An Automated External Defibrillator, or AED, is a portable electronic device designed to deliver an electrical shock to the heart during sudden cardiac arrest (SCA). SCA occurs when the heart’s electrical activity becomes chaotic, preventing it from pumping blood effectively. The AED analyzes this chaotic rhythm and, if necessary, stops it with a controlled electrical current, allowing the heart to re-establish a normal, effective rhythm. Since survival decreases significantly with every minute defibrillation is delayed, the immediate and proper use of an AED is a powerful intervention. Understanding the necessary considerations for its use ensures this time-sensitive action is safe and effective.
Preparing the Scene and the Patient
Before applying the electrode pads, the environment must be assessed for safety, and the patient prepared to ensure the electrical energy is properly conducted. If the patient is lying in water, snow, or excessive moisture, they must be moved to a dry surface, as electricity and water are a dangerous combination. If the patient’s chest is wet, it must be quickly wiped dry to prevent the current from conducting across the skin surface, which reduces the shock’s effectiveness and risks burns.
Metallic objects or transdermal medication patches on the chest must also be addressed. Metal, such as underwire bras or necklaces, can conduct the current away from the heart, potentially causing burns. Medication patches should be removed from the pad placement area because they can block conductivity or cause small explosions and burns. While these preparatory steps are performed, someone should activate the emergency response system by calling EMS.
Addressing Physical Obstacles to Pad Placement
Achieving full, direct contact between the electrode pads and the patient’s skin is necessary for the AED to analyze the heart rhythm accurately and deliver an effective shock. For patients with excessive chest hair, the hair can prevent the pads from adhering securely, which may lead to arcing of the electrical current. If a razor is available in the AED kit, the hair should be quickly shaved from the areas where the pads will be placed. If no razor is available, use the first set of pads to rapidly rip off the hair, then apply a fresh, second set of pads to the cleared skin.
The AED pads must also be placed several inches away from any implanted medical devices, which are often visible as a small, firm lump beneath the skin, typically in the upper chest. Placing a pad directly over an implanted pacemaker or implantable cardioverter-defibrillator (ICD) can damage the device or block the shock’s energy from reaching the heart muscle. Correct pad size is a consideration, particularly for younger patients, as most AEDs come with adult pads that deliver a higher energy dose. Pediatric pads, which reduce the energy level of the shock delivered, should be used for children under eight years old or weighing less than 55 pounds if available.
If pediatric pads are not available, standard adult pads may still be used, but the pad placement must be adjusted to ensure the pads do not touch each other and that the electrical current pathway crosses the heart. The standard anterior-lateral placement, with one pad on the upper right chest and the other on the lower left side, is intended to send the current through the ventricles. For smaller children, an anterior-posterior placement, with one pad on the front of the chest and the other on the back, is often recommended to create this effective electrical pathway.
Transitioning Care After Defibrillation
Once the AED delivers a shock, or advises “no shock,” the rescuer must immediately continue life support measures. The rescuer should be prepared to restart high-quality chest compressions the moment the shock is delivered or the AED prompts for a rhythm check. The protocol involves providing two minutes of cardiopulmonary resuscitation (CPR) before the AED re-analyzes the heart rhythm.
The AED must remain connected, powered on, and the pads attached throughout the entire resuscitation effort. The device continues to monitor the heart rhythm and prompts the rescuer when the next analysis is due or if another shock is required. This continuous monitoring allows for the rapid delivery of a subsequent shock if the chaotic rhythm returns.
As EMS personnel arrive, a clear and concise handover of information is necessary to ensure continuity of care. The rescuer should communicate the patient’s status, actions taken (such as the number of shocks delivered and CPR duration), and any relevant observations. Handing over the patient with the AED still attached allows professionals to access the device’s recorded data, providing valuable insights into the patient’s heart rhythm history during the event.