Syncope
at the bedside
- airway, breathing, circulation; lie flat; full vitals, SpO₂, cardiac monitor, IV access
- glucose now → hypoglycemia
- 12-lead ECG now → compare with the old one
- still not fully awake → this is not syncope → altered mental status
- just before the event → getting out of bed, toileting, physiotherapy, a new drug on the MAR, a procedure or line
- presyncope gets the same workup; ask the witness and the nurse what happened before, during and after
escalate now if
- on exertion or lying flat, no prodrome, or palpitations just before → cardiac syncope until proven otherwise
- abnormal ECG → high-grade AV block, pauses, VT, pre-excitation, long QT, Brugada pattern, ischemia → cardiac syncope, cardiology tonight
- chest pain or dyspnea with the event → ACS, PE, dissection → chest pain, dyspnea
- bleeding, melena, or a hemoglobin drop → hypovolemia / bleeding
- vitals that stay abnormal after the event → hypotension
- new murmur, known structural heart disease or heart failure, or family history of sudden death young → cardiology tonight
- focal neurological signs → CT head now → neurological deficit; head strike on an anticoagulant or antiplatelet with headache, vomiting, drowsiness, amnesia or confusion → CT head now; with none of these → consider CT head within 8 h (NICE NG232) → injury
differentials
true syncope: transient loss of consciousness from cerebral hypoperfusion, rapid onset, full spontaneous recovery
- reflex (vasovagal) → trigger (prolonged standing, heat, pain, emotion, micturition), prodrome (nausea, warmth, sweating, visual dimming), quick recovery
- orthostatic → on standing; antihypertensives, diuretics, vasodilators; dehydration, bleeding; autonomic failure (diabetes, Parkinson disease)
- cardiac, arrhythmic → AV block, sinus pauses, VT, SVT with structural disease; no warning, or palpitations first
- cardiac, structural or obstructive → aortic stenosis, hypertrophic cardiomyopathy, PE, tamponade, dissection; on exertion, with chest pain or dyspnea
not syncope
- seizure → lateral tongue bite, sustained tonic-clonic activity, prolonged confusion after → seizures
- hypoglycemia, intoxication → slow recovery, not spontaneous
- mechanical fall → tripped, no loss of consciousness
- stroke or TIA → rarely causes isolated loss of consciousness; focal signs decide
- psychogenic → long duration, eyes closed, frequent episodes; a diagnosis for the treating team
focused check
- before → position (standing, sitting, lying, exertion), trigger, prodrome or none, palpitations, chest pain
- during → duration, color, jerks (brief jerks after the collapse are common in syncope), tongue bite, injury
- after → recovery in seconds to a minute vs prolonged confusion; incontinence does not distinguish seizure from syncope
- history → why admitted, previous episodes, structural heart disease, heart failure, arrhythmia, diabetes, family history of sudden death
- drug chart → antihypertensives, diuretics, nitrates, alpha-blockers, QT-prolonging drugs, insulin, anticoagulant, anything new
- exam → murmur (aortic stenosis), JVP and crackles, pulse rate and regularity, focal neurology, pallor, melena if bleeding is possible, injuries
send now
- ECG on everyone, already at the bedside
- orthostatic BP → after ≥ 5 min lying, measure within 3 min of standing; positive if SBP drops ≥ 20 or DBP ≥ 10 mmHg (SBP ≥ 30 if supine hypertension); a positive test does not exclude a cardiac cause
- CBC; electrolytes and renal profile; glucose if not done
- troponin → chest pain, ischemic ECG, or possible myocardial injury without chest pain (elderly, diabetic, dyspnea, new heart failure) → troponin; PE workup only if PE is suspected, by Wells or PERC → dyspnea
- CT head → not routine: focal deficit or persistent confusion → CT now; a head strike on an anticoagulant or antiplatelet → consider within 8 h → injury
- telemetry if a cardiac cause is possible; echo if murmur, abnormal ECG or structural disease suspected (treating team)
