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:
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 is meant to assist students in preparing for emergency simulation sessions as part of their training, not intended to be relied upon for patient care.
Anaphylaxis can present in a wide variety of ways, making early diagnosis sometimes difficult. The Resuscitation Council (UK) have devised a set of criteria that if met suggest anaphylaxis is likely:
A history of exposure to a known allergen also helps support the diagnosis of anaphylaxis. Other key points:
General tips for applying an ABCDE approach in an emergency setting include:
When managing potentially acute anaphylaxis scenarios, it is important to begin with a brief handover from a member of the nursing staff. This should include the patient's name, age, background and the reason why the review has been requested. For example, you may be asked to review a patient with anaphylaxis due to rash, facial swelling, shortness of breath and/or wheeze.
Start by introducing yourself to whoever has requested a review of the patient and listening carefully to their handover. When you meet the patient, introduce yourself, including your name and role. Ask how the patient is feeling as this may provide some useful information about their current symptoms.
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.
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).
If the patient can talk, their airway is patent and you can move on to the assessment of breathing.
If the patient cannot talk, look for signs of airway compromise, such as 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 for anything obstructing the airway such as secretions or a foreign object.
Open the patient's airway using a head-tilt chin-lift manoeuvre:
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:
Review the patient's respiratory rate:
Review the patient's oxygen saturation (SpO2):
Auscultate both lungs:
Take an ABG if indicated (e.g. low SpO2) to quantify the degree of hypoxia.
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:
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:
If the patient loses consciousness and there are no signs of life on assessment, put out a crash call and commence CPR.
Make sure to re-assess the patient after any intervention.
Tachycardia is a common finding in anaphylaxis and bradycardia is a late sign often suggestive that the patient is peri-arrest.
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.
Patients with anaphylaxis are typically peripherally cool, with a thready pulse and prolonged capillary refill time.
Calculate the patient's fluid balance including oral fluids, intravenous fluids, urine output, drain output, stool output, vomiting. Reduced urine output (oliguria) is typically defined as less than 0.5ml/kg/hour in an adult.
Insert two wide-bore intravenous cannulas (14G or 16G).
Collect blood tests after cannulating the patient including FBC, U&Es, LFTs, coagulation, CRP, and mast cell tryptase.
Perform an ECG to look for evidence of acute myocardial ischaemia, which may occur secondary to anaphylaxis. An ECG should not delay the emergency management of anaphylaxis.
Administer IM adrenaline (1:1000) immediately. Adult dose: 0.5ml of 1:1000 l adrenaline should be given IM usually in the lateral thigh.
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.
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 lie the patient flat with their legs elevated (or on their left side if pregnant).
Administer nebulised bronchodilators if there is suspicion of bronchospasm (e.g. wheezing on auscultation):
If the patient loses consciousness and there are no signs of life on assessment, put out a crash call and commence CPR.
Make sure to re-assess the patient after any intervention.
Administer 50 mL of 1:1000 epinephrine and repeat every 5 minutes if the patient remains haemodynamically unstable (max 5mL). Injection should be made on the anterolateral aspect of the middle third of the thigh. If two doses do not stabilize the patient, consideration should be given to an adrenaline infusion (decision to be made by consultant/critical care).
Patients with anaphylaxis require urgent fluid resuscitation:
If the patient loses consciousness and there are no signs of life on assessment, put out a crash call and commence CPR.
Make sure to re-assess the patient after any intervention. If the patient has a cardiac arrest, follow basic life support guidelines.
In the context of anaphylaxis, a patient's consciousness level may be reduced due to hypoxia or hypovolaemia. Assess the patient's level of consciousness using the AVPU scale:
If a more detailed assessment of the patient's level of consciousness is required, use the Glasgow Coma Scale (GCS).
Assess the patient's pupils:
Review the patient's drug chart for medications which may cause neurological abnormalities (e.g. opioids, sedatives, anxiolytics).
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).
Take a history and identify potential triggers for anaphylaxis. Looking into relevant medical history may also be necessary if the patient is confused. Collateral history can be obtained from staff or family members if appropriate.
Inspect for evidence of anaphylaxis such as an urticarial rash and angioedema.
Look for potential allergens (e.g. an intravenous antibiotic infusion) and review the output of the patient's catheter and any surgical drains.
Request a CT head if intracranial pathology is suspected after discussion with a senior.
If a potential allergen is identified and you suspect an allergic aetiology, remove the allergen (e.g. stop the antibiotic infusion).
Alert a senior immediately if consciousness level is concerning (GCS of 8 or below). Meanwhile, assess and maintain the patient's airway.
If the patient loses consciousness and there are no signs of life on assessment, put out a crash call and commence CPR.
Non-sedating oral antihistamines (e.g. cetirizine) can be used to treat skin symptoms once the patient has been stabilised.
Re-assess the patient using the ABCDE approach to identify changes in their clinical condition and assess effectiveness of interventions. If signs of deterioration are observed, act upon it immediately. Seek a senior's help if there is no improvement or if you have any doubts.
You should have another member of the clinical team aiding you in the ABCDE assessment, such as a nurse, who can perform observations, take samples to the lab and catheterise if appropriate. Using an effective SBARR handover can effectively communicate the key information to other medical staff.
Once the patient is stabilised, revisit history taking to identify triggers for anaphylaxis and explore relevant medical history. Review the patient's notes, charts and recent investigation results.
Review the patient's current medications and check that any regular medications are prescribed appropriately.
Clearly document your ABCDE assessment, including history, examination, observations, investigations, interventions, and the patient's response.
Discuss the patient's current clinical condition with a senior clinician using an SBARR style handover.
Questions which may need to be considered include:
The next team of doctors on shift should be made aware of any patient in their department who has recently deteriorated.
