An AED, or automated external defibrillator,is a device that has the ability to detect and treat, through electrical energy, the lethal arrhythmias known as ventricular fibrillation and ventricular tachycardia.
Ventricular fibrillation is a condition in which the lower chambers of the heart, the ventricles, quiver in an unorganized fashion, which renders them incapable of pumping blood to the rest of the body. Untreated, ventricular fibrillation rapidly causes cardiac arrest. Ventricular tachycardia is a rapid rhythm originating in the ventricles. In ventricular tachycardia, the ventricles contract so quickly, albeit in a somewhat organized fashion, that inadequate blood flow is produced. Ventricular tachycardia often precedes ventricular fibrillation. Both rhythms are lethal if not treated.
An AED sends electrical energy (a ‘shock’) through the heart, which stuns the heart and allows the normal pacemaker of the heart, usually located in the right atrium, to take over and restore a normal heart rhythm.
Early defibrillation is key to survival in cardiac arrest. For each minute that defibrillation is delayed, the chance of survival is reduced by 10%. (after 10 minutes, few people are successfully resuscitated.)
Early defibrillation can increase survival rates to greater than 50%. Rescuers should immediately begin chest compressions, and use the AED as soon as it is available and ready to use.
AEDs can be found wherever crowds of people gather- swimming pools, airports, malls, sporting arenas, schools, hotels…More and more businesses are also investing in these life-saving machines. In some communities, private AED owners are registering their AEDs with ambulance dispatch, so that they can be easily located by bystanders when needed. Make it a point to learn where the AEDs in your neighborhood or town are located- you never know when you might need one!
AEDs have been designed to be extremely “user friendly”. All you need to do as a rescuer is turn on the machine (the most important step) and listen as the machine guides you through the steps to use the AED safely and effectively. Although there are many brands of AEDs on the market, they all work in a similar fashion and are designed to be used by lay rescuers.
When an AED becomes available (i.e., when you or another rescuer have retrieved it), place it at the victim’s side, closest to the rescuer who will operate it. In this way, the other rescuer can continue performing CPR until the AED is ready to analyze and deliver a shock (if needed).
There are four universal steps to using any AED. These will be highlighted in the following list of steps so they are easily recognizable.
The steps to use an AED are as follows:
- Turn on the machine.This is the most important step- turning on the machine will enable the AED unit to guide you through the next steps. To turn on the AED, open the top of the carrying case and push the ON button. Note: some models will turn on automatically when you lift the lid of the carrying case.
- ATTACH AED pads to the victim’s bare chest. Expose the patient’s chest. Dry it off if wet, shave excessive hair if possible. Choose adult pads for victims who are 8 years of age or older. Peel off the adhesive backing. Place one pad on the upper right chest just below the collarbone. Place the other pad on the patient’s lower left ribcage, a couple of centimeters beneath the armpit. Some pads are marked- there will be a red heart on the pad that is to be placed on the victim’s left side (the heart side).
Press pads firmly onto the patient’s chest. Then attach the connecting cables to the AED unit. Note: some cables will come preconnected.
- Analyze the rhythm. If the AED unit instructs you to, CLEAR the victim while the machine is analyzing the victim’s heart rhythm. This means you should ensure that no one is touching the victim, including yourself. The rescuer performing chest compressions or giving breaths will need to stop at this point. Note: some AEDs will begin to analyze the victim’s rhythm independently; for others, you will need to push the ANALYZE button. Analyzing the victim’s rhythm will take up to 10 seconds, so don’t be alarmed by this.
- Push to shock. If a shock is advised, the machine will clearly state “SHOCK ADVISED, STAND CLEAR”. You should ensure that no one is touching the victim, including yourself. You need to look around to make sure no one is touching the victim’s body while stating “CLEAR” or some similar message that warns others a shock is to be delivered. Once you are certain that no one is touching the victim, push the SHOCK button. You will notice that the victim’s muscles contract strongly.
- If a shock is not necessary (the rhythm is not ventricular fibrillation or pulseless ventricular tachycardia), the AED will state NO SHOCK ADVISED and tell you to resume CPR
- After approximately 5 cycles of compressions and ventilations, or 2 minutes of CPR, the AED will instruct you to repeat steps 3 and 4- analyze the rhythm and push to shock if the rhythm requires a shock and the AED instructs you to do so.
- Continue CPR alternating with analysis of the rhythm until help arrives (i.e. EMS)