A 34-year-old man is brought to the hospital by ambulance after being involved in a motor vehicle collision. He was an unrestrained passenger and sustained considerable trauma. On arrival to the emergency department, he is hypotensive and bleeding from several sites. The patient receives an emergency blood transfusion as part of the resuscitation efforts. Abdominal ultrasound reveals splenic laceration and blood in the peritoneal cavity. En route to the operating room, the patient develops difficulty breathing, chills, and pain in the chest and back. Urine drainage from the Foley catheter was initially clear but now appears brown in color. Which of the following is the most likely cause of this patient's new findings?

Question

A 34-year-old man is brought to the hospital by ambulance after being involved in a motor vehicle collision.  He was an unrestrained passenger and sustained considerable trauma.  On arrival to the emergency department, he is hypotensive and bleeding from several sites.  The patient receives an emergency blood transfusion as part of the resuscitation efforts.  Abdominal ultrasound reveals splenic laceration and blood in the peritoneal cavity.  En route to the operating room, the patient develops difficulty breathing, chills, and pain in the chest and back.  Urine drainage from the Foley catheter was initially clear but now appears brown in color.  Which of the following is the most likely cause of this patient's new findings?

Quizplus · Accepted Answer

11ec160b_37cc_e9e2_9249_21cec71eef6d_MD0001_00 This patient is most likely experiencing an acute hemolytic transfusion reaction. This condition presents with fever and chills, hypotension, dyspnea, chest and/or back pain, and hemoglobinuria (red- to brown-colored urine). Patients may also develop disseminated intravascular coagulation and renal failure. Acute hemolytic reactions occur within minutes to hours of starting a blood transfusion and are most often due to ABO incompatibility between the donor and recipient. These reactions can be fatal and require immediate cessation of the transfusion when the diagnosis is suspected. Acute hemolytic transfusion reactions are an example of an antibody-mediated (type II) hypersensitivity reaction. Anti-ABO antibodies (mainly IgM) in the recipient bind the corresponding antigens on transfused donor erythrocytes, leading to complement activation. Anaphylatoxins (C3a and C5a) cause vasodilatation and symptoms of shock, while formation of the membrane attack complex (C5b-C9) leads to complement-mediated cell lysis. Hemolytic disease of the newborn due to Rh-incompatibility is another example of type II hypersensitivity. (Choice A) Cytotoxic CD8⁺ T-lymphocytes are responsible for destroying cells infected with intracellular pathogens (eg, viruses). Recognition of an antigen-MHC class I complex by the T-cell receptor activates CD8⁺ lymphocytes, which then initiate apoptosis of the infected cell. (Choice C) TNF-α is produced by macrophages in response to bacterial endotoxin and causes symptoms of septic shock (eg, fever, hypotension, and tachycardia) when released in large amounts. Transfusion transmitted bacterial infection could cause septic shock, but it would not result in hemoglobinuria. (Choice D) Allergic transfusion reactions are IgE-mediated (type I) hypersensitivity reactions against plasma proteins found in transfused blood. They can be mild (urticaria, itching) or result in severe anaphylaxis (most common in IgA-deficient patients with anti-IgA antibodies). (Choice E) Vascular deposition of immune complexes is an example of type III hypersensitivity. In conditions such as systemic lupus erythematosus and rheumatoid arthritis, antigen-antibody complexes deposit in various tissues and activate complement, causing tissue inflammation and destruction. Educational objective: Acute hemolytic transfusion reaction is a antibody-mediated (type II) hypersensitivity reaction caused by pre-existing anti-ABO antibodies that bind antigens on transfused donor erythrocytes. Subsequent complement activation results in erythrocyte lysis, vasodilation, and symptoms of shock. Common findings include fever, hypotension, chest and back pain, and hemoglobinuria.

A 34-Year-Old Man Is Brought to the Hospital by Ambulance