Paediatrics: Anaphylaxis

Anaphylaxis

Anaphylaxis is a life-threatening allergic event. It is the extreme clinical example of an immediate hypersensitivity reaction.

Symptoms

The reaction includes the involvement of:

• Skin: urticaria and angioedema.
• Respiratory: acute airway obstruction with laryngeal oedema and bronchospasm.
• Gastrointestinal: severe abdominal cramping and diarrhoea.
• Systemic: hypotension and shock.

Aetiology

The symptoms of anaphylaxis are abrupt, often within minutes of exposure to an antigen. The causes are:

• Drugs: penicillin, aspirin.
• Injections: radiographic contrast dyes.
• Stings: bites and envenomations.
• Foods: shellfish, nuts, peanuts, eggs.

Diagnosis

Take a careful history and aim to determine the time between the onset of symptoms and exposure to the potential precipitating cause.

Initial treatment

Follow a standard protocol

• ABC.
• Epinephrine (adrenaline): give SC 0.01mL/kg (1:1000, maximum dose0.5mL). Repeat every 15min if required.
• Hypotension: put the patient head-down at 30° (Trendelenburgposition) and give IV normal saline (20mL/kg bolus). IV epinephrine may be given over 2–5min (0.1mL/kg, 1:10,000), while an infusion is being prepared.
• Salbutamol: give nebulized salbutamol 0.05–0.15mg/kg in 3mL normalsaline. Approximately 2.5mg for child <30kg and 5mg for child >30kg, every 15min if required.
• Antihistamine.
• Steroid: give IV bolus methylprednisolone (2mg/kg). This dose should be followed by IV methylprednisolone 2mg/kg/day (divided every 6hr), or oral prednisolone 2mg/kg (bolus once a day).