Cardiopulmonary Resuscitation (CPR) is an emergency life-saving procedure performed when someone’s heart stops beating or they stop breathing. This technique manually circulates oxygenated blood to the brain and other organs until medical help arrives. For decades, the most recognized framework used to help rescuers remember the proper sequence of actions was the three-letter mnemonic known as the “ABCs” of resuscitation.
Defining the Traditional Sequence: Airway, Breathing, Circulation
The traditional “ABCs” of CPR stood for Airway, Breathing, and Circulation, establishing the sequence rescuers followed for many years. This order was based on the logic that securing a clear airway was the first priority, as a person cannot breathe if the airway is blocked.
The sequence began with “A” for Airway, involving opening the victim’s mouth, clearing obstructions, and positioning the head to prevent the tongue from blocking the throat. “B” for Breathing was next, requiring the rescuer to provide two rescue breaths, typically mouth-to-mouth. Only after Airway and Breathing were addressed did the rescuer move to “C” for Circulation, initiating chest compressions to pump blood. This sequence was the standard, emphasizing mouth-to-mouth resuscitation as the necessary first step.
Understanding the Modern Change: Prioritizing Compressions
Modern resuscitation science led to a significant shift in the recommended order, changing the sequence to CAB: Compressions, Airway, and Breathing. Organizations like the American Heart Association (AHA) implemented this change around 2010, acknowledging that chest compressions are the most important factor for survival in most adult cardiac arrests. The time spent on opening the airway and delivering initial rescue breaths often delayed starting compressions, which is detrimental to the patient.
Prioritizing “C” means beginning compressions immediately to circulate the blood that still contains residual oxygen. This immediate action maintains a steady flow of oxygenated blood to the brain and heart, buying valuable time until the heart can be restarted. Compressions must be delivered at a rate of 100 to 120 pushes per minute. For adults, compressions should be pushed down to a depth of at least two inches, but no more than 2.4 inches, and interruptions must be minimized.
Practical Application: Performing Rescue Breaths and Airway Management
In the modern CAB sequence, the Airway and Breathing steps follow the initial cycle of compressions. To manage the airway, a rescuer uses the head-tilt/chin-lift maneuver, placing one hand on the victim’s forehead and two fingers under the chin to gently tilt the head back. This action repositions the lower jaw, lifting the tongue away from the back of the throat to create a clear passage for air.
Once the airway is open, the rescuer proceeds to the Breathing step by delivering two rescue breaths after every 30 chest compressions. Each breath should be a gentle puff lasting approximately one second and should be just enough to make the victim’s chest visibly rise. If the first breath does not result in the chest rising, the rescuer must quickly reposition the head with the head-tilt/chin-lift before attempting the second breath.
For bystanders who are not formally trained or are hesitant to perform mouth-to-mouth resuscitation, current guidelines recommend “Hands-Only CPR.” This simplified method involves continuous, high-quality chest compressions without stopping for rescue breaths. Hands-Only CPR for adults is considered as effective as conventional CPR in the first few minutes of sudden cardiac arrest, significantly increasing the likelihood of bystander intervention.