An automated external defibrillator (AED) is a portable device that delivers an electrical shock to restore a normal heart rhythm during sudden cardiac arrest. The effectiveness of an AED depends entirely on its readiness to function. Proper maintenance, including the timely replacement of consumable components, is crucial for saving a life. The electrode pads are the interface between the device and the patient, making their replacement schedule a primary concern for AED owners.
Understanding Pad Shelf Life
AED pads have a defined shelf life, typically ranging from 18 to 60 months, depending on the model and manufacturer. This expiration date is clearly printed on the sealed packaging. The limited lifespan is primarily due to the conductive gel applied to the pad surface.
This gel ensures proper electrical transmission and adhesion to the patient’s skin, which is necessary for the AED to analyze the heart rhythm and deliver an effective shock. Over time, even in sealed packaging, the gel dries out and its chemical composition degrades. Loss of moisture compromises the pad’s ability to stick firmly to the skin, especially during chest compressions.
Poor adhesion results in an ineffective electrical connection, reducing energy transfer to the heart. Pads must be replaced before the printed expiration date, even if the packaging is undamaged and the pads have never been used. Using expired pads means the device’s ability to deliver therapy cannot be guaranteed.
Immediate Replacement After Deployment
Immediate pad replacement is required after any instance of deployment or usage. Pads must be replaced once they are removed from their sealed packaging and applied to a patient, even if no electrical shock was delivered. Once the seal is broken, the adhesive properties and gel conductivity are compromised.
Pads are designed for single-use only and cannot be reused. Applying used pads risks poor adhesion, which interferes with the device’s analysis and the effectiveness of any subsequent shock. The fundamental safety protocol is to discard the used set and install a new, unexpired set of pads immediately following any rescue attempt.
Custodians should have spare pads readily available or order a replacement set without delay to restore the AED to a rescue-ready state. Immediate replenishment ensures the device is prepared for a potential second sudden cardiac arrest incident.
Maintaining Overall AED Readiness
While the pads are a component, overall AED readiness depends on a comprehensive maintenance approach that includes the power source. AED batteries have their own standby life, typically between two and five years, varying based on the model and frequency of self-tests. The battery must be replaced when it expires and also after the device has been used to deliver a shock, as defibrillation significantly drains the remaining power.
Most modern AEDs conduct automatic self-tests daily, weekly, or monthly to verify the status of the battery, circuitry, and pad connection. These devices feature a readiness indicator light or status display that provides a simple visual confirmation, such as a green checkmark. If this indicator changes color or displays a warning symbol, it is an alert that the device has detected a fault, often a low battery or expired pads, and requires attention.
The owner or custodian of the AED should perform routine visual inspections to check the readiness indicator and confirm that the pad packaging seal is intact and the expiration date has not passed. Establishing a regular schedule for these checks and tracking the expiration dates of both the pads and the battery are necessary actions. A proactive maintenance plan ensures the AED will operate as designed when an emergency occurs.