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 involvement of:

·  Skin: urticaria and angioedema.

·  Respiratory: acute airway obstruction with laryngeal oedema and bronchospasm.

·  Gastrointestinal: severe abdominal cramping and diarrhea.

·  Systemic: hypotension and shock.

Aetiology

The symptoms of anaphylaxis are abrupt, often within minutes of expo-sure 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 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 dose 0.5mL). Repeat every 15min if required.

·  Hypotension: put the patient head-down at 30° (Trendelenburg position) 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 normal saline. 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).