Anaphylaxis | Acute Management | ABCDE

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This guide provides an overview of the recognition and immediate management of anaphylaxis using an ABCDE approach.

The ABCDE approach can be used to perform a systematic assessment of a critically unwell patient. It involves working through the following steps:

• Airway
• Breathing
• Circulation
• Disability
• Exposure

Each stage of the ABCDE approach involves clinical assessment, investigations and interventions. Problems are addressed as they are identified and the patient is re-assessed regularly to monitor their response to treatment.

This guide has been created to assist students in preparing for emergency simulation sessions as part of their training, it is not intended to be relied upon for patient care.

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Clinical features of anaphylaxis

Anaphylaxis can present in a wide variety of ways, making early diagnosis sometimes difficult.

The resuscitation council (UK) have devised the following set of criteria that if met suggest anaphylaxis is likely:

• Sudden onset and rapid progression of symptoms (most reactions occur over several minutes)
• Life-threatening airway and/or breathing and/or circulation problems
• Skin and/or mucosal changes (flushing, urticaria, angioedema)

A history of exposure to a known allergen also helps support the diagnosis of anaphylaxis.

Other key points:

• Skin or mucosal changes alone are not a sign of an anaphylactic reaction.
• Skin and mucosal changes can be subtle or absent in up to 20% of reactions.
• There can also be gastrointestinal symptoms (e.g. vomiting, abdominal pain, incontinence).

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Tips before you begin

General tips for applying an ABCDE approach in an emergency setting include:

• Treat all problems as you discover them.
• Re-assess regularly and after every intervention to monitor a patient’s response to treatment.
• Make use of the team around you by delegating tasks where appropriate.
• All critically unwell patients should have continuous monitoring equipment attached for accurate observations.
• Clearly communicate how often would you like the patient’s observations relayed to you by other staff members.
• If you require senior input, call for help early using an appropriate SBARR handover structure.
• Review results as they become available (e.g. laboratory investigations).
• Make use of your local guidelines and algorithms in managing specific scenarios (e.g. acute asthma).
• Any medications or fluids will need to be prescribed at the time (in some cases you may be able to delegate this to another member of staff).
• Your assessment and management should be documented clearly in the notes, however, this should not delay initial clinical assessment, investigations and interventions.

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Initial steps

Acute scenarios typically begin with a brief handover from a member of the nursing staff including the patient’s name, age, background and the reason the review has been requested.

You may be asked to review a patient with anaphylaxis due to rash, facial swelling, shortness of breath and/or wheeze.

Introduction

Introduce yourself to whoever has requested a review of the patient and listen carefully to their handover.

Interaction

Introduce yourself to the patient including your name and role.

Ask how the patient is feeling as this may provide some useful information about their current symptoms.

Preparation

Make sure the patient’s notes, observation chart and prescription chart are easily accessible.

Ask for another clinical member of staff to assist you if possible.

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Airway

If anaphylaxis is suspected, potential anaphylactoid triggers should be removed immediately (e.g. intravenous antibiotics).

You should also ask another member of staff to source adrenaline (1:1000) to allow this to be administered as soon as you have confirmed the diagnosis (there is often an emergency box containing the relevant drugs on the ward).

Clinical assessment

Can the patient talk?

Yes: if the patient can talk, their airway is patent and you can move on to the assessment of breathing.

No:

• Look for signs of airway compromise: these include cyanosis, see-saw breathing, use of accessory muscles and stridor.
• Look for evidence of angioedema which is typically associated with anaphylaxis.
• Note any evidence of airway swelling such as pharyngeal/laryngeal oedema causing the patient to have difficulty speaking (hoarse voice), breathing, and swallowing (the patient may complain of feeling like their airway is closing up)
• Open the mouth and inspect: look for anything obstructing the airway such as secretions or a foreign object.

Interventions

Head-tilt chin-lift manoeuvre

Open the patient’s airway using a head-tilt chin-lift manoeuvre:

1. Place one hand on the patient’s forehead and the other under the chin.

2. Tilt the forehead back whilst lifting the chin forwards to extend the neck.

3. Inspect the airway for obvious obstruction. If an obstruction is visible within the airway, use a finger sweep or suction to remove it.

