An Automated External Defibrillator (AED) is a portable medical device designed to treat sudden cardiac arrest, a condition where the heart’s electrical system malfunctions, causing it to stop beating effectively. This malfunction, often a chaotic rhythm like ventricular fibrillation, prevents blood from being pumped to the brain and other organs. The AED delivers an electrical shock to reset the heart’s rhythm, providing the best chance for survival. Survival rates decrease rapidly without intervention, making the correct sequence of actions paramount for a successful rescue.
Immediate Steps Before Using the Device
Before retrieving the AED, a rescuer’s initial actions must focus on safety and activating the emergency response system. The first step is to quickly assess the scene to ensure it is safe, removing hazards like water or live wires. Once the environment is secure, the rescuer must confirm the victim’s unresponsiveness and check for the absence of normal breathing, which are the hallmarks of sudden cardiac arrest.
The Emergency Medical Services (EMS) system (typically 911) must be activated, and if possible, a bystander should be directed to retrieve the AED. While waiting for the device, high-quality chest compressions must be initiated without delay. Chest compressions circulate oxygenated blood, temporarily sustaining life until the AED can deliver treatment. Compressions should be delivered hard and fast, at a rate of 100 to 120 beats per minute, minimizing interruptions as much as possible.
The Essential AED Sequence: Power On, Then Pads
The device should be powered on first. Most modern AEDs are designed to begin providing clear, audible instructions the moment they are turned on, or sometimes automatically when the lid is opened. Following these voice prompts ensures the user performs the steps in the correct order, which is helpful in a high-stress situation.
Once the AED is active, it will prompt the user to attach the electrode pads to the victim’s bare chest. The chest must be exposed and dry to ensure proper pad adhesion and effective electrical conduction. For an adult, the standard pad placement is anterolateral: one pad is placed on the upper right side of the chest, just below the collarbone, and the other is placed on the lower left side of the ribcage, below the armpit.
If the victim is a small child, typically under eight years old or weighing less than 55 pounds, pediatric-specific pads should be used if available, as they deliver a reduced energy dose. The placement for a child is often anteroposterior, with one pad on the center of the chest and the other on the back between the shoulder blades, ensuring the pads do not touch. This placement sandwiches the heart between the two electrodes, creating a clear pathway for the electrical current. Once the pads are firmly attached and connected to the AED unit, the machine is ready to begin its analysis of the heart’s electrical rhythm.
Following the Defibrillation Cycle
With the pads connected, the AED will automatically instruct the rescuer to stop touching the victim and begin analyzing the heart rhythm to determine if a shockable rhythm, such as ventricular fibrillation, is present. The analysis process is rapid, and no one should touch the victim during this time, as contact can interfere with the machine’s reading. If the AED detects a rhythm requiring defibrillation, it will loudly advise a shock and begin charging its internal capacitor.
Before delivering the shock, the rescuer must verbally confirm that everyone is clear of the patient. If the AED is semi-automatic, the rescuer will press a flashing button to deliver the electric current, but a fully automatic unit will deliver the shock on its own. Whether a shock is delivered or the machine advises “no shock advised,” the rescuer must immediately resume high-quality chest compressions for a full two-minute cycle.
The two-minute period of Cardiopulmonary Resuscitation (CPR) following a shock is a standard protocol designed to maximize the chances of a sustained return to a normal heart rhythm. After two minutes, the AED will automatically re-analyze the heart rhythm and repeat the cycle of analysis, shock (if advised), and subsequent CPR. This continuous cycle should only be interrupted when the victim begins to move, breathe normally, or when professional emergency personnel arrive.