Inspections, Compliance, Enforcement, and Criminal Investigations
GUIDE TO INSPECTIONS OF ELECTROMAGNETIC
COMPATIBILITY ASPECTS OF MEDICAL DEVICE
statistical confidence of measurements, and costs. However, EMC cannot be achieved in every environment. Additional appropriate labeling may be necessary in some situations.
Comments on this guide are welcome and may be sent to: Joanne Barron, FDA/CDRH (HFZ-342), 2098 Gaither Road, Rockville, MD 20850 (e-mail address: email@example.com) and/or DEIO, Medical Device Group (HFC-130), 5600 Fishers Lane, Rockville, MD 20857 (internal e-mail address: firstname.lastname@example.org@fdaorahq).
- Design Control Guidance for Medical Device Manufacturers, FDA/CDRH, March 11, 1997;
- Do It By Design, An Introduction to Human Factors in Medical Devices, FDA/CDRH, December 1996;
- Design Control Inspectional Strategy Report, FDA, May 1997; and,
- Medical Device Quality Systems Manual: A Small Entity Compliance Guide, FDA/CDRH, December 1996.
Electrical and electronic products are capable of being interfered with and interfering with other products through transfer of any of several forms of energy. These forms of electromagnetic energy include:
radiated energy - through air or media such as walls,
conducted energy - through power and signal lines and cables, or
electrostatic discharges (ESD) - through air or direct contact.
FDA investigators may be familiar with the terms radiofrequency interference (RFI) and ESD with regard to GMP process controls. However, current standards use the term electromagnetic disturbance (EMD) for the electromagnetic environment to distinguish it from either of two possible responses of the product, electromagnetic interference (EMI) or electromagnetic compatibility (EMC). Electrical and electronic products can both produce and receive such energy (intentionally or unintentionally), referred to as "transmitters" and "receivers." Receivers are susceptible to degradation of performance - EMI - unless they are designed and constructed to be immune to the energies -EMC.
The goal of EMCis that expected energy in the environment - EMD - will not degrade the performance of a product and that the product will not interfere with another product. This means medical devices should:
- Account for the expected electromagnetic environment in the design and labeling of the device (from other medical devices, consumer electronic products, commercial and private radio transmissions, power line disturbances, and (ESD),
- Accomplish its intended purpose without degradation of performance in the expected environments, and
- Not interfere with other devices expected to be used in the same environment or provide sufficient labeling for safe use.
REMINDER: These can be confusing terms and acronyms.
- EMC - compatibility in the same environment - is our goal.
- EMI - interference - is what we want to prevent.
- EMD - disturbance - is the electromagnetic environment.
Over the past 20 years, several standards applicable to medical devices were developed with EMC requirements, primarily standards for military products (MIL-STD), the Association for the Advancement of Medical Instrumentation (AAMI) pacemaker standard, and a 1979 medical device EMC standard (MDS-201-0004). The latter two standards were written under contracts from FDA but were not adopted as mandatory; they are considered voluntary guidance. Recently, the international standards development process, in which FDA has participated, has developed significant and appropriate standards.