Anaphylaxis

A 28 year old lady has been referred in via GP as she has not been feeling too well. She has had a headache for a day for which she has been taking OTC medications but now is complaining of nausea, swelling of her lips intermittently and wheezing.

Past medical history: Nil

Medications: Nil regular, Ibuprofen PRN

Observations: HR 125 bpm, BP 92/60, Sats 92% on air, RR 20, Temp 37.8

Please discuss your approach in this patient.

Model answer:

The candidate should identify this patient as clinically unwell and haemodynamically unstable. The patient should be managed in resus if in ED or in a level 1 area. The patient should be assessed using the A-E approach, ensuring their airway is safe and GCS is stable. An attempt to get history should be made, with specific questions around any existing allergies, new medications, or recreational drugs. The candidate should also ask about the timing and frequency of any drugs taken.

The clinical examination reveals that the patient is clammy, complaining of nausea, with hives visible and angioedema. Treatment should not be delayed here. IM adrenaline 500 mcg should be given as the first-line treatment (a second dose can be given after 5 minutes if symptoms persist before starting the refractory anaphylaxis algorithm). Provide O2 and bedside monitoring.

A-E manner of treatment includes IV fluids. High-scoring candidates will consider giving steroids after initial resuscitation for refractory reactions or ongoing asthma/shock. Bronchodilators may also be considered for the same reason.

Once the patient is stabilized, send off further investigations: bloods including VBG, FBC, U&Es, CRP, glucose, clotting, ECG, and CXR. High-scoring candidates will take mast cell tryptase, with 3 samples: the first sample as soon as possible, a second sample 1–2 hours (but no later than 4 hours) after the onset of symptoms, and a third sample at least 24 hours after complete resolution, or in convalescence (for example, at a follow-up allergy clinic).

Here, the suspicion should be a drug reaction (Ibuprofen). Differentia include vasovagal reactions, acute urticaria and angioedema, acute asthma exacerbation, foreign body aspiration, acute anxiety, and hereditary angioedema.

Further Events:

The patient is feeling better after 20 minutes and is keen on going home. Her observations are better, and the nurse asks for your advice. How would you manage this patient further?

The candidate may show knowledge of biphasic reactions and the need for monitoring. A 2-hour discharge can be considered if there is complete resolution of anaphylaxis, only one dose of adrenaline used, and the patient has adrenaline auto-injectors and knows how to use them. These decisions would need to be made by a senior clinician.

Prescription of adrenaline auto-injectors is appropriate for all patients who have had anaphylaxis, with the exception of those with a drug-induced reaction (unless it is difficult to avoid future exposure to the trigger drug). This may be the case in this patient, so senior review is appropriate.