Cardiopulmonary Resuscitation (CPR)

Cardiopulmonary resuscitation (CPR) is the emergency procedure that combines external chest compressions with rescue ventilation to generate artificial circulation and gas exchange in a person whose heart has stopped. It is the foundational intervention of basic life support and the action that buys time until a shockable rhythm can be defibrillated or a perfusing rhythm restored.

Definition

Cardiopulmonary resuscitation is the combination of external chest compressions and assisted ventilation applied to a person in cardiac arrest to maintain blood flow and oxygenation to vital organs until spontaneous circulation can be restored.

Scope

This entry covers the physiology and principles of CPR — chest compressions, ventilation, the compression-to-ventilation relationship, and the place of CPR within basic and advanced life support and the chain of survival. It is descriptive and educational and does not provide step-by-step performance instructions or replace certified training.

Key concepts

• Chest compressions and forward blood flow
• Compression depth, rate, and recoil
• Compression-to-ventilation ratio
• Minimizing interruptions (chest-compression fraction)
• Bystander and compression-only CPR
• Chain of survival
• Return of spontaneous circulation (ROSC)

Mechanisms

Chest compressions generate forward blood flow by raising intrathoracic pressure and directly compressing the heart, producing enough cerebral and coronary perfusion to delay irreversible injury. Effective compressions require adequate depth, an adequate rate, full chest recoil between compressions, and as few interruptions as possible, because flow falls rapidly whenever compressions pause. Ventilation restores oxygenation and removes carbon dioxide; basic life support guidance describes a defined relationship between compressions and ventilations, while emphasizing that high-quality, minimally interrupted compressions are the central determinant of outcome.

Clinical relevance

CPR is the core skill of basic and advanced life support and a major focus of public training, because early bystander CPR is consistently associated with better survival from out-of-hospital cardiac arrest. This entry describes the underlying principles for reference; actual technique, ratios, and decision-making follow current resuscitation guidelines and formal training rather than this summary.

Epidemiology

Out-of-hospital cardiac arrest affects a large number of people each year, and survival is strongly influenced by whether bystander CPR is started before emergency services arrive. Large studies of advanced life support added to basic CPR and defibrillation have shown that the early links in the chain of survival carry much of the survival benefit.

History

Modern CPR emerged in the mid-twentieth century when closed-chest compression was combined with expired-air ventilation, replacing earlier and less effective manual methods, and was subsequently integrated with external defibrillation into a unified resuscitation sequence. The approach has since been refined through successive international consensus statements and the periodic European Resuscitation Council and American Heart Association guidelines.

Debates

Compression-only versus standard CPR for bystanders

For untrained or hesitant bystanders, compression-only CPR is promoted to increase the likelihood that resuscitation is attempted at all, while standard compressions-plus-ventilation remains the reference for trained rescuers and for certain arrest causes; how to balance simplicity against completeness is an ongoing discussion.

Seminal works

• olasveengen-2021
• panchal-2020
• stiell-2004

Frequently asked questions

What is the purpose of chest compressions in CPR?

They generate artificial blood flow that keeps oxygen reaching the brain and heart during cardiac arrest, slowing irreversible organ injury until a perfusing heart rhythm can be restored.

Why is bystander CPR emphasized so strongly?

Survival from out-of-hospital cardiac arrest falls rapidly with each minute of delay, so CPR started by a bystander before professional help arrives is consistently linked to better outcomes.