It can be used only at the following points.
1. Confirm that it's a cardiac arrest. If you see a person who looks like he's having a heart attack, you need to make sure he's in sudden cardiac arrest before you use an automated external defibrillator. Check his breathing, pulse and whether he is conscious or not. This can be checked by following the emergency assessment method.
2. Try to wake up the patient. If you see a person lying on the floor, not knowing how long he has been unconscious, you have to make sure that he is having a heart attack and not asleep. Shake him, speak loudly into his ear or clap your hands to try to wake him up. If the patient shows no sign of waking up, confirm that it is a heart attack. If it is an infant or young child, he should not be shaken as hard as possible as this can cause serious injury.
3. Call 120. Call the emergency number as soon as you recognize a medical emergency. Say where you are and what the situation is. Explain that you have a defibrillator nearby and that you are prepared to use it. If there are other people around, let them call the emergency number and you will start the first aid immediately. If you don't have a defibrillator nearby, have someone close to you rush to get the nearest defibrillator. One second faster is one more second of hope for saving a life.
4. Begin cardiac resuscitation. If there are other people around, you can resuscitate the patient while the others are looking for a defibrillator. If no one else is around, call 120 and then start resuscitation. For every 30 chest compressions, give 2 artificial breaths. Do not give artificial respiration for more than 1 second at a time. Do not hyperventilate, only provide enough air to allow the patient's chest to expand. Continue chest compressions at 100 per minute. Do not exceed 125 compressions per minute. Press to a depth of about 5 centimeters, with the palm of the hand open and the five fingers pointing upward. If you don't know how long the patient has been unconscious, you should perform immediate cardioversion before using a defibrillator.