Transfusion medicine

• Decrease in blood pressure during or within 1 hour after cessation of a transfusion
• In adults, hypotension is defined as a drop in systolic blood pressure of ≥ 30 mmHg and a systolic blood pressure of ≤ 80 mmHg
• All other adverse transfusion reactions which may present with hypotension, such as septic reactions, acute hemolytic reactions, transfusion related lung injury and anaphylaxis, must be excluded
• Reference: CDC: NHSN Biovigilance Component Surveillance Protocol [Accessed 28 May 2021]

• Isolated hypotensive transfusion reactions typically occur < 15 minutes after the start of the transfusion and respond rapidly to cessation of transfusion and supportive care
• Rare, accounting for 2.8% of reported transfusion reactions, however, the true incidence may be higher due to the difficulty in recognizing these reactions (Anesth Analg 2016;123:268)
• National Healthcare Safety Network (NHSN) Hemovigilance Module criteria defines hypotension as:
  • In adults 18 years and older, a drop in systolic blood pressure of ≥ 30 mmHg and systolic blood pressure ≤ 80 mmHg
  • In children and adolescents 1 year to < 18 years old, a greater than 25% drop in systolic blood pressure from baseline
  • In neonates and small infants (< 1 year old or < 12 kg), a greater than 25% drop in baseline value using whichever measurement is being recorded (CDC: NHSN Biovigilance Component Surveillance Protocol [Accessed 28 May 2021])

• Stop transfusion
• Maintain IV access
• Supportive care and if necessary, fluid bolus or vasopressors (Transfusion 2015;55:1668)

• Acute hemolytic transfusion reaction (AHTR):
  • Typically presents with hypotension but with additional symptoms, such as fever, rigors and back pain
  • Should also show laboratory evidence of hemolysis with a positive direct antiglobulin test
• Transfusion related acute lung injury (TRALI):
  • Presents with hypotension
  • Also with hypoxemia and radiographic evidence of pulmonary edema
• Anaphylaxis:
  • Presents with hypotension
  • Also with a rash or airway symptoms, such as dyspnea and mucocutaneous edema

A 65 year old man with a history of hypertension, hyperlipidemia, coronary artery disease and diabetes is 1 day status postcoronary bypass surgery. He is transfused a unit of red blood cells for a hemoglobin of 7 g/dL. Within 10 minutes of the transfusion, his blood pressure decreases from 102/57 to 45/30. All other vital signs remain stable. He has no other symptoms. The transfusion is stopped, a bolus of normal saline is given and the patient quickly recovers. Which of the following is the most likely diagnosis?

1. Acute hemolytic transfusion reaction
2. Anaphylaxis
3. Hypotensive transfusion reaction
4. Transfusion associated circulatory overload (TACO)
5. Transfusion associated lung injury (TRALI)

C. Hypotensive transfusion reaction. Hypotensive transfusion reactions present as a sudden decrease in blood pressure of at least 30 mmHg typically within the first 15 minutes of a transfusion and respond rapidly to the cessation of transfusion and supportive care. Other transfusion reactions may present with hypotension; however, they often present with additional signs and symptoms. An acute hemolytic transfusion reaction may present with fever, rigors and back pain and will have laboratory evidence of hemolysis with a positive direct antiglobulin test. Transfusion associated lung injury (TRALI) presents with hypoxemia and radiographic evidence of pulmonary edema. Transfusion associated circulatory overload (TACO) presents with hypertension (not hypotension) due to volume overload. Anaphylaxis presents with airway symptoms, such as dyspnea and mucocutaneous edema, in addition to hypotension.

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Reference: Hypotension

Which of the following statements is true regarding hypotensive transfusion reactions?

1. Associated with the use of angiotensin converting enzyme (ACE) inhibitors
2. Associated with the use of prestorage leukoreduced blood products
3. Caused by the infusion of cytokines
4. Caused by the infusion of leukocytes
5. Prevented by premedicating patients with diphenhydramine

A. Associated with the use of angiotensin converting enzyme (ACE) inhibitors. Hypotensive transfusion reactions are associated with the use of bedside leukocyte reduced blood products. They are thought to occur due to the accumulation of bradykinin and are strongly associated with ACE inhibitor use. ACE inhibitors block the degradation of bradykinin, leading to its accumulation. Hypotensive transfusion reactions have also occurred in patients receiving blood products that are filtered through bedside leukoreduction filters which are negatively charged and can generate kinins through the contact system, however, bedside leukoreduction filters are no longer used and have been replaced by prestorage leukoreduction. Infusion of cytokines is associated with febrile nonhemolytic transfusion reactions. Infusion of leukocytes is associated with febrile nonhemolytic transfusion reactions, HLA alloimmunization and transfusion associated graft versus host disease. Diphenhydramine may be used to treat allergic transfusion reactions.

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Reference: Hypotension