This is common symptom in Emergency Medicine, often initially labelled as "collapse ?cause."

Definition of Syncope

  • Transient self-limited loss of consciousness
  • The onset is usually rapid and the recovery is spontaneous, complete and usually (but not always) prompt

Patients who are still unconscious when they are brought into the ED have not had a syncopal episode since their recovery doesn't fit the criteria. They should be evaluated for coma.

EM assessment of syncopal patients

  1. Full diagnostic assessment
  2. Risk stratification (SFSR) and appropriate disposition. Note that patients with syncope of a cardiac origin are at risk of sudden death and must be assessed in detail
  3. Exclusion of significant injury
  4. Consideration the patient's occupation and driving status to guide immediate discharge advice

Principal causes of syncope

Cardiac syncope

  • Arrhythmias
  • Structural cardiac or cardiopulmonary disease: 
    • includes valvular heart disease, LV outflow obstruction (aortic stenosis is particularly important), cardiac tamponade, pulmonary embolism


  • Simple faint
  • Situational syncope: micturition, cough, defecation, pain, swallowing
  • Carotid sinus syndrome

Severe orthostatic hypotension


Assessment (risk)


  • Circumstances prior to the episode (position, activity, predisposing factors or precipitating events)
  • Symptoms at onset of episode (nausea, aura, visual, cardiac symptoms etc.)
  • Details of the episode (you will need a witness, or collateral history from the ambulance crew): skin colour, duration of loss of consciousness, breathing pattern, movements, tongue biting etc.
  • End of the episode: confusion, muscle aches, colour, injury, incontinence
  • Previous pre-syncopal or syncopal episodes, previous cardiac and medical history, family history (sudden cardiac death, epilepsy etc
  • Medications
  • Occupation and driving status

Physical examination and investigations

  • Focus particularly on the cardiovascular and neurological systems
  • Note the resting heart rate, BP, and SpO2 on air
  • Look for aortic stenosis
  • Check for injury
  • Walk the patient and observe gait / steadiness
  • Diagnostic carotid sinus massage should only be performed by an experienced operator, who is familiar with both the contraindications and interpretation of any effect
  • 12 lead ECG in all patients. Look for arrhythmias and conduction defects (i.e. AV block, BBB, prolonged QTc etc ). If patient has symptoms whilst in the department obtain a contemporaneous ECG
  • Blood tests are useful only if clinically indicated.
  • You should do a blood glucose
  • Consider a pregnancy test in women of childbearing age
  • Please note a CT brain is not routinely required

Orthostatic hypotension (OH) is an unusual primary cause of syncope. It might be worth looking for in patients who have syncope immediately related to assuming an upright posture. Because the test (using standard BP equipment) has a low sensitivity in detecting OH, it is important to document whether symptoms occur in the absence of BP change.

San Francisco Syncope Rule (SFSR)

SFSR is a simple rule for evaluating the risk of adverse outcomes in patient who present with fainting or syncope.


  • C - Hx of CCF
  • H - Haematocrit <30%
  • E - ECG abnormal
  • S - Shortness of breath
  • S - Systolic BP (triage) <90

ECG abnormalities include:

  1. Aortic stenosis
  2. Brugada (saddle STE V1-V3)
  3. Corrected QT (LQTS beware >500ms)
  4. Delta wave (WPW)
  5. Epsilon wave of ARVD
  6. Fluid (alternans, low voltage of pericardial fluid)
  7. Giant PE (RAD, RBBB, TV1 - V3, S1Q3T3)
  8. Hypertrophy where not expected (HOCM)
  9. Intervals - (PR , 2nd/3rd degree block, BBB)
  10. Ischaemia

A patient with any of the above measures is considered at high risk (death, AMI, arrhythmia, PE, stroke, SAH, haemorrhage).

SFSR has a sensitivity of 74-98% and specificity of 56%. This means that in patients with none of the above criteria, 74-98% had no serious outcome and may be considered as suitable candidates for outpatient monitoring.

Measuring lying and standing BP

Identify if you are going to need assistance to stand the patient and simultaneously record a BP. Use a manual sphygmomanometer if possible and definitely if the automatic machine fails to record.

