Anaphylactic or anaphylactoid reactions

Notes

1. QLD data is unavailable for 2012–13.
2. Sex and facility location data is unavailable for NSW.
3. Time of transfusion data is unavailable for NSW and SA.
4. Data is unavailable for WA.
5. Uncategorised refers to those reports where no data was provided.

An anaphylactic reaction involves a severe, life threatening, generalised or systemic hypersensitivity reaction characterised by rapidly developing airway and/or breathing and/or circulation problems usually associated with skin and mucosal changes.^[14]

From 2011–12 to 2012–13, there were 29 reports of anaphylactic or anaphylactoid reactions to the National Haemovigilance Program, accounting for 2.8% of all reports (1,044) for this period. The number of cases rose from 8 in 2008–09 to 33 in 2010–11 and then dropped to 16 in 2011–12. It dropped further in 2012–13 due to the unavailability of QLD data.

In the period 2011–12 to 2012–13, 22 out of 29 cases were assigned an imputability score of likely/probable or confirmed/certain, including five cases of life threatening severity and seven cases with severe morbidity. Two confirmed cases of life threatening severity were related to the transfusion of platelets and red cells respectively.

Notes

1. Outcome severity and imputability data unavailable for QLD for 2012–13.
2. Outcome severity and imputability data unavailable for WA.

Anaphylaxis is an acute hypersensitivity reaction that can present as, or rapidly progress to, a severe life threatening reaction.^[15] Anaphylactoid reactions are clinically indistinguishable from anaphylaxis reactions, but differ in their immune mechanism. Distinguishing between anaphylaxis and anaphylactoid reactions is impossible on the basis of clinical signs and symptoms alone; a clinical definition cannot differentiate between the two.

This position is consistent with suggestions for a revised nomenclature for allergy, issued by the European Academy of Allergy and Clinical Immunology (EAACI) and World Allergy Organization referring to anaphylactoid reactions simply as 'non‑allergic anaphylaxis'.^{[16],[17],[18]} Diagnosis of anaphylactic and anaphylactoid reactions can be difficult, and an international symposium recently acknowledged that a widely accepted definition of anaphylaxis is lacking, which contributes to the wide variation in standards of diagnosis and management.^[18]

Clinical recommendation

The Blood Service provides guidance on the recognition, investigation and management of anaphylactic reactions.^[19]

• When to suspect these adverse reactions?
  

  Reactions usually begin within 1 to 45 minutes after the start of the transfusion.

  Patients present with a sudden onset of severe hypotension, cough, bronchospasm (respiratory distress and wheezing), laryngospasm, angioedema, urticaria, nausea, abdominal cramps, vomiting, diarrhoea, shock and loss of consciousness. This may be a fatal reaction.

  This occurs in 1:20,000 to 1:50,000 of transfusions.

• Usual causes?
  

  Anaphylactic transfusion reactions can occur when IgE antibody in the patient interacts with an allergen, usually a plasma protein in the blood component.

  The following mechanisms have been implicated in anaphylactic reactions:

  • IgA-deficient patients who have anti-IgA antibodies
  • patient antibodies to plasma proteins (such as IgG, albumin, haptoglobin, transferrin, C3, C4 or cytokines)
  • transfusing an allergen to a sensitised patient (for example, penicillin or nuts consumed by a donor)
  • rarely the transfusion of IgE antibodies from a donor to an allergen present in the recipient.
• Investigation
  

  Anaphylaxis usually has a typical clinical presentation. Occasionally the differential diagnosis is acute haemolysis.

  DAT, blood count and repeat ABO grouping may be indicated.

  Check the recipient's pretransfusion sample for IgA deficiency and presence of anti-IgA antibodies.

• What to do?
  

  Stop transfusion immediately and follow other steps for managing suspected transfusion reactions. This may become a medical emergency.

  Maintain open airway and intravenous line, support blood pressure.

  Administer supplemental oxygen, antihistamines, adrenaline and corticosteroids as required, resuscitation may also be necessary.

  Consult a haematologist before administering additional blood packs. To prevent recurrent anaphyaxis the following options may be considered:

  • pre-medication with steroids and antihistamine
  • if patient is IgA deficient with anti-IgA, the use of IgA-deficient or washed blood components is recommended.