Encountering an unresponsive adult demands swift and focused action to maximize the chance of survival. Cardiac arrest, where the heart abruptly stops beating effectively, is a time-sensitive medical emergency requiring immediate intervention from bystanders. Cardiopulmonary resuscitation (CPR) helps circulate blood and oxygen until professional medical help arrives. A lone rescuer must follow a precise sequence of steps, prioritizing the activation of the emergency response system and the delivery of high-quality chest compressions.
Scene Safety and Activating Emergency Services
The first action upon approaching an unresponsive person is ensuring the surrounding area is safe for both the victim and the rescuer. Hazards like traffic, fire, or electrical wires must be assessed and neutralized. If the scene is unsafe, the victim should be moved only if the rescuer can do so without personal risk.
After confirming safety, check the victim for responsiveness by gently tapping the shoulder and shouting. If the adult does not respond and is alone, immediately activate the local emergency response system (e.g., 9-1-1). This call should be made before starting CPR, unless the rescuer can use a mobile phone on speaker while performing the next steps.
The dispatcher provides instructions and simultaneously sends professional help. If an Automated External Defibrillator (AED) is nearby, retrieve it or send a bystander to get it immediately after the emergency call. The priority for a lone rescuer is to “Call First” for an adult who has suddenly collapsed.
Checking for Breathing and Pulse
Once the emergency call is made, quickly determine if the adult requires CPR by checking for breathing. Look for chest rise and fall and listen for breath sounds for no more than 5 to 10 seconds. Abnormal breathing, such as gasping or agonal respirations, should not be mistaken for normal breathing and indicates cardiac arrest.
Trained rescuers should check for a pulse using the carotid artery in the neck. For lay rescuers, abnormal or absent breathing is the primary indicator to begin CPR without a formal pulse check, as this can delay compressions. If breathing is absent or abnormal, assume the adult is in cardiac arrest and immediately proceed to chest compressions. The goal is to start compressions within 10 seconds of recognizing the lack of responsiveness and breathing.
Delivering Effective Chest Compressions
Initiating high-quality chest compressions pumps blood to the brain and heart. Position the adult on a firm, flat surface and kneel beside them. Place the heel of one hand on the center of the chest (lower half of the breastbone), with the second hand directly on top. Keep fingers off the ribs to prevent injury.
Keep the rescuer’s arms straight, with shoulders directly over the hands, using body weight to push down. Compressions must be delivered at a consistent rate of 100 to 120 per minute. The depth should be at least 2 inches (5 centimeters) but not exceed 2.4 inches (6 centimeters) for an average adult.
Allowing the chest to fully recoil between each compression is important for effective blood flow. Full recoil permits the heart to refill with blood before the next pump. Minimizing interruptions to compressions is necessary, as pausing for more than a few seconds reduces the blood pressure and flow.
Integrating Rescue Breaths and Ongoing Care
The compression-to-ventilation ratio for a single rescuer performing conventional CPR on an adult is 30 compressions followed by 2 rescue breaths (30:2). This ratio must be maintained until the AED arrives or emergency medical services take over. To deliver breaths, open the airway using the head-tilt, chin-lift maneuver, pinch the nostrils closed, and form a seal over the victim’s mouth.
Give each breath over about one second, ensuring the chest visibly rises while avoiding excessive ventilation. If the rescuer is untrained or unwilling to provide mouth-to-mouth breaths, the American Heart Association recommends continuous chest compressions, known as Hands-Only CPR. Hands-Only CPR maintains circulation and is effective for adult victims of sudden cardiac arrest.
Once an AED arrives, immediately apply the pads to the adult’s bare chest and follow the device’s audio prompts. The AED analyzes the heart rhythm and advises whether a shock is necessary. Continue high-quality chest compressions while the AED is charging or if no shock is advised. Stop cycles only if the adult shows signs of life or until professional help arrives.