Center for Devices and
Radiological Health
An FDA Perspective on
Medical Device EMC and
Wireless
Jeffrey L. Silberberg
US Food and Drug Administration (FDA)
Center for Devices and Radiological
Health (CDRH)
Jeffrey L. Silberberg, MSEE
Senior Electronics Engineer
FDA/CDRH
Office of Science and Engineering
Laboratories
Secretary, IEC SC62A MT23
May 8, 2015
Wireless Electronics and Electrical Medical Devices
2
Summary


Medical device EMI continues to be reported
 Most reports involve active implanted
devices
 Defibrillators
 Pacemakers
 Neurostimulators
 Infusion pumps
RF wireless technology in healthcare is
proliferating
May 8, 2015
Wireless Electronics and Electrical Medical Devices
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Summary (cont’d)

RF Wireless Technology




FDA guidances
Coexistence
FDA participates in many standards activities
FDA currently recognizes (among many
others)



IEC 60601-1-2 Ed. 3
IEC 60601-1-2 Ed. 4
Many 60601-2-X and 80601-2-X standards
May 8, 2015
Wireless Electronics and Electrical Medical Devices
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Summary (cont’d)


FDA coordinates with FCC on EMC and
wireless issues
Completeness/quality of EMC information in
regulatory submissions varies
 It saves time and money to get it right the
first time!
May 8, 2015
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Topics
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Introduction
Medical device EMI reports
FDA research
FDA standards activities
FDA recognition of IEC 60601-1-2
RF Wireless Technology in Medical Devices
Regulatory issues
Conclusions
May 8, 2015
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Introduction

U.S. Food and Drug Administration (FDA)
Center for Devices and Radiological Health
(CDRH)

We assure that patients and providers have
timely and continued access to
 safe, effective, and high-quality medical
devices
 safe radiation-emitting products.



May 8, 2015
medical
occupational
consumer products
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CDRH Coordination with FCC



New wireless technology that could affect
medical devices
Rules changes that could affect medical
devices
New medical applications of wireless
technology

More on this later
May 8, 2015
Wireless Electronics and Electrical Medical Devices
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Office of Science and Engineering
Laboratories





Assesses state-of-the-art of device technology
Performs leading-edge research
Develops novel test methods and performs testing
Participates in the development of consensus
standards
Consults with other offices in CDRH
 Reviews of regulatory submissions
 Enforcement actions
 Problem identification and resolution
May 8, 2015
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May 8, 2015
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Experiences

We continue to receive reports of medical device
electromagnetic interference (EMI)


Proliferation of RF wireless technology





Most reports involve implanted ICDs, pacemakers,
neurostimulators, and infusion pumps
In medical devices
In hospitals
WLAN and telemetry
RFID
EMC information in regulatory submissions is
often incomplete and has errors
May 8, 2015
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Sources of EMI Information
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Mandatory reports
Voluntary reports
Compliance (enforcement) actions
Professional contacts

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Device and system professionals
EMC engineers and consultants
Hospital engineers
Trade and professional organizations
Consensus standards groups
Published literature
May 8, 2015
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Mandatory reporting requirements –
Medical Device Manufacturers


Medical-device-related

Deaths

Serious injuries

Malfunctions that caused or could have
caused the above
To the FDA
May 8, 2015
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Mandatory reporting requirements –
User facilities

Medical-device-related deaths


to both the FDA and the manufacturers
Medical-device-related serious injuries

only to the manufacturer
May 8, 2015
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Voluntary reports

MedWatch
www.fda.gov/safety/medwatch/default.htm

Reporters can include




Healthcare professionals
Patients
The general public
MedSun

Hospitals
May 8, 2015
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MAUDE Database



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Manufacturer and User Facility Device
Experience Database
Includes manufacturer, user facility, and
voluntary reports
Searchable at
www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfM
AUDE/search.CFM
In 2013 there were more than 630,000 individual
reports entered into MAUDE
May 8, 2015
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MAUDE Search Screen
May 8, 2015
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Maude Simple Search Screen
May 8, 2015
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Recent MAUDE data
Slide courtesy MDR Analyst Karen Nast
May 8, 2015
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A quick search of 2014 reports

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(Simple) text search on 12/18/2014 for
“electromagnetic interference”
Over 500 reports found for 2014
Almost all were for implanted devices, primarily
 Cardioverter defibrillators (ICDs)
 Pacemakers
 Neurostimulators
 Infusion pumps
Some implants had “EMI detection”
Some “EMI detections” were due to lead wire
problems
May 8, 2015
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Pacemaker and ICD Sensing Characteristics

Pacemakers and ICDs must be able to sense low-level
signals to be able to perform their intended use
1V
Pacemaker Sensing Curve
100mV
Sense
10mV
ICD Sensing Curve
Reject
1mV
Reject
100uV
10uV
1
10
Slide courtesy Seth Seidman
May 8, 2015
100
1000
Frequency (Hz)
Wireless Electronics and Electrical Medical Devices
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A quick search of 2014 reports (cont’d)

In a more thorough EMI search, many
additional related search terms would also be
used that were not used for this quick
(simple) search, e.g.






