The FDA has released a final guidance for electromagnetic compatibility (EMC) for medical devices, a policy that applies to PMA, 510(k), and de novo devices. However, the scope of the guidance also covers investigational devices, suggesting that these products may have to demonstrate EMC compatibility even when the final design is still under consideration.
The new EMC final guidance replaces a guidance that went into force in 2016, while the draft version of this latest edition was released in November 2020. The guidance does not apply to in vitro diagnostics until June 2023, but is already applicable to all other device products, although the guidance does not specifically mention combination products with a device component. A number of products that are regulated by the FDA’s Center for Biologics Evaluation and Research also fall within the scope of the guidance.
The guidance acknowledges that it may not be practicable to evaluate the EMC of an investigational device with the use of consensus standards. In this instance, the manufacturer may make use of alternative approaches, such as ad hoc standards, to demonstrate compatibility, but any such approaches to a demonstration of EMC in an investigational device should be justified and documented.
The FDA made reference to a number of relatively novel potential sources of EM interference, such as cellular 5G transmissions, as a potential source of concern. Because electrocautery devices are infrequently encountered, device manufacturers may not be aware of a need to account for these and other rarely encountered devices as sources of EM. These and other potential sources of interference should be factored into risk management activities, the guidance stated.
The FDA defined EMC as the ability to function safely and effectively in its intended electromagnetic (EM) environment, which entails a demonstration of immunity to EM disturbances without introducing another set of disturbances that affect other medical devices or equipment. However, this may require a different type of testing depending on the environment of intended use. The guidance lists the healthcare facility environment, the home healthcare environment and the special environment as each presenting a more or less unique set of considerations for demonstrating EMC.
The guidance includes the operation of magnetic resonance imaging (MRI) systems as an example of a special environment rather than as an example of a healthcare facility environment. In this instance, the distinction revolves around the use of high energy magnetic and/or electrical fields, such as would be the case with short-wave therapy equipment.
Of some interest for the FDA are devices that employ electricity to perform their function, including active implanted medical devices and devices that rely on sensors to perform the indicated function. However, the process of determining a device’s EMC pass/fail criteria is somewhat dependent on several factors, such as whether the device is a component of a larger device or is a device with electronic components that may be subject to EM interference.
Another point of consideration is whether the device is likely to be exposed to continuous sources of EM interference rather than intermittent or occasional exposures. A recovery time may be permitted when the environment of use seems to suggest non-continuous sources of interference, but a device that may encounter a continuous source of interference may have to demonstrate the ability to continue functioning despite the interference.
A sponsor or manufacturer may make changes to an existing device design in order to create compatibility, which should be documented in the device’s record. The FDA indicated that EMC testing might not be required after making such changes to a device, but said that the manufacturer should be able to justify a decision to not conduct additional EMC testing. Any such changes should also be evaluated for any potential impact on considerations such as biocompatibility, sterility, and the potential to interfere with the operation of any embedded software.