16th February 2025

Management of anaphylaxis

Immediate management

The latest Resuscitation Council guidelines (2021) emphasise the importance of an A-to-E approach with early adrenaline administration and prioritising repeated use of adrenaline over the administration of other drugs. Adrenaline is usually given as 0.5 mg IM repeated up to every 5 minutes. Alternatively, it can be given in 50 mcg boluses IV in experienced hands.

Intravenous crystalloid fluid resuscitation should be aggressive, with fluid requirements sometimes being up to 5 litres.

Nebulised salbutamol and ipratropium can be given if there is wheeze present. Antihistamines may be used to treat cutaneous symptoms following initial resuscitation. The routine use of corticosteroids is no longer advised, though they may be used if asthma plays a role in the presentation or for refractory cases.

Refractory anaphylaxis

This is where there is ongoing cardiorespiratory compromise after two doses of IM adrenaline. The most important ongoing management is to administer further adrenaline, preferably by IV infusion. Other possible treatments include:

• Nebulised adrenaline (1 mg in 5 ml) for airway obstruction
• Tracheal intubation
• IV salbutamol or aminophylline for persistent bronchospasm
• Corticosteroids

Further management and follow up

Five percent of patients experience a biphasic anaphylaxis reaction and, as such,, patients should be observed for 6-12 hours following resolution of symptoms.

Serum mast cell tryptase should be measured in any patient where anaphylaxis is considered. Ideally, three samples should be taken: the first as soon as feasible, the second 1-2 hours after onset and the third 24 hours after complete resolution. A normal tryptase level does not exclude anaphylaxis.

All patients should be educated about the condition and given an adrenaline auto-injector, which comes in doses of 150-500 mcg. They should be referred to a specialist allergy clinic for skin prick testing and follow up.