Basic Life Support and Cardio Pulmonary Resuscitation

Learning CPR is the largest gift you can give your family and friends. CPR is easy for most adults and teens to learn. It is a technique designed to temporarily circulate oxygenated blood through the body of a person whose heart has stopped.

Patients who are unresponsive and not breathing normally have a high likelihood of being in cardiac arrest. Calling for help (911 in the US) allows for CPR instructions by phone that substantially increase the likelihood of adequate bystander CPR performance and improve survival from cardiac arrest.

  • The vast majority of cardiac arrests occur in adults
  • The highest survival rates from cardiac arrest are reported among patients of all ages with witnessed arrest and a rhythm of VF or pulseless VT
  • In these patients the critical initial elements of CPR are chest compressions and early defibrillation

The original A-B-Cs (Airway- Breathing-Circulation (chest compressions) of CPR have been replaced since 2010 with:


C - Chest Compressions, Defibrillation with an AED

A - Airway

B - Breathing

In 2015 these guidelines have been further modified to include the rapid identification of potential cardiac arrest by dispatchers, with immediate provision of CPR instructions to the caller via mobile phones that can allow the rescuer to activate the emergency response system without leaving the victim’s side. 

High-quality CPR improves survival from cardiac arrest. Components of high-quality CPR include

  • Ensuring chest compressions of adequate rate
  • Ensuring chest compressions of adequate depth
  • Allowing full chest recoil between compressions
  • Minimizing interruptions in chest compressions
  • Avoiding excessive ventilation


Depending on the skills of bystander rescuers, different scenarios of emergency treatment are recommended:

  • Untrained Lay Rescuer
    • Untrained lay rescuers should provide compression-only CPR, with or without dispatcher assistance and continue compression-only CPR until the arrival of an AED or rescuers with additional training
  • Trained Lay Rescuer
    • The 2010 Guidelines recommended that trained rescuers should provide rescue breaths in addition to chest compressions because they may encounter victims with asphyxial causes of cardiac arrest or they may be providing CPR for prolonged periods of time before additional help arrives.
    • All lay rescuers should, at a minimum, provide chest compressions for victims of cardiac arrest. In addition, if able to perform rescue breaths, he or she should add rescue breaths in a ratio of 30 compressions to 2 breaths.
    • The rescuer should continue CPR until an AED arrives and is ready for use or EMS providers take over care of the victim
  • Healthcare Provider
    • Optimally, all healthcare providers should be trained in BLS. As in past Guidelines, healthcare providers are trained to provide both compressions and ventilation. 
    • It is reasonable for healthcare providers to provide chest compressions and ventilation for all adult patients in cardiac arrest, from either a cardiac or noncardiac cause.In addition, it is realistic for healthcare providers to tailor the sequence of rescue actions to the most likely cause of arrest. For example, if a lone healthcare provider sees an adolescent suddenly collapse, the provider may assume that the victim has had a sudden arrhythmic arrest and call for help, get a nearby AED, return to the victim to use the AED, and then provide CPR.
    • If a lone healthcare provider aids an adult drowning victim or a victim of foreign body airway obstruction who becomes unconscious, the healthcare provider may give about 5 cycles (approximately 2 minutes) of CPR before activating the emergency response system. 

From: The 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care