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Automatic External Defibrillator (AED)


An automated external defibrillator (AED) is a portable electronic device that automatically diagnoses the potentially life threatening cardiac arrhythmias of ventricular fibrillation and ventricular tachycardia in a patient, and is able to treat them through defibrillation, the application of electrical therapy which stops the arrhythmia, allowing the heart to reestablish an effective rhythm.

With simple audio and visual commands, AEDs are designed to be simple to use for the layman, and the use of AEDs is taught in many first aid, first responder, and basic life support (BLS) level cardiopulmonary resuscitation (CPR) classes

What are the first steps in selecting the right AED for your needs?

When choosing an AED remember that the simplest possible layout is the easiest to use. When someone has to use an AED to help a victim of cardiac arrest the rescuer may be trained or they may be totally untrained. The rescuer will probably also be under a lot of stress as they attempt to save someones life. For these reasons look for a defibrillator with a simple intuitive layout. Avoid AEDs with lots of unnecessary controls, buttons or switches, they will only confuse the user when a real resuscitation is attempted.

In general, all AEDs on the UK market today operate in the same way. The AED will first need to be switched on either by pressing an “on” button, opening a case or pulling a handle (depending on the model chosen).

As soon as the AED is switched on it will start to give voice instructions. AEDs with text screens will also give text instructions on the screen. The first instruction you will hear will be to remove clothing from the patients chest and to place the two pads on the patients chest as shown on the pads and/or on the AED itself. Once the pads are in place the AED detects the pads have been attached and analyses the patients heart beat, this takes a few seconds and the AED will instruct you not to touch the patient. If the AED detects that the heart is in cardiac arrest and that a defibrillation shock is required it will (if you have a SEMI AUTOMATIC AED) give voice and/or text instructions for the rescuer to press the shock button. The AED will not allow a shock to be delivered unless it detects a potentially fatal heart rhythm that requires a shock so you cannot accidentally deliver a shock to the patient. If you have a FULLY AUTOMATIC AED you will not need to press the shock button as the machine will automatically deliver a shock once it has warned the rescuers to stand clear. A Manual AED allows the user to set defibrillation energy levels and to deliver a shock without the AED carrying out an analysis. This option is only suitable for use by appropriately qualified medical staff or doctors. Manual AEDs require an ECG display to allow the user to view the patients heart rhythm. AEDs may have various differences in specification for example energy levels delivered or escallating or fixed energy levels. These differences need normally only be considered if you have a specific technical or medical need for a particular specification in which case you should consult with a technical or medical specialist from the AED supplier. In most cases a standard 200J (Joule) energy level is considered appropriate for an AED. As stated above all AEDs essentially operate in the same manner. To select an AED suitable for your particular requirements you should consider the questions listed here——>

Where is the AED likely to be used?

If used only indoors you do not need a high level of environmental protection. Look for an “IP” number in the specification (for example “IP54” ) which will tell you what sort of protection from rain and dirt is built into the AED. See the table here for a full description of the various IP levels. A good “general purpose” AED suitable for most indoor and outdoor applications should have an environmental protection IP number of IP54 or better. If the AED may be used in a very noisy environment voice commands may be difficult to hear. In this case a unit with a backlit LCD text display may be appropriate as instructions can be read from the screen and you dont have to rely on voice instructions. If the AED may be used in dark or poorly lit environments you may need a unit with a backlit LCD text display and/or ensure that a good quality head torch is included in your AED package. Semi Automatic or Fully Automatic? As described opposite you can purchase either semi automatic or fully automatic AEDs. In most cases UK users prefer semi automatic AEDs as this allows the rescuer to confirm the final decision to deliver a shock after the AED has advised that a shock is needed. It has however been suggested by some researchers that some users are reluctant to press the shock button (even though the machine has identified a potentially fatal heart rhythm that requires defibrillation). This problem can be overcome by a fully automatic AED as the AED does not need the rescuer to press the shock button to deliver a defibrillation shock. What sort of battery do you need? In general AEDs can be supplied with non rechargable Lithium batteries or rechargable batteries. Most AEDs use dedicated batteries made by the AED manufacturer and cannot use standard battery types although there are a few exceptions to this. Batteries not only power the AED when it is being used for a rescue but also maintain the AED in a “standby” condition and power daily or weekly self tests of the AED to ensure the AED is functioning correctly at all times. Non Rechargable batteries have the advantage of a long shelf life, lower cost and a long life once installed in an AED. Typically non rechargable batteries will last for about 4 years in “standby” mode and can provide power for a number of rescue attempts. Rechargable batteries are more expensive and require a seperate recharger however if the AED is likely to be used frequently for rescue attempts or for training then a rechargable battery is a good choice. It is however important to note that a regular program of recharging must be established to ensure a rechargable battery is always fully charged when needed for a rescue attempt. Some AEDs can be used with both rechargable and non rechargable batteries. This means you can switch between battery types as required. Some other AEDs can only be used with one or the other and do not have the option of switching between battery types Most non medical users of an AED normally choose a non rechargable battery for their AED. It is important to note that one of the most common reasons for AEDs not functioning when needed for an emergency is a flat battery! For this reason AED batteries of all types should be checked regularly and replaced as recommended in the AED user manual. A spare non rechargable battery is also worth considering.

