An Automated External Defibrillator (AED) is a portable electronic device designed to treat sudden cardiac arrest (SCA), a condition where the heart’s electrical activity becomes chaotic or stops entirely. During SCA, the heart quivers uselessly (ventricular fibrillation), preventing it from pumping blood to the brain and other organs. The AED delivers a controlled electrical shock to stop the abnormal rhythm, allowing the heart’s natural pacemaker to re-establish a normal heartbeat. Survival decreases by approximately ten percent for every minute that passes without defibrillation. Using an AED quickly, alongside high-quality chest compressions, significantly increases the chance of a successful outcome before medical help arrives.
Recognizing the Need and Initial Steps
The first action when encountering a collapse is to determine if the person is unresponsive and not breathing normally. A person in sudden cardiac arrest collapses without warning, will not respond to voice or touch, and may be gasping or not breathing. Once SCA is suspected, immediately activate the emergency response system by calling the local emergency number, such as 911. If others are present, instruct one person to call for help and another to locate and retrieve the nearest AED.
While waiting for the AED, begin chest compressions (CPR) to maintain blood flow to the brain and organs. This action buys time but cannot correct the underlying electrical problem; only a defibrillating shock can do that. Proper preparation involves moving the person onto a firm, flat surface and ensuring their chest is bare and dry. Remove any metal jewelry or clothing that may interfere with pad placement, as moisture and metal can reduce the shock’s effectiveness.
Step-by-Step Operation
Once the AED is at the person’s side, turn on the machine. It will immediately begin providing voice prompts that guide you through the entire sequence. Open the electrode pad package and peel them from the plastic liner, preparing to attach them directly to the bare skin of the chest.
For an adult, the standard placement is called anterolateral, which establishes an electrical pathway that crosses the heart. Place one pad on the upper right side of the chest, just below the collarbone and to the right of the breastbone. The second pad should be placed on the lower left side of the chest, below the left nipple and slightly to the side. For children under the age of eight or weighing less than 55 pounds, special pediatric pads should be used, which reduces the energy level of the shock. If pediatric pads are not available, use the adult pads, but place one pad on the center of the chest and the other on the back to prevent them from touching.
After the pads are firmly attached to the skin, plug the electrode cable into the AED unit, which will then begin to analyze the person’s heart rhythm. During this analysis phase, loudly instruct everyone to stand clear and ensure no one is touching the person, as any contact can interfere with the analysis or endanger the rescuer. The AED determines if the rhythm is shockable, typically ventricular fibrillation or pulseless ventricular tachycardia.
If the machine determines a shock is needed, it will charge its internal capacitor and instruct the user to press a flashing button to deliver the electric current. Before pressing the shock button, loudly announce “Clear” to confirm all bystanders are separated from the person. Once the shock is delivered, the AED will immediately prompt the next action.
Post-Shock Care and Handover
Immediately following the delivery of a shock, or if the AED advised “no shock,” resume chest compressions without delay. The shock may have momentarily reset the electrical activity, but continuous CPR is necessary to circulate oxygenated blood to the brain and vital organs. Continue compressions for two minutes, following the rate and depth guidance provided by the AED’s metronome or voice prompts.
Do not remove the electrode pads or turn off the AED unit once it is attached, as the device will automatically re-analyze the heart rhythm after the two-minute interval. If the abnormal rhythm persists, the AED will advise another shock, and the entire process of clearing the person and delivering the shock is repeated. Continue following the AED’s prompts and performing CPR until the person begins to move, speak, or breathe, or until Emergency Medical Services (EMS) personnel take over care.
When EMS arrives, provide a concise handover report, including the time the person collapsed, the total duration of CPR, and the number of shocks delivered by the AED. Good Samaritan laws offer protection to individuals who act in good faith to provide emergency care.