Automated External Defibrillator (AED) – For Public Information

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Automated External Defibrillator (AED) is a lifesaving portable medical instrument used in case of emergencies such as a cardiac arrest. It gives electric shocks through the chest to the heart to the person who suffered a sudden cardiac arrest (SCA) or an abnormal heartbeat. The instrument can be used by any non-medical person and is safe to use.

Sudden cardiac Arrest (SCA) is an abrupt loss of heart function; it can lead to death if not treated immediately as it’s a complete electrical blackout. Also, a heart attack is a plumbing problem whereas, SCA is an electrical problem. Mostly SCAs occur due to ventricular fibrillation; a heart rhythm disturbance, the lower chambers quiver and the heart can’t pump any blood, causing cardiac arrest. Therefore, the heart must be “defibrillated” quickly, because the chances of survival decrease by 7-10% per minute if the normal heartbeat is not restored. Though SCA can happen to anyone anywhere, these factors increase the risk of getting SCA: men and women aged 40 and above, diabetes, smoking, high blood pressure, lack of exercise, stress.

The heart produces electrical signals for its proper rhythmic functioning, and when these signals are not produces in a coordinated manner it causes SCA. In order to prevent the heart failure, AED is used and is connected to the chest, the computer fitted machine checks the heart rhythm through adhesive electrodes and tell if a shock is required or not, if it observes that the shock is required then the device sends voice instructions to guide the user and accordingly the shock is given so that the heart resumes beating.

AED is designed to produce a 3-shock mechanism. This means, as soon as the AED is attached to the chest the heart beat is analyzed and the shock is transmitted, if it is still complaisant a second shock is advised, the rhythm is then re-analyzed and if it is still complaisant, a third shock is advised. In between the whole process if at any point the heart rhythm is not found to be complaisant to the shock, no shock message is displayed and CPR should be commenced.


This article provides only the basic information.