Synopsis
Distinguish syncope from falls, seizure and delirium through witness chronology, identify cardiac and orthostatic danger, measure postural physiology correctly, and restore function with cause-specific, medication-aware and driving-safe management.
- Syncope is transient loss of consciousness from global cerebral hypoperfusion with rapid onset, short duration and spontaneous complete recovery.
- First-line assessment is witness history, examination, capillary glucose when relevant and a 12-lead ECG; classify red flags before ordering broad tests.
- Ask posture, activity, prodrome, colour, breathing, movements, tongue injury, duration, recovery, injury, medicines and prior or family cardiac history.
- Measure orthostatic pressure after at least five minutes supine and during standing, including at one and three minutes with symptoms and pulse.
- Classical orthostatic hypotension is a sustained fall within three minutes of at least 20 mmHg systolic or 10 mmHg diastolic; absolute pressure and symptoms still matter.
- A blunted heart-rate rise suggests neurogenic failure or rate-limiting medicine; a marked rise may support volume depletion, but neither is diagnostic alone.
- First-line orthostatic management is cause treatment, medicine review, hydration, safe salt advice, slow transitions, counter-pressure manoeuvres, compression and rehabilitation.
- Midodrine is a specialist option for severe neurogenic orthostatic hypotension after non-drug care, with supine-pressure and urinary monitoring.
- Tilt testing and carotid sinus massage are specialist tests for selected recurrent unexplained events, not routine first-line screening.
- Advise no driving after unexplained loss of consciousness and use current DVLA rules for diagnosis and vehicle group; document the discussion.
Key red flags
Exertional or supine syncope, no prodrome, palpitations, heart failure, murmur or abnormal ECG requires urgent cardiovascular assessment.
Family history of sudden cardiac death under 40 or inherited cardiac disease materially raises arrhythmic concern.
Persistent focal neurology is not uncomplicated syncope and requires an acute stroke or neurological pathway.
Repeated syncope with head injury, anticoagulation or inability to rise requires injury and immediate safety assessment.
Postural symptoms with melaena, anaemia, dehydration, sepsis or adrenal features may reflect acute volume or endocrine disease.
New collapse after antihypertensive, diuretic, nitrate, alpha-blocker, insulin or psychoactive change requires prompt medication and physiology review.
Sudden collapse without warning, during exertion or supine, with palpitations or abnormal ECG is high risk.
Weakness, aphasia or neglect after the event requires acute neurological care rather than a syncope label.
Investigation priorities
Classify loss of consciousness and risk.
Management branches
A fall may have involved transient loss of consciousness.
- Perform ABCDE and glucose, assess injury and obtain witness chronology and medicine timing.
- Examine and obtain 12-lead ECG and correctly measured postural pressure.
- Escalate cardiac or neurological red flags and select rhythm, echo or other testing from the suspected mechanism.