What Semi- and Fully-Automatic AEDs Have in Common

Both fully- and semi-automatic AEDs function largely the same way:

• Both types of AEDs require that the rescuer properly apply the electrode pads to the patient.
• When using either type of AED to deliver a shock, nobody else can be touching the patient when the shock is administered.
• Neither a semi-automatic nor a fully-automatic AED will shock a patient unless the device detects a shockable rhythm in the patient’s heartbeat. This means there’s no risk in “accidentally” shocking or hurting a person with a normally functioning heart who just happens to be unconscious.
• Depending on the make and model of the AED, rescue instructions will be provided via voice and may include text prompts or light indicators. CPR instructions may also be provided.
• Both types of AEDs provide a life-saving shock to someone experiencing a cardiac event.

Benefits of a Semi-Automatic AED

With a semi-automatic AED, if the unit advises the rescuer that a shock is required, the rescuer has two specific actions to take:

1. Ensure everyone is clear and nobody is touching the patient.
2. Push the flashing shock button.

Semi-automatic AEDs provide the rescuer(s) with control over when the shock is administered. This can be desirable because it allows rescuers to ensure nobody is in contact with the patient’s body at the time of shock. While an AED won’t shock a patient unless a shockable rhythm is detected, the device doesn’t know if someone else is touching the patient. Delivering an appropriate shock will be beneficial to the patient but may also leak to another person who’s touching the patient at the time the shock is delivered. This may be unpleasant, to say the least, but may also bleed off current needed to re-establish an effective heartbeat.

Benefits of a Fully-Automatic AED

Once the electrode pads are applied to the patient, a fully-automatic AED administers the shock automatically when needed, without any further human action. It gives the rescuer time to stop CPR, advises them to not touch the patient, and gives a countdown to the shock. An example would be: “Shock advised. Do not touch the patient. Do not touch the patient. Shock will be delivered in 3…2…1. {shock} Shock delivered. Start CPR.”

When using a fully-automatic AED, the rescuer isn’t responsible for pushing the button and instead only has one action to take: making sure no one is touching the patient when the shock is delivered.

How to Choose Between Semi- and Fully-Automatic AEDs

When choosing between semi-automatic and fully-automatic AEDs, consider who may potentially use your AED:

• Are they likely to remain cool and calm?
• Will they be inclined to tense up during a crisis?
• Have they had any training in AED use?
• Is the AED going in a public place, so anyone (trained or untrained) could use it?