What is the best course of treatment for a patient experiencing an out of hospital cardiac arrest?

Out-of-Hospital Cardiac Arrest Management

For witnessed adult out-of-hospital cardiac arrest, bystanders must immediately call 911 and begin high-quality hands-only CPR (pushing hard and fast in the center of the chest with minimal interruptions) until an automated external defibrillator (AED) arrives or EMS takes over. 1

Immediate Bystander Response

Recognition and Activation

• Emergency dispatchers should systematically question callers to identify potential cardiac arrest and immediately provide CPR instructions if CPR is not already in progress. 1
• The "No-No-Go" framework is effective for dispatcher identification: unresponsive patient with absent or abnormal breathing indicates cardiac arrest. 1
• Dispatchers must provide confident, assertive chest compression-only instructions to achieve early hands-only CPR for adults who suddenly collapse. 1

Hands-Only CPR Protocol

All bystanders—trained or untrained—should provide hands-only CPR for witnessed adult sudden collapse. 1 This represents a critical shift from traditional CPR with rescue breaths:

• Untrained bystanders: Provide continuous chest compressions only until AED or EMS arrives (Class IIa). 1
• Previously trained bystanders confident in their skills: May provide either conventional CPR (30:2 compression-to-ventilation ratio) OR hands-only CPR (both Class IIa). 1
• Previously trained bystanders NOT confident: Should provide hands-only CPR only (Class IIa). 1

The evidence supporting hands-only CPR is compelling: dispatcher-assisted compression-only CPR instructions can potentially double the proportion of arrest patients receiving bystander CPR. 1 Early bystander CPR significantly improves survival, particularly when initiated within 4-6 minutes of collapse and followed by advanced life support within 10-12 minutes. 2

Early Defibrillation

Public Access Defibrillation

Communities must establish public access defibrillation programs at sites where cardiac arrest is relatively common (schools, sports stadiums, airports, casinos) or where no other defibrillation access exists (trains, cruise ships, airplanes). 1

• AEDs should be used as soon as available—prompt defibrillation is far more likely than delayed defibrillation to restore organized rhythm and stable cardiac output. 1
• Public access defibrillation linked with CPR is more effective than CPR alone. 1

EMS Defibrillation Timing

EMS providers should deliver 46-195 seconds of CPR before first defibrillation for VF/VT cardiac arrest. 3 This brief period of chest compressions before shock delivery improves survival compared to immediate defibrillation (≤45 seconds), though the benefit diminishes when CPR duration exceeds 195 seconds. 3

Chain of Survival Components

Pre-Hospital System Requirements

All communities must maintain a strong Chain of Survival including: 1

1. Early access (recognition and 911 activation by bystander)
2. Early CPR
3. Early defibrillation
4. Early advanced cardiac life support

All EMS first responders must be trained and equipped to provide early defibrillation. 1 Public safety first responders (police, firefighters) should also carry AEDs. 1

Dispatcher Performance Standards

EMS systems must implement quality assurance programs that monitor dispatcher performance through audio recording review. 1 Key metrics include:

• Cardiac arrest recognition rates
• Time to CPR instruction delivery
• Compression-only instruction adherence
• This requires cooperation between EMS and hospital stakeholders with individual and organizational-level feedback. 1

Post-Resuscitation Care

Transport Considerations

A regionalized approach to post-cardiac arrest care may be reasonable when comprehensive post-arrest care is unavailable at local facilities. 1 While specialized cardiac arrest centers offer advanced protocols and technology, the literature on their impact remains mixed. 1

Quality Improvement

System-wide structured data collection and review leads to improved resuscitation processes and survival in both out-of-hospital and in-hospital settings. 1 Structured debriefing protocols improve resuscitation team performance in subsequent events. 1

Critical Pitfalls to Avoid

• Do not delay CPR for any reason—even untrained bystanders should begin compressions immediately while awaiting dispatcher instructions. 1
• Do not use precordial thump for unwitnessed out-of-hospital cardiac arrest—it is ineffective and delays definitive treatment. 1
• Do not recommend rescue breaths to untrained bystanders—this delays chest compressions and reduces overall CPR quality. 1 The evidence consistently favors compression-only instructions for dispatcher-assisted CPR despite theoretical concerns about asphyxial arrests. 1
• Avoid excessive interruptions in chest compressions—even brief pauses significantly reduce perfusion and worsen outcomes. 1

Special Considerations

For suspected asphyxial cardiac arrest (drowning, pediatric arrests), rescue breathing becomes more important, but this determination is difficult for bystanders to make reliably. 1 The American Heart Association prioritizes compression-only instructions for all adult sudden collapse scenarios to maximize bystander participation and minimize delays. 1

Survival from out-of-hospital cardiac arrest requires immediate recognition, rapid high-quality CPR, early defibrillation, and seamless transition to advanced care—each link in this chain is essential and time-critical. 1