Electromagnetic compatibility
EMI
EMC
Interfer
Incompatible
Incompatibility
May 8, 2015
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A quick search of 2014 reports (cont’d)


Some of the reports found appeared to be
confirmed or reproducible actual EMI
problems
Many mentions of “EMI” were NOT confirmed
EMI problems. Examples:

Implantable cardioverter defibrillator - A secure
sense warning was observed during device
interrogation. Electromagnetic interference was
suspected. The device was reprogrammed. The
patient condition was good.
May 8, 2015
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A quick search of 2014 reports (cont’d)

Example mentions of “EMI” that were NOT
confirmed EMI problems (cont’d)


Implanted cardioverter defibrillator - A review
of the device data was completed by an engineer
and because the source of EMI cannot be
confirmed, must consider the possibility that the
device malfunction [sic].
Programmer - The electromagnetic interference
tape was slightly lifted and was also replaced.
May 8, 2015
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Apparent EMI problem examples


MDR Report Key 3626655, Rec. 02/13/2014
Event Description: It was reported the patient
had electromagnetic interference due to use of
their electric razor. The patient had felt their
stimulation turn on and off when they used the
electric razor. It was stated the report showed 48
activations and a previous time of 170
activations. It was noted the close proximity of
the electric razor to the implantable
neurostimulator was likely the cause of the
high activation count.
May 8, 2015
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Apparent EMI problem examples (cont’d)


MDR Report Key 4149571 (cont’d)
Event description (cont’d): Additional information
was received indicating that electromagnetic
interference was conclusively identified as the
cause of low impedance measurement as it was
determined that patient has weekly electric
stimulation therapy.
May 8, 2015
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Apparent EMI problem examples (cont’d)


MDR Report Key 4245101, Rec. 11/12/2014
Event Description: There was an
electromagnetic interference issue that occurred
approximately two days prior to the initial report.
The patient went through a theft detector in a
shop, received strong stimulation, and the lead
at the cervical level displaced. Impedance
testing and reprogramming were performed. The
implantable pulse generator (IPG) had a
power on reset, which was resolved through
reprogramming. The patient experienced pain
and less than 50% therapy relief at the lead
location. There was no patient injury.
May 8, 2015
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EMI report examples (cont’d)


Ventilator
MDR Report Key 2949491 Rec Jan 31, 2013
Respiratory therapist was standing in front of a
high-frequency oscillatory ventilator. She had
noticed that there was a change in delta-p and
mean airway pressure was fluctuating by 10.
Behind the therapist were 7 staff members using
[smart phones]. When [they were] asked to
move away from the ventilator, the delta-p
stopped fluctuating. Manufacturer response:
known issue documented in operator’s manual.
May 8, 2015
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EMI report examples (cont’d)


Ventilator (cont’d)
Manufacturer said that the root cause of the
reported event was EMI from cell phone use by
the end user. EMI causes erroneous pressure
readings that are not due to fluctuations in the
actual pressure but are the effect of EMI on the
components of the measurement circuits. Mfr
continued that as the reported event was caused
by the device being exposed to higher than
normal EMI, an investigation is not required.
May 8, 2015
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Adverse events reported to FDA

Provide a qualitative snapshot of adverse
events

Vary in quality and usefulness

Include both coding of problems as well as
narrative text

Can be coded with multiple problem codes
Slide courtesy MDR Analyst Karen Nast
May 8, 2015
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FDA adverse event report caveats

Under-reporting of events

Insufficient or inadequate information

Inability to establish causality

Inability to establish rate of adverse events

Lack of denominator data

“Trends” in numbers should be interpreted
cautiously

One report can be important
Adapted from a slide by MDR Analyst Karen Nast
May 8, 2015
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MedSun

Medical Product Safety Network
www.fda.gov/medicaldevices/safety/medsunmed
icalproductsafetynetwork/default.htm

Participants

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

Clinical sites
Participation is voluntary
Feedback
Follow-up
May 8, 2015
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EMI information from EMC professionals


Noise in the image or ECG trace (conducted
EMI)
Telemetry dropouts (radiated EMI)
Artifacts in the Image
Noise in the ECG Trace
Telemetry Dropouts
Slide courtesy EMC engineer Dara McLain
May 8, 2015
Wireless Electronics and Electrical Medical Devices
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Examples of published EMI reports

