An automated external defibrillator (AED) is a battery-operated electronic device with a built-in microprocessor that is used in the diagnosis, and if needed, in the treatment of irregular heartbeat conditions which may cause sudden cardiac arrest (SCA) through therapy involving application of electric shocks aimed at restoring normal heart rhythm. It is an important piece of first aid equipment that can potentially help save many lives.
According to the American Red Cross’ manual, CPR/AED for the Professional Rescuer, for each minute that someone in cardiac arrest is not treated with defibrillation (as in, with an AED device), his survival decreases by 7 percent per minute within the first 3 minutes and by 10 percent after the 3 minute mark. An estimate based on American Heart Association (AHA) statistics say that up to 60 percent of SCA fatalities could have been saved had there been timely AED intervention.
A condition which may lead to SCA is ventricular fibrillation. Here the ventricles, or the heart’s lower chambers, quiver irregularly and rapidly. Another condition is ventricular tachycardia. In this instance, the ventricles beat regularly but for a few or more seconds at a very fast rate. Both conditions, or arrhythmia, can cause the heart to stop pumping blood suddenly and unexpectedly. Once the heart stops beating, circulation ceases, in turn depriving the brain and other vital organs of supply of oxygenated blood. Fortunately, in cases of SCA resulting from either ventricular fibrillation or ventricular tachycardia, defibrillation through use of electrical shock from the AED device can temporarily halt the irregular, erratic beating of the heart, thereby allowing the pacemaking cells enough time to re-establish normal heart rhythm.
How is the AED used? Once turned on, voice and screen prompts will direct the operator to connect the electrode pads to the victim’s chest. Through the electrode pads, the AED’s built-in computer can examine the electrical impulses from the heart, analyze the rhythm, and calculate whether defibrillation is needed. Should defibrillation be warranted, the voice and screen prompt will advise the operator accordingly. At the same time, the device will charge the internal capacitor that will deliver the electric shock with power from the battery. Once charged, the AED’s voice and screen prompts will instruct the operator to press the “shock” button. The electric shock is delivered to the patient’s chest through the electrode pads. After the delivery, the device will re-analyze the patient’s condition and advice the operator on whether another shock should be administered. The electrode pads should be left attached to the victim’s chest to allow the AED to continue monitoring the condition of the heart until professional help finally takes over.
The AED is safe to use by anyone with just minimal training. It is designed to be generally “idiot-proof.” It will not deliver a shock if the readings show that defibrillation is not needed. In most of the states in the US, there are Good Samaritan laws that can protect an untrained lay rescuer who uses an AED on a cardiac arrest victim should something untoward happen to the victim.
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