The following is a guide to the key features to look for when
purchasing an Automated External Defibrillator. (AED)
1) Fully automatic defibrillator vs semi-automatic
All AEDs automatically analyse the heart rhythm to determine if a shock is needed. However, there are
two types of lay-user AEDs – fully automatic and semi-automatic. If a shock is needed, semi-automatic
AEDs prompt rescuers to press a shock button. A fully automatic AED is designed to give a shock
automatically, if needed, without the rescuer having to push a button to deliver that shock. The device
communicates step-by-step instructions that let rescuers know when a victim is about to be shocked.
A fully automatic defibrillator requires minimal training to use. Fully automatic models are designed to
help responders who may hesitate in cardiac arrest emergencies, and may reduce extended delays
associated with hesitation to push the shock button during a rescue.
Automatic
Semi-Automatic
2) Environmental durability (IP Rating)
Electrical items, such as AEDs, can be sensitive to moisture and dust. As such every AED has an 'IP
Rating' which can be found in the AED brochure or user's manual. “IP' stands for 'Ingress Protection'.
This is a standard rating which classifies the level of protection that electrical appliances provide
against the intrusion of dust, water and foreign objects. The first digit in an IP rating refers to how dust
and dirt proof the device is. The second digit refers to how waterproof it is.
The higher the value of each number the higher the resistance to these contaminants. AEDs with
higher numerical IP ratings are designed for use anywhere, but especially in environments where dust
and moisture could be prevalent. You can use an AED's IP rating to determine if is built for the
environment you intend to use or store it in.
e.g. IP ○
2 ○
4
Solid particle protection
0
—
1
>50 mm
2
>12.5 mm
3
>2.5 mm
4
>1 mm
5
Dust protected
6
Dust tight
Liquid ingress protection
Level Protected against
0
Not protected
1
Dripping water
2
Dripping water when tilted up to 15°
3
Spraying water
4
Splashing of water
5
Water jets
6
Powerful water jets
7
Immersion up to 1 m
8
Immersion beyond 1 m
3) Energy – Fixed energy vs variable escalating energy
Fixed energy AEDs deliver the same level of energy for every shock, regardless of the individual.
The amount of energy delivered varies with each manufacturer and ranges from 150 joules to 360
joules. Some AEDs also escalate if the first shock is unsuccessful.
Other AEDs incorporate variable escalating energy. This technology identifies the patient's level of
energy impedance, resulting from muscle tissue, fat tissue and water retention. The AED then delivers
a customized shock based on the level of energy impedance. The level of energy then escalates for
subsequent shocks. This variable escalating energy ensures that even hard-to-defibrillate patients
receive the best chance for a successful outcome, while minimizing the damage to tissue that can result
from excess energy.
Will these two
people require the
same level of
energy for
successful
defibrillation?
4) Battery life
To save valuable time and as they may be needed in an area where there is no electrical outlet, AEDs
are powered by batteries. It can be said that AED batteries are one of the most important components
of an AED unit. Without a battery, the AED will not work. An important part of any AED program is
ensuring that your AED battery is charged and in working order. It can be a matter of life and death.
One quarter of AED failures can be linked to battery failure.
The longer the battery life, the easier an AED is to maintain and the more confident an owner will be.
Batteries can be single use and so need to be replaced after use. Other batteries are replaced on a
regular cycle, regardless of use. This cycle can be as long as four years.
Battery solutions range from consumer batteries purchased by the owner, a charge stick that charges
the internal battery, a battery pack containing CR123 batteries, or a medical grade lithium battery.
Medical grade Battery Pack
CR123 Battery Pack
5) Self-testing
Most AEDs are able to test their own circuitry, software and batteries regularly. A smaller number also
check for the presence and function of the pads. These AEDs will alert an owner if there is a problem.
Self-testing is one of the most important aspects of determining the reliability of an AED. Typically
AEDs with higher capacity batteries will provide the most comprehensive self-testing.
Rescue Ready Indicator
6) AED guidance / voice prompts
a) User paced prompts
All AEDs feature visual and/or voice prompts. These prompts instruct the rescuer on exactly what to do
from the moment they open the lid of the AED, including where to place the pads and how to perform
CPR. Some AEDs also include a metronome counting out the correct rate of compressions to breaths.
b) CPR feedback
Several AEDs now feature CPR feedback to help the rescuer achieve the correct rate and depth of
chest compressions. Recent studies show that correct compression rate and depth improve the
chances of survival. AEDs that include a CPR feedback device provide instructions to a rescuer so that
they perform CPR in accordance with resuscitation council guidelines.
CPR Feedback Device
7) Paediatric capability
Most AEDs offer paediatric capability. This may involve either a key system or paediatric specific pads.
The decision to utilise paediatric capacity mostly depends on the ability for rescuers to quickly decide to
use this capacity and change mode or pads accordingly.
As survival drops by 10% for every minute defibrillation is delayed, many non-professional owners of
AEDs choose to keep it simple and use adult pads. Guidelines also state that should paediatric pads
be unavailable the AED should still be used with Adult pads.
When using adult pads on children, a device with fixed low energy or variable escalating energy will
deliver a more appropriate level shock for their size than a device with fixed high energy.
8) AEDs and corrective action
The FDA reported that ¾ of AEDs require corrective actions so it is likely that your AED will require
some sort of service over its lifetime.
AEDs are a medical device covered by Medicines Regulations 1994 which must be registered with
Medsafe (New Zealand Medicines and Medical Devices Safety Authority) and the supplier is required to
have a process in place to deal with recalls and corrective action.
AED suppliers handle corrective action differently. Some will notify you of the actions required where as
others will manage the whole process. The most important thing is to ensure that you are never without
an AED whilst your product is being serviced. Ensure the supplier is able to provide a loan unit if
required.
Also consider how long the supplier has supplied AEDs. Consider whether they likely to be able to
support the product for its life time and check what manufactures warrantees and guarantees are
available.