Atrial Fibrillation (AF) | Acute Management | ABCDE

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This guide provides an overview of the recognition and immediate management of atrial fibrillation 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.


What is atrial fibrillation?

Atrial fibrillation (AF) is an atrial tachydysrhythmia, ‘tachy’ meaning fast and ‘dysrhythmia’ indicating chaotic and uncoordinated electrical activity.

In AF, multiple waves of electrical activity compete with each other in the atrium and bombard the atrioventricular node. This results in irregular conduction down the bundle of His and as a result, irregular ventricular contraction. If the ventricular response is rapid, cardiac output can become impaired due to uncoordinated myocardial contraction.

The causes of AF are vast and complex but usually, a patient with AF has an underlying abnormal atrium, both anatomically (dilated) and histologically (fibrotic from inflammation).

Patients may suffer from symptoms of AF constantly or intermittently, whilst others may be completely asymptomatic.

What is ‘fast AF’?

Some patients present with sudden onset of palpitations and breathlessness and are found to be tachycardic in atrial fibrillation. You may hear some clinicians referring to this presentation as ‘fast AF’, however, this term should be avoided because all patients with AF have rapid and chaotic atrial activity. Instead, this presentation is AF with a rapid ventricular response (sometimes written as AF with RVR).

Triggers for AF

There are many conditions that can either trigger the first episode of AF or make pre-existing AF worse. The Royal College of Emergency Medicine has created the PIRATES mnemonic to make memorising AF triggers a little easier:

  • Pulmonary embolism
  • Ischaemia
  • Respiratory disease
  • Atrial enlargement or myxoma
  • Thyroid disease
  • Ethanol
  • Sepsis/sleep apnoea
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Clinical features of new-onset AF


Typical symptoms of new-onset AF include:

  • Palpitations (e.g. a sense of fluttering in the chest)
  • Dizziness
  • Shortness of breath
  • Anxiety
  • Chest pain

Clinical signs

Typical clinical signs of AF include:

  • An irregularly irregular pulse
  • Tachycardia (if AF with rapid ventricular response)

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.
  • 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.

Initial steps

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

You may be asked to review a patient with AF due to palpitations, chest pain and/or dizziness.


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


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.


Make sure the patient’s notesobservation chart and prescription chart are easily accessible.

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

If the patient is unconscious or unresponsive, start the basic life support (BLS) algorithm as per resuscitation guidelines.


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.


  • Look for signs of airway compromise: these include cyanosis, see-saw breathing, use of accessory muscles, diminished breath sounds and added sounds.
  • Open the mouth and inspect: look for anything obstructing the airway such as secretions or a foreign object.


Regardless of the underlying cause of airway obstruction, seek immediate expert support from an anaesthetist and the emergency medical team (often referred to as the ‘crash team’). In the meantime, you can perform some 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 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 maneuvres 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.

Other interventions

If the patient has clinical signs of anaphylaxis (e.g. angioedema, rash) commence appropriate treatment as discussed in our anaphylaxis guide.


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.


Clinical assessment


Review the patient’s respiratory rate:

  • normal respiratory rate is between 12-20 breaths per minute.
  • Tachypnoea in the context of AF may indicate pulmonary oedema secondary to heart failure or primary pulmonary pathology which is driving AF with RVR (e.g. pulmonary embolism, pneumonia).

Review the patient’s oxygen saturation (SpO2):

  • normal SpOrange is 94-98% in healthy individuals and 88-92% in patients with COPD who are at high-risk of COretention.
  • Hypoxaemia may be present in the context of heart failure secondary to AF with RVR.


Observe the patient for evidence of pain, distress or anxiety.


Auscultate the lungs:

  • Bibasal coarse crackles may suggest pulmonary oedema secondary to heart failure.
  • A focal region of coarse crackles may indicate an underlying infection which may be the trigger for AF with RVR.

