When there is water present or if the victim is wet, do not use an AED. Because electricity follows the route of least resistance, if there is water on the chest, the shock will pass through the water rather than the heart muscle. No one should come into contact with the victim while an AED is delivering an electrical shock. Other things that can cause you not to deliver a shock are a metal door blocking the path of the current or another person in the room who could be shocked by the discharge. An AED is for use only by people who have been trained in its operation. Even those who have been trained cannot always perform actions quickly enough to save a life. Before you try to use an AED, make sure that you know how to operate it properly. The device's instructions will tell you what action to take if it does not work at first try. An AED is different from a defibrillator used by a doctor because it is designed to be used by someone other than a medical professional. In fact, anyone over the age of 14 can learn how to use an AED. However, experts agree that if you are going to deliver a shock, better to have something like this than nothing at all.