Syncope / presyncope
A streamlined, differential-led presentation for rapid clinical review.
Twenty-second review
- Syncope is transient global cerebral hypoperfusion, commonly reflex, orthostatic, or cardiac; seizure and metabolic events can mimic it.
- Exertional or supine syncope, chest pain, palpitations, abnormal ECG, persistent hypotension, major bleeding, or family history of sudden death raises concern.
- Keep seizure in the differential; overlapping or concurrent illness remains possible.
- For syncope / presyncope, trends and combinations of findings are more informative than one isolated vital sign.
Compare the clinical patterns
The repeated material is grouped inside each possibility. Open only the condition you need.
Cardiac syncopeTime-sensitive high-risk possibility
HPI
Clarify complete loc or near-syncope; preceding symptoms; exertional.
Signs & symptoms
Abrupt event, exertion, abnormal rhythm, structural disease, or absent prodrome.
Focused exam
Assess pulse rate, regularity, strength, skin perfusion, JVP, edema, and lung sounds; Compare current function and exercise tolerance with baseline.
Brief pathophysiology
Cardiac syncope may cause syncope / presyncope through a time-sensitive process capable of rapid physiological deterioration.
What the trend may show
There is no single diagnostic vital-sign pattern for this cardiac differential. Rate/rhythm, pressure, perfusion, and oxygenation are the four most useful serial observations.
Heart rate (bpm)
Assess rate / rhythmRelate rate and rhythm to symptoms, ECG findings, and perfusion.
Blood pressure (mmHg)
Trend pressureBoth hypertension and hypotension can alter risk and management.
MAP (mmHg)
Trend perfusionInterpret MAP with mentation, skin signs, and baseline pressure.
Oxygen saturation (SpO₂)
Usually preservedLow saturation suggests heart failure or concurrent respiratory disease.
Front-load in the triage report
- Cardiac syncope: Abrupt event, exertion, abnormal rhythm, structural disease, or absent prodrome.
- Complete LOC or near-syncope?
- Preceding symptoms?
ReflexCommon presentation pattern
HPI
Clarify complete loc or near-syncope; preceding symptoms; exertional.
Signs & symptoms
Trigger, prodrome, posture, rapid recovery, volume loss, or medication change may support the mechanism.
Focused exam
Assess pulse rate, regularity, strength, skin perfusion, JVP, edema, and lung sounds; Compare current function and exercise tolerance with baseline.
Brief pathophysiology
Reflex may explain the presenting symptoms through a common clinical mechanism, while serial assessment checks for complications or an alternate cause.
What the trend may show
There is no single diagnostic vital-sign pattern for this cardiac differential. Rate/rhythm, pressure, perfusion, and oxygenation are the four most useful serial observations.
Heart rate (bpm)
Assess rate / rhythmRelate rate and rhythm to symptoms, ECG findings, and perfusion.
Blood pressure (mmHg)
Trend pressureBoth hypertension and hypotension can alter risk and management.
MAP (mmHg)
Trend perfusionInterpret MAP with mentation, skin signs, and baseline pressure.
Oxygen saturation (SpO₂)
Usually preservedLow saturation suggests heart failure or concurrent respiratory disease.
Front-load in the triage report
- Trigger, prodrome, posture, rapid recovery, volume loss, or medication change may support the mechanism.
- Complete LOC or near-syncope?
- Preceding symptoms?
Orthostatic syncopeCommon presentation pattern
HPI
Clarify preceding symptoms; exertional; sitting/supine.
Signs & symptoms
Trigger, prodrome, posture, rapid recovery, volume loss, or medication change may support the mechanism.
Focused exam
Compare current function and exercise tolerance with baseline; Assess orthostatic context when safe, rhythm and 12-lead, perfusion, neurologic status, injury, bleeding, and cardiac findings.
Brief pathophysiology
Orthostatic syncope may explain the presenting symptoms through a common clinical mechanism, while serial assessment checks for complications or an alternate cause.
What the trend may show
There is no single diagnostic vital-sign pattern for this cardiac differential. Rate/rhythm, pressure, perfusion, and oxygenation are the four most useful serial observations.
Heart rate (bpm)
Assess rate / rhythmRelate rate and rhythm to symptoms, ECG findings, and perfusion.
Blood pressure (mmHg)
Trend pressureBoth hypertension and hypotension can alter risk and management.
MAP (mmHg)
Trend perfusionInterpret MAP with mentation, skin signs, and baseline pressure.
Oxygen saturation (SpO₂)
Usually preservedLow saturation suggests heart failure or concurrent respiratory disease.
Front-load in the triage report
- Trigger, prodrome, posture, rapid recovery, volume loss, or medication change may support the mechanism.
- Preceding symptoms?
- Exertional?
SeizureImportant alternative presentation
HPI
Clarify complete loc or near-syncope; preceding symptoms; exertional.
Signs & symptoms
Prolonged postictal confusion, lateral tongue injury, or witnessed tonic-clonic activity supports an alternative mechanism.
Focused exam
Assess pulse rate, regularity, strength, skin perfusion, JVP, edema, and lung sounds; Compare current function and exercise tolerance with baseline.
Brief pathophysiology
Seizure can resemble syncope / presyncope through overlapping symptoms or referred physiology despite a different primary mechanism.
What the trend may show
Transient tachycardia and hypoxemia can follow a generalized seizure. Persistent abnormality, fever, recurrent activity, or failure to recover should prompt a search for the cause and complications.
Heart rate (bpm)
Often rises transientlyAutonomic activation commonly causes postictal tachycardia.
Oxygen saturation (SpO₂)
May fall transientlyApnea, obstruction, or hypoventilation can lower saturation.
Blood glucose (mmol/L)
Check earlyHypoglycemia can provoke or mimic seizure; hyperglycemia may be a stress response.
Temperature (°C)
May riseA brief rise may follow seizure; fever raises concern for infection or a provoking illness.
Front-load in the triage report
- Prolonged postictal confusion, lateral tongue injury, or witnessed tonic-clonic activity supports an alternative mechanism.
- Complete LOC or near-syncope?
- Preceding symptoms?
Findings that should escalate concern
- Exertional or supine syncope, chest pain, palpitations, abnormal ECG, persistent hypotension, major bleeding, or family history of sudden death raises concern.
- Cardiac syncope: Abrupt event, exertion, abnormal rhythm, structural disease, or absent prodrome.
Medication recognition
Continue the clinical pathway
Clinical and academic sources
Curated clinical guidance and peer-reviewed evidence supporting this presentation. Current BCEHS guidance, medical direction, and local policy remain authoritative for practice.
BCEHS Handbook — specific CPGs
- A02: Patient AssessmentBC Emergency Health Services Handbook
Official BCEHS clinical practice guidance for patient assessment.
- C01: Acute Coronary SyndromeBC Emergency Health Services Handbook
Official BCEHS clinical practice guidance for acute coronary syndrome.
Supporting clinical and academic evidence
- Guideline for the Management of Patients With Acute Coronary SyndromesACC/AHA/ACEP/NAEMSP/SCAI
2025 evidence-based acute coronary syndrome recognition and management guidance.
- CEDIS Presenting Complaint List updateCanadian Association of Emergency Physicians
Presenting-complaint terminology and categorization context. It does not establish a prehospital “top 100” ranking.
- 2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With SyncopeCirculation · 2017
History, examination, ECG, risk features, and cardiovascular causes of syncope.