Pads Over the Pacemaker, Wet Chest, Sticky Patch
A 66-year-old man collapses in his garage. His wife, who took a CPR class six years ago, starts compressions and sends a neighbor for the AED mounted just inside the front door. The patient has a pacemaker generator visible under the skin below his left clavicle, a nicotine patch on his upper left chest, and skin still damp from a recent shower. The neighbor applies the pads exactly as the cartridge diagram shows: one to the upper right chest, one to the left lateral chest - over the device outline, and partially over the patch. The AED analyzes during a compression pause and announces "shock advised." The wife asks whether they should go ahead.
1. Should the shock be delivered with the pads where they are? What would you change, and how fast?
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Yes, shock - but reposition the left pad first, in seconds, not minutes. Three correctable problems:
- Implanted device. Do not place a pad directly over the generator. Move it at least 8 cm (3 in) away, or switch to an anterior–posterior configuration. Current shunted through the generator may fail to reach the myocardium.
- Transdermal patch. Peel it off and wipe the skin. Patches can cause arcing and small burns and can impair current delivery.
- Wet skin. Quickly towel-dry the chest. Surface moisture lets current travel across the skin instead of through the chest, reducing delivered energy and risking arcing. (If he were lying in standing water, he would first be moved out of it.)
Press each pad firmly. All of this is a few seconds' work and is worth doing once - but the guiding principle remains: do not delay defibrillation. If repositioning were going to take more than a brief moment, deliver the shock at the alternative pad position, resume compressions, and fix the details on the next cycle.
2. After the shock, the wife asks whether she should check for a pulse. Two minutes later the AED reanalyzes and says "no shock advised," but the man is still unresponsive and not breathing. What now?
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No pulse check after the shock. Resume chest compressions immediately - the shock stuns the heart and the first minutes of perfusion are what restore an organized rhythm. The AED will prompt the next analysis in 2 minutes.
When the AED says "no shock advised" in a patient who is still unresponsive and not breathing normally:
- Resume CPR immediately and continue full cycles.
- Leave the pads on and the device powered; it will reanalyze every 2 minutes and can advise a shock later if the rhythm degenerates.
- Do not remove the pads or power the device down.
- Only if the patient shows signs of life (purposeful movement, normal breathing, palpable pulse) would you stop compressions and move to post-arrest positioning and monitoring.
"No shock advised" means this rhythm at this moment is not shockable - it does not mean the arrest is over.
3. What should the rescuers understand about the pacemaker's effect on the AED's analysis, and what must they tell the arriving EMS crew?
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A pacemaker's pacing spikes can be misread by the AED's rhythm algorithm as QRS complexes. The practical consequence is a false "nonshockable" classification - the device may withhold a shock from a patient who is actually in VF. So in a pulseless patient, a "no shock advised" message from an AED with a pacemaker in the field must not be treated as proof that the rhythm is non-shockable; compressions continue and the treating team confirms the rhythm on a monitor.
Handoff details EMS needs:
- Witnessed collapse, time of collapse, time CPR started.
- Number of shocks delivered and the AED's messages at each analysis.
- Implanted pacemaker (location and that pads were moved off it), a pacemaker dependency history if known, and any ICD.
- Nicotine patch removed; chest dried.
- No ROSC, no pulse at any check, no bystander report of normal breathing.
The AED should travel with the patient so its rhythm record is available.