An Automated External Defibrillator (AED) delivers an electrical shock to interrupt a chaotic, ineffective rhythm like ventricular fibrillation. By stopping this electrical disorder, the AED gives the heart’s natural pacemaker a chance to reset and restore a functional rhythm. The shock is not the end of the rescue process, but a transition point to the next, equally important phase of care. The AED’s voice prompts and display guide the user through specific actions that must be followed to maximize the patient’s chance of survival.
Immediately Resume Chest Compressions
The most important action immediately following the delivery of a shock is the prompt resumption of chest compressions. Do not waste valuable seconds checking for a pulse, as this pause significantly reduces the effectiveness of the preceding shock. High-quality cardiopulmonary resuscitation (CPR) must be initiated within seconds of the shock to circulate oxygenated blood. Minimizing the time between the shock and the start of compressions is directly linked to better patient outcomes.
Rescuers should aim for a compression rate between 100 and 120 compressions per minute. The depth of these compressions is standardized for adults, requiring a push of at least two inches (five centimeters) but no more than 2.4 inches (six centimeters) into the chest. Allowing the chest to fully recoil after each compression is a requirement for high-quality CPR, ensuring the heart can refill with blood. The AED pads should be left in place and connected throughout this intervention.
Following the AED’s Next Prompts
The AED works in continuous cycles, instructing the rescuer to perform two minutes of CPR before automatically reanalyzing the heart’s electrical activity. This two-minute period of chest compressions and rescue breaths (if trained) builds up the circulation needed to support a normal rhythm. Many modern AEDs incorporate a metronome feature that assists the rescuer in maintaining the correct compression rate of 100 to 120 beats per minute.
After the two-minute interval, the AED instructs the rescuer to “stop CPR” and “stand clear” for rhythm analysis. The analysis results in one of two outcomes: “Shock Advised” or “No Shock Advised.” If another shock is advised, the rescuer must clear the patient, press the shock button when prompted, and immediately return to compressions for another two-minute cycle. If the AED advises “No Shock,” the rescuer should continue with two minutes of CPR or check for signs of circulation and breathing if instructed by the device, as the heart’s rhythm is either normal or non-shockable.
Sustained Care Until EMS Arrival
The AED should remain connected and powered on, regardless of the patient’s condition. The device continuously monitors the heart rhythm and is programmed to advise another shock if the dangerous rhythm returns. Never remove the electrode pads, as they are part of the ongoing monitoring and treatment system.
If the patient regains consciousness, starts breathing normally, and shows signs of circulation, the AED remains attached while the patient is placed in the recovery position. This position, typically on the side, helps keep the airway open and reduces the risk of aspiration. If the patient is still unresponsive but breathing, the recovery position is appropriate while waiting for professional help.
The rescuer should continuously monitor the patient’s breathing and responsiveness until Emergency Medical Services (EMS) personnel arrive. Maintaining scene safety, managing any bystanders, and preparing a concise handover report for the arriving EMS team are also important duties. The information provided to EMS—such as how many shocks were delivered and when CPR was started—is valuable data for subsequent medical treatment.