The ABCs (Airway, Breathing, and Circulation) represent a foundational, systematic framework used in nursing and emergency medical care to quickly assess a patient’s immediate life-sustaining needs. This mnemonic dictates the sequence of assessment and intervention because the failure of one system compromises all others. Applying this systematic approach ensures that the most critical, life-threatening problems are addressed first. The nurse’s ability to rapidly identify and manage issues related to these three components directly influences patient outcomes.
Airway: Securing the Passage (A)
The first priority is establishing a patent, or open, airway because oxygen cannot reach the lungs if the passage is blocked. Loss of consciousness is a common cause of obstruction, as the tongue can relax and fall back to occlude the pharynx. Other mechanical obstructions include foreign objects, blood, vomit, or severe swelling from trauma or allergic reactions.
Nurses must quickly assess for signs of obstruction, such as absent or noisy breathing like gurgling, crowing, or stridor, which suggests a narrowed airway. If the patient is unconscious and no cervical spine injury is suspected, the head-tilt/chin-lift maneuver is performed. This technique involves tilting the head backward and lifting the chin to move the tongue away from the back of the throat, effectively opening the pathway.
If a spinal injury is possible, the jaw-thrust maneuver is used instead, as it achieves the same result without hyperextending the neck. This involves placing fingers under the angles of the patient’s lower jaw and lifting it forward. Clearing the airway can also involve suctioning visible fluids or secretions, which must be done rapidly.
Breathing: Evaluating Gas Exchange (B)
Once the airway is secured, the nurse evaluates the adequacy of gas exchange. This assessment involves looking, listening, and feeling for the rate, rhythm, depth, and effort of respirations. A normal respiratory rate for an adult is between 12 and 20 breaths per minute at rest, with movements that are regular and quiet.
Signs of inadequate breathing include abnormal rates (too slow or too fast), irregular patterns, or shallow chest rise indicating poor air entry. The nurse also observes for increased respiratory effort, such as flaring of the nostrils or the use of accessory muscles in the neck and chest. Using these muscles, which are not typically engaged for quiet breathing, signals that the patient is working hard to overcome resistance.
Further signs of compromised function include central cyanosis, a bluish discoloration of the lips or mucous membranes, which indicates low oxygen levels. Immediate interventions may involve administering supplemental oxygen via a mask or nasal cannula. If breathing is inadequate or absent, the nurse must quickly initiate assisted ventilation with a bag-mask device.
Circulation: Maintaining Perfusion (C)
Circulation focuses on the body’s ability to maintain adequate blood flow, or perfusion, to all vital organs and tissues. Assessment begins with checking for the presence of a pulse, noting its rate, rhythm, and strength. For an unresponsive adult, the pulse is checked at the carotid artery in the neck, as central pulses are reliable indicators of cardiac output.
The nurse rapidly assesses for signs of poor peripheral perfusion by checking the color and temperature of the skin, noting if the patient is pale, cool, or mottled. Capillary refill time is assessed by pressing on a nail bed and observing how quickly color returns; a time greater than two seconds suggests compromised blood flow. Inadequate circulation can quickly lead to shock, where blood pressure drops and the delivery of oxygen and nutrients to tissues becomes insufficient.
A major immediate threat to circulation is severe external hemorrhage, which must be identified and controlled immediately, often by applying direct pressure to the wound. If the patient has no pulse, indicating a complete absence of circulation, chest compressions must be started without delay. This action is prioritized because circulatory arrest is rapidly fatal, making manual blood flow the most immediate life-saving intervention.