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onset of transfusion‐related acute lung injury is required to have occurred within 6 hours of the last transfusion. Transfusion‐associated circulatory overload (TACO) was defined as acute onset or worsening respiratory distress during or up to 12 hours after transfusion, plus evidence of acute or worsening pulmonary edema and volume overload. Signs/symptoms include fever, dyspnea, and hypotension. The treatment of TRALI is respiratory support, including measures to avoid worsening of lung injury. Transfusion of all types of blood products can cause TRALI. Pathogenesis is related to donor antibodies in the transfused blood and may also be related to modifications of stored blood. Measures to prevent TRALI include a restrictive transfusion policy, as well as blood bank measures such as predominant use of plasma from male donors.Answer: ASemple, J.W., Rebetz, J., and Kapur, R. (2019) Transfusion‐associated circulatory overload and transfusion‐ related acute lung injury. Blood , 133 (17), 1840–1853.

      4 A 45‐year‐old man requires helicopter evacuation following a farming accident in which he was pinned under a peanut trailer experiencing crush injuries to his lower extremities. Transport time to nearest facility is approximately 35 minutes. His heart rate is 145 per minute, systolic blood pressure is 80 mmHg, and he appears confused. Prehospital providers obtained IV access and administered 1 L of crystalloid in the field. Repeat vitals en route demonstrate a heart rate of 125 and systolic blood pressure of 90. What additional resuscitation, if any, would offer the greatest survival benefit while traveling to the nearest hospital?Additional 1 L of crystalloid1 unit packed red blood cell (PRBC)1 unit fresh frozen plasma (FFP)1 unit PRBC + 1 unit FFPNo additional resuscitation requiredMore than one‐third of preventable deaths due to hemorrhage occur in the field. Evidence gathered from the Prehospital Air Medical Plasma Trial and its secondary analysis, patients with signs of shock should receive prehospital blood products whenever available. Crystalloid alone appears to be inferior to blood products and has a dose–response increase in mortality in this setting. If both PRBC and plasma are available, patients should receive both, as reduction in mortality has been demonstrated. If only 1 product can be added, plasma should be favored, as there is level 1 evidence to support it. The additive benefit of PRBC and plasma also suggests that there may be a benefit to the use of whole blood in the prehospital setting. Finding a balance between organ perfusion and hemostasis is critical when resuscitating a severely injured trauma patient. Answer E would allow for permissive hypotension which would not be advisable for this patient given that his mechanism may have also resulted in a traumatic brain and/or spinal cord injury which have yet to be ruled out. Permissive hypotension is not recommended in the setting of central nervous system injury.Answer: DGuette, F.X., Sperry, J.L., Peitzman, A.B., et al. (2019) Prehospital blood product and crystalloid resuscitation in the severely injured patient: A secondary analysis of the prehospital air medical plasma trial. Ann Surg. doi: 10.1097/SLA.0000000000003324.

      5 Which of the following patients would receive the most benefit from administration of tranexamic acid (TXA)?25‐year‐old male with massive transfusion protocol activated approximately 9 hours post fall from height.80‐year‐old female with a nondisplaced pelvic fracture and stable vital signs on Warfarin.35‐year‐old male with massive transfusion protocol activated for hemodynamic instability 1‐hour after sustaining gunshot wounds to the chest.8‐year‐old male receiving 1:1 component resuscitation immediately following motor vehicle collision.65‐year‐old female with a history of stroke receiving 1:1 component resuscitation after being struck by a car.TXA is a synthetic derivative of the amino acid lysine that inhibits fibrinolysis by blocking the lysine binding site on plasminogen. In patients undergoing elective procedures, TXA has been shown to reduce the need for blood transfusion. The CRASH‐2 trial, a randomized, placebo‐controlled trial of TXA in trauma patients with significant bleeding, demonstrated a significant reduction in all‐cause mortality, as well as deaths due to hemorrhage, in the patients who received TXA within 3 hours. Trial results have been met with both enthusiasm and controversy regarding the application antifibrinolytics for patients with traumatic bleeding. As a consequence, several high‐quality randomized controlled trials are currently underway to help further elucidate the utility of TXA and other antifibrinolytics in traumatic injury, as well as other conditions with severe bleeding. Based on current evidence, TXA is most beneficial in the setting of trauma when empirically used in massive transfusion situations in those patients presenting within 3 hours of injury. Further trials are needed to refine and optimize TXA dosing regimens due to concern for seizures with higher dosing. There was no increase in vascular occlusive events in patients receiving TXA in the CRASH‐2 trial. However, history of or risk factors predisposing to thromboembolic events is considered a relative contraindication, as is the use of TXA in patients with subarachnoid hemorrhages owing to the association with increased cerebral ischemia. Although TXA has been studied extensively in the adult trauma patient, less evidence exists for children, and its use in the pediatric trauma population is not as widespread.Answer: CRamirez, R.J., Spinella, P.C., and Bochicchio, G.V. (2017) Tranexamic acid update in trauma. Crit Care Clin , 33 (1), 85–99.The CRASH‐2 Collaborators (2010) Effects of tranexamic acid on death, vascular occlusive events, and blood transfusion in trauma patients with significant hemorrhage (CRASH‐2): a randomized, placebo‐controlled trial. Lancet , 376 (9734), 23–32.

      6 A 28‐year‐old man is taken emergently to the operating room for abdominal exploration after sustaining a gunshot wound to the right upper quadrant. On arrival, he was found to be in hemorrhagic shock and massive transfusion protocol was initiated. Intraoperatively, the bleeding is difficult to control, and diffuse oozing is noted as the case progresses. Rapid thrombelastography (TEG) is performed and reveals a prolonged R value, K value is slightly prolonged, 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,

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