Cardiac arrest / ROSC
A streamlined, differential-led presentation for rapid clinical review.
Twenty-second review
- Cardiac arrest is loss of effective circulation from an electrical, mechanical, respiratory, metabolic, or toxic cause; ROSC leaves vulnerable brain and myocardium at risk of recurrent instability.
- Any absent normal breathing and no signs of circulation requires immediate resuscitation; post-ROSC hypotension, hypoxia, or recurrent dysrhythmia is critical.
- Keep seizure or syncope in the differential; overlapping or concurrent illness remains possible.
- For cardiac arrest / rosc, 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.
Reversible noncoronary causeTime-sensitive high-risk possibility
HPI
Clarify witnessed; collapse/downtime; bystander cpr.
Signs & symptoms
Hypoxia, hemorrhage, PE, tension physiology, toxins, hypothermia, or electrolyte disturbance.
Focused exam
Assess pulse rate, regularity, strength, skin perfusion, JVP, edema, and lung sounds; Compare current function and exercise tolerance with baseline.
Brief pathophysiology
Reversible noncoronary cause may cause cardiac arrest / rosc through a time-sensitive process capable of rapid physiological deterioration.
What the trend may show
Absent or nonperfusing observations are expected in arrest. SpO₂ is not a reliable confirmation of circulation; follow the resuscitation or expected-death pathway for the clinical context.
Heart rate (bpm)
Absent / nonperfusingConfirm a central pulse and rhythm; monitor rate alone does not establish perfusion.
Blood pressure (mmHg)
UnobtainableAn unobtainable pressure is expected without effective circulation.
Respiratory rate (breaths/min)
Absent or agonalAgonal gasps are not effective breathing.
Oxygen saturation (SpO₂)
UnreliablePulse oximetry is unreliable during absent or severely reduced perfusion.
Front-load in the triage report
- Reversible noncoronary cause: Hypoxia, hemorrhage, PE, tension physiology, toxins, hypothermia, or electrolyte disturbance.
- Witnessed?
- Collapse/downtime.
Primary cardiac arrestCommon presentation pattern
HPI
Clarify witnessed; collapse/downtime; bystander cpr.
Signs & symptoms
Shockable rhythm or ischemic context may support a coronary cause.
Focused exam
Assess pulse rate, regularity, strength, skin perfusion, JVP, edema, and lung sounds; Compare current function and exercise tolerance with baseline.
Brief pathophysiology
Primary cardiac arrest 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
Absent or nonperfusing observations are expected in arrest. SpO₂ is not a reliable confirmation of circulation; follow the resuscitation or expected-death pathway for the clinical context.
Heart rate (bpm)
Absent / nonperfusingConfirm a central pulse and rhythm; monitor rate alone does not establish perfusion.
Blood pressure (mmHg)
UnobtainableAn unobtainable pressure is expected without effective circulation.
Respiratory rate (breaths/min)
Absent or agonalAgonal gasps are not effective breathing.
Oxygen saturation (SpO₂)
UnreliablePulse oximetry is unreliable during absent or severely reduced perfusion.
Front-load in the triage report
- Shockable rhythm or ischemic context may support a coronary cause.
- Witnessed?
- Collapse/downtime.
SeizureImportant alternative presentation
HPI
Clarify witnessed; collapse/downtime; bystander cpr.
Signs & symptoms
Agonal breathing can confuse recognition; assess for actual circulation promptly.
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 cardiac arrest / rosc 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
- Agonal breathing can confuse recognition; assess for actual circulation promptly.
- Witnessed?
- Collapse/downtime.
SyncopeImportant alternative presentation
HPI
Clarify collapse/downtime; bystander cpr; initial rhythm.
Signs & symptoms
Agonal breathing can confuse recognition; assess for actual circulation promptly.
Focused exam
Compare current function and exercise tolerance with baseline; Confirm arrest rapidly; after ROSC assess rhythm, 12-lead, perfusion, ventilation, temperature, neurologic response, and reversible-cause clues.
Brief pathophysiology
Syncope can resemble cardiac arrest / rosc through overlapping symptoms or referred physiology despite a different primary mechanism.
What the trend may show
Absent or nonperfusing observations are expected in arrest. SpO₂ is not a reliable confirmation of circulation; follow the resuscitation or expected-death pathway for the clinical context.
Heart rate (bpm)
Absent / nonperfusingConfirm a central pulse and rhythm; monitor rate alone does not establish perfusion.
Blood pressure (mmHg)
UnobtainableAn unobtainable pressure is expected without effective circulation.
Respiratory rate (breaths/min)
Absent or agonalAgonal gasps are not effective breathing.
Oxygen saturation (SpO₂)
UnreliablePulse oximetry is unreliable during absent or severely reduced perfusion.
Front-load in the triage report
- Agonal breathing can confuse recognition; assess for actual circulation promptly.
- Collapse/downtime.
- Bystander CPR.
Findings that should escalate concern
- Any absent normal breathing and no signs of circulation requires immediate resuscitation; post-ROSC hypotension, hypoxia, or recurrent dysrhythmia is critical.
- Reversible noncoronary cause: Hypoxia, hemorrhage, PE, tension physiology, toxins, hypothermia, or electrolyte disturbance.
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
- N02: Adult Cardiac ArrestBC Emergency Health Services Handbook
Official BCEHS clinical practice guidance for adult cardiac arrest.
- N03: Return of Spontaneous CirculationBC Emergency Health Services Handbook
Official BCEHS clinical practice guidance for return of spontaneous circulation.
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.
- Adult Advanced Life Support: 2025 AHA Guidelines for CPR and Emergency Cardiovascular CareCirculation · 2025
Adult cardiac arrest algorithms, reversible causes, defibrillation, medications, and post-arrest transition.