Semi-Automatic vs. Fully-Automatic AEDs

Which to choose?

Semi Automatic AEDs

Many makes and models of automated external defibrillators (AEDs) come in two configurations – semi-automatic (SAED) and fully-automatic (FAED). The difference is that a semi-automatic AED has a button for the rescuer to push if a shock is required, and a fully-automatic AED does not; it automatically shocks the patient if a shockable heart rhythm is detected.

Sometimes the fully-automatic version is slightly more expensive. Someone investing in an AED may wonder if there really is enough of a significant difference between the two to warrant the slight price increase, especially considering all the other choices they are faced with during an AED purchase. In this article, we’ll shed some light on the differences, benefits, and which type might be best for you.

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?

We at AED Superstore have heard stories of well-intentioned or untrained lay users who have rushed to help perform a rescue, applied electrode pads, and then frozen when it came time to push the “shock” button. It may seem scary or risky in an already-stressful situation, and panicking is understandable.

A fully-automatic AED eliminates this opportunity for a rescuer to hesitate or freeze and not deliver a shock when it’s needed. The simple fact is that someone in sudden cardiac arrest is technically dead – they cannot be made any deader. Any and all rescue efforts can only be beneficial to the patient.

The Bottom Line

Both semi-automatic and fully-automatic AEDs are equally effective at saving lives. All AEDs provide clear, concise instructions throughout the rescue process. In addition, whether the AED is semi-automatic or fully-automatic, all AEDs will analyze the victim’s heart rhythm and determine whether a shock is required. No AED will shock someone “accidentally”, no matter how many times the shock button is pushed, if a shock is not advised.

The fact is, either configuration is a good choice. As long as there is an AED at hand, potential victims of SCA are better protected.

Here’s a sampling of the fully- and semi-automatic AEDs we offer:

To learn more, call 800-544-0048 Monday to Friday 7am – 7pm Central, and talk with a customer service expert who can answer your questions about AEDs.

One Response to “Semi-Automatic vs. Fully-Automatic AEDs”

November 19, 2017 at 2:55 am, Sammy said:

It’s a pity you don’t have a donate button! I’d certainly donate to this fantastic blog!
I guess for now i’ll settle for bookmarking
and adding your RSS feed to my Google account.
I look forward to new updates and will share this blog with my Facebook group.

Talk soon!


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