Watch enough detective or hospital television dramas and you’re bound to notice dramatic scenes where doctors attempt to bring patients back to life using a defibrillator! In reality, defibrillators are typically used on patients with cardiac dysrhythmias, also known as irregular heartbeat, and ventricular fibrillation.
As the name suggests, defibrillation stops fibrillation, the useless trembling that a person’s heart muscles can adopt during a cardiac arrest. Simply put, a defibrillator works by using a high-voltage to pass an electric current through the heart so it’s shocked into working normally again.
The kind of defibrillator you see on TV consists of an electric supply unit and two metal electrodes called paddles that are pressed very firmly to the patient’s chest using insulating plastic handles to ensure that the person handling it doesn’t get a shock too.
The important thing is getting the current to flow through the heart, so where the paddles are applied is crucial. One way of applying them is to put one paddle above and to the left of the heart and the other slightly beneath and to the right; another method involves placing one paddle on the front of the body and the other round the back.
In order for the electric current to flow properly, and to reduce the risk of skin burns, the electrodes have to be applied close enough together. They must also make good electrical contact with the skin, so a solid or liquid conducting gel is usually applied to the patient’s chest first.
You might have noticed that there are a lot more defibrillators in public places than there used to be and the reason for this is simple. If someone collapses with a cardiac arrest, immediate defibrillation, even by an untrained member of the public following step-by-step instructions, dramatically increases the chance of survival, compared to delayed defibrillation when the emergency medical services eventually arrive!