An Automated External Defibrillator (AED) is a portable medical device designed to deliver an electrical shock to a person experiencing sudden cardiac arrest (SCA). SCA occurs when the heart’s electrical activity becomes chaotic, causing it to stop beating effectively. Timely defibrillation is the single most important action for survival, with the chance of survival decreasing significantly for every minute treatment is delayed.
The success of an AED depends on the correct placement of the electrode pads. Proper application creates an optimal pathway for the electrical current to pass through the heart muscle. Understanding the precise technique for pad placement ensures the device works as intended during a time-sensitive emergency.
Essential Preparation Before Application
Before the pads can be placed, the patient’s chest must be prepared to ensure maximum electrical conductivity and adhesion. The pads must be applied directly to bare skin, requiring the quick removal of all clothing. Moisture, such as sweat or water, can divert the electrical current, reducing the shock’s effectiveness and risking burns. Therefore, the chest must be wiped clean and thoroughly dried.
Excessive chest hair prevents the adhesive pads from making firm contact with the skin, increasing resistance to the electrical current. If a razor is available in the AED kit, the hair should be shaved from the placement areas. Alternatively, one set of pads can be used to “wax” the area by pressing them down firmly and quickly ripping them off. A fresh set of pads must then be applied for defibrillation.
Any metallic objects, including necklaces, body piercings, or underwire bras, must be removed or moved away from the pad placement area. Metal can conduct electricity and cause sparks or burns upon shock delivery, posing a danger to both the patient and the rescuer. If the patient has an implanted medical device like a pacemaker or internal defibrillator, the AED pads must be placed at least one inch away from the visible bulge of the device.
Correct Pad Placement for Adults
The standard method for adults, and children over 8 years old or weighing more than 55 pounds, is the “anterolateral” position. This placement ensures the electrical current passes diagonally through the heart muscle to restore a normal rhythm. The first pad is positioned on the patient’s upper right side of the chest, just below the collarbone and to the right of the breastbone.
The second pad is placed on the lower left side of the chest, situated on the lower rib cage. This is typically below the left nipple and slightly to the side, along the mid-axillary line. This diagonal placement brackets the heart between the two electrodes. The pads must not touch each other, as overlapping causes a short circuit and prevents the shock from reaching the heart.
For female patients, the second pad may need to be placed beneath the left breast tissue to ensure proper skin contact. If the standard anterolateral position is obstructed by wounds, a pacemaker, or piercings, an alternative is the “anteroposterior” placement. In this method, one pad is placed on the front center of the chest, and the other is placed on the back, between the shoulder blades.
Modified Pad Placement for Children and Infants
For pediatric patients (infants to children under 8 years old or weighing less than 55 pounds), special considerations apply. The most significant difference is the mandatory use of attenuated pediatric pads or a key, which delivers a reduced energy dose appropriate for a smaller body. These smaller pads are designed to ensure they do not touch on the child’s chest.
The preferred placement method for this age group is the anteroposterior (front/back) configuration. One pediatric pad is placed on the front of the chest, often on the center of the sternum. The second pad is then positioned on the patient’s back, placed between the shoulder blades. This front-and-back setup effectively sandwiches the heart between the electrodes, guaranteeing the electrical current crosses the necessary tissue.
If the child is too small for the standard adult anterolateral placement without the pads touching, the anteroposterior method must be used to prevent a short circuit. If pediatric pads are unavailable, adult pads can be used, but they must be placed in the anteroposterior position to ensure they do not overlap. This alternative placement maintains a sufficient pathway for the shock while adjusting for the child’s smaller torso size.