Gimbel et. al., Electronic Article Surveillance
Systems and Interactions With Implantable
Cardiac Devices: Risk of Adverse Interactions in
Public and Commercial Spaces
Mayo Clin Proc. 2007;82:318-322,
A 71-year-old man with a biventricular ICD
reported receiving 2 ICD shocks while shopping
in the automotive center of a large commercial
retail store. There was an electronic article
surveillance (EAS) pedestal near the checkout
counter.
May 8, 2015
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Example of EMI identification in
published research

Remko van der Togt et al., Electromagnetic
Interference From Radio Frequency
Identification Inducing Potentially Hazardous
Incidents in Critical Care Medical Equipment,”
Journal of the American Medical Association,
June 25, 2008, Vol. 299, No. 24, pp. 2884 –
2890.
May 8, 2015
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Example regulatory investigation


Ambulatory insulin infusion pump
exhibited lockup in use
Manufacturer was able to mitigate
problems by increasing ESD immunity to
30 kV
May 8, 2015
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An EMC recall case study:
EMC conformity gone wrong
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Date Recall Initiated: March 17, 2008
Date Posted: July 23, 2008
Recall Number: Z-1902-2008
Product: Model X extracorporeal blood
circulation system
Reason for Recall: Stops pumping:
Interruption of Model X support may occur
when using a Model Y Electrocautery Unit
See Appendix for more information
May 8, 2015
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FDA/CDRH/OSEL EMC research

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Immunity testing, immunity test method
development
 Susceptibility of patient cables of automatic
external defibrillators (AEDs) below 80 MHz
 Comparison of results of conducted and
radiated immunity testing
Pacemakers and ICDs with cell phones
Powered wheelchairs
Ventilators
May 8, 2015
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OSEL EMC and wireless research



Pacemakers, ICDs, and nerve stimulators
with security systems
Wireless technology / wireless coexistence
 Working with University of Oklahoma at
Tulsa
 C63.27 Round robin
RFID (readers) and medical devices
May 8, 2015
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FDA/CDRH/OSEL EMC research –
publications

Seidman S. et al.: In vitro tests reveal sample
radiofrequency identification readers inducing
clinically significant electromagnetic
interference to implantable pacemakers and
implantable cardioverter defibrillators, Heart
Rhythm, vol. 7, no. 1, pp. 99-107, 2010
May 8, 2015
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FDA/CDRH/OSEL EMC research –
publications (cont’d)


Seidman, Seth J., and Guag, Joshua W.: Ad
hoc electromagnetic compatibility testing of nonimplantable medical devices and radio
frequency identification, BioMedical Engineering
OnLine, http://www.biomedical-engineeringonline.com/content/12/1/71, 11 July, 2013
Seidman, Seth J. et al.: Design of Unique
Simulators to Evaluate Medical Device
Susceptibility to Radio Frequency Identification
Exposure, 2014 IEEE Electromagnetic
Compatibility Magazine, Vol. 3, Quarter 1
May 8, 2015
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A few of the many CDRH standards
activities


2010 data



240 representatives
30 standards
development
organizations
500 standards
activities
May 8, 2015

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AAMI
AIM REG HCI
ASC C63®
ASTM
IEC
ISO
RESNA
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CDRH EMC and wireless activities

AAMI

Wireless coexistence TIR working group



Working group – EMC test protocols for
cardiac rhythm management


FDA co-chair
Document development in process
FDA co-chair
Working on EMC section of a standard
for cochlear implants
May 8, 2015
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CDRH EMC activities (cont’d)

RFID
 Working with Association for Automatic
Identification and Mobility (AIM Global)
RFID Experts Group (REG) on protocol for
testing immunity of medical devices to
RFID systems



Protocol (test method) completed
Circulated to the REG for comment
4 May 2015
Comments due 22 May 2015
May 8, 2015
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CDRH EMC activities (cont’d)


C63® standards
 C63.12, limit and test level setting
 C63.16, ESD
 C63.27, wireless coexistence
IEC standards
 IEC TR 60601-4-2, Medical electrical
equipment – Part 4-2: Guidance and
interpretation – Electromagnetic immunity;
performance of medical electrical
equipment and medical electrical systems
May 8, 2015
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CDRH EMC activities (cont’d)- IEC

IEC TR 60601-4-2




Scope: The IMMUNITY of medical electrical
equipment and medical electrical systems
Immunity test levels
 -1-2: reasonably foreseeable maximum
 -4-2: typical, the same for home and hospital
Scheduled to be circulated for comment
8 May 2015
IEC 60601-1-2 Ed 5
May 8, 2015
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Standards recognition


Declaration of conformity to consensus
standards recognized by FDA can be used in
regulatory submissions
Recognition and Use of Consensus
Standards; Final Guidance for Industry and
FDA Staff, issued 20 June 2001
http://www.fda.gov/medicaldevices/devicereg
ulationandguidance/guidancedocuments/ucm
077274.htm
May 8, 2015
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Search for recognized standards
http://www.accessdata.fda.gov/scripts/cdrh/cfdoc
s/cfStandards/search.cfm


