An FDA Perspective on Medical Device EMC and Wireless ... · An FDA Perspective on Medical Device EMC and ... Device and system professionals ... The patient went through a theft

An FDA Perspective on Medical Device EMC and Wireless

Jeffrey L. SilberbergUS Food and Drug Administration (FDA) Center for Devices and Radiological Health (CDRH)

Center for Devices and Radiological Health

Jeffrey L. Silberberg, MSEE

Senior Electronics EngineerFDA/CDRHOffice 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


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


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!


Topics

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


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. medical occupational consumer products


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


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





Experiences We continue to receive reports of medical device

electromagnetic interference (EMI) Most reports involve implanted ICDs, pacemakers,

neurostimulators, and infusion pumps Proliferation of RF wireless technology In medical devices In hospitals WLAN and telemetry RFID

EMC information in regulatory submissions is often incomplete and has errors


Sources of EMI Information Mandatory reports Voluntary reports Compliance (enforcement) actions Professional contacts Device and system professionals EMC engineers and consultants Hospital engineers Trade and professional organizations Consensus standards groups

Published literatureMay 8, 2015 Wireless Electronics and Electrical Medical Devices 14

Mandatory reporting requirements –Medical Device Manufacturers

Medical-device-related Deaths

Serious injuries

Malfunctions that caused or could have caused the above

To the FDA


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


Voluntary reports MedWatch

www.fda.gov/safety/medwatch/default.htm Reporters can include Healthcare professionals Patients The general public

MedSun Hospitals


MAUDE Database

Manufacturer and User Facility Device Experience Database

Includes manufacturer, user facility, and voluntary reports

Searchable at www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfMAUDE/search.CFM

In 2013 there were more than 630,000 individual reports entered into MAUDE


MAUDE Search Screen


Maude Simple Search Screen


Recent MAUDE data


Slide courtesy MDR Analyst Karen Nast

A quick search of 2014 reports (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


Pacemaker and ICD Sensing Characteristics Pacemakers and ICDs must be able to sense low-level

signals to be able to perform their intended use


1 10 100 1000

ICD Sensing Curve

1V

100mV

10mV

1mV

100uV

10uV

Frequency (Hz)

Sense

Reject Reject

Pacemaker Sensing Curve

Slide courtesy Seth Seidman

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


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.


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 interferencetape was slightly lifted and was also replaced.


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.


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.


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.


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.


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.


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

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

MedSun

Medical Product Safety Networkwww.fda.gov/medicaldevices/safety/medsunmedicalproductsafetynetwork/default.htm

Participants Clinical sites

Participation is voluntary Feedback Follow-up


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

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 SpacesMayo Clin Proc. 2007;82:318-322, A 71-year-old man with a biventricular ICDreported 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.



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.


Example regulatory investigation

Ambulatory insulin infusion pumpexhibited lockup in use

Manufacturer was able to mitigate problems by increasing ESD immunity to 30 kV


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

See Appendix for more informationMay 8, 2015 Wireless Electronics and Electrical Medical Devices 40

FDA/CDRH/OSEL EMC research

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


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


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


FDA/CDRH/OSEL EMC research –publications (cont’d) Seidman, Seth J., and Guag, Joshua W.: Ad

hoc electromagnetic compatibility testing of non-implantable medical devices and radio frequency identification, BioMedical Engineering OnLine, http://www.biomedical-engineering-online.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


A few of the many CDRH standards activities

AAMI AIM REG HCI ASC C63®

ASTM IEC ISO RESNA


2010 data 240 representatives 30 standards

development organizations

500 standards activities

CDRH EMC and wireless activities

AAMI Wireless coexistence TIR working group FDA co-chair Document development in process

Working group – EMC test protocols for cardiac rhythm management FDA co-chair

Working on EMC section of a standard for cochlear implants


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


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


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


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 2001http://www.fda.gov/medicaldevices/deviceregulationandguidance/guidancedocuments/ucm077274.htm


Search for recognized standards

http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfStandards/search.cfm

Enter “Standard Designation Number” Click “Search”



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 Wireless Electronics and Electrical Medical Devices 53

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


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.


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


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



RF Wireless Guidance Accessible athttp://www.fda.gov/medicaldevices/deviceregulationandguidance/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



RF Wireless Guidance (cont’d)

Methods Risk-based approach References to FDA Quality System

Regulation


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



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



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.


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


Example wireless coexistence test setup



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


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


FDA wireless activities (cont’d)

Mobile Medical Applications Guidance http://www.fda.gov/ucm/groups/fdagov-

public/@fdagov-meddev-gen/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


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


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


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 Wireless Electronics and Electrical Medical Devices 77

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)


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

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)


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



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.

IMMUNITY test IEC 60601 TEST LEVEL

Compliance level Electromagnetic environment – guidance

Conducted RF IEC 61000-4-6 Radiated RF IEC 61000-4-3

3 Vrms 150 kHz to 80 MHz 3 V/m 80 MHz to 2,5 GHz

3 Vrms

3 V/m

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

P=d 2,1

P=d 2,1 80 MHz to 800 MHz

P=d 3,2 800 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 deter-mined 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)

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


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


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!


Jeffrey L. Silberberg, MSEE

Senior Electronics EngineerFDA/CDRHOffice of Science and Engineering

[email protected]

Secretary, IEC SC62A MT23


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


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


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


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


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


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


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


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 PATIENTcoupling point and earth should be no greater than 250 pF.


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


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


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 commercially-

available 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


Test specificationsRFID 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

May 8, 2015Wireless Electronics and Electrical

Medical Devices 100

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


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


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 in-band transmitters used in the vicinity that might adversely impact a device’s operation


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 wireless-related risks are managed/mitigated


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


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


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


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


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).


RF Wireless Guidance – Premarket submissions (cont’d)

Labeling should include (cont’d) Labeling required by applicable EMC and

wireless standards


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).


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.


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.


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.


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”.


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.


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”.


Example EMI reports (cont’d) Pulse oximeter MDR Report Key 504200 Rec January 6, 2003Upon 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 oximetercaused 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.


Example EMI reports (cont’d) Infusion pump MDR Report Key 679280 Rec February 21, 2006The 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.


Example EMI reports (cont’d)

Infusion pump MDR Report Key 736554 Received June 19, 2006The 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.


Case StudiesConducted EMI– Ultrasound Artifacts


Reproduced

Actual

Spectrum Analysis of a noisy power supply from a patient monitor

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.

Case Studies – HVAC Controllers


Interference began at the same time as installation of this new HVAC system,and continued for 11 months before mitigation was achieved.


Case Studies - HVAC Control Circuitry Relay


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.

Normally Open

Normally Closed


Case StudiesPatient 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.


Case StudiesAutomated Door Mechanism


Broadband noise from automated door into the NICU. These solenoids had degraded over time. Replacement was recommended.


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.


Case StudiesElevator 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.


Case Studies – Co-channel Occupancy


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.


Documents

An FDA Perspective on Medical Device EMC and Wireless ... · An FDA Perspective on Medical Device EMC and ... Device and system professionals ... The patient went through a theft