When a person experiences sudden cardiac arrest, the heart’s electrical system malfunctions, often leading to a chaotic, ineffective rhythm known as ventricular fibrillation. The Automated External Defibrillator (AED) delivers a controlled electrical shock to interrupt this dangerous rhythm, allowing the heart a chance to reset to a normal, pumping pattern. While the shock is a potentially life-saving moment, it is only one component of the overall resuscitation effort. The actions taken immediately after the AED discharges are equally important for maximizing the person’s chance of survival and recovery. A successful outcome depends on the quick, structured continuation of care following the electrical intervention.
Immediate Post-Shock Action: Resuming Chest Compressions
The most immediate and important action following an AED shock is to resume chest compressions without delay. Even if the shock successfully resets the heart’s rhythm, the heart muscle may be stunned and unable to generate adequate blood flow. Prompt resumption of compressions artificially circulates oxygenated blood to the brain and vital organs, sustaining life until the heart can take over.
The rescuer should aim for high-quality compressions, pushing hard and fast in the center of the chest. For an adult, this means a compression depth of at least 2 inches (5 centimeters) but no more than 2.4 inches (6 centimeters), delivered at a rate between 100 and 120 per minute. This consistent rhythm ensures continuous blood flow.
It is necessary to allow the chest to fully recoil after each compression, permitting the heart to refill with blood. The AED pads must remain firmly attached, and the machine should not be turned off or disconnected. Rescuers should not pause to check for a pulse or breathing immediately after the shock; the priority is continuous mechanical support of circulation.
The Two-Minute Cycle and AED Re-Analysis
Resumption of chest compressions begins a structured two-minute cycle of cardiopulmonary resuscitation (CPR). This period of continuous compressions and ventilations is performed before the AED automatically re-analyzes the person’s heart rhythm. For those trained in CPR, the standard ratio is 30 chest compressions followed by two rescue breaths.
The AED typically provides voice prompts to guide the rescuer through the two-minute interval, often including a metronome feature to assist in maintaining the correct rate. At the end of the cycle, the AED will announce it is time for a rhythm analysis and instruct everyone to stand clear. It is imperative that no one touches the person during this analysis, as contact can interfere with the machine’s reading and pose a safety risk.
The re-analysis results in one of two outcomes: “Shock Advised” or “No Shock Advised.” If a shock is advised, the rescuer must ensure the area is clear before delivering the electrical impulse, then immediately resume CPR for another two-minute cycle. If the AED advises “No Shock,” it means a shockable rhythm is no longer detected, and the rescuer should then check for signs of circulation and breathing. This cycle continues until emergency medical services (EMS) arrive or the person shows clear signs of life.
Monitoring and Transition of Care
If the AED advises “No Shock” and the person begins to breathe normally and shows signs of responsiveness, active CPR should be stopped. The person should be placed in a recovery position to maintain an open airway and prevent aspiration. Continuous monitoring of the person’s pulse and breathing is necessary, as the heart rhythm may become unstable again.
If the person remains unresponsive but is breathing and has a pulse, they should still be monitored closely in the recovery position. The AED must remain turned on and connected throughout this period, as it continuously monitors the heart rhythm and will prompt if a shockable rhythm returns. Never remove the AED pads or turn off the device, as the data collected is valuable to incoming medical professionals.
Upon the arrival of EMS personnel, a verbal report must be given to facilitate the smooth transition of care. This report should include the person’s initial condition, the actions taken, the number of shocks delivered, and any changes in the person’s status. Providing this concise history allows the medical team to continue treatment without delay, maximizing the person’s chances for a full recovery.