Enter “Standard Designation Number”
Click “Search”
May 8, 2015
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Standards recognition (cont’d)

Clicking on the title opens the supplementary
information page for that recognition





Date of Standard
Address of Standards Organization
CDRH Office and Division Associated with
Recognized Standard
Devices Affected
Processes Affected:
 510(k), PMA, PDP, HDE, GMP, Design
Controls
May 8, 2015
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Standards recognition (cont’d)

Supplementary information page (cont’d)





Type of Standard
Extent of Recognition
 Portion of standard recognized
or entire standard
 Any transition dates from older version(s)
Related CFR Citations and Product Codes
Relevant Guidance
FDA Technical Contacts
May 8, 2015
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Recognition of IEC 60601-1-2



Ed. 2 and Ed. 2.1 no longer recognized
Ed. 3 will be recognized until April 1, 2017
 (Subject to change)
Ed. 4 recognized as of June 2014
 Extent of Recognition
Complete standard with the following
exceptions:
 In Subclause 8.9, Table 8 on Page 39: The
citation of Note b) under “Conducted
disturbances induced by RF fields” (4th Row)
is not recognized.
May 8, 2015
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Recognition of IEC 60601-1-2 (cont’d)


Ed. 4 Extent of Recognition (cont’d)
Exceptions (cont’d)
 Please note the following corresponding
titles, subtitles or provisions:
 Subclause 8.9: IMMUNITY TEST LEVELS
 Table 8: Signal input/output parts PORT
 Note b): SIP/SOPS whose maximum cable
length is less than 3 m in length are
excluded
 4th Row: Conducted disturbances induced
by RF fields
May 8, 2015
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Recognition of 60601-2-X and 80601-2-X
standards


Many are recognized
Examples


IEC 60601-2-10:2012, Medical electrical
equipment - Part 2-10: Particular requirements
for the basic safety and essential performance
of nerve and muscle stimulators
ISO 80601-2-12:2011, Medical electrical
equipment - Part 2-12: Particular requirements
for the safety of lung ventilators - Critical care
ventilators
May 8, 2015
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May 8, 2015
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RF Wireless Guidance
Accessible at
http://www.fda.gov/medicaldevices/deviceregulation
andguidance/guidancedocuments/ucm077210.htm
 Motivation





Increasing use of RF wireless in healthcare
Increasing congestion (e.g., in ISM bands)
Medical devices can be both source and recipient
of disturbances
Need for awareness of potential pitfalls
 By FDA reviewers
 By manufacturers
May 8, 2015
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May 8, 2015
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RF Wireless Guidance (cont’d)

Methods
 Risk-based approach
 References to FDA Quality System
Regulation
May 8, 2015
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RF Wireless Guidance (cont’d)

Considerations for design, testing, and use of
wireless medical devices







Selection and performance of wireless
technology
Wireless quality of service (QoS)
Wireless coexistence
Security of wireless signals and data
EMC of the wireless technology
Information for proper setup and operation
Considerations for maintenance
May 8, 2015
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RF Wireless Guidance (cont’d)

Recommendations for Premarket
Submissions for Devices that Incorporate RF
Wireless Technology




Description of device
Risk-based approach to verification and
validation
Test data summaries
Labeling related to wireless medical devices
May 8, 2015
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RF Wireless Guidance (cont’d)

EMC

Because IEC 60601-1-2:2007 exempts RF
receivers from immunity testing in the
exclusion band, the medical device’s wireless
communication(s) should be actively
transmitting during EMC immunity testing.
May 8, 2015
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Wireless coexistence



FDA reviewers have been asking manufacturers
for wireless coexistence testing
 since at least 2004
No standardized test method
FDA asked C63 to develop a test method
October 2010
 Assigned to SC7, Spectrum Etiquette
October 2011
 Designated C63.27, Chair: Steve Berger
 Participants from government, industry,
academia
May 8, 2015
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Example wireless coexistence test setup
Example wireless coexistence test setup
Example wireless coexistence test setup
Example wireless coexistence test setup from draft C63.27
Example wireless coexistence test setup from draft C63.27
Example wireless coexistence test setup from draft C63.27
Wireless coexistence conclusions



C63.27 development in progress
AAMI wireless coexistence TIR in progress
Good cooperation and division of labor


C63: Test methods
AAMI
 Medical intended use
 Risk management
 Guidance on pass/fail criteria
May 8, 2015
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FDA wireless activities (cont’d)

Meetings/working with FCC
 (And also with SAE) on wireless
charging of electric vehicles (wireless
power transfer)
 FCC/FDA Joint Workshop on Wireless
Medical Test Beds

March 31, 2015
May 8, 2015
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FDA wireless activities (cont’d)

