What is the role of pheniramine and hydrocortisone in preventing allergic reactions during PCV (Packed Cell Volume) transfusion?

Role of Pheniramine and Hydrocortisone in Preventing Allergic Reactions During PCV Transfusion

Routine premedication with pheniramine (antihistamine) and hydrocortisone (corticosteroid) before PCV transfusion is not recommended as there is insufficient evidence supporting their efficacy in preventing transfusion reactions. 1

Current Evidence and Recommendations

Against Routine Premedication

• The Association of Anaesthetists explicitly advises against indiscriminate use of steroids and/or antihistamines for transfusion reactions 2, 1
• Repeated doses of steroids may further suppress immunity in patients who are immunocompromised 2
• A 2021 meta-analysis found no evidence that antihistamines or corticosteroids can prevent transfusion reactions 3
• Premedications have potential toxicity, particularly in ill patients, and studies have failed to demonstrate their effectiveness in preventing transfusion reactions 4

Appropriate Approach to Transfusion Reactions

Instead of routine premedication, a personalized approach based on the type of reaction is recommended:

1. For febrile reactions:

   • Only intravenous paracetamol may be required 2
   • No antihistamines or corticosteroids needed

2. For allergic reactions:

   • Only an antihistamine should be administered 2
   • If an antihistamine is needed, second-generation antihistamines (cetirizine 10 mg or loratadine 10 mg) are preferred over first-generation ones like pheniramine 1
   • First-generation antihistamines can potentially convert minor reactions into hemodynamically significant events through sedation, hypotension, and tachycardia 1

3. For severe reactions/anaphylaxis:

   • Follow local anaphylaxis protocols 2
   • This may include epinephrine, fluid resuscitation, combined H1 and H2 antagonists, and corticosteroids 2

Special Considerations

Previous Transfusion Reactions

• For patients with a documented history of allergic transfusion reactions:
  • Consider individualized premedication based on the specific previous reaction type 1
  • However, evidence suggests that patients who have had an allergic reaction to one blood product type rarely react to different blood product types 5
  • Therefore, premedication for all subsequent transfusions is not warranted 5

Monitoring During Transfusion

• Proper monitoring is crucial regardless of premedication:
  • Observations should be completed before transfusion, 15 minutes after start, and within 60 minutes of completion 2
  • Monitor pulse, blood pressure, temperature, and respiratory rate 2

Management Algorithm for Transfusion Reactions

1. If reaction occurs during transfusion:

   • Stop the infusion immediately
   • Assess severity of reaction
   • Maintain IV access and monitor vital signs

2. For mild allergic reactions (Grade 1/2):

   • Administer antihistamine only (preferably second-generation)
   • Consider slowing rather than stopping the transfusion
   • Monitor closely

3. For febrile reactions:

   • Administer paracetamol/acetaminophen
   • No antihistamines or corticosteroids needed

4. For severe reactions (Grade 3/4):

   • Stop transfusion completely
   • Follow anaphylaxis protocol including epinephrine if indicated
   • Consider H1/H2 antagonists and corticosteroids
   • Do not rechallenge with the same product

Conclusion

The evidence does not support routine premedication with pheniramine and hydrocortisone before PCV transfusions. Instead, a targeted approach to managing reactions if they occur is recommended, with specific medications based on the type and severity of the reaction. Proper monitoring during transfusion is more important than premedication in ensuring patient safety.