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What is an AED?

An automated external defibrillator (AED) is an emergency life-saving device for use in the event of sudden cardiac arrest. It is a portable device that analyses the heart rhythm and administers an electrical charge to the heart if needed (to establish a regular heartbeat in the event of a cardiac arrest).

 

Only within the first few minutes following cardiac arrest will a victim be in a ‘shockable rhythm’; rapid defibrillation is therefore vital. Placing AEDs in the community can dramatically reduce the time from collapse to defibrillation and can greatly improve survival rates.
 

When switched on the AED will instruct the user to connect the pads to a patient’s bare chest. The pads enable the AED to examine the patient’s heart and determine if the patient is in a viable, shockable rhythm. If the device determines that a shock is required, it will charge in preparation to deliver a shock. The AED is very safe as it will only charge if it determines a shockable rhythm is present.


When charged, the device instructs the user to ensure that no one is touching the patient and to then press a button to deliver the shock. Or, in the case of a fully automatic AED, the unit will advise the user that it is about to deliver the shock without further intervention. After the shock is delivered, the device will instruct the user to start/continue cardiopulmonary resuscitation (CPR) for a period of two minutes, after which it will analyse the patient’s heart rhythm once again, advising a further shock or further CPR.

An AED has an internal memory, which stores an ECG of the patient’s heartbeat along with details of the time the unit was activated and the number and strength of any shocks delivered. All this memorised data can be either downloaded to a computer, or printed out, so that it can be analysed by appropriate medical personnel.
Technological advances have meant that AEDs can be used by anyone with minimal or no training and little or no experience.  The Resuscitation Council UK guidelines instruct that the use of AEDs should not be restricted to trained personnel. However, chances of survival increase if the person has had some awareness training in its use.  For this reason, Arrhythmia Alliance recommends running public awareness sessions and training opportunities when placing a community AED.