TECHNICAL NOTE
DEFIBRILLATION ON A
WET OR METAL SURFACE
SUMMARY
It is safe to defibrillate a patient on either a wet or metal surface as long as the appropriate
safety precautions are taken. Specifically, care should be taken to ensure that no one is
touching the patient when the shock button is pressed.
HeartStart Automated External Defibrillators are designed to be easy to use and have clear
text and/or voice prompts that reinforce the proper use of the product. When the HeartStart
defibrillator is analyzing the ECG, it will announce, "Do not touch the patient. " When it
decides to shock and charges, it will tell the user to stay clear of the patient. It will also inform
the user when it is safe to touch the patient. All these messages are intended to make the
unit safer and easier to use.
BACKGROUND
When a patient is externally defibrillated, the current that travels between the pads will
always seek the path of least resistance. Some of this current will pass over the surface of
the patient's skin, and if the patient is resting on an electrically insulating surface, all
defibrillation energy is kept within the patient. If the user does not touch the patient during
the discharge, there is no danger of them receiving a shock, as there is not a current path
that would cause the user to experience a shock. However, if the patient is resting on a
somewhat electrically conductive material, such as a wet surface, some of this energy may
pass outside the patient. It is the presence of this energy near the patient that has prompted
concern of electrical shock hazards to caregivers or bystanders during delivery of
defibrillation.
Historically, patients have been defibrillated without harm on both insulating and conductive
surfaces. For example, dry flooring (such as wood) does not conduct stray currents, hence
inducing no potential gradient around the patient. At the other extreme, patients on metal
surfaces (such as the floor of a helicopter) are also defibrillated safely, as the electricity is
completely conducted through the metal and away from any bystanders. According to the
American Heart Association (Guidelines 2000), metal surfaces "pose no shock hazard to
either the victim or rescuer. "
