On the 6th of June, 2022, the United States (U.S.) Food and Drug Administration (FDA) released a new electromagnetic compatibility (EMC) guidance for medical devices [1]. This new guidance replaces the guidancefrom 2016 [2] and does now also explicitly cover in-vitro diagnostic (IVD) products. This blog gives an overview of the FDA EMC guidance from 2022.
1. What has changed?
What has changed from the FDA EMC guidance for medical devices of 2016 to the guidance of 2022? Generally speaking, the guidance of 2022 gives more concrete information and goes much more into detail than the guidance from 2016. Here are some points:
Scope II. IVD products and medical device accessories are now also covered by the FDA EMC guidance 2022 (with a transition period for IVD products of 1 year after the release date of the guidance, compared to 60 days for all other medical devices).
Scope II. IVD products and medical device accessories with functions or sensors implemented using electrical or electronic circuitries are now explicitly covered by the FDA EMC guidance 2022.
Overview III. IEC/ISO 80601 standards are explicitly mentioned in the FDA EMC guidance 2022.
Section IV.
A. Compared to the 2016 guidance, the guidance of 2022 gives concrete examples of how to describe EMC-related device characteristics and lists examples of the Intended Use Environments of the medical devices.
B. Compared to the 2016 guidance, the guidance of 2022 explicitly mentions the categories of the severity levels of the medical device risk assessment.
C. Compared to the 2016 guidance, the guidance of 2022 explicitly lists the FDA-recognized consensus standards.
D. Compared to the 2016 guidance, the guidance of 2022 gives a definition of the term Essential Performance and describes the pass/fail criteria in more detail.
E. Compared to the 2016 guidance, the guidance of 2022 gives a detailed description of how to describe the product's configuration (modifications, power supply, and external connections) and in which operating modes a product should be tested.
F. Compared to the 2016 guidance, the guidance of 2022 describes how the EMC test results should be described and summarized.
G. Compared to the 2016 guidance, the guidance of 2022 describes allowances in more detail.
H. Compared to the 2016 guidance, the guidance of 2022 describes deviations in more detail and explains the difference between an allowance and a deviation.
I. The section about modifications has not changed significantly from the guidance 2016 to the guidance 2022.
J. Compared to the 2016 guidance, the guidance of 2022 adds a section about common electromagnetic emitters, that may not be covered adequately by the FDA-recognized consensus EMC standards.
K. Compared to the 2016 guidance, the guidance of 2022 describes the labeling of the product in more detail.
Section V. Compared to the 2016 guidance, the guidance of 2022 describes how to handle EMC testing for Investigational Device Exemptions (IDE) and Investigational New Drugs (IND).
Appendix A. Compared to the 2016 guidance, the guidance of 2022 examples of medical device locations and links them to the Intended Use Environments.
2. Terms and Definitions
Before we start off, you can find below definitions of some of the most important terms of the FDA EMC guidance.
2.1. Essential Performance
The term Essential Performance is at the core of the 60601/80601 and 61326 EMC standards.
"Essential Performance is the performance of a clinical function, other than that related to Basic Safety, where loss or degradation beyond the limits specified by the manufacturer results in an unacceptable risk. Note: Essential Performance is most easily understood by considering whether its absence or degradation would result in an unacceptable risk." - ANSI/AAMI/ES 60601-1:2005
The Essential Performance is defined by the manufacturer of the medical device and it is stated in the EMC test plan. Essential Performance statements could be: "Providing a test result within the specified range.", "To be able to perform pump blood with the specified flow rate.", "Providing no test result with an error or warning message to the user.".
2.2. Immunity Pass/Fail Criteria
Immunity pass/fail criteria should address the degradation of the medical device’s functions caused by the test disturbance. The EMC test plan should specify which degradations are considered acceptable. Acceptance criteria should be documented in the EMC test plan before testing. It is recommended that the manufacturer specify detailed immunity pass/fail criteria that are (1) quantitative, (2) specific to the medical device and functions, and (3) observable.
2.3. Allowance vs. Deviation
Allowances are specifications within a consensus standard that permit well-defined or conditional variations of, or exemptions from, certain requirements of the standard.
A deviation from a consensus standard is when a requirement of the consensus standard is intentionally not satisfied, or testing is performed in an alternative way other than that specified and allowed in the standard.
The difference between a deviation and an allowance is that an allowance is specified in a standard, whereas a deviation is not.
3. Medical Devices and EMC
Compared to other electrical and electronic products like TVs or general electronic devices, medical devices have to prove their immunity to electromagnetic phenomena in the U.S.