Investigations and procedures

Arterial blood gas

Take an ABG if indicated (e.g. low SpO2) to quantify the degree of hypoxia and assess for metabolic abnormalities.

Chest X-ray

A chest X-ray may be indicated if abnormalities are noted on auscultation (e.g. reduced air entry, coarse crackles) to screen for evidence of AF triggers (e.g. pneumonia, pulmonary oedema). A chest X-ray should not delay the emergency management of atrial fibrillation.

See our CXR interpretation guide for more details.

Sputum culture

Ask the nursing staff to obtain a sputum sample to be sent to the microbiology lab for culture and sensitivity if the patient has a productive cough.

This information can be useful later to understand the causative organism and its antibiotic sensitivities.



Administer oxygen to all critically unwell patients during your initial assessment if oxygen saturations are below the normal range (<94%). This typically involves the use of a non-rebreathe mask with an oxygen flow rate of 15L. If the patient has COPD and a history of COretention you should switch to a venturi mask as soon as possible and titrate oxygen appropriately.

If the patient is conscious, sit them upright as this can also help with oxygenation.


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.


Clinical assessment


Assess the patient’s pulse rate:

  • Patients with AF with RVR will be tachycardic.

Blood pressure

Assess the patient’s blood pressure:

  • Most patients with AF will be haemodynamically stable, however, a minority may become haemodynamically unstable. Haemodynamic instability is typically associated with prolonged periods of tachycardia (e.g. >150 bpm).
  • If a patient develops haemodynamic instability in the context of AF, urgent senior input should be sought as DC cardioversion may be required to prevent cardiac arrest.

Capillary refill time

Capillary refill time may be prolonged in atrial fibrillation with associated haemodynamic instability.

Fluid status assessment

Assess the patient’s fluid status to determine if they are hypervolaemic, euvolaemic or hypovolaemic.

Fluid status assessment involves:

  • Inspecting the oral mucosa for hydration
  • Capillary refill time assessment as above
  • Assessment of jugular venous pressure (JVP)
  • Review of the patient’s fluid input and output

Hypovolaemia is a known trigger for AF and should be treated appropriately.

Apex beat

Locate and palpate the apex beat:

  • The apex beat is typically located in the 5th intercostal space in the midclavicular line.
  • A displaced apex beat may indicate underlying ventricular hypertrophy.

Investigations and procedures

Intravenous cannulation

Insert at least one wide-bore intravenous cannula (14G or 16G) and take blood tests as discussed below.

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: to assess renal function and rule out electrolyte disturbances.
  • CRP: to screen for evidence of inflammation (e.g. pneumonia).
  • Troponin: if considering acute myocardial infarction or rate-related ischaemia.
  • Coagulation studies: to assess for coagulopathy or assess the patient’s current level of anticoagulation (e.g. INR).
  • Thyroid function tests: to rule out hyperthyroidism which is a known trigger for AF.


An ECG should be performed to confirm the diagnosis of AF and to screen for evidence of ischaemic (e.g. ST elevation). Typical ECG findings in the context of AF include:

  • Irregularly irregular rhythm
  • Absence of P waves

See our ECG interpretation guide to learn more.



Emergency electrical cardioversion is required in people with life-threatening haemodynamic instability caused by new-onset atrial fibrillation.

Consider either pharmacological (e.g. flecainide, amiodarone) or electrical cardioversion depending on clinical circumstances and resources in people with new‑onset atrial fibrillation who will be treated with a rhythm control strategy.

In people with atrial fibrillation in whom the duration of the arrhythmia is greater than 48 hours or uncertain and considered for long‑term rhythm control, delay cardioversion until they have been maintained on therapeutic anticoagulation for a minimum of 3 weeks. During this period offer rate control as appropriate.

Treating precipitating factors

AF is commonly triggered by other factors (see PIRATES above) and definitive management of AF requires the underlying triggers to be addressed (e.g. fluid resuscitation for hypovolaemia, antibiotics for an infection).