What other features should I consider? Some AEDs provide an “ECG DISPLAY”. This displays the patients heart rhythm as a moving graphical trace and can be extremely useful for users who have been trained in reading and understanding ECG traces. ECG stands for ElectroCardioGram and is a graphic tracing of the electrical signals generated by the heart as detected on the body surface. Do I need an ECG Display?

ECG diplays can be useful where the AED is likley to be used by an operator who is qualified to read and interpret ECG tracings. For most AED users ECG Displays are not necessary however a unit with an LCD Display frequently offer the user the option of viewing an ECG. ECG signals may be detected through the defibrillation pads or on some AEDs there is an option for a seperate patient cable and ECG electrodes to enable long term monitoring of the patient. This can be useful where monitoring of the patients condition is important and immediate emergency evacuation is unavailable for example in remote or inaccesable locations, on ships or boats etc.

Will I need anything else? If you have reviewed the links above suggested for everyone considering an AED purchase you will realise that some form of training is highly recommended. The training you require will be dependant on many factors and you should read the guidance of the Resuscitation Council (UK) for more information. You will need to consider where you are going to locate your AED, how it is going to be stored and how you are going to indicate its location. The Resuscitation Council (UK) offer guidance on some of these issues. A Number of other items such as wall mounts, response kits etc may also be required. Please visit our PRODUCT RANGE page to see the full range of SaverOne AEDs with full details of their features and capabilities.

What Training will I Need? Training is strongly recommended although there is no legal requirement to be trained in order to use an AED. Modern AEDs are designed to be used by untrained personnel and in an emergency an untrained user using an AED can successfully help save a life. Training will however increase the chance of a sucessful resuscitation and should be undertaken by anyone who thinks they may need to use an AED at some time. Training can be undertaken at training courses run by various organisations, on site training is available from many different training companies and some ambulance services also offer training. The “Resuscitation Council (UK) CPR/ AED training manual with DVD” Is the definitive guide to training on AEDs and Cardio Pulmonary Resuscitation (CPR) and is supplied as standard with some AED packages.

Do I need anything else? You should consider suitable signs and stickers to indicate the location of your AED. The Resuscitation Council (UK) has a recommended standard sign which should be used in the UK and Ireland. This is available from many AED suppliers and may be included in some AED packages You should also consider where your AED will be stored. It needs to be easily accessed by potential users. In most cases the AED is best stored in a highly visible location such as the wall of an office, warehouse, factory or reception area and should be mounted on a wall bracket fixing, wall mount or in a suitable AED cabinet. If the AED is kept outdoors a suitable environmentally controlled cabinet may be required for protection from heat, cold, rain and physical damage. A Wall poster that summarises how an AED should be used is an invaluable item to be displayed next to you AED. This poster will refresh trained users on the steps required for a sucessful resuscitation and can also provide guidance for untrained users in an emergency. Suitable posters may be included in some AED packages A response kit is a useful kit of items that may be required to assist with a resuscitation. Typically such a kit will include a pair of paramedic shears to cut clothes, ties etc to speed up the process of clearing clothing to access the patients chest, a “pocket mask” to assist with CPR (mouth to mouth resuscitation), a chest razor to remove hair from hairy chests which can prevent pads sticking to the skin correctly, high absorbancy towel to dry the patients chest before pads are attached (patients chest may be wet due to perspiration, rain, immersion in water etc). Some kits also contain a head torch for resuscitation in a dark or poorly lit environment, a card listing the main elements of the resuscitation process and other items.


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