Jaw thrust

If the patient is suspected to have suffered significant trauma with potential spinal involvement, perform a jaw-thrust rather than a head-tilt chin-lift manoeuvre:

1. Identify the angle of the mandible.

2. With your index and other fingers placed behind the angle of the mandible, apply steady upwards and forward pressure to lift the mandible.

3. Using your thumbs, slightly open the mouth by downward displacement of the chin.

Oropharyngeal airway (Guedel)

Airway adjuncts are often helpful and in some cases essential to maintain a patient’s airway. They should be used in conjunction with the manoeuvres mentioned above as the position of the head and neck need to be maintained to keep the airway aligned.

An oropharyngeal airway is a curved plastic tube with a flange on one end that sits between the tongue and hard palate to relieve soft palate obstruction. It should only be inserted in unconscious patients as it is otherwise poorly tolerated and may induce gagging and aspiration.

To insert an oropharyngeal airway:

1. Open the patient’s mouth to ensure there is no foreign material that may be pushed into the larynx. If foreign material is present, attempt removal using suction.

2. Insert the oropharyngeal airway in the upside-down position until you reach the junction of the hard and soft palate, at which point you should rotate it 180°. The reason for inserting the airway upside down initially is to reduce the risk of pushing the tongue backwards and worsening airway obstruction.

3. Advance the airway until it lies within the pharynx.

4. Maintain head-tilt chin-lift or jaw thrust and assess the patency of the patient’s airway by looking, listening and feeling for signs of breathing.

Nasopharyngeal airway (NPA)

A nasopharyngeal airway is a soft plastic tube with a bevel at one end and a flange at the other. NPAs are typically better tolerated in patients who are partly or fully conscious compared to oropharyngeal airways. NPAs should not be used in patients who may have sustained a skull base fracture, due to the small but life-threatening risk of entering the cranial vault with the NPA.

To insert a nasopharyngeal airway:

1. Check the patency of the patient’s right nostril and if required (depending on the model of NPA) insert a safety pin through the flange of the NPA.

2. Lubricate the NPA.

3. Insert the airway bevel-end first, vertically along the floor of the nose with a slight twisting action.

4. If any obstruction is encountered, remove the tube and try the left nostril.

CPR

If the patient loses consciousness and there are no signs of life on assessment, put out a crash call and commence CPR.

Re-assessment

Make sure to re-assess the patient after any intervention.

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Breathing

Clinical assessment

Observations

Review the patient’s respiratory rate:

• A normal respiratory rate is between 12-20 breaths per minute.
• Tachypnoea is a common feature of anaphylaxis and indicates significant respiratory compromise.
• Bradypnoea in the context of hypoxia is a sign of impending respiratory failure and the need for urgent critical care review.

Review the patient’s oxygen saturation (SpO₂):

• A normal SpO₂ range is 94-98% in healthy individuals and 88-92% in patients with COPD who are at high-risk of CO₂ retention.
• Hypoxaemia is a typical clinical feature of anaphylaxis.

Auscultation

Auscultate both lungs:

• Wheeze is a common finding in anaphylaxis (it can become less apparent with increasing airway obstruction).
• Reduced air entry is a concerning finding indicating significant airway compromise and a need for senior clinical input.

Investigations and procedures

Arterial blood gas

Take an ABG if indicated (e.g. low SpO₂) to quantify the degree of hypoxia.

An ABG should not delay the management of anaphylaxis.

Chest X-ray

A chest X-ray may be useful in ruling out other respiratory diagnoses if shortness of breath is the primary issue (e.g. pneumothorax, pneumonia, pulmonary oedema). Chest X-ray should not delay the emergency management of anaphylaxis and should only be performed if the diagnosis is in doubt.

Interventions

Oxygen

Administer oxygen to all critically unwell patients during your initial assessment. This typically involves the use of a non-rebreathe mask with an oxygen flow rate of 15L.

