The Food and Drug Administration is warning consumers that some automated external defibrillators (AED) may not work during a cardiac emergency.

An AED analyzes heart rhythm and can deliver an electric shock which can restart the heartbeat of those experiencing cardiac arrest or the sudden loss of heart function. They are usually found in public places to help during an emergency before paramedics can arrive.

The devices in question are made by Philips Medical Systems, a division of Philips Healthcare. They were the focus of a previous recall, but some people may still have them in their possession. The FDA urged consumers to inspect and monitor the capabilities of these AEDs, as well as know how to use them during an emergency in case they are the only option available.

In this case, the FDA says it is better to keep using the defibrillators until they can be replaced even though they might fail. It says the risk of not using the device is greater than the risk of doing nothing if someone is having a cardiac emergency.

The defibrillators under question were manufactured and distributed between 2005 and 2012 under the names HeartStart FRx, HeartStart HS1 Home, and HeartStart HS1 OnSite. The recall of these devices started in 2012 because it was discovered that an internal electrical component was not working, causing the machine not to give a shock.

Here is a link to more information from the FDA.