When should intubation be performed during an adult cardiac arrest?

When to Intubate During Cardiac Arrest

Endotracheal intubation should be delayed until after initial CPR and defibrillation attempts have failed or return of spontaneous circulation (ROSC) is achieved, with priority given to minimally interrupted chest compressions and basic airway management during the first critical minutes of resuscitation. 1

Initial Airway Management Strategy

Start with Basic Airway Techniques

• Begin with bag-mask ventilation using a 30:2 compression-to-ventilation ratio before any advanced airway is placed 2
• Use a two-person bag-mask technique when possible (one person maintains mask seal, one person ventilates) to ensure adequate ventilation 3
• Deliver each breath over less than 1 second with just enough tidal volume to produce visible chest rise 3

Timing for Advanced Airway Consideration

• For witnessed shockable rhythms (VF/pulseless VT): Delay endotracheal intubation until after initial defibrillation attempts fail or ROSC is achieved (Class IIb, LOE C) 1
• For prolonged resuscitations: Consider advanced airway placement after initial CPR and defibrillation cycles have been completed 1, 4
• For asphyxial arrests: Advanced airway may be considered earlier, as these patients benefit more from ventilation 3

Specific Indications for Intubation

Proceed with endotracheal intubation when:

• The provider cannot adequately ventilate the unconscious patient with bag-mask ventilation 2
• Prolonged transport time is anticipated 1, 3
• Limited numbers of experienced personnel are available to maintain effective bag-mask ventilation 3
• The patient has absent airway protective reflexes requiring definitive airway protection 2

Critical Requirements Before Attempting Intubation

Provider Qualifications

• Only skilled providers with frequent experience or regular retraining should perform intubation during cardiac arrest (Class I, LOE B) 4
• Inexperienced providers produce unacceptably high complication rates including prolonged compression interruptions, unrecognized esophageal intubation, tube displacement, and hypoxemia 4
• EMS systems performing prehospital intubation must provide ongoing quality improvement programs (Class IIa, LOE B) 4

Compression Interruption Limits

• Interruptions for laryngoscopy and tube passage must be limited to less than 10 seconds 2, 1, 4
• The intubating provider must be fully prepared with laryngoscope blade and endotracheal tube ready at hand before compressions are paused 2, 1
• Chest compressions should resume immediately after the tube passes through the vocal cords 2, 4
• If the initial attempt is unsuccessful, strongly consider using a supraglottic airway rather than making repeated intubation attempts 2

Alternative to Endotracheal Intubation

Supraglottic Airways as First-Line Advanced Airway

• Supraglottic airways are reasonable alternatives to both bag-mask ventilation (Class IIa, LOE B) and endotracheal intubation (Class IIa, LOE A) 1, 4
• Supraglottic airways can be inserted without interrupting chest compressions at all 2, 1
• They require easier initial training and skill maintenance compared to endotracheal intubation 1
• They do not require direct visualization of the vocal cords 1

Post-Intubation Management

Ventilation Strategy After Advanced Airway Placement

• Deliver 10 breaths per minute (one breath every 6 seconds) with continuous uninterrupted chest compressions 2, 4
• Avoid hyperventilation, which compromises venous return and causes hypotension 4
• Target normocapnia with PaCO2 of 35-40 mmHg 4

Mandatory Tube Confirmation

• Use continuous waveform capnography as the most reliable method for confirming and monitoring correct endotracheal tube placement (Class I, LOE A) 2, 1, 4
• Waveform capnography demonstrates 100% sensitivity and 100% specificity for identifying correct tube placement in cardiac arrest victims 2, 1
• If waveform capnography is unavailable, use colorimetric CO2 detectors in addition to clinical assessment (Class IIa, LOE B) 2

Ventilator Management

• If the patient is on a mechanical ventilator when cardiac arrest occurs, disconnect from the ventilator and switch to manual ventilation 5
• Modern mechanical ventilators erroneously sense chest compressions as spontaneous respiratory triggers, delivering excessive respiratory rates that decrease venous return and cardiac output 5
• Use manual self-inflating resuscitation bags synchronized with compressions at 10 breaths per minute 5

Common Pitfalls to Avoid

• Do not interrupt compressions for more than 10 seconds for any intubation attempt—each additional 5-second pause increases odds of death (OR 1.86,95% CI 1.10-3.15) 1
• Do not make repeated intubation attempts if the first attempt fails; switch to a supraglottic airway instead 2
• Do not use cricoid pressure during intubation attempts 3
• Do not hyperventilate after advanced airway placement, as this impairs hemodynamics 4
• Do not delay chest compressions to place an advanced airway 1, 3

Evidence Supporting Delayed Intubation

The 2015 International Consensus found that bundles of care involving minimally interrupted cardiac resuscitation showed significant benefit, with an odds ratio of 3.6 (95% CI 1.77-7.35) for survival with favorable neurologic outcome 1. Delayed endotracheal intubation combined with passive oxygen delivery and minimally interrupted chest compressions was associated with improved neurologically intact survival after out-of-hospital cardiac arrest in patients with witnessed VF/pulseless VT 1.