In most situations, the advice is to sit the patient upright if this makes breathing easier for the patient, however, in the context of anaphylaxis, the patient is likely hypotensive, therefore it is generally better to lie the patient flat with their legs elevated (or on their left side if pregnant).

Nebulised bronchodilators

Administer nebulised bronchodilators if there is suspicion of bronchospasm (e.g. wheezing on auscultation):

Re-assessment

Make sure to re-assess the patient after any intervention.

Circulation

Clinical assessment

Pulse

Tachycardia is a common finding in anaphylaxis and bradycardia is a late sign often suggestive that the patient is peri-arrest.

Blood pressure

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.

Clinical examination

Patients with anaphylaxis are typically peripherally cool, with a thready pulse and prolonged capillary refill time.

Fluid balance assessment

Calculate the patient’s fluid balance:

• Calculate the patient’s current fluid balance using their fluid balance chart (e.g. oral fluids, intravenous fluids, urine output, drain output, stool output, vomiting) to inform resuscitation efforts.
• Reduced urine output (oliguria) is typically defined as less than 0.5ml/kg/hour in an adult.

Investigations and procedures

Intravenous cannulation

Insert two wide-bore intravenous cannulas (14G or 16G) and take blood tests as discussed below (unless already performed to administer IV drugs to treat a breathing problem).

See our intravenous cannulation guide for more details.

Blood tests

Collect blood tests after cannulating the patient including:

• FBC: to rule out anaemia and to look for a raised white cell count which may suggest underlying infection.
• U&Es
• LFTs
• Coagulation
• CRP
• Mast cell tryptase: useful later to support the diagnosis of anaphylaxis.

ECG

An ECG should be performed to look for evidence of acute myocardial ischaemia, which may occur secondary to anaphylaxis.²

An ECG should not delay the emergency management of anaphylaxis.

Interventions

Intramuscular (IM) adrenaline

Administer IM adrenaline (1:1000) immediately:²

• Adult dose: 0.50 mL of 1:1000 adrenaline
• Repeat administration every 5 minutes if the patient remains haemodynamically unstable (max 5mL).
• The recommended site for injection is the anterolateral aspect of the middle third of the thigh.
• If the patient remains haemodynamically unstable after 2 doses then an adrenaline infusion may be required (this will be a consultant/critical care led decision). 

Intravenous (IV) fluids

Patients with anaphylaxis require urgent fluid resuscitation:

• Administer an initial bolus of 500-1000ml Hartmann’s solution or 0.9% sodium chloride over less than 15 mins.
• Re-assess the patient after each fluid bolus and administer further boluses as required (large volumes of fluid may be required in the context of anaphylaxis).²
• Patients who are unresponsive to fluid resuscitation will require critical care input for inotropic support.

CPR

If the patient loses consciousness and there are no signs of life on assessment, put out a crash call and commence CPR.

Re-assessment

Make sure to re-assess the patient after any intervention.

If the patient has a cardiac arrest, commence CPR basic life support guidelines.

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Disability

Clinical assessment

Consciousness

In the context of anaphylaxis, a patient’s consciousness level may be reduced secondary to hypoxia or hypovolaemia.

Assess the patient’s level of consciousness using the AVPU scale:

• Alert: the patient is fully alert, although not necessarily orientated.
• Verbal: the patient makes some kind of response when you talk to them (e.g. words, grunt).
• Pain: the patient responds to a painful stimulus (e.g. supraorbital pressure).
• Unresponsive: the patient does not show evidence of any eye, voice or motor responses to pain.

If a more detailed assessment of the patient’s level of consciousness is required, use the Glasgow Coma Scale (GCS).

Pupils

Assess the patient’s pupils:

• Inspect the size and symmetry of the patient’s pupils. Asymmetrical pupillary size may indicate intracerebral pathology.
• Assess direct and consensual pupillary responses which may reveal evidence of intracranial pathology or lung cancer (e.g. Horner’s syndrome).