Mobile Medical Applications Guidance




http://www.fda.gov/ucm/groups/fdagovpublic/@fdagov-meddevgen/documents/document/ucm263366.pdf
Those that are not medical devices
Those that are medical devices that FDA
“intends to exercise regulatory discretion”
Those that are medical devices that FDA
plans to regulate
May 8, 2015
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Experience with EMC information in
regulatory submissions


Submissions with little or no EMC information
Submissions with incomplete EMC
information



Only certification submitted
EMC test report submitted
 But evidence of conformity with labeling
requirements is missing
For RF receivers, no indication whether
passed immunity in exclusion band or
exemption was used
May 8, 2015
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Experience with EMC information in
regulatory submissions (cont’d)






EMI missing from list of hazards
ERP not specified for transmitters
Immunity pass/fail criteria were not based on
Essential Performance
Product-specific pass/fail criteria not specified
Test failures
No wireless coexistence testing for
transmitter / receiver or testing inadequate
May 8, 2015
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Experience with EMC information in
regulatory submissions (cont’d)


Some submissions include complete EMC
information and meet all requirements of
referenced standards
Some manufacturers go above and beyond the
requirements
 One manufacturer of surgical device
controllers worked with chip manufacturer to
 reduce RF output power of remote control
 reduce risk of outside wireless detecting and
causing problems with system
May 8, 2015
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Deficiencies in test planning





Essential Performance not specified
Pass/fail criteria listed, “if associated with BS
and EP,” but EP not specified
Pass/fail criteria A/B/C/D specified
Intended use environments not specified
Default hospital test levels used for all
environments (Ed 3)
May 8, 2015
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Deficiencies in testing


Min and max mains voltages not used for
EFT/burst; surge; and voltage dips, short
interruptions and voltage fluctuations tests
(Ed 3)
Entire system not included in the test and/or
subsystems not simulated adequately
Deficiencies in the test report


Essential Performance not specified, etc.
(see test planning)
Photos not legible
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Deficiencies in labeling

Statements and warnings omitted





Performance determined to be EP
Stacking/adjacent warning
“Special precautions… put into service
according to the EMC information…” (Ed 3)
Accessories statement and warning
Portable and mobile RF communications
equipment can affect medical electrical
equipment (Ed 3)
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Deficiencies in EMC guidance tables (Ed 3)





Guidance tables (four) missing
Calculation of equation coefficients e.g.,
.
not completed
Rounding not as specified by 60601-1-2
Conducted and radiated RF separation
distance equations not aligned with
compliance levels
Compliance level and EMC guidance not
modified when higher immunity test levels are
used
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Guidance and manufacturer’s declaration – electromagnetic immunity
The Model 006 is intended for use in the electromagnetic environment specified below. The customer or the user of
the Model 006 should assure that it is used in such an environment.
I MMUNITY test
IEC 60601 TEST
LEVEL
Compliance
level
Electromagnetic environment
– guidance
Portable and mobile RF communications equipment
should be used no closer to any part of the Model
006, including cables, than the recommended
separation distance calculated from the equation
applicable to the frequency of the transmitter.
Recommended separation distance
Conducted RF
3 Vrms
IEC 61000-4-6
150 kHz to 80 MHz
Radiated RF
3 V/m
IEC 61000-4-3
80 MHz to 2,5 GHz
3 Vrms
d = 1,2 P
d = 1,2 P 80 MHz to 800 MHz
3 V/m
d = 2,3 P 800 MHz to 2,5 GHz
where P is the maximum output power rating of the
transmitter in watts (W) according to the transmitter
manufacturer and d is the recommended separation
distance in metres (m).
Field strengths from fixed RF transmitters, as determined by an electromagnetic site survey, a should be
less than the compliance level in each frequency
range. b
Interference may occur in the vicinity of equipment
marked with the following symbol:
(Ed 3)
May
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Conclusions


Medical device EMI continues to be reported
 Most reports involve active implanted
devices
 Defibrillators
 Pacemakers
 Neurostimulators
 Infusion pumps
RF wireless technology in healthcare is
proliferating
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Conclusions (cont’d)

RF Wireless Technology




FDA guidances
Coexistence
FDA participates in many standards activities
FDA currently recognizes (among many
others)



IEC 60601-1-2 Ed. 3
IEC 60601-1-2 Ed. 4
Many 60601-2-X and 80601-2-X standards
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Conclusions (cont’d)


FDA coordinates with FCC on EMC and
wireless issues
Completeness/quality of EMC information in
regulatory submissions varies
 It saves time and money to get it right the
first time!
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Jeffrey L. Silberberg, MSEE
Senior Electronics Engineer
FDA/CDRH
Office of Science and Engineering
Laboratories
1-301-796-2584
jeffrey.silberberg@fda.hhs.gov
Secretary, IEC SC62A MT23
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Thank you for your
attention!
Questions?
Appendix
Supplemental material
An EMC recall case study:
EMC conformity gone wrong





