An Automated External Defibrillator (AED) is a portable device that analyzes the heart’s rhythm during sudden cardiac arrest and delivers an electrical shock. This controlled shock is intended to reset the chaotic electrical activity, allowing a normal rhythm to resume. The speed and accuracy of applying the electrode pads are directly related to the treatment’s success rate. Understanding the proper physical steps beforehand can significantly reduce the time to therapy.
Preparation Prior to Pad Application
The first action upon retrieving the device is to immediately power it on, allowing the AED’s voice prompts to guide the rescuer. Before applying the pads, the patient’s chest must be completely exposed by removing all clothing and undergarments. This ensures the pads adhere directly to the skin for optimal electrical contact.
The skin must be as dry as possible, as moisture interferes with the electrical current and reduces shock effectiveness. If the patient is wet or heavily sweating, the chest area should be quickly wiped dry. Additionally, any metal jewelry or transdermal medication patches in the pad placement areas must be removed to prevent electrical arching or burns.
Standard Adult Pad Placement
The optimal method for placing pads on an adult patient (older than eight years or weighing more than 55 pounds) is the anterior-lateral position. This placement maximizes the electrical current passing through the heart muscle by creating a pathway that effectively “sandwiches” the heart between the two electrodes.
The first pad should be placed on the patient’s upper right chest, positioned just below the collarbone and to the right of the breastbone. The second pad is positioned on the lower left side of the ribcage, several inches below the left armpit, along the mid-axillary line.
This diagonal arrangement directs the electrical current through the greatest mass of the ventricular muscle tissue. Placing the pads too close together or allowing them to touch can cause the current to bypass the heart entirely, rendering the defibrillation ineffective. Visual confirmation of these precise locations is often provided by diagrams printed on the pads or the AED unit.
Modifications for Pediatric Patients
When treating a child (under eight years of age or weighing less than 55 pounds), modifications are necessary to adjust the energy delivered and ensure correct electrical flow. If available, pediatric attenuated pads should be used, as they reduce the shock energy appropriate for a smaller body size. The AED unit may also require a special key or switch to activate the pediatric mode.
For smaller patients, the risk of pads overlapping is higher, which can short-circuit the electrical current. Therefore, the anterior-posterior placement method is used: one pad is placed on the center of the chest, and the second pad is placed on the center of the back, between the shoulder blades.
If pediatric pads are unavailable, standard adult pads must still be used with the anterior-posterior method. This alternate placement ensures the electrical current passes through the heart while preventing the larger adult pads from touching. Using adult pads in this manner is preferable to delaying defibrillation.
Addressing Obstacles to Pad Adhesion
Effective defibrillation relies on solid pad-to-skin contact, and several common obstacles can compromise this adhesion. Excessive chest hair prevents the adhesive gel from making full contact with the skin, increasing electrical resistance and reducing shock effectiveness. If the chest hair is dense, a razor, often included in the AED response kit, should be used to quickly shave the application area.
Moisture on the skin, such as sweat or water, conducts electricity and can divert the current away from the heart, so the area must be dried thoroughly. An implanted medical device, such as a pacemaker or implantable cardioverter-defibrillator (ICD), can interfere with the AED’s function or be damaged by the shock. These implants often create a small bulge under the skin, typically near the collarbone. The pads must not be placed directly over a visible implant, instead being positioned at least one inch away. If the standard anterior-lateral placement covers an implant, the anterior-posterior placement should be considered as an alternative. Following pad placement, the pads must be pressed down firmly to ensure complete surface contact and minimize air pockets.