A 29-year-old man comes to the emergency department following a motor vehicle collision. The patient is alert and oriented; trauma evaluation shows an unstable pelvis with a pelvic fracture confirmed on imaging. He receives multiple boluses of intravenous fluids and is started on a packed red blood cell transfusion. A few minutes after the transfusion starts, the patient develops shortness of breath and has an episode of nonbloody emesis. He has no chest or back pain. Temperature is 37 C (98.6 F), blood pressure is 88/40 mm Hg, pulse is 140/min, and respirations are 30/min. Pulse oximetry is 86% on 100% oxygen provided via a nonrebreather mask. The patient answers questions in short phrases. Lung examination shows decreased breath sounds bilaterally. Pulses are weak. Urinalysis is normal. Which of the following is the most likely cause of this patient's respiratory distress?

Question

A 29-year-old man comes to the emergency department following a motor vehicle collision.  The patient is alert and oriented; trauma evaluation shows an unstable pelvis with a pelvic fracture confirmed on imaging.  He receives multiple boluses of intravenous fluids and is started on a packed red blood cell transfusion.  A few minutes after the transfusion starts, the patient develops shortness of breath and has an episode of nonbloody emesis.  He has no chest or back pain.  Temperature is 37 C (98.6 F), blood pressure is 88/40 mm Hg, pulse is 140/min, and respirations are 30/min.  Pulse oximetry is 86% on 100% oxygen provided via a nonrebreather mask.  The patient answers questions in short phrases.  Lung examination shows decreased breath sounds bilaterally.  Pulses are weak.  Urinalysis is normal.  Which of the following is the most likely cause of this patient's respiratory distress?

Quizplus · Accepted Answer

11ec25c8_d40e_5a37_bc81_53eb0fe59afa_MD0003_00 This patient's rapid deterioration immediately after blood transfusion initiation is consistent with an anaphylactic reaction. Anaphylaxis occurs seconds to minutes after initiation of transfusion due to massive histamine release. Symptoms include respiratory distress (eg, dyspnea, hypoxia), angioedema, and hypotension. Wheezing is often appreciated, although decreased breath sounds can occur with severe bronchospasm preventing air entry. Vomiting and urticaria may also be present. Without treatment, symptoms can rapidly progress to respiratory failure and shock. The first step in management is to immediately stop the transfusion and administer intramuscular epinephrine. Bronchodilators and antihistamines are typically also administered. In some cases, hemodynamic and respiratory support (eg, vasopressors, mechanical ventilation) may be required. Patients with IgA deficiency are at higher risk of anaphylactic transfusion reaction because they may have anti-IgA antibodies that react with donor blood IgA and contribute to histamine release. Although IgA deficiency can present with recurrent sinopulmonary infections, it is often asymptomatic and may be diagnosed only after an anaphylactic transfusion reaction. Future transfusions should include IgA-deficient plasma and washed red blood cell products. (Choice B) Aspiration pneumonitis is caused by gastric acid aspiration, most commonly in the setting of altered mental status or dysphagia. It can lead to hypoxia but typically causes crackles and would be unexpected in a patient with no history of aspiration. (Choice C) Fat embolism can be a complication of femoral or pelvic fracture and typically presents with respiratory distress and hypoxia. However, patients typically develop symptoms >24 hours after injury and often also have altered consciousness and petechial rash. (Choice D) Acute hemolytic transfusion reaction from ABO incompatibility is rare but can occur due to clerical errors (eg, misidentification of patient). Patients are hypotensive but also have fever, flank pain, and hemoglobinuria. (Choice E) Febrile nonhemolytic transfusion reaction, the most common adverse reaction to transfusion, occurs within 1-6 hours of transfusion. During blood storage, leukocytes release cytokines that, when transfused, cause transient fevers, chills, and malaise. Febrile nonhemolytic transfusion reaction is unlikely given this patient's respiratory distress, shock, and lack of fever. (Choice F) Transfusion-associated circulatory overload is characterized by pulmonary edema due to volume overload. Patients have respiratory distress and hypoxia, but hypotension would not be expected (many patients are hypertensive). Educational objective: Anaphylactic transfusion reaction is characterized by a rapid onset (seconds to minutes) of respiratory distress and hypotension, which quickly progresses to respiratory failure and shock. Acute management includes immediate transfusion cessation and administration of epinephrine. IgA-deficient patients are at increased risk. References: Transfusion of blood and blood products: indications and complications. (http://www.ncbi.nlm.nih.gov/pubmed/21404983)

A 29-Year-Old Man Comes to the Emergency Department Following a Motor