Date Recall Initiated: March 17, 2008
Date Posted: July 23, 2008
Recall Number: Z-1902-2008
Product: Model X extracorporeal blood
circulation system
Reason for Recall: Stops pumping:
Interruption of Model X support may occur
when using a Model Y Electrocautery Unit
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EMC recall case study: System details




Includes primary and backup pump consoles
Was claimed to conform to IEC 60601-1-2:
2007 (Ed. 3)
Manufacturer claimed system was tested for
immunity to electrosurgical units (ESU) / HF
surgical equipment
Designed to stop and alarm if problem
detected with pump motor
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EMC recall case study: Adverse events

At least three adverse event reports








Argentina (1), UK (1) and Spain (1)
System performed OK in OR
Patient moved to ICU, was bleeding
ESU used in ICU in monopolar coagulate
mode
Pump stopped and alarmed – “Motor Fail”
Required restart, taking several minutes
No reported patient injury
RF coupled to device through the blood
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EMC recall case study: EMI incident details

Manufacturer said:


Pump stopping and alarming was OK
 Performed as intended
Recommended user mitigation
 “Switch” to bipolar mode
 Reboot
 Warning: Don’t use Model Y ESU with
Model X blood pump
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EMC recall case study: EMI incident details

FDA said:






Pump is intended to pump blood
Pump monitoring system was mistaken
 No problem with pump motor
 EMI was detected erroneously as a pump
problem
Patient at risk during reboot
Backup console equally susceptible
Further coagulation might be needed
Please mitigate via design modification
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EMC recall case study (cont’d)


Nine hospitals had ONLY Model X blood pump
and ONLY Model Y ESU!
 Recommended using Model Y in bipolar mode
only when Model X in use
The fallacy of fail-safe
 Some say that safe failure is OK in hospitals
because of the availability of other equipment;
however,
 Other equipment might have the same
susceptibility
 Some hospitals might not have alternatives
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Recall:
IEC 60601-1-2:2007 considerations

Tested for “ESU immunity” by performing IEC
61000-4-3 (radiated RF immunity) test down to
150 kHz
 ESU emissions are broadband, IEC 61000-4-3
is narrowband
 Could not have met IEC 61000-4-3’s field
uniformity requirement
 Test lab should have known better than to
test down to 150 kHz with radiated RF
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Recall:
60601-1-2:2007 considerations (cont’d)

IEC 60601-1-2:2007 says that patient simulators
should not be grounded

6.2.1.7 PATIENT simulation [from 60601-1-2]
…The simulator used shall not provide an
intentional conductive or capacitive connection to
earth during testing, except as otherwise specified
in a subclause of this collateral standard.
Unintentional capacitance between the PATIENT
coupling point and earth should be no greater than
250 pF.
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Standards considerations (cont’d)


IEC 60601-1-2 (all editions): PATIENT
COUPLING includes via conductive fluids
IEC 60601-2-2 (Ed. 4 and later) includes an
annex on testing immunity to ESU
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EMC recall case study Summary


Mitigation by design is best
Conformance to standards is important





Patient simulator requirements of 60601-1-2
Field uniformity requirements of 61000-4-3
ESU immunity recommendations of 60601-2-2
Particular (“Part 2”) requirements and test
methods are needed for ESU immunity of
external blood pumps (and other devices)
The manufacturer fixed the problem with a
software upgrade
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AIM/REG/HCI test method details



Minimum and maximum occupied BW
Compliance criteria: 8.1 of 60601-1-2:2014
IEC 61000-4-3 methods and modified calibration
procedure




Calibrate uniform field area using commerciallyavailable signal generator
Replace sig gen with custom RFID sig gen and
validate at one point
HF test levels based on 2.5 cm separation
distance
LF and UHF test levels based on 20 cm
separation distance
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Test specifications
RFID SPECIFICATION
FREQUENCY
TEST LEVEL
ISO 14223
134.2 kHz
65 A/m
ISO/IEC 14443 Type A
13.56 MHz
7.5 A/m
ISO/IEC 14443 Type B
13.56 MHz
7.5 A/m
ISO/IEC 15693
(ISO 18000-3 Mode 1)
13.56 MHz
5 A/m
ISO/IEC 18000-3 Mode 3
13.56 MHz
12 A/m
ISO/IEC 18000-7
433 MHz
3 V/m
ISO/IEC 18000-63 Type C
860-960 MHz
54 V/m
ISO/IEC 18000-4 Mode 1
2.45 GHz
54 V/m
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Medical Devices
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RF Wireless Guidance – Considerations

Information that should be provided to users
 The specific RF wireless technology type,
characteristics of the modulation, and effective
radiated RF power
 Specification of each RF frequency or
frequency band of transmission and the
preferred frequency or frequency band (if
applicable), and specification of the bandwidth
of the receiving section of the equipment or
system in those bands
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RF Wireless Guidance – Considerations
(cont’d)

