11/13/24, 7\:36 PM Guide | Anaphylaxis

Anaphylaxis

Table of contents

Introduction

This guide provides an overview of the recognition and immediate management of anaphylaxis using an ABCDE approach.
The ABCDE approach is used to systematically assess an acutely 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 identi
This guide has been created to assist healthcare students in preparing for emergency simulation sessions as part of their
training. It is not intended to be relied upon for patient care.

Background

Clinical features
The clinical presentation of anaphylaxis can be variable, and making an early diagnosis can be challenging.
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 (
reactions
Skin or mucosal changes alone are not a sign of an anaphylactic reaction. There can also be gastrointestinal symptoms (e.g.
vomiting, abdominal pain, incontinence).
A history of exposure to a known allergen also helps support the diagnosis of anaphylaxis. Common allergens that can cause
anaphylaxis are foods (most commonly nuts), medications, and insect stings/venom.
Treatment algorithm
Anaphylaxis treatment algorithm. Reproduced with the kind permission of Resuscitation Council UK.

Tips before you begin

General tips for applying an ABCDE approach in an emergency setting include\:
Treat problems as you discover them and re-assess after every intervention
Remember to assess the front and back of the patient when carrying out your assessment (e.g. looking underneath the
patient’s legs or at their back for non-blanching rashes or bleeding)
If the patient loses consciousness and there are no signs of life, put out a crash call and commence CPR
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Make use of the team around you by delegating tasks where appropriate
All critically unwell patients should have continuous monitoring equipment attached
If you require senior input, call for help early using an appropriate SBAR handover
Review results as they become available (e.g. laboratory investigations)
Use local guidelines and algorithms to manage speciacute asthma)
Any medications or must be prescribed at the time (you may be able to delegate this to another sta
Your assessment and management should be documented clearly in the notes; however, this should not delay
management
Methodical approach
For each section of the ABCDE assessment (e.g. airway, breathing, circulation etc.), ask yourself\:
Have I checked the relevant observations for this section? (e.g. checking respiratory rate and SpO2 as part of your
‘breathing’ assessment)
Have I examined the relevant parts of the system in this section? (e.g. peripheral perfusion, pulses, JVP, heart sounds,
and peripheral oedema as part of your ‘circulation’ assessment)
Have I requested relevant investigations based on my
glucose as part of your ‘disability’ assessment)
Have I intervened to correct the issues I have identi
depletion/hypotension as part of your ‘circulation’ assessment)

Initial steps

Acute scenarios typically begin with a brief handover, 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.
If anaphylaxis is suspected, potential anaphylactoid triggers should be removed immediately (e.g. stop intravenous
antibiotics).
You should also ask another sta
con
Introduction
Introduce yourself to whoever has requested a review of the patient and listen carefully to their handover.
Preparation
Ensure the patient’s notes, observation chart, and prescription chart are easily accessible.
Ask for another clinical member of sta
Interaction
Introduce yourself to the patient, including your name and role.
Ask how the patient is feeling, as this may provide useful information about their condition.
If the patient is unconscious or unresponsive, and there are no signs of life, start the basic life support (BLS) algorithm as per
resuscitation guidelines.
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Airway

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\: angioedema (typically associated with anaphylaxis), cyanosis, see-saw breathing, use
of accessory muscles and stridor.
Listen for abnormal airway noises\: stridor, snoring, gurgling
Note any evidence of airway swelling, such as pharyngeal/laryngeal oedema causing the patient to have di
(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
Regardless of the underlying cause of airway obstruction, seek immediate expert support from an anaesthetist and the
emergency medical team (often called the ‘crash team’). You can perform basic airway manoeuvres to help maintain the
airway whilst awaiting senior input.
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
and remove it. Be careful not to push it further into the airway.
Jaw thrust
If the patient is suspected of having su
than a head-tilt chin-lift manoeuvre\:
1. Identify the angle of the mandible
2. Place two
3. Lift the mandible forwards
Other interventions
Airway adjuncts are helpful and, in some cases, essential to maintain a patient’s airway. They should be used in conjunction with
the manoeuvres mentioned above.
An oropharyngeal airway is a curved plastic tube with a
relieve soft palate obstruction. It should only be inserted in unconscious patients as it may induce gagging and aspiration in
semi-conscious patients.
A nasopharyngeal airway is a soft plastic tube with a bevel at one end and a
tolerated in partly or fully conscious patients than oropharyngeal airways.
Intramuscular (IM) adrenaline
IM adrenaline is the
Delayed administration of adrenaline is associated with worse outcomes, and adrenaline must not be delayed to perform other
investigations (e.g. ECG, ABG).
2
The adult dose is 0.5 mL of 1\:1000 adrenaline administered intramuscularly into the anterolateral aspect of the middle third of
the thigh.
If there is no response, a second dose can be administered after 5 minutes. If the patient remains haemodynamically unstable
after two doses, an adrenaline infusion may be required (this will be a consultant/critical care-led decision).
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 signi
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 (SpO )\:
2
A normal SpO 2 2
range is 94-98% in healthy individuals and 88-92% in patients with COPD at high risk of CO retention
Hypoxaemia is a typical clinical feature of anaphylaxis
Auscultation
Auscultate the patient’s chest and identify any abnormalities such as\:
Wheeze is a common
Reduced air entry (sometimes called a 'silent chest') is a concerning
need for senior clinical input
Investigations and procedures
Arterial blood gas
Take an ABG if indicated (e.g. low SpO ) to quantify the degree of hypoxia.
2
An ABG should not delay the management of anaphylaxis with IM adrenaline.
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
Patient positioning
Patients with airway or breathing problems can be placed in a semi-recumbent position to aid breathing. However, patients
with hypotension should be laid
Oxygen
Administer oxygen to all critically unwell patients during your initial assessment. This typically involves using a non-rebreathe
mask with an oxygen
Nebulised bronchodilators
Administer nebulised bronchodilators if there is evidence of bronchospasm (e.g. wheezing on auscultation)\:
Salbutamol\: doses can vary; continuous nebulisation is advised in severe cases.
Ipratropium bromide\: 500mcg nebulised
Re-assessment
Make sure to re-assess the patient after any intervention.

