Incidence of Hypersensitivity Reactions Within 4 Hours Post-Blood Transfusion

Overall Incidence of Acute Transfusion Reactions

• The incidence of febrile, allergic, and hypotensive reactions occurring within 24 hours following transfusion is increasing, which may be partly due to enhanced reporting mechanisms, according to the Anaesthesia guideline society 1

Specific Reaction Types and Their Frequencies

• Allergic reactions occur at a rate of 1:591 to 1:2,184 plasma units transfused for any allergic reaction, and 1:18,000 to 1:172,000 transfusions for anaphylactic reactions specifically, as reported by the Journal of Hepatology 2
• Plasma and platelet products are most frequently implicated in allergic reactions due to their high plasma protein content, as stated by the Anaesthesia guideline society 1

Blood Component-Specific Risk Profiles

• Red blood cell units are more commonly associated with febrile reactions, according to the Anaesthesia guideline society 1
• Fresh frozen plasma (FFP) carries the highest risk for severe reactions including TRALI, with allergic/anaphylactic reactions occurring in 1:591 to 1:2,184 units, as reported by the Journal of Hepatology 2

Critical Timing Considerations

• The first 10 minutes of transfusion are the most critical period, as immediate reactions typically occur within the first minute of infusion, as stated by the Praxis Medical Insights guideline society 3
• TRALI presents within 1-2 hours after transfusion, according to the Praxis Medical Insights guideline society 3, 4
• TACO can occur during or up to 12 hours after transfusion, as reported by the Anaesthesia guideline society 1 and the Praxis Medical Insights guideline society 3

Monitoring Requirements to Detect These Reactions

• Vital signs should be monitored at minimum: pre-transfusion (within 60 minutes), 15 minutes after starting each unit, and within 60 minutes of completion, as recommended by the Anaesthesia guideline society 1
• Respiratory rate should be monitored throughout transfusion as it is a sensitive indicator of serious transfusion reactions, according to the Anaesthesia guideline society 1

Prevention Strategies That Reduce Incidence

• Leukoreduction has substantially reduced FNHTR incidence but cannot eliminate it entirely, as stated by the Praxis Medical Insights guideline society 5
• Current recommendations from SHOT advise against indiscriminate use of steroids and antihistamines as premedication, instead recommending a personalized approach based on symptoms: intravenous paracetamol for febrile reactions and antihistamines only for allergic reactions, as reported by the Anaesthesia guideline society 1