Rate control

In people with atrial fibrillation presenting acutely without life‑threatening haemodynamic instability, offer rate or rhythm control if the onset of the arrhythmia is less than 48 hours, and start rate control if it is more than 48 hours or is uncertain.

Rate control is commonly required in the management of AF with rapid ventricular response. In the acute context, beta-blockers (e.g. metoprolol) and diltiazem/verapamil are preferred over digoxin because of their rapid onset of action. The choice of drug and target heart rate will depend on individual patient characteristics (e.g. pre-existing cardiovascular disease, ejection fraction). Generally, cardiac output is sufficiently optimised by maintaining a heart rate of less than 110 bpm at rest. More than one drug may be required. If heart rate cannot be controlled to less than 110 bpm in the acute setting patients may require admission under a medical team for further rate-controlling therapies.

Rhythm control

Rhythm control therapy is indicated to improve symptoms in patients who remain symptomatic on adequate rate control therapy, it has not however been shown to improve long-term outcomes.

Rhythm control may be offered at presentation to patients presenting with AF without life‑threatening haemodynamic instability.


Patients with AF are at increased risk of stroke from atrial emboli. Long-term oral anticoagulation with a suitable agent (e.g. direct-acting oral anticoagulant or warfarin) significantly reduces this risk. The risk of stroke and the risk of bleeding can be calculated using the CHA2DS2-VASc and ORBIT scoring tools respectively. In the acute setting, anticoagulation may be initially established using heparin.

Fluid resuscitation

Hypovolaemic patients require fluid resuscitation:

  • Administer a 500ml bolus of Hartmann’s solution or 0.9% sodium chloride (warmed if available) over less than 15 mins.
  • Administer 250ml boluses in patients at increased risk of fluid overload (e.g. heart failure).

After each fluid bolus, reassess for clinical evidence of fluid overload (e.g. auscultation of the lungs, assessment of JVP).

Repeat administration of fluid boluses up to four times (e.g. 2000ml or 1000ml in patients at increased risk of fluid overload), reassessing the patient each time.

Seek senior input if the patient has a negative response (e.g. increased chest crackles) or if the patient isn’t responding adequately to repeated boluses (i.e. persistent hypotension).

See our fluid prescribing guide for more details on resuscitation fluids.


Consider administration of intravenous furosemide to treat pulmonary oedema:

  • Furosemide will increase the patient’s urine output and help to shift fluid out of the lungs.
  • As mentioned previously, if the patient is hypotensive then diuretics can precipitate hypovolaemic shock, therefore critical care input should be sought to decide on the most appropriate management strategy.


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.


Clinical assessment


In the context of atrial fibrillation, a patient’s consciousness level may be reduced secondary to hypotension or secondary stroke.

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).


Assess the patient’s pupils:

  • Inspect the size and symmetry of the patient’s pupils
  • Assess direct and consensual pupillary responses

Drug chart review

Review the patient’s drug chart for medications which may cause a reduced level of consciousness (e.g. opioids, sedatives, anxiolytics, insulin, oral hypoglycaemic medications).

Investigations and procedures

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.

See our blood glucose measurement guide for more details.


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.


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.


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.


It may be necessary to expose the patient during your assessment: remember to prioritise patient dignity and conservation of body heat. 

Clinical assessment


Inspect for evidence of peripheral oedema (e.g. heart failure) or swollen painful calves (e.g. deep vein thrombosis).


Measure the patient’s temperature:

  • If fever is present, make sure to consider co-existing infection.



If an infection is suspected (e.g. consolidation on chest X-ray and fever) administer antibiotics as per local guidelines.


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.

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.


You should have another member of the clinical team aiding you in your ABCDE assessment, such 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.

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

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


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

See our documentation guides for more details.


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)?


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


  1. ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. European Heart Journal. Published in 2016.
  2. NICE guidelines. Atrial fibrillation: management. Published June 2014. Available from: [LINK].


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