Several types of defibrillators are used to deliver electric currents to the heart muscles and correct abnormal and life threatening heart rhythms.
The four main types of defibrillator include:
Advanced life support (ALS) unit
These tools are used in the healthcare setting such as in hospitals and ambulances and allow staff to monitor the patient’s heart rhythm and intervene manually if a shock is required.
The majority of units contain an in-built function that uses advanced algorithms to perform waveform analysis and recommend the charge that should be used. Many ALS units are equipped with additional functions such as the monitoring of carbon dioxide and oxygen levels, blood pressure measurement, temperature monitoring, and a myocardial infarction alert system.
Automated external defibrillator (AED)
AEDs are easy to operate units that may be used by the lay person or healthcare personnel who only have basic training. These machines analyze the cardiac rhythm and either instruct the delivery of shocks when required or deliver them automatically. As well as recommending that a shock is needed, the system can advise on the extent of the shock that should be delivered.
The drawbacks of this technology are that the AED systems can only be used to treat ventricular fibrillation and ventricular tachycardia and not other forms of cardiac arrhythmia. In addition, the machines can take around 10 to 20 seconds to diagnose the rhythm, a gap in time that can be by-passed by a trained healthcare provider using a manual unit.
Furthermore, in order to allow the machine time to analyze the cardiac rhythm, chest compressions usually need to be stopped.
Implantable cardioverter defibrillators (ICDs)
These units are placed directly into the chest of patients who are at high risk of sudden death, such as those with a medical conditions known to put them at risk or patients who have already experienced ventricular fibrillation or ventricular tachycardia.
These devices are used for patients who are known to be at a short-term risk of sudden death and in those who do not qualify as candidates for an ICD.
Reviewed by Sally Robertson, BSc