Information that should be provided to users
(cont’d)
 Applicable FCC labeling
 A warning that other equipment could interfere
with the medical device or device system,
even if the other equipment complies with
CISPR emission requirements.
 Information about the needed quality of
service and security
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RF Wireless Guidance – Considerations
(cont’d)

Information that should be provided to users
(cont’d)
 Functions and performance of the wireless
data transmissions including data throughput,
latency, and data integrity
 Information about any limitations on the
number, output power, or proximity of other inband transmitters used in the vicinity that
might adversely impact a device’s operation
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RF Wireless Guidance – Premarket
submissions

Device description should include
 Description of wireless technology and
functions
 How the design of the device’s wireless
functions assures timely, reliable, accurate,
and secure data transfer
 If wireless is used for alarms, alarm
description, priority, and how RF wirelessrelated risks are managed/mitigated
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RF Wireless Guidance – Premarket
submissions (cont’d)

Device description should include (cont’d)
 Whether other wireless products or devices
are able to make a wireless connection to the
device. If so, identify them and explain how
the medical device functions are protected
from adverse effects of such connections
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RF Wireless Guidance – Premarket
submissions (cont’d)

Test data should include
 Tests performed
 Reference to applicable medical device, RF
wireless technology, and EMC standards
 Explanations for any deviations
 Operating modes used and explanation of
their significance
 Pass/fail criteria
 Statement that modifications made to pass
testing will be made to production units
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RF Wireless Guidance – Premarket
submissions (cont’d)

Labeling should include
 A summary of the medical device wireless
functions and specific wireless technology
incorporated into the medical device
 A summary of the operating characteristics of
the wireless technology, effective RF radiated
power output and operating range,
modulation, and bandwidth of receiving
section
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RF Wireless Guidance – Premarket
submissions (cont’d)

Labeling should include (cont’d)
 A description of the wireless QoS needed for
safe and effective operation
 A description of the recommended wireless
security measures
 Information addressing wireless issues and
what to do if problems occur
 Information about any wireless coexistence
issues and mitigations
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RF Wireless Guidance – Premarket
submissions (cont’d)

Labeling should include (cont’d)
 Appropriate EMC and telecommunications
standards compliance and test results
 Appropriate RF wireless communications
information such as those required by FCC
rules
 Warnings about possible effects from RF
sources in the vicinity of the device (e.g.,
electromagnetic security systems, cellular
telephones, RFID or other in-band
transmitters).
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RF Wireless Guidance – Premarket
submissions (cont’d)

Labeling should include (cont’d)
 Labeling required by applicable EMC and
wireless standards
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A quick search of 2014 reports (cont’d)

Example mentions of “EMI” that were NOT
confirmed EMI problems (cont’d)

Implanted neurostimulator for incontinence The caller was with the patient and trying to
interrogate stimulator with clinician programmer
and getting telemetry failure message. Caller also
states they cannot interrogate stimulator using
patient programmer. Caller states they are in
room where they typically interrogate devices and
were not near EMI (electromagnetic interference).
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A quick search of 2014 reports (cont’d)

Example mentions of “EMI” that were NOT
confirmed EMI problems (cont’d)

A critical alarm was heard. The healthcare
provider (HCP) thought the pump might have
been empty. However, the HCP later interrogated
the pump, which revealed that multiple motor
stalls occurred, for ~ 3 hours. The stalls only
occurred on some days. On [date], the patient
was in the emergency room due to the event. The
patient did use a microphone/amplifier but not all
of the time. The patient’s wife was going to try to
rule out any electromagnetic interference that
could have caused the stalls. The device system
was used to deliver compounded baclofen.
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Apparent EMI problem examples (cont’d)


MDR Report Key 4149571, Rec. 10/07/2014
Event description: [Mfr] received information that
this implantable cardioverter defibrillator and
right ventricular lead exhibited low, out of
range shocking lead impedance measurement
of 0 ohms detected via the patient remote
monitoring system. A review on shock
impedance trend revealed a measurement of
greater than 200 ohms, but no alert was
received.
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Older EMI report examples

Implanted pacemaker, in a hospital

During breast surgery, the doctor was using
the 9900 electrosurgery generator and the
patient’s pacemaker stopped working.
Cardiopulmonary resuscitation (CPR) was
used to resuscitate the patient.
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Older EMI report examples (cont’d)

External pacemaker, public place

The device manufacturer reported that while a
female patient (age unknown) was being
transported by helicopter, “the patient’s pacing
was intermittently interrupted by radio
frequency interference. The patient
subsequently died”.
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Older EMI report examples (cont’d)


