An Automated External Defibrillator (AED) is a portable device designed to treat sudden cardiac arrest by delivering an electrical shock to restore a normal heart rhythm. Designed for use by bystanders with minimal training, AEDs are common fixtures in public spaces. The effectiveness of an AED relies entirely on its readiness, meaning every component must be fully functional and up-to-date. Understanding the lifespan and necessary maintenance of the unit, its electrode pads, and its batteries is paramount.
Electrode Pad Shelf Life
AED electrode pads are medical consumables with a limited shelf life due to the degradation of the conductive hydrogel. This gel facilitates the transfer of the electrical impulse and ensures proper adhesion to the skin. Over time, the moisture in the gel evaporates, compromising both its conductivity and adhesive properties.
If the conductive gel is degraded, the pad may not stick securely to the chest, or the electrical current may not be delivered effectively, reducing the chance of a successful rescue. Pad expiration dates are typically printed on the packaging and commonly range from two to four years, though some may last up to five years.
Adult and pediatric pads often have different expiration schedules, even for the same AED unit. For example, some manufacturers’ adult pads may last five years, while their corresponding pediatric pads expire after just two years. Regardless of the printed date, pads are single-use items and must be replaced immediately after any use, even if no shock was delivered.
Battery Lifespan and Replacement Scheduling
The power source is the most complex maintenance component, as its longevity is defined by two distinct metrics: standby life and operational life. Standby life refers to the time the battery remains installed, keeping the unit ready while performing routine self-tests. For most non-rechargeable lithium batteries, this standby period typically ranges from two to seven years, with four to five years being a frequent manufacturer specification.
Operational life refers to the actual capacity of the battery to deliver shocks or run the device during a rescue sequence. Using the AED for a rescue significantly drains the battery, and manufacturers mandate immediate replacement after any emergency use. The battery label may include a “Manufacture Date,” an “Install By Date,” and an “Expiration Date” to help track its viability, as the life clock often starts upon installation.
The AED’s visible status indicator is the primary tool for monitoring battery health in standby mode. This indicator, typically a flashing green light or an on-screen icon, confirms the battery has passed its most recent automatic self-test. If the indicator changes to red, or if the device begins to chirp, it signals a low power status or a failed test, requiring immediate replacement regardless of the printed expiration date.
Functional Lifespan of the AED Unit
The main AED hardware unit has a life expectancy separate from its consumable parts like pads and batteries. Most manufacturers design their units to have a functional lifespan of approximately eight to ten years from the date of manufacture. This period is often dictated less by physical breakdown and more by factors related to technology and support.
The unit’s lifespan is frequently tied to the manufacturer’s warranty period, which often extends for seven to eight years. After this period, the device may reach technological obsolescence, meaning replacement parts become scarce or the unit no longer meets new regulatory guidelines. Continued use is inadvisable if manufacturers cease providing essential support, service, or software updates.
Maintaining Operational Readiness
Ensuring an AED is ready for use requires a consistent, proactive maintenance routine that goes beyond checking expiration dates. All modern AEDs perform mandatory self-tests, which automatically check the internal circuitry, battery charge, and pad connectivity on a scheduled basis. The successful completion of these internal checks is communicated via the visual readiness indicator, which should be inspected frequently, often daily.
Routine visual checks should confirm that the electrode pads are sealed in their packaging and that the entire unit is free from physical damage. Documentation of these inspections and all component replacements is necessary to maintain compliance and a clear chain of readiness. Furthermore, installing firmware or software updates is a necessary part of long-term maintenance to keep the unit functional and effective.