Anaphylaxis

Anaphylaxis is immunologically mediated. It is potentially life threatening and can present with or progress to:

• Upper and lower airway obstruction
• Shock due to acute vasodilatation and capillary leak

Important points in history

• Ingestion of drug (e.g. Penicillin and other beta-lactam antibiotics)
• Ingestion of food (e.g. nuts, fish)
• Insect bite or sting (e.g. bee stings)
• Previous history of allergic reaction
• Known history of anaphylaxis
• Family history of allergy

Important point in examination

• Prodromal symptoms: Flushing, itching, facial swelling, urticaria
• Abdominal pain, diarrhoea, nausea
• Sweating
• Oral swelling (lips and tongue)
• Stridor
• Cough
• Wheeze
• Shock

Management

IF POSSIBLE REMOVE ALLERGEN Call for HELP!!!

• Assess and manage airway
• Give oxygen
• Give IM adrenaline (NOT IV)
• Nebulised adrenaline
• Intubation may be required (call for senior help)
• If wheeze/ bronchospasm
• Nebulised salbutamol
• IV hydrocortisone
• Consider aminophylline infusion
• If in shock
• IV/ IO access - 20 ml/kg bolus of Normal Saline/ Ringer Lactate
• Chlorpheniramine

Drug doses in anaphylaxis

• Adrenaline IM (NOT IV!)
  • 0.01ml/kg of 1:1000 Adrenaline (1mg/ml) max 0.5 ml
    • Doses of Adrenaline might have to be repeated
• Adrenaline infusion in life-threatening shock, when IM Adrenaline is insufficient (ALWAYS DISCUSS WITH SENIOR FIRST):
  • 0.3mg/kg in 50ml Saline or Dextrose 5%
  • 1ml/hr = 0.1 microgram/kg/min
  • Dose = 0.05 - 2 microgram/kg/min
  • Use syringe driver
  • When being given by a peripheral line use quarter strength
• Adrenaline nebulised
  • 1-2ml of 1:1000 in 2mls of saline
• Hydrocortisone IV
  • 4mg/kg, then 2-4mg/kg 6 hourly
• Salbutamol nebuliser
  • <5years: 2.5mg dilute in 2-3 ml Normal saline
  • > 5years: 5mg
• Chlorpheniramine oral (continue TDS for 48 hours)
  • > 12 years: 10-20mg
  • 6- 12 years: 5-10mg
  • 1-5 years: 2.5 - 5mg
  • 1 month- 1 year: 250 micrograms/kg
• Aminophylline
  • 25 mg/kg in 500ml of Normal Saline (or 5mg/kg in 100ml)
  • 10ml/hour = 0.5mg/kg/hour
  • Dose range: 0.3-1mg/kg/hour (use lower dose - 0.5mg/kg/hour in older children > 12 years)
  • Consider loading dose of 5mg/kg over 20 -30 min
  • Or 25mg/kg in 50ml N-Saline via syringe driver: 1ml/hour = 0.5mg/kg/hour
  • Always re-check drug doses!