An Automated External Defibrillator (AED) delivers an electrical shock to the heart, which is the only effective treatment for many cases of sudden cardiac arrest (SCA). When SCA occurs, the heart stops beating effectively, and every minute without defibrillation significantly decreases the chance of survival. Correct and rapid placement of the AED pads ensures the electrical current travels across the heart muscle, linking directly to the success of the shock. Understanding the proper technique, especially anatomical considerations for women, is paramount for a successful rescue.
Universal Principles of AED Pad Placement
The standard method for placing adult AED pads is the anterior-lateral placement, designed to create a path for the electrical current to cross the heart. This placement is the same for all adults, regardless of gender. One pad is placed on the upper right side of the chest, just below the collarbone and to the side of the breastbone.
The second pad is positioned on the lower left side of the torso, typically below the left breast and along the mid-axillary line (the side of the ribcage). This configuration ensures the electricity passes through the ventricular mass of the heart, allowing the device to analyze the rhythm and deliver a therapeutic shock if needed. Rescuers should follow the diagrams printed directly on the pads or the AED device for guidance.
Adapting Pad Placement for Breast Tissue
The presence of breast tissue requires a specific adaptation to the standard lower-left pad placement to ensure effective current delivery. Breast tissue is primarily composed of fat, which does not conduct electricity well and can block the current from reaching the heart muscle. Therefore, the pad must be applied directly to the bare skin of the chest wall.
To achieve this, the rescuer should lift the breast tissue and place the lower-left pad underneath it, ensuring full adhesive contact with the skin of the ribcage. The pad should be positioned along the side of the chest, below the breast fold, so the electrical energy bypasses the fatty tissue. The upper-right pad placement remains unchanged, positioned below the collarbone.
If the victim has a smaller chest or the adult pads are large, the pads might touch or overlap, which can short-circuit the electrical pathway. If this risk exists, or if standard placement is not possible, an alternative anterior-posterior (front-back) placement can be used. This method involves placing one pad on the center of the chest over the breastbone. The second pad is placed on the person’s back, between the shoulder blades and to the left of the spine, allowing the electrical current to pass through the heart without obstruction.
Essential Preparation Steps Before Applying Pads
Before applying the pads, the chest must be prepared to maximize skin contact and electrical conductivity. All clothing must be removed or quickly cut away from the chest area to expose the bare skin. It is especially important to cut through or remove bras, particularly those with rigid metal underwires, as metal can interfere with the shock or cause arcing or burns near the pad sites.
The skin surface must be dry, as moisture like sweat or water interferes with electricity conduction and pad adhesion. Any medication patches, such as nitroglycerin patches, must be removed from the chest area before applying the AED pads, as they can block the electrical current or cause a skin burn. If possible, metal jewelry or body piercings near the pad sites should be removed, or the pads must be placed at least one inch away to prevent electrical interference. AED use is safe and necessary for pregnant women experiencing cardiac arrest, and treatment should not be delayed.