Anaphylactic Shock/Anaphylaxis

Clinical Features

Clinical Criteria for Anaphylaxis

Anaphylaxis is highly likely when any 1 of the 3 criteria below occur

1.    Acute onset of illness with involvement of skin or mucosa (swelling, rash) and one of;

a.    Respiratory compromise

b.    Reduced BP or other evidence of end organ hypo-perfusion e.g. syncope

2.    2 or more of the following occurring rapidly after exposure to likely allergen

a.    Involvement of skin or mucosa

b.    Respiratory compromise

c.    Hypotension or evidence of same e.g. syncope, incontinence

d.    Persistent GI symptoms e.g. nausea, vomiting, diarrhoea

3.    Hypotension after exposure to known allergen for patient

Clinical Investigations

Anaphylaxis is a clinical diagnosis. No investigations are necessary and should not delay treatment.

Patient should have baseline bloods and ECG once treatment commenced. Other investigations may be warranted if diagnosis is in doubt.

Bedside

• VBG, ECG

Laboratory

• FBC, U&E, May be role for Tryptase level in follow up

Radiology

• CXR if concerned for pulmonary oedema, pneumothorax or infection

Management & Disposition

Initial Resuscitation

Single most important treatment is rapid administration of Adrenaline

• 500mcg IM Adrenaline repeated every 5-10 mins according to response or relapse

• If cardiovascular collapse and patient has IV access or if patient refractory to IM adrenaline an IV adrenaline infusion should be commenced

Following administration of Adrenaline securing airway is next priority

• If airway oedema patient will be a difficult airway ++. Call for help

• Nebulised adrenaline if airway oedema

High Flow O2

IV crystalloid if hypotensive post adrenaline

Decontamination i.e. remove any allergen that may still be on patient/in patients mouth/in patients cannula.