Thrombocytopenia (HIT) and started on argatroban postoperatively. What is the mechanism of action of argatroban?Direct factor Xa inhibitorDirect factor IIa inhibitorIndirect factor IIa inhibitorBinds antithrombin IIIIndirect factor Xa inhibitorHIT is a life‐threatening disorder that occurs after exposure to unfractionated, or less commonly, low‐molecular‐weight heparin. HIT usually occurs after 5–10 days of heparin therapy and is caused by antibodies against the heparin‐platelet factor 4 complex. Thrombotic complications occur in 20–50% of patients. The thrombus associated with HIT has been described as “white clot” with predominantly fibrin platelet aggregates and few red blood cells. Thrombocytopenia is common in the critically ill, and diagnosis of HIT can be difficult. Delays in obtaining test results often mean that management decisions must be made on the basis of clinical suspicion. Clinical findings that imply a diagnosis HIT are:Platelet fall of more than 50% from baseline, with platelet nadir > 20 000. Profound thrombocytopenia suggests a cause other than HIT.Onset on day 5–10 of heparin exposure.Thrombosis, skin necrosis, or an anaphylactoid reaction after heparin bolus.No other cause for the thrombocytopenia is present.Treatment of HIT includes discontinuation of all sources of heparin and if anticoagulation is clinically warranted, use of a direct thrombin (factor IIa) inhibitor such as argatroban is recommended.Answer: BGreinacher, A. (2015) Heparin‐induced thrombocytopenia. N Eng J Med , 373 (3), 252–261.17
17 An 18‐year‐old man is undergoing an exploratory laparotomy and right groin exploration for a gunshot wound to the right hip. Injuries to the right common femoral vein, bladder, and sigmoid colon are noted. Massive blood loss was reported at the scene and the patient was found to be in hemorrhagic shock on arrival. He has received 12 units of packed red blood cells, 12 units of fresh frozen plasma, and 2 units of apheresis platelets while in the operating room. His vital signs are: blood pressure 100/60 mm Hg, heart rate 120 beats/min, temperature 34.8 °C. Laboratory studies: hemoglobin 8.5 g/dL, platelets 100 000/mm 3 , prothrombin time 14 second, partial thromboplastin time 40 second. pH 7.1. His femoral vein has been ligated, bladder injuries were repaired, and sigmoid colon was resected. What is the next most appropriate treatment for his ongoing bleeding?Transfuse platelets, create a stoma, and close the abdomen.Transfuse fresh frozen plasma, perform primary anastomosis, and close the abdomen.No transfusion required, create stoma, and close the abdomen.External warming, primary anastomosis, and close the abdomen.Leave in discontinuity, place temporary abdominal closure device, and admit to surgical intensive care unit for external rewarming.This patient is severely hypothermic and acidotic. Following surgical control of bleeding and massive resuscitation, ongoing aggressive resuscitation is required to reverse the “lethal triad” of coagulopathy, acidosis, and hypothermia. Damage control operation should be performed with prompt admission to surgical intensive care unit for resuscitation and rewarming. Clotting factor and platelet deficiencies have been addressed during this resuscitation by maintaining 1:1 component replacement. Hypothermia < 35 °C is a strong independent risk factor for mortality in trauma patients, with more severe hypothermia conveying greater risk of mortality. Hypothermia contributes to coagulopathy through platelet and clotting factor dysfunction. Recommended measures for rewarming a patient with low body temperature include forced air warming, infusion of warmed fluids, under‐body heating pads, radiant warmers, and humidified ventilation. If bleeding continues after aggressive warming and correction of clotting abnormalities, the patient must return to the operating room without further delay.Answer: EInaba, K., Teixeira, P., Rhee, P., et al. (2009) Mortality impact of hypothermia after cavitary explorations in trauma. World J Surg , 33 (4), 864–869.Perlman, R., Callum, J., Laflamme, C., et al. (2016) A recommended early goal‐directed management guideline for the prevention of hypothermia‐related transfusion, morbidity, and mortality in severely injured trauma patients. Crit Care , 20 (1), 1–11.
