Anaphylaxis

• What is anaphylaxis?


  Life-threatening medical emergency

  Caused by severe type 1 hypersensitivity reaction
• How does anaphylaxis occur?

  IgE stimulates mast cells to rapidly release histamine + other pro-inflam chemicals (mast cell degranulation) -> rapid onset of symptoms
• What are the common triggers for anaphylaxis?


  Insect stings

  Animal dander

  Nuts

  Peanuts

  Shellfish

  Fish

  Eggs

  Milk

  Abx

  IV contrast media

  NSAIDs
• What is shown in this image?

  Angioedema in a pt with anaphylaxis

  
• What are the signs & symptoms of anaphylaxis?


  Hoarse voice

  Lip swelling

  Stridor (upper airway obstruction, laryngeal oedema)

  Wheeze

  SOB

  Fatigue

  O2 sats < 94%

  Tachycardia

  Hypotension/shock

  Angioedema

  Confusion

  Abdo pain

  Diarrhoea

  Vomiting

  Urticaria

  Itching

  Presyncope/Syncope
• What is urticaria?


  Hives

  
• What are the DDx of anaphylaxis?

  Anaphylactoid reaction (similar, not due to IgE)

  Vasovagal reaction

  Panic attack

  Asthma exacerbation

  Carcinoid syndrome
• Vasovagal reaction - presenation


  Hypotension

  Bradycardia

  Pallor

  Diaphoresis

  Nausea
• Panic attack - presentation


  SOB

  Tachycardia

  Sweating

  Tremors

  Feeling of impending doom

  Lacks skin involvement
• Asthma exacerbation - presentation


  Primarily resp symptoms

  • wheeze
  • cough
  • SOB

  w/o systemic involvement
• Carcinoid syndrome - presentation


  Flushing

  Diarrhoea

  Abdo pain

  Wheeze

  Due to serotonin release, generally more chronic cause
• What are the Inx for anaphylaxis?


  A-E assessment

  Obs

  Bloods (FBC, U&Es, LFTs, CRP, Mast cell tryptase)

  NOTE: Inx should not delay treatment.
• What is the initial management of anaphylaxis?


  Adrenaline (1:1000, IM)

  • over 12 yrs -> 500 μg IM (0.5 mL)
  • 6-12 yrs -> 300 μg IM (0.3 mL)
  • 6 months - 6 yrs -> 150 μg IM (0.15 mL)
  • less than 6 months -> 100-150 μg IM (0.1-0.15 mL)

  -> If not response after 5 mins, repeat adrenaline

  -> No improvement, follow refractory anaphylaxis guidelines

  Antihistamines

  Steroids (usually IV hydrocortisone)

  Remove trigger (if possible)

  Early call for help

  Pt in supine position w/legs raised

  Manage airway + O2

  IV fluids (10 mL/kg bolus)

  Continue to monitor vitals
• What is the post-crisis management of anaphylaxis?


  Pts should be monitored for 6-12 hours (in case of rebound episode)

  Anaphylaxis can be confirmed -> serum mast cell tryptase

  Counsel family & child

  • allergy
  • how to avoid allergens
  • signs of anaphylaxis
  • parents should be trained in BLS & use of adrenaline auto-injectors (EpiPen)
  • give 2 EpiPens to take home
  • refer to local allergy service for follow up
• When should adrenaline auto-injectors be given?


  All pts with anaphylactic reactions

  Consider in pts with generalised allergic reactions w/RFs

  • asthma requiring ICS
  • poor access to medical treatment
  • adolescents
  • nut or insect sting allergies
  • significant comorbidities (e.g. CVD)
• When does mast cell tryptase need to be measured?


  Within 6 hours of anaphylactic reaction (after 6 hrs it will no longer be raised)