Almost 750 defibrillators across Ireland are in need of "urgent safety and maintenance updates", the Health Products Regulatory Authority has warned.
A software update or the replacement of a component is required in seven different models of Automated External Defibrillators.
"If the AEDs are not appropriately updated, the devices across the seven affected models may not work as required in the event of an emergency," the HPRA said.
It has called on all groups or organisations in possession of the estimated 10,000 defibrillators in Ireland to check if theirs is a model affected.
The seven AEDs models which require corrective actions are:
AED Plus (Zoll)
Samaritan 300P (Physio Control formerly HeartSine)
Samaritan 500P (Physio Control formerly HeartSine)
Lifepak 1000 (Physio Control)
Lifepak CR Plus (Physio Control)
Lifepak Express AED (Physio Control)
Fred Easyport (Schiller AG)
The HPRA website has further information for owners of affected models.
The HPRA is also calling on all AED owners to ensure that their devices are stored correctly and regularly checked during the winter months.
"Even if an AED has received all of the updates required, owners should remember that as we enter the winter months, it is critical that they store their AEDs appropriately. Defibrillators and their accessories can be badly affected by the weather and other environmental conditions," said Anne Tobin, HPRA Medical Devices Vigilance Manager.