Defibrillators (AEDs)

How does a defibrillator work?

Designed to administer a therapeutic electrical charge to the patient, Defibrillators attempt to stabilise the rhythm of their heart. An AED (Automated External Defibrillator) first provides instructions to the carer to place the pads on the patient so it can diagnose whether the patient requires de-fibrillation. It does this by monitoring the hearts rhythm and if necessary, controls the strength of the electrical charge to be administered to the patient.

Technology has now developed to the point that some AEDs can be used by virtually any person regardless of training (although some basic training is always better than none). These models, which automatically deliver shocks to the patient, are known simply as fully-automatic defibrillators. They give clear auditory and visual instructions to the user ensuring their correct use and should the patient need to be shocked, the defibrillator will automatically administer it.

Semi-automatic AEDs are designed for users who have received previous AED training. Semi-automatic units will detect when a shock is required and alert the user, who can then deliver the shock. The device will still instruct the user when it determines that a shock is required but a button must be pushed for this to be carried out. Many semi-automatic units also have a pacemaker function for occasions where the victim's heart rate is too slow (bradycardia).

Who is responsible for maintenance of an AED?

There is no legal obligation for a defibrillator to be regularly serviced, simply that each AED is maintained according to its user manual. This typically involves a visual inspection and basic cleaning. Many defibrillators carry out automatic self tests on a daily, weekly and monthly basis and have a visual indicator if there is a problem with the unit. This is why regular visual inspection is absolutely essential.

Defibrillator batteries and electrode pads have a stand-by lifespan, and it is the Health and Safety Manager's responsibility to ensure that these components are replaced before the time scale is exceeded, and that the battery remains fully charged (if rechargeable) ready for an emergency. A defibrillator does not have a set lifespan. As long as the battery and electrode pads are replaced when needed, the defibrillator should continue to function correctly past its warranty period. A fault notification would be given should there be any problems.

We would always highly recommended some degree of training however it is no longer compulsory for people to be trained before using a defibrillator and for first aiders to attend regular refresher courses on how to operate them.

Adult vs Child-Suitable AEDs

Every AED in our range is suitable for use on adults and most, but not all, can also be used on children and infants. The difference in operation between the two is that child patients require a lower level of power, and how the different levels are applied varies between models.

The most common method is to attach child-specific pads to the electrodes that restrict the amount of electrical energy that is transferred. Other AED manufacturers opt for a system in which a key is inserted that puts the device into an infant-specific mode that reduces the output power level. This means that the same pads can be used on either adults or children, thereby reducing the need to replace more pads when they reach their expiry date.

Where children are among those who may potentially need the device, a model that supports it should certainly be purchased. However, it is commonly agreed that in cases involving a child patient who requires treatment with only an adult-specific AED available, it would be better to use the defib than to not in such an emergency situation.

Life-Saving Accessories

On some models a CPR (cardiopulmonary resuscitation) device is built in or can be attached. As per good first aid practice, CPR should be carried out on the patient in between shocks but the rate and efficiency with which chest compressions are carried out can vary greatly in the heat of the moment, particularly for those who do not regularly carry out CPR.

A CPR device can be built into the defibrillator or can be supplied as an additional pad which, when attached to the patient, gives audible feedback on the effectiveness of the CPR thereby letting the user know if chest compressions are being delivered with the correct rhythm and speed and to the right force and depth. This can mean the difference between the patient surviving or otherwise.