18 A 22‐year‐old man was involved in a drive by shooting. He is noted to have multiple gunshot wounds to his back, abdomen, and extremities. He has a distended abdomen that is diffusely tender. His blood pressure is 80/60 mm Hg. What fluid should be administered while preparing for emergent laparotomy?Lactated ringersHypertonic salinepositive bloodType‐specific bloodCrossmatched bloodThe described physical exam findings are consistent with hemoperitoneum resulting in hemorrhagic shock; therefore, the patient requires emergent resuscitation and operative hemorrhage control to avoid mortality. Crystalloid solution should be minimized and resuscitation with blood products should be initiated without delay. Type O positive blood is readily available in most centers and can be used for emergent transfusion of male patients and women beyond childbearing age. If uncrossmatched blood resources are limited, type O negative blood may be used but is typically reserved for women of childbearing age to avoid the risk of Rh isoimmunization. Type O positive blood has been shown to be safe for transfusion in hemorrhaging trauma patients, with a very low rate of transfusion reaction. Advantages of using uncrossmatched type O blood include immediate availability before type‐specific blood becomes available and avoidance of errors in multi‐casualty situations. The safety of type O blood has been improved by prescreening donor blood for anti‐A and anti‐B antibodies, which can lead to hemolysis of native red blood cells.Answer: CBall, C.G., Salomone, J.P., Shaz, B., et al. (2010) Uncrossmatched blood transfusions for trauma patients in the emergency department: incidence, outcomes and recommendations. Can J Surg , 54 (2), 111–115.Dutton, R., Shih, D., Edelman, B., et al. (2005) Safety of uncrossmatched type‐O red cells for resuscitation from hemorrhagic shock. J Trauma , 59 (6), 1445–1449.
19 A 90‐year‐old man presents after a ground‐level fall. He is found to have bruising on all extremities and a scalp laceration that requires suture repair for hemostasis. His daughter accompanies him to the emergency department and reports that he took dabigatran for his chronic atrial fibrillation 4 hours prior to the admission. Imaging reveals a moderate subdural hematoma. What is the best option for reversing effects of dabigatran?No reversal is required if the INR is < 2Administer idarucizumabAdminister plateletsAdminister fresh frozen plasmaAdminister cryoprecipitateOral anticoagulants alternative to warfarin for reducing the risk of thromboembolic events in patients with chronic atrial fibrillation include rivaroxaban, apixaban, and dabigatran. Rivaroxaban and apixaban are factor Xa inhibitors. Dabigatran is a direct thrombin inhibitor. A major advantage of these medications is that they do not require routine INR monitoring. In clinical trials, bleeding events on these medications were comparable to, or lower than warfarin for similar indications. The major drawbacks of these agents are (1) their anticoagulation effect is not reliably measured by common laboratory tests, and (2) effects can be difficult to reverse. In 2016, the FDA approved idarucizumab as a specific reversal agent for dabigatran. Fresh frozen plasma (FFP) can be used to resuscitate patients on these medications who suffer low‐ to moderate‐risk bleeding events. However, FFP is not a specific reversal agent. It takes time to infuse and cannot rapidly reverse coagulopathy. Administration of FFP can also lead to volume overload and transfusion reactions. For all of these reasons, FFP is not an ideal therapy. This patient has a life‐threatening intracranial hemorrhage that requires rapid reversal of dabigatran. Idarucizumab is a monoclonal antibody fragment developed to rapidly, durably, and safely reverse the anticoagulant effect of dabigatran in emergency situations. PCC can also be considered to reverse dabigatran if idarucizumab is unavailable.Answer: BPollack, C.V., Reilly, P.A., Van Ryn, J., et al. (2017) Idarucizumab for Dabigatran reversal – full cohort analysis. N Engl J Med , 377 (5), 431–441.Faraoni, D., Levy, J.H., Albaladejo, P., et al. (2015) Updates in the perioperative and emergency management of non‐vitamin K antagonist oral anticoagulants. Crit Care , 19, 1–6.
12 Analgesia and Anesthesia
Toni Manougian, MD, MBA1 and Bardiya Zangbar, MD2
1 Department of Critical Care Anesthesiology, New York Medical College, Westchester Medical Center, Valhalla, NY, USA
2 Division of Trauma and Acute Care Surgery, New York Medical College, Westchester Medical Center, Valhalla, NY, USA
1 Which of the following effects of epidural analgesia is correct:For patients without serious lung pathology, mid thoracic epidural analgesia has no effect on lung function.Decreased gastric secretions, peristalsis, and enhanced gastric motility results from sympathetic splanchnic blockade at the T5‐L1 level.Renal blood flow is increased and