3.1 Device Characteristics and Intended Use Environment
Firstly, for a manufacturer of medical devices, it is necessary to describe all EMC-related device characteristics:
Overview of the device and its functions and modes, including block diagrams, photographs, cables, relevant accessories, and device interoperability.
Description of the power supply (i.e., mains-powered only, internally-powered only, mains and internally-powered) including if the internally-powered medical device can be used while charging.
Statement regarding the environments in which the medical device is intended to be used.
Description of any wireless technology (for additional considerations regarding wirelessly-enabled medical devices, refer to FDA guidance, Radio Frequency Wireless Technology in Medical Devices [3]).
Description of any intentional RF emitters in the medical device that could be sources of EM disturbances.
Secondly, it is necessary to specify the Intended Use Environments:
Professional Healthcare Facility Environment. Any environment where personnel with medical training are continually available to oversee or administer the use of medical devices. This includes, but is not limited to, hospitals, long-term care facilities, nursing homes, limited care facilities, emergency medical services, clinics, physicians’ offices, outpatient treatment facilities, and clinical laboratories.
Home Healthcare Environment. Any environment where personnel with medical training are not continually available to oversee or administer the use of medical devices. This includes, but is not limited to, outdoor environments, office environments, schools, vehicles, emergency shelters, and independent living retirement homes.
Special Environment. Any environment with EM characteristics is different from those specified in EMC consensus standards. This includes, but is not limited to, aircraft, military areas, heavy industrial areas, medical treatment areas with
3.2. Risk Assessment
The manufacturer has to summarize the risks associated with malfunction, disruption, or degradation of the performance of the subject medical device due to EM disturbances. More guidance about risk assessment by the FDA can be found here [4].
3.3. Consensus EMC Standards
The medical device configuration and intended use environments can determine the applicability of FDA-recognized consensus standards for EMC.
Non-implantable Medical Devices. ANSI/AAMI/IEC 60601-1-2 is recognized by FDA for testing non-implantable medical devices that are within its scope. Most laboratory equipment and IVD devices are outside the scope of 60601-1-2. The FDA does partially recognize IEC 61326-1:2020 (general laboratory) and IEC 61326-2-6:2020 (IVD) and recommends using the test methods from these standards. However, the FDA recommends using acceptance criteria specific to the device’s functions and intended use. Additionally, FDA recommends using test levels specified by 60601-1-2 or, alternatively, determining the reasonably foreseeable maximum levels of the electromagnetic phenomena in the device's intended use environments (e.g., through the study of published literature or environmental measurements).
Active Implantable Medical Devices (AIMDs). The ISO 14708 Series and ISO 14117 standards assess AIMD performance when exposed to commonly encountered EM sources and particular sources that an implantable device is likely to encounter. For example, cardiac implantable electronic device consensus standards (e.g., ISO 14117) include immunity testing for exposure to defibrillation devices, which inject high-energy electrical signals into the heart for life-saving functions.
Special Environments. It is important to understand the scope and limitations of each standard. For example, 60601-1-2 is generally applicable to both the home healthcare environment and the professional healthcare facility environment. However, if a medical device is intended to be used in a special environment, FDA recommends that the manufacturer provides additional EMC information and perform testing for the given special environment. This could be achieved by referencing appropriate standards for each special environment. For example, the FDA recommends immunity testing to RTCA DO-160 Environmental Conditions and Test Procedures for Airborne Equipment for non-implantable medical devices that are intended or expected to be used in an aircraft environment. Note that some AIMD consensus standards do not specify EMC test parameters for use in a magnetic resonance imaging (MRI) environment (e.g., exposure within the bore of an MRI system). Where an applicable AIMD standard does not specify such requirements, the FDA recommends test methods specific to this potentially high-risk environment, such as those described in ISO/TS 10974 Assessment of the safety of magnetic resonance imaging for patients with an active implantable medical device.
More information about consensus standards by the FDA can be found here [5].
3.4. Essential Performance and Immunity Pass/Fail Criteria
The manufacturer has to provide clear immunity pass/fail criteria, and, if applicable, a clear statement of the device’s Essential Performance.
3.5. Medical Device Configuration and Functions Tested
The manufacturer has to provide a detailed description of the medical device under test, including the configuration, functions, modes, and settings that were tested. The most sensitive functions of the medical device should be tested in the most sensitive operation mode, which most likely results in an unacceptable risk or to not achieve its intended use. The description of the device under test should include the medical device name, model number, manufacturer, and an indication of whether the device is the final production-ready medical device currently under review.
3.6. Results of EMC Testing
The FDA recommends that the summary of EMC testing include the following:
Name and location of the test facility, the date of the testing.
