Resuscitation is a series of life-saving interventions performed when someone’s breathing or heart has stopped. A foundational concept in emergency first aid and cardiopulmonary resuscitation (CPR) has long been represented by the acronym “ABC”. This sequence of actions guides rescuers in the immediate steps to take during a medical emergency.
The Airway Component
The “A” in ABC stands for Airway. Ensuring a clear airway is paramount because air must reach the lungs for oxygen exchange. Common obstructions include the tongue falling back in an unconscious person, or the presence of foreign objects or vomit.
To open the airway, the head-tilt/chin-lift maneuver is performed by tilting the head backward and lifting the chin. This action helps move the tongue away from the back of the throat, preventing it from blocking the passage of air. In cases where a neck injury is suspected, a jaw-thrust maneuver is preferred to minimize spinal movement.
The Breathing Component
Once the airway is open, the “B” focuses on Breathing. This involves assessing whether the person is breathing normally and, if not, providing rescue breaths. Rescuers can quickly check for breathing by looking for chest movement, listening for breath sounds, and feeling for air on their cheek for up to 10 seconds. Agonal breathing, which involves gasping, is not considered normal breathing and indicates the need for CPR.
If the person is not breathing or is only gasping, rescue breaths are administered to deliver oxygen to their lungs. These breaths help oxygenate the blood, which is then circulated to the brain and other organs. Exhaled air from a rescuer contains enough oxygen (16-17%) to support life during this emergency.
The Circulation Component
Historically, “C” stood for Circulation, involving checks for a pulse and managing severe bleeding. Current CPR guidelines, however, place a strong emphasis on Compressions, specifically chest compressions, as the primary action for circulation. When the heart stops, effective chest compressions manually pump blood to the brain and other organs.
Chest compressions are performed by pushing hard and fast in the center of the chest. For adults, this involves compressing the chest at least 2 inches (5 cm) but no more than 2.4 inches (6 cm) deep, at a rate of 100 to 120 compressions per minute. Allowing the chest to fully recoil after each compression is important for effective blood flow.
The Shift in Resuscitation Priorities
Historically, the ABC sequence prioritized opening the Airway, then checking for Breathing, and finally addressing Circulation, based on the rationale that an open airway and effective breathing were necessary to provide oxygen for circulation.
A significant change occurred in 2010 when major resuscitation guidelines, such as those from the American Heart Association, shifted the recommended order for most adult cardiac arrest cases to CAB: Compressions, Airway, and Breathing. This change prioritized immediate chest compressions to maintain blood flow to the brain and heart, as delays in compressions reduce survival chances. Research indicated that enough residual oxygen exists in the bloodstream for a short period, making immediate blood circulation the most pressing need. While the order changed, the components of Airway, Breathing, and Circulation remain fundamental to effective resuscitation. The ABC sequence may still be relevant in specific situations, such as certain pediatric emergencies, drowning incidents, or cases of respiratory arrest where the cause is primarily a breathing problem.
Why Formal Training Matters
This knowledge is not a substitute for formal, hands-on CPR and first aid training. Accredited organizations provide structured courses that teach proper techniques and build confidence for real-life emergencies.
Learning CPR equips individuals with the skills to act decisively in an emergency, potentially doubling or tripling a person’s chance of survival after cardiac arrest. Formal training covers practical application, including the correct depth and rate of compressions and how to deliver rescue breaths effectively. It is also important to call emergency services immediately when an individual is unconscious or not breathing.