Anaphylaxis is a life-threatening condition that you need to be able to recognise and manage in an acute setting. This guide gives an overview of the recognition and immediate management of anaphylaxis (using an ABCDE approach).
Clinical features of anaphylaxis²
Feelings of anxiety
Sensations of warmth and itching – particularly in the axillae/groin
Rash – erythematous or urticarial
Oedema – face / neck / soft tissues
Hypotension – anaphylactic shock
Bronchospasm – wheezing
Laryngeal oedema – stridor / aphonia / drooling
Arrhythmias – potentially leading to cardiac arrest
Hypoxaemia – cyanosis
Often patients’ may develop severe symptoms immediately, without any preceding early or progressive signs.
Remove anaphylactoid triggers– e.g. IV antibiotics
Is the patient able to talk?
- If so the airway can be considered patent
- Listen for evidence of stridor or a hoarse voice
- In severe anaphylaxis, the patient may be unable to talk (aphonia)
Noisy breathing suggests airway compromise
1. Perform head tilt, chin lift manoeuvre
2. If noisy breathing persists try a jaw thrust
3. If airway still appears compromised use an airway adjunct:
- Insert an oropharyngeal airway (Guedel) only if unconscious (as otherwise may gag/aspirate)
- Alternatively, use a nasopharyngeal airway (better tolerated if the patient is partially conscious)
Sit the patient upright if hypoxia is the primary issue, however, if the patient is hypotensive this can result in loss of consciousness and therefore should be avoided (in this instance the patient may need to be laid flat with their legs elevated).
Give high-flow oxygen (40–60%) with a tight-fitting mask. If pulse oximetry is available, adjust the flow rate to maintain an oxygen saturation of 94–98%.
Assess the patient
Oxygen saturation monitoring – aim for 94-98%
- Tachypnoea is concerning and suggestive of significant respiratory compromise.
- A falling or normal respiratory rate in the context of hypoxia is a sign of impending respiratory failure and need for urgent critical care review.
Auscultate both lungs:
- Assess air entry – reduced air entry suggests significant airway compromise and need for critical care input
- Note any wheezing – wheeze becomes less apparent with increasing airway obstruction
Administer nebulised bronchodilators
Give nebulised bronchodilators if there is suspicion of bronchospasm:
- Salbutamol – doses vary – in severe cases, continuous nebulisation is advised
- Ipratropium bromide – 500mcg nebulised
Administer IM adrenaline
Administer IM adrenaline (1:1000) immediately:²
- Adults – 0.50 mL
- Repeat every 5 minutes if patient remains in haemodynamic shock (max 5mL)
- If the patient remains shocked after 2 doses then an adrenaline infusion may be needed (this will be a consultant / critical care led decision).
Assess the patient
Signs of shock – clammy/pale
- Haemodynamic shock occurs secondary to fluid compartment shifts resulting in significant hypotension
- The patient may complain of feeling faint or lose consciousness if hypotension is severe
- Tachycardia is common due to hypovolaemic shock
- Bradycardia is a late sign, often preceding cardiac arrest ³
Capillary refill time (CRT):
- Assess centrally (as may be peripherally shut down)
- Should be <2 seconds
- Prolonged CRT is seen in hypovolaemic shock
Administer fluids and medication
Gain IV access – large bore cannula
Fluids (STAT) – e.g. NaCl 0.9% / Hartmann’s solution
- Titrate to fluids depending on haemodynamic stability¹ – large volumes may be required (an initial bolus of 500-1000mls is recommended) 3
Chlorphenamine – 10mg IV – stabilises mast cells – reducing histamine release¹ (give after fluid resuscitation – DO NOT delay fluid resuscitation)
Hydrocortisone – 200mg IV – prevents rebound of inflammation over next few hours¹ (give after fluid resuscitation – DO NOT delay fluid resuscitation)
Take blood samples (ideally during cannulation) – FBC / U&E / LFT / Clotting / CRP / Mast cell tryptase
Perform arterial blood gas – hypoxia and acidosis are concerning signs that indicate the need for critical care input
Record an ECG – this should not delay any other treatment however an ECG should be performed at some point as anaphylaxis can cause myocardial ischaemia (even in patients with normal coronary arteries).³
If the patient remains hypotensive, they need admission to critical care for inotropic support.
Assess level of consciousness – AVPU / GCS:
- Confusion can be present if the patient is hypoxic
- Loss of consciousness can occur due to hypotension and severe hypoxia
A falling level of consciousnesses is a sign of serious deterioration and will require critical care input for further support (e.g. intubation).
Allergens – e.g. IV antibiotics
Expose patient’s body looking for skin or mucosal changes:
- Erythema – patchy or generalised
- Can appear anywhere on the body (weals may be pale, pink or red and may look like nettle stings)
- They can be different shapes/sizes and are often surrounded by a red flare
- They are usually itchy
- Similar to urticaria but involves swelling of deeper tissues
- Most commonly the areas affected include the eyelids, lips, mouth and throat
It is essential to continually reassess ABCDE and treat issues as you encounter them. This allows continual reassessment of the response to treatment and early recognition of deterioration.
If the patient does not respond to treatment or deteriorates, critical care input should be involved as soon as possible.