When buying an automated external defibrillator (AED), choosing a model can be a daunting task. When evaluating a defibrillator, you don’t need an exhaustive background in electronics or cardiac medicine, but with a growing number of manufacturers and a plethora of models and features, how can you know which type of AED will suit your needs?
Keep in mind that all defibrillators do one fundamental thing: they deliver an electric shock that resets the heart’s natural pacemaker and converts an irregular, unstable heart rhythm to a sustainable one. To accomplish this, all AED’s possess three basic elements: a battery that provides energy for the cardiac shock; a main unit that analyzes heart rhythms and generates the electrical charge; and the electrodes, or pads, that deliver the shock to the patient.
These similarities lead some to believe that all AED’s are the same, but there are differences. The features that distinguish defibrillators are component quality, user interface, and innovations in technology.
AED Shopping Tips
Getting to know a few simple details will quickly determine the overall quality of an AED:
- Better quality AEDs use medical-grade, lithium-ion batteries and do not rely on any secondary source of power to run self-checks or power the unit.
- Many units use a diagram to show the proper placement for electrodes and the polarity (positive or negative) of each. The best public-use AED’s simplify this process and use non-polarized electrodes that can be placed interchangeably.
- Most Health-Canada approved AEDs have been drop tested to just over a meter and are designed to survive rough treatment.
A product specification associated with durability of any electronic equipment is the IPX rating. The IP Code is an International (or Ingress) Protection Rating and is expressed as IP followed by a two-digit number. The first digit indicates the level of protection against particles such as dust or dirt; the second gives the level of protection from water. The higher the number, the greater the resistance. Every AED has an IP Code which can usually be found in the user’s manual.
The most visible features that differentiate AED’s are those that indicated ease of use and quality of performance. As public access defibrillation programs become more commonplace, simplicity in design and use become paramount. There are a few factors to consider when purchasing an AED:
- How many buttons (if any) do I have to push for a shock?
- Are there voice prompts and a display to guide me during a rescue?
- Will the unit’s prompts assist me with delivering CPR to the victim?
Many units run daily, weekly and monthly self checks. It is important to purchase a unit that checks issues such as the presence of electrodes, pad connectivity, battery life and wire conductivity as they increase the potential life of your unit.
Time spent remembering or figuring out how an AED works and how to apply the pads can make the difference between a save and a non-save when using a defibrillator. Features that limit this time are invaluable.
The most important component of an AED’s design is the technology used to deliver a shock.
There are two methods of shock delivery: fixed energy and escalating energy. With fixed energy, a shock is delivered once at a given level measured in joules (J), and then subsequently redelivered until there is a correction in the heart’s rhythm. With escalating energy, if the first shock is unsuccessful, the AED progressively increases the energy of subsequent shocks until reaching the maximum allowable number of joules and redelivers shocks at that level.
When purchasing an AED, it is important to find a unit that is not only capable of escalating the shock energy, but of doing so beyond 200J. While an initial shock of 200J is usually successful in an out-of-hospital environment, there are exceptions and escalation above 200J is necessary to maintain success for multi-shock patients. In cases of sudden cardiac arrest (SCA), refibrillation is not just common, it is expected… as long as the AED is up to the task.
There are some costs associated with buying and setting up an AED. Making an informed purchase decision ensures that the hard-earned money you to spend will give a potential SCA victim the very best chance of survival.