CPR is a critical step in the AHA’s Chain of Survival. The term Chain of Survival provides a useful metaphor for the elements of the ECC systems concept.

The 5 links in the adult out-of-hospital Chain of Survival are:

• Recognition of cardiac arrest and activation of the emergency response system (calling 9-1-1 in the US)
• Early CPR with an emphasis on chest compressions
• Rapid defibrillation
• Basic and advanced emergency medical services
• Advanced life support and post-cardiac arrest care

A strong Chain of Survival can improve chances of survival and recovery for victims of cardiac arrest.

1. For healthcare providers and those trained: conventional CPR using chest compressions and mouth-to-mouth breathing at a ratio of 30:2 compressions-to-breaths. In adult victims of cardiac arrest, it is reasonable for rescuers to perform chest compressions at a rate of 100 to 120/min and to a depth of at least 2 inches (5 cm) for an average adult, while avoiding excessive chest compression depths (greater than 2.4 inches [6 cm]).
2. For the general public or bystanders who witness an adult suddenly collapse: compression-only CPR, or Hands-Only CPR. Hands-Only CPR is CPR without mouth-to-mouth breaths. It is recommended for use by people who see a teen or adult suddenly collapse in an out-of-hospital setting (such as at home, at work, or in a park).