June 18, 2024

Vitavo Yage

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Why Did CPR Change from A-B-C to C-A-B?

3 min read

In CPR, CAB refers to the specific order of steps: Chest Compressions, Airway, and Breathing. This is a change from ABC, the old order of CPR steps, which stood for Airway, Breathing, and Compressions. This change to the American Heart Association’s (AHA) Guidelines for CPR was implemented in 2010.

The CPR guidelines changed from A-B-C to C-A-B to place greater importance on chest compressions and blood flow.

This article goes over the CPR guidelines and why chest compressions should be done first.

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Why is CAB in CPR Important?

People in cardiac arrest need blood flow; any delay in blood flow reduces a person’s chance of survival. Chest compressions given during CPR help blood circulate through the body.

The process of clearing the airway and initiating breathing can cause significant delays. Any seconds or minutes lost add to the amount of time a person has been without adequate blood flow.

In its summary of the changes, the American Heart Association explained:

“By changing the sequence to C-A-B, chest compressions will be initiated sooner and ventilation only minimally delayed until completion of the first cycle of chest compressions (30 compressions should be accomplished in approximately 18 seconds).”

By starting chest compressions first, the patient only has to hold their breath an extra 18 seconds while the blood gets flowing again.

Since the 2010 AHA Guidelines for CPR were released, the science of CPR has continued to support chest compressions in lieu of rescue breathing. In fact, the AHA now recommends performing hands-only CPR on most adults who experience sudden cardiac arrest.

Even some professional rescuers have removed rescue breathing from CPR. When rescuers do provide artificial breathing, they aren’t as likely to do advanced procedures, opting instead for more basic ventilation.

Moving blood along, even blood with diminishing amounts of oxygen, is the most important function of CPR.

Chest Compressions in CAB CPR

Chest compressions should be at least two inches deep for adult patients and should be delivered at a rate between 100-120 per minute.

Deliver chest compressions too slowly and there won’t be enough blood pressure to adequately supply the brain. Deliver them too fast and there won’t be enough time for blood to return to the chest before the next compression.

Airway and Breathing in CAB CPR

The AHA still recommends rescue breathing for infants and children and people who have drowned or overdosed on drugs. Someone who collapses because of a breathing issue will also need rescue breathing.

In these situations, clear the airway after the first cycle of chest compressions. Opening the airway ensures that the person can breathe so they continue to receive oxygen. To open the airway, tilt the person’s head back and elevate their chin.

Rescue breathing is the third component of CAB CPR. If the person is not breathing, it is important to alternate rescue breaths with chest compressions to ensure an adequate flow of blood and oxygen to the brain.


The most recent CPR guidelines put chest compressions before rescue breathing. This change was made because resuming blood flow with chest compressions is the most important goal of CPR. Starting with airway clearing and rescue breathing can delay chest compressions and reduce the person’s chances of survival.

In adults who experience sudden cardiac arrest, hands-only CPR may be enough to keep them alive until health arrives. For children and people who have collapsed because of a breathing problem, it is still important to clear the airway and perform rescue breathing.

Rod Brouhard, EMT-P

By Rod Brouhard, EMT-P

Rod Brouhard is an emergency medical technician paramedic (EMT-P), journalist, educator, and advocate for emergency medical service providers and patients.


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