Canadian Syncope Risk Score · MDCalc ↗︎ was derived for first presentations, not admitted patients: context only; the escalate box decides
treat
cardiac syncope, suspected
- telemetry now; cardiology tonight
- bradycardia, pauses, AV block → bradycardia; tachyarrhythmia → palpitations
- long QT → stop QT-prolonging drugs, correct K and Mg, magnesium sulfate 2 g IV over 10–15 min if torsades
- murmur of aortic stenosis or hypertrophic cardiomyopathy → echo; avoid nitrates, vasodilators and dehydration; fluids in small boluses, reassess; cardiology tonight
- ACS, PE, dissection, tamponade → chest pain, dyspnea
orthostatic
- lie flat, legs raised; hypovolemic → balanced crystalloid 250–500 mL IV, reassess
- hold tonight → by BP and indication, not the whole list: antihypertensives, nitrates, alpha-blockers not needed tonight; diuretics if dry, keep them in decompensated heart failure; the treating team decides what returns
- stand slowly, sit before standing, call for help to mobilize; autonomic failure is for the treating team
reflex (vasovagal), clear story and normal ECG
- reassure; hydration; avoid the trigger; counter-pressure at the next prodrome (cross legs and tense, grip and tense the arms)
- a normal ECG does not exclude an intermittent arrhythmia: telemetry by suspicion and risk (no prodrome, structural disease, injury); a clear vasovagal story with nothing in the escalate box can go without
hypovolemia / bleeding
- two large IV cannulas, group and save, crossmatch if bleeding; fluids, then blood by the loss
- GI bleed → GI bleed; hemoglobin drop → hemoglobin drop; massive → massive hemorrhage
injury from the fall
- examine head, hips, wrists, spine; analgesia → analgesia
- head strike → vomiting, confusion or a focal sign → CT head now
- head strike on an anticoagulant or antiplatelet → actual or suspected head injury with no other CT indication: consider CT head within 8 h of the injury, by the clinical assessment and the bleeding risk, aspirin alone excluded; assessed more than 8 h after the injury → consider CT within the hour; headache, vomiting, drowsiness, amnesia or a focal sign → CT head now; keep the threshold low when the fall was unwitnessed, the history is unreliable or the neurological exam is limited; no head injury → anticoagulation alone is not an indication for CT; neurological observations and the next-dose decision → falls: head strike; reversal is a treating team and hematology decision → anticoagulation (NICE NG232 fallback when there is no local protocol; ACEP 2023)
reassess
- when → after each fluid bolus, then with every set of vitals
- what → recurrent dizziness or collapse, BP and HR trends, orthostatics repeated when safe, telemetry findings, new symptoms after a head strike
- not settling → a second event, an arrhythmia on telemetry, or BP that stays low → back to the escalate box, cardiology or ICU; mobilize with nursing assistance only until reviewed
- shock persists → hypotension, advanced: shock
- hand over → what the patient was doing, ECG findings, orthostatics, drugs held and why, telemetry plan, scan decision if a head strike
MOC+ Volume 2 · Cardiopulmonary covers syncope & collapse. order here.
evidence
| source | type |
|---|---|
| 2017 ACC/AHA/HRS syncope guideline | international guideline |
| 2018 ESC syncope guideline | international guideline |
| Consensus definition of orthostatic hypotension (American Autonomic Society / AAN) | consensus statement |
| Canadian Syncope Risk Score validation studies | validated prognostic tool |
| ACEP 2023 clinical policy, mild traumatic brain injury (head strike on an anticoagulant) | specialty-society guidance |
| NICE NG232 2023 · Head injury: consider CT within 8 h for anticoagulated patients ↗︎ | national guideline |
Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.
free the on-call checklist covers the whole shift on one printable page.
studying for the IM exam? the IM Rapid Review covers syncope in the same format. see the sample chapter.
updated Oct 2026file complaint/syncope