More than Just a Defibrillator?

Time is ticking when someone has a sudden cardiac arrest and, as we know, the sooner bystander CPR starts the better the chances of resuscitation. Even so, survival rates are only between 2-15%. Most sudden cardiac arrests encountered by a lay first aider exhibit ventricular fibrillation (VF) and while CPR can maintain a shockable rhythm for longer only defibrillation can reverse VF.

A study using data from the 1997 London Ambulance Service database showed 48 percent of witnessed cardiac arrests with bystander CPR had a shockable rhythm when EMS arrived, but only 27 percent of witnessed arrests without bystander CPR. (Dowie et al., 2003).

When individuals in VF receive CPR and early defibrillation, survival rates are massively increased to between 40-75%. Combined with the increasing availability of public and community AEDs in many countries, this is great news. Automated External Defibrillators (AEDs) are an integral part of EFR courses, so if you’re not already teaching AED use it’s time to get with the program!

But the benefits of AEDs are more than just defibrillation:

Public AEDS in places such as airports, leisure and shopping centres, usually trigger the activation of emergency medical services. So not only do you get an AED but the professionals are alerted and on their way, knowing which AED station you are near.

Community AEDs are usually in a “safe box” and have a pin code to unlock them, which is given by the emergency dispatcher when you call EMS. This has the benefit of protecting the AED until it needs to be used, ensuring EMS are on their way, giving the rescuer a trained dispatcher to advise them and making sure that, after use, the AED is returned to service as soon as possible.

AEDs talk their users through exactly what to do. Emphasise that we always follow the AED. Encourage your students to turn them on first and follow the prompts rather than assume they know what it will say. This helps users when they encounter a new style of AED or when protocols change and the AED has updated software. Demonstrate looking at the pictures on the pads and placing pads according to the diagram to ensure correct placement and use of the correct pads.

Many AEDs now also give feedback on the quality of CPR you are providing. They talk you through the steps, help maintain the correct rhythm and can even, in some cases, tell you whether you are pushing hard enough! Most AEDS do this by comparing what you’re doing to a preset range but others actually base their feedback on  how the CPR is affecting the patient rather than just what the rescuer is doing. They do this by measuring the impedance* between the pads.

As well as reminding users of the steps, AEDs automatically reassess the patient regularly to check for a shockable rhythm and make sure that a shock is only provided when beneficial. The average number of shocks varies, but usually between 2 and 3, however, be prepared to give as many shocks as indicated by the AED – there is nothing to lose.

In 2012, Fabrice Muamba, a professional footballer, suffered a cardiac arrest during a televised football game in the UK. It took 78 minutes for his heart to restart during which time he received numerous defibrillator shocks both on the pitch and during his transfer to hospital. Although he retired from professional football he recovered to lead a normal life and coach young footballers.

Most AED websites have stories about people who have survived cardiac arrest with the help of an AED – find local stories to inspire your EFR course participants and give them the confidence to care with an AED when available.

*Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied. In this respect the circuit is completed by the patient when attached to the AED.

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