Are cardiac arrest and respiratory arrest the same?

Are Cardiac Arrest and Respiratory Arrest the Same?

No, cardiac arrest and respiratory arrest are distinct clinical entities, though respiratory arrest frequently progresses to cardiac arrest if not promptly treated. 1

Key Distinctions

Respiratory Arrest

• Definition: Complete absence of spontaneous breathing (apnea) or severe respiratory insufficiency (agonal gasping) requiring immediate respiratory assistance 2
• Pathophysiology: Isolated respiratory arrest involves cessation of breathing while cardiac function initially remains intact 1
• Clinical presentation: Patient has no breathing or only gasping, but may still have a palpable pulse 1

Cardiac Arrest

• Definition: Absence of cardiac mechanical activity, confirmed by absence of central pulse, signs of circulation (movement, cough, normal breathing), or unresponsiveness with absent breathing 2
• Pathophysiology: Complete cessation of effective cardiac pumping, leading to immediate circulatory collapse 1
• Clinical presentation: No pulse, no breathing, unresponsive 1

The Critical Continuum

Respiratory arrest commonly progresses to cardiac arrest within minutes if ventilation is not restored. 1 This progression occurs because:

• Prolonged hypoxia from respiratory arrest causes secondary cardiac arrest 1
• In drowning, opioid overdose, and other respiratory emergencies, the sequence is typically respiratory arrest → hypoxic cardiac arrest 1
• The time window between respiratory and cardiac arrest is brief, making early intervention critical 1

Clinical Challenge in Differentiation

Distinguishing between respiratory arrest and cardiac arrest at the bedside is notoriously difficult because pulse checks are unreliable, particularly in the recommended 10-second assessment window. 1 This is why:

• Rescuers frequently misidentify the arrest type, especially in first aid and basic life support contexts 1
• Any patient who is unresponsive and not breathing normally should be treated as if in cardiac arrest unless a definite pulse is confirmed 1
• The difficulty in accurate pulse palpation means treatment recommendations must account for potential misclassification 1

Treatment Implications

For Respiratory Arrest (Definite Pulse Present)

• Immediate rescue breathing or bag-mask ventilation is the priority 1
• Continue ventilatory support until spontaneous breathing returns 1
• Standard CPR is not indicated if pulse is definitely present 1
• In opioid overdose with respiratory arrest, naloxone administration is reasonable alongside ventilatory support 1, 3

For Cardiac Arrest

• Standard CPR with chest compressions takes priority 1
• The traditional C-A-B sequence applies for most cardiac arrests 1
• However, when cardiac arrest results from a respiratory cause (drowning, opioid overdose), an A-B-C approach focusing on airway and breathing is recommended for healthcare providers 1

Etiology-Specific Considerations

Drowning

• Progresses from respiratory arrest due to submersion-related hypoxia to cardiac arrest 1
• Airway management and ventilation are of paramount importance 1
• In-water rescue breathing by trained rescuers may prevent progression to cardiac arrest 1

Opioid Overdose

• Isolated opioid toxicity causes CNS and respiratory depression that progresses to respiratory then cardiac arrest 1
• Most deaths involve respiratory arrest that was not promptly treated 1
• For respiratory arrest with definite pulse, rescue breathing plus naloxone is reasonable 1, 3
• For cardiac arrest, standard CPR takes priority over naloxone administration 1

Lightning Strike and Electrical Injury

• Can cause primary cardiac arrest (VF or asystole) 1
• Concomitant respiratory arrest from thoracic muscle spasm may persist after return of spontaneous circulation 1
• Unless ventilation is supported, secondary hypoxic cardiac arrest will develop 1

Common Pitfalls to Avoid

• Do not delay CPR while attempting to determine if pulse is present if the patient is unresponsive and not breathing normally 1
• Do not assume all arrests are cardiac in origin—respiratory causes require modified resuscitation emphasis on ventilation 1
• Do not withhold ventilation in presumed respiratory arrests while waiting for advanced interventions 1
• Do not rely solely on pulse checks in emergency situations, as they are frequently inaccurate even among healthcare providers 1

Prognostic Differences

Cardiac arrests from presumed respiratory causes have worse outcomes compared to primary cardiac causes. 4 This reflects:

• Greater hypoxic insult preceding the arrest 4
• Higher lactate levels on admission (6.3 vs 3.2 mmol/L) 4
• Lower rates of favorable neurological outcome (19% vs 42%) 4
• Less frequent shockable rhythms (5% vs 68%) 4