Circulation

Clinical assessment
Pulse
Tachycardia is a common
Blood pressure
A severe allergic reaction typically causes a drop in blood pressure (hypotension). The patient may complain of feeling faint or
lose consciousness if hypotension is severe.
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Anaphylactic shock may occur if there is a signi
response. This is a type of distributive shock which causes signi
Clinical examination
Patients with anaphylaxis are typically peripherally cool, with a thready pulse and prolonged capillary re
Fluid balance assessment
Calculate the patient’s
Calculate the patient's current
drain output, stool output, vomiting) to inform resuscitation e
Reduced urine output (oliguria) is typically de
Investigations and procedures
Intravenous cannulation
Insert two wide-bore intravenous cannulas (14G or 16G) and take blood tests as discussed below.
See our intravenous cannulation guide for more details.
Blood tests
Request a full blood count (FBC), urea & electrolytes (U&E) and liver function tests (LFTs) for all acutely unwell patients. In
the context of anaphylaxis, also request\:
Mast cell tryptase\: useful later to support the diagnosis of anaphylaxis
ECG
An ECG should be performed to identify evidence of acute myocardial ischaemia secondary to anaphylaxis.
²
An ECG should not delay the emergency management of anaphylaxis.
Interventions
Fluid resuscitation
Patients with anaphylaxis require urgent
2
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
required in the context of anaphylaxis)
Patients who are unresponsive to
Re-assessment
Make sure to re-assess the patient after any intervention.

Disability

Clinical assessment
Consciousness
In anaphylaxis, a patient's consciousness level may be reduced secondary to hypoxia or hypovolaemia.
Assess the patient’s level of consciousness using the ACVPU scale\:
Alert\: the patient is fully alert
Confusion\: the patient has new onset confusion or worse confusion than usual
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
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Assess direct and consensual pupillary responses
Brief neurological assessment
Perform a brief neurological assessment by asking the patient to move their limbs.
If a patient cannot move one or all of their limbs, this may be a sign of focal neurological impairment, which requires a more
detailed assessment.
Drug chart review
anxiolytics).
Review the patient's drug chart for medications which may cause neurological abnormalities (e.g. opioids, sedatives,
Also, look for medications which may have caused the anaphylactic reaction.
Are the patient’s allergies documented on their drug chart?
If so, is there anything on the drug chart that has been prescribed and given in error?
Has the correct drug chart been used for the correct patient?
Investigations
Blood glucose and ketones
Measure the patient’s capillary blood glucose level to screen for abnormalities (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 de≤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.
Interventions
Maintain the airway
Alert a senior clinician immediately if you have concerns about a patient’s consciousness level.
A GCS of 8 or below, or a P or U on the ACVPU scale, 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.
Correct hypoglycaemia
Hypoglycaemia should always be considered in patients presenting with a reduced level of consciousness, regardless of
whether they have diabetes. The management of hypoglycaemia involves the administration of glucose (e.g. oral or
intravenous).
Re-assessment
Make sure to re-assess the patient after any intervention.

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, wasp sting, recently consumed food).
Review the output of the patient's catheter and any surgical drains.
Interventions
Allergen removal
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If a potential allergen is identi
Antihistamines
Non-sedating oral antihistamines (e.g. cetirizine) can treat skin symptoms once the patient has been stabilised. Antihistamines
are not used in the emergency management of anaphylaxis.
Discontinue causative medications and record allergy
Ensure that any medications on the drug chart are removed if they are believed to have caused the reaction.
Ensure that the patient's allergies are updated and recorded.
Re-assessment
Make sure to re-assess the patient after any intervention.

Re-assessment and escalation

Re-assess the patient using the ABCDE approach to identify any changes in their clinical condition and assess the
e
Any clinical 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.
Escalation
Patients with anaphylaxis who are not responding to treatment (refractory anaphylaxis) will require urgent critical care input.
Use an eSBAR handover to communicate the key information to other medical sta

Next steps

Take a history
Revisit history taking to identify triggers for anaphylaxis and explore relevant medical history.
See our history taking guides for more details.
Review medical records
Review the patient's notes, charts and recent investigation results.
Review the patient's current medications and check for any allergies.
Discuss
Discuss the patient’s clinical condition with a senior clinician using an SBAR 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)?
The next team of clinicians on shift should be informed of any acutely unwell patient.
Document
Clearly document your ABCDE assessment, including history, examination, observations, investigations, interventions, and the
patient's response.
The ABCDE approach can also form the structure for documenting your assessment.
See our documentation guides for more details.
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Reviewer

Dr Leah Williams
Doctor

References

1. Resuscitation Council (UK). Emergency treatment of anaphylactic reactions\: Guidelines for healthcare providers. Available from\:
[LINK].
Source\: geekymedics.com
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