An Automated External Defibrillator (AED) is a portable device that delivers an electric shock to restore a normal heart rhythm during sudden cardiac arrest. This condition, often caused by ventricular fibrillation, requires immediate intervention, as delay significantly reduces the chance of survival. Proper use of the AED is paramount, and rescuers must select the appropriate electrode pads based on the patient’s size and age.
How Pediatric Pads Differ from Adult Pads
Pediatric AED pads differ from adult pads in physical dimensions and the electrical energy they deliver. Adult pads are larger to maximize contact area, distributing the high-energy current across the chest. Pediatric pads are smaller to prevent them from touching on a child’s torso, which could cause a short circuit and ineffective treatment.
The most substantial difference is the energy delivered. Standard adult AEDs deliver high-energy shocks, typically 150 to 360 Joules. Pediatric pads incorporate specialized attenuation circuitry, often a current-limiting resistor, built into the pad or cable connector. This technology reduces the delivered energy to a much lower, safer level for a child, usually 50 Joules or less. This reduction is calibrated for the lower body mass and smaller heart size of pediatric patients.
The Consequences of Using Pediatric Pads on Adults
Using pediatric pads on an adult risks treatment failure because the delivered energy is insufficient to stop the fatal heart rhythm. The adult body has greater thoracic impedance—resistance to electrical current—due to larger body mass and thicker chest walls. Successfully terminating ventricular fibrillation requires a substantially higher energy level to depolarize the heart muscle cells.
Since pediatric pads reduce energy to about 50 Joules, this is only a fraction of the 150 to 360 Joules required for an adult. A shock delivered at this low level is highly unlikely to halt the chaotic electrical activity, meaning ventricular fibrillation will likely persist. This ineffective shock wastes precious time, as every defibrillation attempt involves pausing chest compressions. Furthermore, the smaller surface area of pediatric pads fails to adequately distribute the current, resulting in localized, high-current density that is still insufficient to convert the rhythm.
Why Adult Pads Should Not Be Used on Children
Applying high-energy adult pads to a child poses two serious risks: physical harm and ineffective shock delivery. The primary concern is excessive electrical energy. A child’s smaller body mass and lower thoracic impedance mean that the 150 to 360 Joules delivered by adult pads could cause significant damage to the heart muscle and internal tissues. This high current density can also result in severe external burns where the electrodes are placed.
The second risk relates to pad size. Adult pads are too large for a child’s torso and may touch when placed in the standard anterior-lateral position. If the pads overlap, the current bypasses the heart, resulting in an ineffective shock. If adult pads must be used when pediatric pads are unavailable, a front-to-back placement technique is recommended. This alternative placement involves placing one pad on the front of the chest and the other on the back between the shoulder blades, ensuring they do not touch while still delivering current across the heart.
Immediate Steps for AED Application
Recognizing sudden cardiac arrest requires immediate action, starting with calling emergency services. Once the AED arrives, the rescuer must prioritize speed and adherence to the device’s instructions.
The machine should be powered on immediately, as the voice prompts will guide the rescuer through the procedure. The specific pads should be chosen based on the patient’s age and applied to the bare chest, ensuring good contact with the skin. After the pads are connected to the machine, the AED will analyze the heart rhythm, and during this brief period, no one should touch the patient.
If the AED determines that a shockable rhythm is present, it will charge and prompt the rescuer to push the shock button, requiring everyone to stay clear. Following the shock, or if the AED advises that no shock is needed, the rescuer must immediately resume high-quality chest compressions and rescue breaths. The AED will continue to analyze the rhythm every two minutes, and the rescuer should continue this cycle until emergency medical services take over or the patient begins to move.