The ABCs of first aid represent a universally recognized sequence for the initial assessment and management of a person in an emergency situation. This mnemonic provides a systematic framework for non-medical rescuers to prioritize immediate, life-threatening problems in a specific order. Following this protocol allows a rescuer to rapidly identify and address time-sensitive conditions that require immediate intervention to maximize the chance of survival.
Preliminary Steps Before Assessing the Victim
The first and most important step upon encountering an injured or unconscious person is to ensure that the environment is safe for both the victim and the rescuer. Checking for danger, such as moving traffic, live electrical wires, or unstable structures, must always precede any physical intervention. If the scene poses a risk, the rescuer must take steps to eliminate the threat or move the victim to a safe location if it can be done without causing further injury.
After securing the scene, the next immediate action is to confirm the victim’s level of consciousness, often using a “Shout, Tap, Shout” sequence. The rescuer should loudly ask, “Are you okay?” while gently tapping the person’s shoulder to elicit a response. If the person is unresponsive, the Emergency Medical Services (EMS) system must be activated immediately by calling the local emergency number.
Calling for help should ideally happen before or simultaneously with the start of the primary assessment. If a second person is present, they should be directed to call the emergency number and retrieve an Automated External Defibrillator (AED) if one is nearby. When the rescuer is alone, they must quickly decide whether to provide immediate care, such as two minutes of Cardiopulmonary Resuscitation (CPR), or call for help first, depending on the victim’s likely cause of collapse.
Understanding the ABC Sequence
The traditional ABC sequence—Airway, Breathing, Circulation—is the assessment tool used to determine which life-saving interventions are required. This systematic approach dictates the order in which the body’s critical functions are checked. While the steps for intervention, particularly in cardiac arrest, have shifted, the assessment framework remains centered on these three priorities.
A: Airway
Airway management is the first priority because obstruction prevents oxygen from reaching the lungs. In an unresponsive person, the most common obstruction is the tongue falling back and blocking the throat due to muscle relaxation. To open the airway, the rescuer should use the head-tilt/chin-lift maneuver. This involves placing one hand on the forehead and two fingers under the chin, gently tilting the head back.
This maneuver lifts the tongue away from the back of the throat, which can often resolve the obstruction. The rescuer should also quickly check the mouth for visible foreign material, such as vomit or food. If a foreign object is seen and can be easily swept out without pushing it further down, it should be removed, but blind finger sweeps are not recommended.
B: Breathing
Once the airway is open, the rescuer must check for normal breathing, which should take no more than 10 seconds. This is done using the “Look, Listen, and Feel” technique: the rescuer looks for the rise and fall of the chest, listens for breath sounds, and feels for air movement. If the person is breathing normally, the rescuer proceeds to the circulation check. If the person is not breathing or is only gasping, resuscitation measures are required, as gasping is treated as an absence of breathing and a sign of cardiac arrest.
C: Circulation/Compressions
Checking for signs of circulation primarily involves looking for severe external bleeding. While checking for a pulse is difficult for lay rescuers, identifying and controlling catastrophic blood loss is a priority. Severe bleeding, such as arterial hemorrhage, must be addressed immediately by applying direct pressure to the wound with a clean cloth or hand.
For an adult who is unresponsive and not breathing normally, the intervention sequence shifts to C-A-B (Compressions, Airway, Breathing) to initiate CPR. High-quality chest compressions are the most immediate action to circulate oxygenated blood. Compressions should be performed at a rate of 100 to 120 per minute and to a depth of at least two inches for an adult. The current standard recommends starting with 30 compressions, followed by two rescue breaths, in a continuous cycle until professional help arrives or the victim shows signs of life.
Post-Resuscitation Management
Once the victim regains consciousness or begins to breathe normally, or if they were found unconscious but breathing, the rescuer’s focus shifts to ongoing care. The most important action is to place the victim into the recovery position. This position helps maintain an open airway by allowing the tongue to fall forward and facilitates the drainage of fluids, such as vomit or blood, preventing aspiration into the lungs.
To place an adult into the recovery position, the rescuer should gently roll the person onto their side, supporting the head and neck during the movement. The person’s upper leg should be bent at the knee to stabilize the body, and the upper arm should be positioned to support the head. The mouth should be the lowest point to encourage gravity-assisted drainage.
Continuous monitoring of the victim’s responsiveness, breathing, and circulation is necessary until EMS takes over. The rescuer should regularly check for normal breathing and observe for any changes in the person’s condition. When the emergency services arrive, the rescuer must provide a clear and concise handover of information, including what happened, the interventions performed, and any changes observed in the victim’s status.