There are four major categories of defibrillators:


Advanced Life Support (ALS) Units

ALS defibrillators, used by healthcare professionals in hospitals and ambulances, allow professionals to monitor the patient rhythm and manually intervene if it is determined that a shock is required. In addition, most of these units offer an Advisory or AED function, in which waveform analysis and shock recommendations are made based upon sophisticated algorithms contained within the device.

ALS units can be used with either paddles or electrodes, though the trend today is to use the defibrillation electrode as it is much safer for the rescuer and delivers the shock more uniformly and effectively.


Beyond the ability to deliver a shock, ALS defibrillators are often outfitted with a number of parameters to aid rescuers.

Most in-hospital ALS units will have an external pacing capability to allow external pacing of bradycardias.

Many will also offer SPO2, a means to monitor the oxygenation level of the patient via an external sensor.  

Other options available on ALS defibrillators include:

EtCO2 to monitor carbon dioxide levels.

Non-Invasive Blood Pressure (NIBP) units to automatically measure the patient’s blood pressure via a cuff.

Invasive Blood Pressure (IBP) used mainly with advanced transport units where patients with invasive lines can be managed during transport, either within the hospital or via ambulance or aircraft.

Temperature to monitor patient temperature.

Widely used by paramedics in the field is 12-lead EKG, which allows for rapid identification and classification of myocardial infarction. The EKG reading can be transmitted to receiving hospitals and alert cardiology teams that a patient requiring intervention is on the way. 

 CPR support:


A growing number of ALS defibrillators now also provide support for cardiac compressions. It has become exceedingly clear that good CPR is vital to improving resuscitation outcomes; it has also been determined that delivering good consistent CPR is difficult – even for highly trained professionals. Therefore, there is growing acceptance of the need for defibrillation products to not only be capable of delivering a shock, but also capable of assisting with delivery of optimal circulatory support.


Automatic External Defibrillators (AEDs)

SCA Survivor Stories and AED NewsThese units are designed for use by laypersons and basic life support-trained personnel. They are widely available in airports, schools, casinos and other public areas. They guide users through the application of the electrodes and automatically analyze the patient’s rhythm and either tell the rescuer to deliver a shock, or actually deliver the shock automatically. Many will also tell bystanders to start CPR, but only one AED, the ZOLL AED Plus currently coaches rescuers to deliver the correct rate and depth of compressions via the use of an accelerometer built into the electrode pad. As the importance of CPR delivery is increasingly realized to be a critical part of a successful rescue, this capability will most likely expand to other manufacturers.


Implantable Cardioverter Defibrillators (ICDs)

Type5These units are implanted directly into the patient’s chest and designed to protect those patients at high risk of sudden death. Generally, these are patients who have either a known medical condition that puts them at risk, or have actually experienced an episode of VF/VT. These products are beyond the scope of this website, and an in-depth discussion of these products can be found at the manufacturers' websites highlighted in the links to the right.



Wearable Defibrillators

LifeVest Jan 2006

These are an intermediate care option for patients with a short-term known risk of sudden death or who are not candidates for an implantable device. They are discussed more fully in the wearable defibrillator section of this website.