Results for each emissions test. Pass/Fail criteria should be expressed in terms of limits, against which the medical device’s measured emissions are compared and should not exceed.
Results for each immunity test performed (e.g., ESD, voltage dips, radiated immunity). This should include any degradations that were observed during and after each immunity test for continuous phenomena and after each immunity test for transient phenomena. For all degradations, you should detail how the medical device continued to meet the
3.7. Allowances
The FDA recommends that the manufacturer provide a description of all allowances used, with a justification to support the use of each allowance. The allowance should only be used if all the specified conditions of the allowance are satisfied. The use of allowances should not increase risks to patients or operators. If the conditions for use of an allowance cannot be justified, then the allowance should not be used.
3.8. Deviations
The FDA recommends that the manufacturer provide a description of all deviations used along with a justification to support the use of each deviation. Deviations from a referenced consensus standard should be supported with a justification that explains how the deviation would not adversely impact the safety or performance of the medical device.
3.9. Modifications
When a medical device is modified to pass EMC testing, the FDA recommends the following information be provided:
A description of all changes or modifications that were made to the medical device in order to pass EMC testing.
A statement of whether the provided EMC test results occurred before or after the modifications were incorporated into the medical device. If EMC testing was not performed after the modifications were made to the medical device, risk analysis and scientific justification should be provided that the modified medical device does not adversely impact the safety or performance of the medical device.
A statement indicating that the changes will be incorporated into the final finished medical device prior to marketing; the changes must be documented in the design history file in accordance with design controls.
An analysis as to whether these modifications might impact other aspects of the medical device safety or performance, such as whether they increase risks to patients or operators, alter the biocompatibility or sterility, affect electrical safety, or introduce software anomalies/defects.
The FDA recommends that manufacturers consider the following to help determine the appropriate device configuration(s) for testing:
The device should be tested as a system with all medical device accessories, components, and subsystems connected and functioning as intended. If non-medical equipment is used in a medical system and could affect the ability of the medical device to meet the immunity pass/fail criteria, the non-medical equipment should also be tested as part of the medical device system. Examples of non-medical equipment include mobile phones, tablets, and computers. Any non-medical equipment, medical device accessories, or subsystems not included in the EMC test should be listed with a rationale for why they were not tested. You should provide a scientific justification for how the test configuration demonstrates EMC of the entire medical device system.
If a medical device has multiple subsystems or accessories (e.g., a left ventricular assist device (LVAD) that includes an implantable blood pump and external controller), or more than one function (e.g., a ventilator with physiological monitoring), then the medical device system test specifications should consider all EMC-related consensus standards applicable to those subsystems, accessories, and functions. This can be used to formulate an appropriate superset of test specifications.
If EMC testing is performed on a subsystem basis, each subsystem not included in the testing should be simulated, including any potential third-party medical devices or connections.
Medical device and test or ancillary equipment should be configured in the modes and with settings considered to be representative of the medical device’s intended use. For example, a medical device that can operate in battery power mode and in mains power mode should be tested in both modes. Additionally, batteries with embedded electronic circuitry (i.e., smart batteries) that are intended to be handled by the user should be removed from the medical device and tested separately for immunity to ESD due to the potential of ESD damaging the circuitry of the battery.
Patient simulators should be used where specified by the referenced EMC consensus standards or as appropriate for the medical device. For example, certain EMC test methods for AIMDs specify that the medical device be submerged in a saline phantom with specific conductivity. Other consensus standards such as 60601-1-2 specify that patient-coupled medical devices be electrically loaded in a way that simulates a patient and be provided with electrical or mechanical signals that simulate a patient.
If wireless technology is used in the medical device to achieve its intended use, the wireless technology should be “on” and communicating with other medical device subsystems or ancillary equipment during EMC testing. This is important because having active connections at each antenna could affect whether the subject medical device operates as intended when exposed to EM disturbances.
3.10. Common Electromagnetic Emitters
The FDA recommends mitigating the risks associated with common electromagnetic emitters like:
RFID readers
Electronic security systems (e.g. metal detectors)
Near-field communication systems (NFC)
Wireless power transfer (WPT)
Cellular 5G
Unique medical emitters based on the intended use environments
etc.
