When an Automated External Defibrillator (AED) delivers an electrical shock to an unresponsive person who is not breathing normally, it is a targeted attempt to correct a chaotic heart rhythm, such as ventricular fibrillation. Although the shock is a significant intervention, it is only one step in a standardized sequence of care designed to maximize the chances of survival. Actions immediately following the shock must be swift and precise, guided by the principle of minimizing interruptions to blood flow until professional help arrives.
Immediate Action: Resuming Chest Compressions
The immediate requirement following the delivery of an electrical shock is to resume high-quality chest compressions without delay. Rescuers should not pause to check for a pulse or breathing. The goal is to promptly circulate oxygenated blood, achieved by restarting compressions immediately after the device advises “shock delivered.”
High-quality chest compressions are the cornerstone of post-shock care, requiring specific technique. For an adult, compressions must be delivered at a rate between 100 and 120 beats per minute. The depth must be at least 2 inches (5 cm) but should not exceed 2.4 inches (6 cm).
It is important to allow the chest to fully recoil after each compression, which permits the heart to refill with blood. Rescuers must avoid leaning on the chest between compressions, as this diminishes effectiveness. If two trained rescuers are present, maintain a compression-to-ventilation ratio of 30 compressions followed by two rescue breaths.
The AED itself will continue to monitor the patient and often provides a metronome or voice prompts to help maintain the correct compression rate. Minimizing the time between stopping compressions for the shock and restarting them is a measure of high-quality care, as even short interruptions can significantly decrease the chance of a successful outcome.
The Two-Minute Reassessment Cycle
Continuous high-quality compressions are maintained for approximately two minutes, or about five cycles of 30 compressions and two breaths, before the AED initiates its next step. This period allows circulation to deliver the shock energy to the heart muscle. After this interval, the AED prompts the rescuer to stop compressions so it can analyze the heart’s electrical rhythm again.
The AED is assessing whether a shockable rhythm, such as ventricular fibrillation, is still present. Based on this analysis, the device will either advise another shock or advise no shock. If a second shock is advised, the rescuer must ensure everyone is clear of the patient before pressing the shock button, following safety procedures.
If the AED advises no shock, the rescuer must quickly check the patient for signs of circulation or responsiveness. If the patient remains unresponsive and a pulse is absent, immediately resume chest compressions and ventilations for another two-minute cycle. If the patient is responsive and breathing normally, leave the AED pads in place and position the patient for recovery while awaiting Emergency Medical Services (EMS). This two-minute cycle repeats continuously until EMS arrives or the patient recovers.
Transitioning to Professional Care
When Emergency Medical Services (EMS) personnel arrive on the scene, the bystander’s role shifts from primary rescuer to assistant and informant. Provide a concise and accurate report of the events that have transpired. This report should include the patient’s status when the cardiac arrest was first recognized and the timeline of the intervention. Specifically state how many shocks were delivered by the AED and the total duration of the resuscitation effort.
The AED device should be left powered on and connected to the patient. The EMS team may use the information recorded by the machine, such as the electrocardiogram data and shock times. The handover of care should be seamless, even if EMS personnel swap the bystander’s AED for their own advanced monitor-defibrillator. Follow any instructions from the EMS team, such as stepping back to allow them space to work.
After the patient has been transferred to the care of the medical professionals, the rescuer should be aware that the experience can be emotionally taxing. Following up with the organization responsible for the AED program to document the event is important, and emotional support or debriefing is often available and can be beneficial. The documentation often involves submitting a report that includes key details of the incident, which contributes to tracking and improving survival rates in the community.