  1. Explain procedure to the patient
  2. The first BP should be taken after lying for at least five minutes
  3. The second BP should be taken after standing in the first minute
  4. A third BP should be taken after standing for three minutes
  5. This recording can be repeated if the BP is still falling
  6. Symptoms of dizziness, light-headedness, vagueness, pallor, visual disturbance, feelings of weakness and palpitations should be documented
  7. A positive result is:
    1. ↓ in SBP of ≥20mmHg (± symptoms)
    2. ↓ <90mmHg on standing even if the drop is less than 20mmHg. (with or without symptoms)
    3. DBP of 10mmHg with symptoms (although clinically less significant than a drop in systolic BP)
  8. Advise patient of results and if the result is positive,
    1. inform the medical and nursing team
    2. take immediate actions to prevent falls and or unsteadiness
  9. In the instance of positive results, repeat regularly until resolved
  10. If symptoms change, repeat the test

NICE Clinical Guideline 161 Falls in older people: assessing risk and prevention says that the following groups of inpatients should be regarded as being at risk of falling in hospital and should receive an individualised, multi-factorial assessment: all patients aged 65 and patients aged 50 to 64 years who are judged by a clinician to be at higher risk of falling because of an underlying condition.


The majority of patients with syncope will have normal findings on examination and be fully recovered when assessed. However risk stratification, particularly seeking cardiac causes, is crucial to disposition. If in doubt, please seek advice.

Patients may warrant referral to a Syncope Clinic for diagnostic work-up (EEG, CT, tilt test etc.). Even if you suspect the patient is suffering from simple faints remember there are other proven interventions for those with recurrent vasovagal syncope.

The incidence of 'simple faints' can be reduced (without referral to a clinic) by advising the patient about avoidance of precipitating situations, maintaining hydration, not getting overheated, and taking avoiding action if warning symptoms appear. Many patients do not realise that lying down can be effective if they feel dizzy.

Adjusting cardiovascular medications may be helpful, especially in elderly patients who are having giddy spells with postural change and occasional syncope. By reducing the dose of a cardioinhibitory medication, or omitting a vasodilator (depending on whether you think they have symptomatic bradycardia or resting hypotension ), symptom frequency can be reduced. Advise both the patient and GP of any adjustments. If reducing a diuretic or antianginal ensure the patient/carer understands that breathlessness or angina are indications for restarting their 'culprit' medications, and to see their GP.


If the patient is not admitted they should either be referred back to GP, or they can be referred directly to a neurology clinic. The latter option is best for patients in Group 2 below, or those with recurrent symptoms.

Fitness to drive

More information s available on our "driving" page.

For patients requesting a formal assessment specifically checking for driving ability, Mr. Sean O' Callaghan (Southern Mobility Assessments 087 9304335) is available for an initial fee of circa €100.

Conditions that can easily be mislabelled as syncope

Disorders with impairment or loss of consciousness

  • Metabolic disorders (hypoglycaemia, hypoxia)
  • Intoxication
  • TIAs of vertebrobasilar origin

Disorders resembling syncope without LOC

  • Cataplexy
  • Drop attacks (although these can be syncopal in origin. If they are recurrent consider referral to syncope clinic)
  • Pseudo-syncope, somatisation disorders
  • TIAs of carotid origin

Points to note

  • Brief symptoms / signs such as nausea, and diaphoresis are common and non-specific in syncope
  • Brief myoclonic jerking is common in syncope. Syncope may also present as a true seizure, due to the cerebral hypoperfusion
  • Pre-syncope should be evaluated as being an identical entity to true syncope

Suggestive of epilepsy

  • a bitten tongue
  • head-turning to 1 side during TLoC
  • no memory of abnormal behaviour that was witnessed before, during or after TLoC by someone else
  • unusual posturing
  • prolonged limb-jerking (note that brief seizure-like activity can occur during an uncomplicated faint and is not necessarily diagnostic of epilepsy)
  • confusion after the event
  • prodromal déjà vu or jamais vu

Seizure less likely

  • prodromal symptoms that on other occasions have been abolished by sitting or lying down
  • sweating before the episode
  • prolonged standing that appeared to precipitate TLoC
  • pallor during the episode.

Neurology clinic (if epilepsy suspected)

To refer a patient write a standard referral letter, preferably typed by the ED secretaries. Include information such as the circumstances of the episode, and ED assessment. A copy of the patient's ECG and any rhythm strips should be enclosed. If relevant request a 24 hour ECG tape prior to the appointment.

Last review Dr ÍOS 16/04/22