Many people know what a defibrillator is and how they are used to save lives.
However, most people don’t realise that, once purchased, these technical pieces of equipment require regular maintenance and testing to ensure they continue to deliver life-saving support.
In fact, the Medicines and Healthcare products Regulatory Agency (MHRA) recently reported that more than 10,000 AEDs across the UK may not deliver the sufficient electrical shock required in a cardiac emergency.
The facts
A cardiac arrest happens when the heart cannot pump blood around the body.
In the UK there are an estimated 30,000 out of hospital cardiac arrests (OHCA) annually. And the chances of surviving an OHCA are 1 in 10, which increases to a 1-in-5 chance of survival if the cardiac arrest occurs within a hospital.
Defibrillators offer basic life support and can be instrumental in keeping someone alive until the emergency services arrive to administer further care
Unless there is immediate intervention from cardiopulmonary resuscitation (CPR) and defibrillation, survival rates fall at a rate of 10% per minute.
So how do defibrillators work?
Defibrillators are medical devices that are commonly used to treat irregular heartbeats known as cardiac arrhythmias.
External defibrillators can be used to treat serious life-threatening cardiac rhythm conditions such as ventricular fibrillation (VF), as well as the lesser ominous rapid rhythms of atrial fibrillation (AF), atrial flutter (AFL) and ventricular tachycardia (VT).
These devices work by applying a countershock (a strong electric current) to a patient with the purpose of converting their rapid, ineffective and unco-ordinated heart rhythm disorder to a more-organised, normal and slower rhythm – allowing the heart to efficiently pump blood around the body.
What devices are on the market?
There are two types of defibrillator: external and internal.
Internal defibrillators – implantable cardioverter defibrillators (ICD) - are similar to pacemakers, monitoring the heart’s electrical activity to deliver a shock if needed.
An external defibrillator can be operated to deliver a shock to the patient suffering from cardiac arrest.
Automated external defibrillators (AEDs), often referred to as public access defibrillators (PADs), are easy to use and are becoming increasingly common in public areas, including health centres, hospitals and care homes.
They offer basic life support and can be instrumental in keeping someone alive until the emergency services arrive to administer further care.
Modern AEDs are robust, portable, and comprehensive medical devices that offer an all-in-one life support solution. Higher-specified, top-of-the-range models can also provide readings on:
- Blood oxygen saturation levels
- Non-invasive blood pressure
- Invasive blood pressure
- Temperature
- Respiration
- Carbon dioxide levels
- ECG
Typically, defibrillators are internally battery powered and can be charged and powered using AC mains power or a DC adaptor. The energy output from the paddles ranges from 1 to 200J, or 1 to 360J into an impedance typically ranging between 25 to 200Ω. Biphasic is also now the waveform of choice by many manufacturers over monophasic, as biphasic shocks are more effective and need less energy.
Who can use a defibrillator?
You don’t need to be trained to use a defibrillator – anyone can use it. There are clear instructions on how to attach the defibrillator pads and use the equipment. The device then assesses the heart rhythm automatically and will instruct you on how to deliver a shock if it’s needed.
Testing
Defibrillators are critical life support and resuscitation devices that must be tested to ensure full functionality is available at all times.
Testing will ensure that the devices are safe, accurate, and meet manufacturers’ specifications as well as their intended purpose of use
Testing will ensure that the devices are safe, accurate, and meet manufacturers’ specifications as well as their intended purpose of use.
A typical test procedure to ensure electrical safety and performance of an external defibrillator will consist of the following tests:
- Visual inspection
- Battery performance
- Energy output
- ECG performance
- Pacer output
- Pulse width
- Electrical safety test
If you have suitable resource and expertise within an organisation, you can carry out the testing in house. However, if that’s not the case, it is worth employing a contractor to carry out the testing for you.
But, as with any contractor you employ, it is important to carry out checks on competence, risk assessments, insurances, method statements etc ahead of commencing work.
