Initial assessment of episode of transient loss of consciousness (NICE guidance)

• if the person with suspected transient loss of consciousness (TLoC) has sustained an injury or they have not made a full recovery of consciousness, use clinical judgement to determine appropriate management and the urgency of treatment
• ask the person who has had the suspected TLoC, and any witnesses, to describe what happened before, during and after the event
• try to contact by telephone witnesses who are not present
• it is important to record details about:
  • circumstances of the event person's posture immediately before loss of consciousness
  • prodromal symptoms (such as sweating or feeling warm/hot)
  • appearance (for example, whether eyes were open or shut) and colour of the person during the event
  • presence or absence of movement during the event (for example, limb-jerking and its duration)
  • any tongue-biting (record whether the side or the tip of the tongue was bitten)
  • injury occurring during the event (record site and severity)
  • duration of the event (onset to regaining consciousness)
  • presence or absence of confusion during the recovery period
  • weakness down one side during the recovery period
    
    
• assess and record:
  • details of any previous TLoC, including number and frequency
  • the person's medical history and any family history of cardiac disease (for example, personal history of heart disease and family history of sudden cardiac death)
  • current medication that may have contributed to TLoC (for example, diuretics)
  • vital signs (for example, pulse rate, respiratory rate and temperature) - repeat if clinically indicated
  • lying and standing blood pressure if clinically appropriate
  • other cardiovascular and neurological signs
    
    
• record a 12-lead electrocardiogram (ECG) using automated interpretation
  • treat as a red flag if any of the following abnormalities are reported on the ECG printout:
    • conduction abnormality (for example, complete right or left bundle branch block or any degree of heart block)
    • evidence of a long or short QT interval, or
    • any ST segment or T wave abnormalities
  • if a 12-lead ECG with automated interpretation is not available, take a manual 12-lead ECG reading and have this reviewed by a healthcare professional trained and competent in identifying the following abnormalities
    • inappropriate persistent bradycardia.
    • any ventricular arrhythmia (including ventricular ectopic beats)
    • long QT (corrected QT > 450 ms) and short QT (corrected QT < 350 ms) intervals
    • Brugada syndrome
    • ventricular pre-excitation (part of Wolff-Parkinson-White syndrome)
    • left or right ventricular hypertrophy
    • abnormal T wave inversion
    • pathological Q waves
    • atrial arrhythmia (sustained)
    • paced rhythm
      
      
• record carefully the information obtained from all accounts of the TLoC. Include paramedic records with this information. Give copies of the ECG record and the patient report form to the receiving clinician when care is transferred, and to the person who had the TLoC
  
  
• refer within 24 hours for specialist cardiovascular assessment by the most appropriate local service, anyone with TLoC who also has any of the following.
  • an ECG abnormality
  • heart failure (history or physical signs
  • TLoC during exertion
  • family history of sudden cardiac death in people aged younger than 40 years and/or an inherited cardiac condition
  • new or unexplained breathlessness
  • a heart murmur
• consider referring within 24 hours for cardiovascular assessment, as above, anyone aged older than 65 years who has experienced TLoC without prodromal symptoms

If during the initial assessment, there is suspicion of an underlying problem causing TLoC, or additional to TLoC, carry out relevant examinations and investigations (for example, check blood glucose levels if diabetic hypoglycaemia is suspected, or haemoglobin levels if anaemia or bleeding is suspected).

If epilepsy is suspected

Refer people who present with one or more of the following features (that is, features that are strongly suggestive of epileptic seizures) for an assessment by a specialist in epilepsy; the person should be seen by the specialist within 2 weeks

• a bitten tongue
• head-turning to one 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 often occur during uncomplicated faints)
• confusion following the event
• prodromal déjà vu, or jamais vu

If orthostatic hypotension was suspected on the basis of the initial assessment when:

• suspect postural hypotension on the basis of the initial assessment when:
  • there are no features suggesting an alternative diagnosis and
  • the history is typical
• in people with symptoms of postural hypotension, including falls or postural dizziness:
  • measure blood pressure with the person lying on their back (or consider a seated position, if it is inconvenient to measure blood pressure with the person lying down)
  • measure blood pressure again after the person has been standing for at least 1 minute
  • if the person's systolic blood pressure falls by 20 mmHg or more, or their diastolic blood pressure falls by 10 mmHg or more, after the person has been standing for at least 1 minute:
    • consider likely causes, including reviewing their current medication
    • manage appropriately (for example, for advice on preventing falls in older people)
    • measure subsequent blood pressures with the person standing
    • consider referral to specialist care if symptoms of postural hypotension persist despite addressing likely causes
  • if the blood pressure drop is less than the thresholds above and the baseline measurement was previously taken from a seated position, repeat the measurements this time starting with the person lying on their back
  • consider referring the person for further specialist assessment if blood pressure measurements do not confirm postural hypotension despite suggestive symptoms

Diagnose uncomplicated faint (uncomplicated vasovagal syncope) on the basis of the initial assessment when:

• there are no features that suggest an alternative diagnosis (note that brief seizure activity can occur during uncomplicated faints and is not necessarily diagnostic of epilepsy) and
• there are features suggestive of uncomplicated faint (the 3 'P's) such as:
  • Posture - prolonged standing, or similar episodes that have been prevented by lying down
  • Provoking factors (such as pain or a medical procedure)
  • Prodromal symptoms (such as sweating or feeling warm/hot before TLoC)
  • if an uncomplicated faint is diagnosed then no further specialist assessment is indicated

If TLoC that is not uncomplicated faint, epilepsy, orthostatic hypotension or immediate (within 24 hours) referral for cardiovascular assessment then refer for cardiovascular assessment

Reference:

• 1) NICE (November 2023). Transient loss of consciousness ('blackouts') management in adults and young people