For medical devices in the risk category “Medical device-related events without reported or potential harm,” the FDA recommends that the medical device labeling (e.g., user manual, instructions for use) mention the potential for EMI from emitters expected to be nearby. If the manufacturer makes specific claims or specifies a specific intended use regarding any particular emitter, the FDA recommends that those claims be supported with additional testing, engineering analysis, or computer modeling. For medical devices in the risk category “Medical device-related deaths and serious injuries” or “Medical device-related non-serious adverse events,” the FDA recommends that:
Testing be performed according to FDA-recognized consensus standards (e.g., FDA-recognized AIM 7351731 Medical Electrical Equipment and System Electromagnetic Immunity Test for Exposure to Radio Frequency Identification Readers - An AIM Standard or IEC 60601-1-2:2020 Clause 8.11 for RFID emitters), or equivalent EMC test methods, with justification. If no consensus standards exist, specific immunity testing should be performed to demonstrate that the medical device is safe with regard to each identified emitter that is foreseeable in the intended use environment; and
Labeling is specific to the risks to patients and operators and includes any mitigations and warnings needed, based on the test results.
3.11. Labeling
The EMC information included in the labeling should meet the specifications of the referenced medical device consensus standards (e.g. 60601-1-2, 60601-4-2). The labeling specifications of IEC 60601-1-2:2020 and IEC TR 60601-4-2:2016 are in Clause 5 and summarized in Annex B.). The FDA recommends that the medical device labeling include the following information related to EMC:
The environments of use for which the medical device is suitable to be used/exposed.
Accessories and other equipment with which the device has been determined to be compatible.
The medical device’s functions/performance and a description of what the operator can expect if the functions/performance are lost or degraded due to EM disturbances. For 60601-4-2, these are the functions/performance needed to demonstrate the medical device performs as intended, and for all other 60601 standards, this is Basic Safety and Essential Performance.
The compliance level for each emissions and immunity test.
The use of any deviations from, or allowances specified by the referenced standards.
Precautions regarding sources of EM energy that:
emit levels of EM energy that exceed the immunity test levels of the referenced EMC standards used, or
have other emission characteristics to which the medical device has not been tested for immunity.
Specifications of the wireless communication for medical devices with RF wireless functions.
Any maintenance instructions needed to ensure that the medical device remains safe and performs as intended with regard to EM disturbances throughout the expected service life.
Markings affixed to the medical device and warnings for certain types of known EM environments, such as in or near an MRI scanner. Medical devices intended for use in the MR environment that have not been shown to be MR Safe or MR Conditional should be marked with the ASTM F2503 symbol for MR Unsafe. (See ASTM F2503-13 Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment.)
The FCC term “harmful interference” has a meaning that is different from that of the term “harm” as used in medical device risk management and ANSI/AAMI/ISO 14971 Medical devices - Application of risk management to medical devices. To avoid confusion and concern regarding the FCC term, we recommend adding the note specified below after the FCC warning in the labeling: NOTE: “Harmful interference” is defined in 47 CFR §2.122 by the FCC as follows: Interference which endangers the functioning of a radio navigation service or of other safety services or seriously degrades, obstructs, or repeatedly interrupts a radio communication service operating in accordance with the [ITU] Radio Regulations.
4. Investigational Device Exemption (IDE) or Investigational New Drug (IND) Submissions
The FDA EMC guidance 2022 does also include a remark regarding the EMC of investigational device exceptions (IDE) and investigational new drugs (IND). The FDA recognizes that there are iterations to the design of medical devices during a clinical study, and thus comprehensive EMC testing to consensus standards might not be the least burdensome approach to demonstrate EMC. Therefore, risk-based ad-hoc EMC emissions and immunity testing and labeling mitigations are recommended by the FDA. The manufacturer should provide in the IDE or IND submission a description of potential risks to patients and operators in case the subject medical device introduces excessive emissions that might interfere with other medical or non-medical equipment or in case the subject medical device has not been tested according to the EMC consensus standards.
5. Conclusion
The FDA guidance 2022 for EMC is a helpful document for any medical device manufacturer. It goes into much more detail than the guidance from 2016 and is, therefore, an improvement.
The FDA does only partially recognize IEC 61326-1:2020 (general laboratory equipment), IEC 61326-2-6:2020 (IVD) and recommends using test levels specified by IEC 60601-1-2. Therefore, it is to be assumed that there will be soon new versions of the EMC standards IEC 61326-1 and IEC 61326-2-6 released, where the immunity test limits are increased to today's versions.
EMC immunity requirements for medical devices are constantly becoming more stringent and device manufacturers are wise when they start to act better sooner than later by improving the EMC immunity of their medical devices.
About the Author
Reto Keller works as a principal electronic development engineer and is currently the president of the Academy of EMC.
References
[2] Food and Drug Administration U.S., Information to Support a Claim of Electromagnetic Compatibility (EMC) of Electrically-Powered Medical Devices Guidance for Industry and Food and Drug Administration Staff, 2016
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