Drug chart review

Review the patient’s drug chart for medications which may cause neurological abnormalities (e.g. opioids, sedatives, anxiolytics).

Investigations

Blood glucose and ketones

Measure the patient’s capillary blood glucose level to screen for causes of a reduced level of consciousness (e.g. hypoglycaemia or hyperglycaemia). 

A blood glucose level may already be available from earlier investigations (e.g. ABG, venepuncture).

The normal reference range for fasting plasma glucose is 4.0 – 5.8 mmol/l.

Hypoglycaemia is defined as a plasma glucose of less than 3.0 mmol/l. In hospitalised patients, a blood glucose ≤4.0 mmol/L should be treated if the patient is symptomatic.

If the blood glucose is elevated, check ketone levels which if also elevated may suggest a diagnosis of diabetic ketoacidosis (DKA).

See our blood glucose measurement, hypoglycaemia and diabetic ketoacidosis guides for more details.

Imaging

Request a CT head if intracranial pathology is suspected after discussion with a senior.

See our guide on interpreting a CT head for more details.

Interventions

Maintain the airway

Alert a senior immediately if you have any concerns about the consciousness level of a patient. A GCS of 8 or below warrants urgent expert help from an anaesthetist. In the meantime, you should re-assess and maintain the patient’s airway as explained in the airway section of this guide.

CPR

If the patient loses consciousness and there are no signs of life on assessment, put out a crash call and commence CPR.

Re-assessment

Make sure to re-assess the patient after any intervention.

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Exposure

Clinical assessment

Inspection

Inspect for evidence of anaphylaxis such as an urticarial rash and angioedema.

Look for potential allergens (e.g. an intravenous antibiotic infusion).

Review the output of the patient’s catheter and any surgical drains.

Interventions

Allergen removal

If a potential allergen is identified and you suspect allergic aetiology remove the allergen (e.g. stop the antibiotic infusion).

Antihistamines

Non-sedating oral antihistamines (e.g. cetirizine) can be used to treat skin symptoms once the patient has been stabilised.

CPR

If the patient loses consciousness and there are no signs of life on assessment, put out a crash call and commence CPR.

Re-assessment

Make sure to re-assess the patient after any intervention.

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Reassess ABCDE

Re-assess the patient using the ABCDE approach to identify any changes in their clinical condition and assess the effectiveness of your previous interventions.

Deterioration should be recognised quickly and acted upon immediately.

Seek senior help if the patient shows no signs of improvement or if you have any concerns.

Support

You should have another member of the clinical team aiding you in your ABCDE assessment, such as a nurse, who can perform observations, take samples to the lab and catheterise if appropriate.

You may need further help or advice from a senior staff member and you should not delay seeking help if you have concerns about your patient.

Use an effective SBARR handover to communicate the key information effectively to other medical staff.

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Next steps

Well done, you’ve now stabilised the patient and they’re doing much better. There are just a few more things to do…

Take a history

Revisit history taking to identify triggers for anaphylaxis and explore relevant medical history. If the patient is confused you might be able to get a collateral history from staff or family members as appropriate.

See our history taking guides for more details.

Review

Review the patient’s notes, charts and recent investigation results.

Review the patient’s current medications and check any regular medications are prescribed appropriately.

Document

Clearly document your ABCDE assessment, including history, examination, observations, investigations, interventions, and the patient’s response.

See our documentation guides for more details.

Discuss

Discuss the patient’s current clinical condition with a senior clinician using an SBARR style handover.

Questions which may need to be considered include:

• Are any further assessments or interventions required?
• Does the patient need a referral to HDU/ICU?
• Does the patient need reviewing by a specialist?
• Should any changes be made to the current management of their underlying condition(s)?

Handover

The next team of doctors on shift should be made aware of any patient in their department who has recently deteriorated.

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References

1. Australian Prescriber. Emergency management of Anaphylaxis. Available from: [LINK].
2. Resuscitation Council (UK). Emergency treatment of anaphylactic reactions. Available from: [LINK].