therefore, it is prudent to utilize TEG to ascertain those patients most likely to benefit from TXA.Answer: BGonzalez, E., Moore, E.E., and Moore, H.B. (2017) Management of trauma‐induced coagulopathy with thrombelastography. Crit Care Clin , 33 (1), 119–134.
9 A 35‐year‐old man is recovering in the intensive care unit 1 day after undergoing a damage control laparotomy for hemodynamic instability following a motorcycle crash in which he suffered a severe left pulmonary contusion, pneumothorax, femur fracture, grade 5 splenic laceration requiring splenectomy and destructive colon injury. He required massive transfusion as part of his resuscitation. Currently, his blood pressure is 110/75 mm Hg and heart rate 100. He is awake and breathing spontaneously on the ventilator with minimal support. His laboratory results reveal a hemoglobin of 7.9 g/dL, platelets 40 000/mm 3 , prothrombin time 16 seconds, partial thromboplastin time 38 seconds, and fibrinogen 255 g/dL. He has remained stable and off vasopressors since admission to the ICU.Which product(s) should be transfused at this time?Red blood cells, platelets, and plasmaRed blood cells, platelets, and cryoprecipitateTranexamic AcidNo products at this timeRed blood cellsBased on guidelines for enrollment in the current Pragmatic, Randomized Optimal Platelets and Plasma Ratios (PROPPR) study, criteria for stopping the massive transfusion protocol should include both anatomic (control of bleeding) and physiologic criteria (normalizing hemodynamic status). In this stable trauma patient without evidence of active bleeding, no blood products are needed at this time. A restrictive transfusion strategy maintaining hemoglobin at 7.0–9.0 g/dL has been shown to be as effective as a liberal transfusion strategy maintaining hemoglobin concentration at 10.0–12.0 g/dL. For those with an APACHE II score ≤ 20, 30‐day mortality is significantly less with a restrictive strategy. In the absence of clinical bleeding, fresh frozen plasma transfusion may be associated with an increased incidence of acute lung injury. Evidence to support prophylactic platelet transfusion in critically ill patients
