A rescuer operating an AED must clear the victim at two specific moments: during the heart rhythm analysis and immediately before delivering a shock. At both points, no one should be touching the victim, and the rescuer should loudly say “CLEAR!” before proceeding.
The Two Times You Must Clear the Victim
The first moment is when the AED analyzes the victim’s heart rhythm. After you attach the electrode pads and power on the device, the AED reads the electrical activity of the heart to determine whether a shock is needed. Any physical contact with the victim during this phase can interfere with that reading. Even slight movement from a rescuer’s hands can introduce electrical noise that the machine misinterprets as heart activity. If the interference is severe enough, many AED models will pause the analysis entirely and prompt you with something like “Analysis halted. Keep patient still.” This wastes critical seconds.
The second moment is right before you press the shock button. Once the AED determines a shock is advised, you must visually confirm that no one is touching the victim, announce “CLEAR!” in a loud, commanding voice, and only then press the button. The American Red Cross protocol reinforces both steps: make sure no one is touching the person, say “CLEAR,” and then deliver the shock.
Why Clearing Matters for Rhythm Analysis
The AED’s ability to correctly identify a shockable rhythm depends on reading a clean electrical signal from the heart. When someone is touching the victim, their own muscle movements and body electricity create signal artifacts that contaminate the reading. The FDA’s guidelines for AED manufacturers are explicit: do not touch the electrode surfaces, the victim, or any conductive material touching the victim during ECG analysis or defibrillation. If you’re using an AED inside a moving vehicle, you should bring the vehicle to a complete stop before analysis begins, because even road vibrations can disrupt the reading.
Radio frequency interference from cell phones and two-way radios can also cause the device to misread heart rhythms, so keeping those devices away from the AED during analysis is a good practice.
Why Clearing Matters Before a Shock
When an AED delivers a shock, it sends a burst of electrical energy through the victim’s chest to reset the heart’s rhythm. If you’re touching the victim at that moment, some of that current can pass through you. Traditional safety training exists specifically to prevent rescuer electrocution during shock delivery. While the exact level of danger is not fully quantified, documented cases show it’s a real concern. In case reports involving implanted cardiac defibrillators (which deliver lower energy than external AEDs), rescuers performing chest compressions during a discharge experienced significant jolts, and one rescuer sustained a peripheral nerve injury.
An external AED delivers considerably more energy than an implanted device, which makes the risk to a rescuer proportionally greater. Clearing the victim is not optional. It protects everyone in the immediate area.
What the AED Voice Prompts Tell You
Modern AEDs guide you through the entire process with recorded voice prompts, so you don’t need to memorize the sequence perfectly. After pads are placed, the device will typically announce that it is analyzing the heart rhythm and instruct everyone to stand back. If a shock is advised, the AED will tell you to stand clear of the patient and press the shock button. Listen for these prompts and follow them exactly. The machine will not automatically deliver a shock on most public-access AEDs; it waits for you to press the button after confirming the area is clear.
If the AED says “no shock advised,” that does not mean the victim is fine. It means the specific heart rhythm detected is not one that responds to defibrillation. You should immediately resume CPR.
When to Touch the Victim Again
After the shock is delivered, resume chest compressions immediately. Current resuscitation guidelines recommend starting compressions right after a defibrillation attempt without pausing to check for a pulse. Continue CPR for about two minutes (roughly five cycles of 30 compressions and two breaths) before the AED will initiate another rhythm analysis. Research on out-of-hospital cardiac arrests supports this approach, finding that most patients need continued compressions even after a successful shock, because the heart often takes time to regain an effective pumping rhythm.
When the AED begins its next analysis cycle, you’ll need to clear the victim again, repeating the same hands-off protocol. This cycle of CPR, analysis, and potential shock continues until emergency medical services arrive or the victim starts showing obvious signs of life.
Special Situations That Affect Clearing
Wet environments add a layer of concern. If the victim is lying in a puddle or near a pool, the standard recommendation is to move them to a dry surface before using the AED. Research simulating defibrillation in pool water and salt water found that voltage levels about six inches from the patient were low enough to be considered non-hazardous, potentially causing only a minor sensation. Still, wiping the victim’s chest dry before placing pads ensures better adhesion and a cleaner electrical path, and moving to dry ground remains best practice when it’s feasible without delaying treatment.
If you see a medication patch on the victim’s chest where a pad needs to go, remove the patch and wipe the area clean before attaching the electrode. For victims with an implanted pacemaker or defibrillator, which typically shows as a visible lump under the skin of the upper chest, place the AED pad at least one inch away from the device. Neither of these situations changes when you need to clear, but they affect pad placement, which you should handle before the analysis begins.
Quick Sequence to Remember
- Turn on the AED and attach the pads to the victim’s bare chest.
- First clear: Stop CPR, ensure no one is touching the victim, and let the AED analyze the rhythm.
- Second clear: If a shock is advised, visually scan to confirm no one is in contact, loudly say “CLEAR,” and press the shock button.
- Resume CPR immediately after the shock. Continue for two minutes until the AED prompts another analysis.
- Repeat the clearing process each time the AED analyzes or shocks.
The entire purpose of clearing is twofold: protecting the accuracy of the AED’s rhythm reading and protecting every person nearby from electrical injury. Both moments require the same action, a quick visual check and a loud verbal warning, but skipping either one can compromise the rescue.