IV syringe pump
MDR Report Key 829521 Rec March 12, 2007
User and biomedical technician noted excessive
60 cycle interference on the ekg waveform
making the waveform unreadable. The biomed
tech unplugged all the [model] syringe pumps
from ac power and noted that the 60 cycle
interference was removed from the ekg
monitor.
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Example EMI reports (cont’d)

Implanted spinal cord stimulator, public
place

The patient walked through the theft detector
at a university library and received a shock
that knocked him to the floor. The implanted
device was reset to "0" by the shock. The
patient sustained no known injury. The device
was reprogrammed and it is functioning
properly. The health care provider stated that
the security system was reportedly “set too
high”.
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Example EMI reports (cont’d)

Pulse oximeter

MDR Report Key 504200 Rec January 6, 2003
Upon transporting a pt intra hosp, pulse oximeter failed in
battery mode. Personnel switched oximeter to a.c. power.
Hosp investigation team tried to duplicate the malfunction.
Fully charged oximeter from ICU would not malfunction
when a two-way radio was keyed next to it. But, when
using oximeter with slightly discharged battery,
malfunction was duplicated. Keying two-way radio approx
one foot [30 cm] from unit created an internal reset
problem and keying two-way radio adjacent to oximeter
caused complete shutdown. Manufacturer’s initial report
suggests effects of EMI contributed to the failure and this
may be related to a low battery/poor battery circuitry.
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Example EMI reports (cont’d)

Infusion pump
MDR Report Key 679280 Rec February 21, 2006
The facility reported an infusion pump with over
infusion. Reportedly a displayed rate changed
during pt infusion. The pt's cell phone rang and the
nurse at the bedside noticed that rate of pitocin was
displayed at 120ml/hr rather than the prescribed rate
of 20 ml/hr. The change was noticed in less than
one minute and there was no harm to the pt. A new
pump was put on the pt. According to the hosp. rep,
the event history did not show any buttons being
pressed for the rate change.

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Example EMI reports (cont’d)

Infusion pump

MDR Report Key 736554 Received June 19, 2006
The facility reported a pump that stopped
infusing during patient use. The pump was
infusing heparin, at which time the patient's
family member used a cell phone in close
proximity to the pump. The pump then stopped
infusing. There was no patient injury or medical
intervention according to the hospital rep.
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Case Studies
Conducted EMI
– Ultrasound Artifacts
Slide courtesy Dara McLain
Reproduced
Spectrum Analysis of a noisy power
supply from a patient monitor
Actual
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Case Studies – HVAC Controllers
Slide courtesy Dara McLain
Broadband noise caused by variable
speed controllers used in the air
handling system. An adjustment on
the controller provided by the
manufacturer significantly reduced
the interference.
Facilities had this new system
installed in a newly constructed wing
and 1) did not review EMC
documentation, and 2) did not notify
Clinical Engineering of this
installation.
Interference began at the same time as installation of this new HVAC system,
and continued for 11 months before mitigation was achieved.
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Case Studies - HVAC Control Circuitry Relay
Slide courtesy Dara McLain
Normally
Open
Normally
Closed
Due to relays in HVAC circuitry that were either not rated for the current through them, or
incorrect for the circuit design, the plastic body melted and caused the normally closed condition
to be slightly open, resulting in arcing. There were two main hallways with an HVAC relay circuit
for each room, more than 60 relays that any one of them could produce broadband interference
of up to 15 minutes in length.
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Case Studies
Slide courtesy Dara McLain
Patient Room Hair Dryer
In-room hair dryers found during a pre-installation RF Survey. Not all hair dryers emitted noise.
Defective hair dryers functioned [in]correctly. The proposed wireless system would not have
functioned properly due to this noise.
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Case Studies
Slide courtesy Dara McLain
Automated Door Mechanism
Broadband noise from automated door into the NICU. These solenoids had degraded over time.
Replacement was recommended.
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Case Studies – Lighting Dimmers
Hallway lighting controlled by automated dimming at specified times. System
cabinets were not equipped with any shielding, though the system
documentation called for it. All dimmer switches are potential broadband
sources.
A broad frequency span shows the
arcing characteristics of the dimmers.
Only the weak signals are affected at
the time the noise occurs.
Recommendations: Install shielding on the dimmer system control cabinets.
Slide courtesy Dara McLain
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Case Studies
Elevator Controls
Doctor’s office building – elevator
motor control circuitry* with
excessive noise emissions (only
one of two elevator control circuits
emitted noise).
This noise was conducted onto
the power line. It radiated as well,
but the building had no wireless
systems.
*These elevators had brushless
motors.
Slide courtesy Dara McLain
May 8, 2015
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Case Studies – Co-channel Occupancy
Slide courtesy
Dara McLain
Two wireless systems programmed to the same frequencies in use, interfering with each
other.
Unknown to Clinical Engineering, the offending system field service tech reprogrammed
the system transmitters. The affected system company resolved the issue at the
customer’s expense.
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