Anaphylaxis Flashcards
Define Anaphylaxis:
Acute life-threatening multisystem syndrome caused by sudden release of mast cell and basophil-derived mediators into the circulation
What are the two types of Anaphylaxis and what causes them?
Immunogenic: IgE-mediated or immune complex/compliment mediated
Non-immunogenic: Mast cell or basophil degranulation without involvement of antibodies (e.g. drug reactions)
Describe the Pathophysiology of Anaphylaxis:
Inflammatory mediators such as histamine are released leading to bronchospasm, increased capillary permeability and reduced vascular tone
This leads to tissue oedema
What are the presenting symptoms of Anaphylaxis?
Wheeze
SOB - sense of choking
Swelling
Itchyness
Rash
What are the common signs of Anaphylaxis?
Tachypnoea
Hypotension
Tachycardia
Wheeze
Cyanosis
Swollen upper airway and face
Rhinitis
Urticarial rash
What may feature in the PMHx of someone presenting with Anaphylaxis?
Allergic hypersensitivity disorders
Asthma
Allergic Rhinitis
(Biphasic reactions (1-72 Hrs after first) occur in 20% patients)
How might you confirm Anaphylaxis if it’s not clinically obvious?
Serum Tryptase: 15min-3hr (marker of mast cell degranulation)
Histamine levels (within 30mins)
Urinary metabolites of histamine (present for several hours)
What is the acute management of Anaphylaxis?
- Stop any suspected drugs/exposure
A: inspect airway, give 15L O2, intubate if necessary
B: intubate if necessary
C: Start CPR if necessary
Adrenaline: IM 0.5ml of 1:1000 every 10 minutes
Chlorphenamine: 10mg IV (antihistamine)
Hydrocortisone: 100mg IV (corticosteroid)
IV fluids - maintain BP
Salbutamol +/- Ipratropium nebs to treat bronchospasm if required
Aminophylline IV if required
What is the management of Anaphylaxis after an attack?
Epi-Pen (prescribe and educate)
IgA immunoassays
Note drug allergies in chart
Refer to allergy specialist - skin testing
