*** - Highly Relevant, ** - Moderately Relevant, * - Less Relevant, NR - Not Relevant
The following abstracts have been categorized into:
3.4.1 Sources of Electromagnetic Interference
3.4.2 Interaction of Wireless Phones and Medical Devices (General Studies)
3.4.3 Interaction of Wireless Phones and Medical Devices (Specific Studies)
Abstract: This paper discusses some of the research on risk estimation of EMI malfunction of medical devices done by the McGill University Biomedical Engineering Group of Electromagnetic Compatibility. The risk for EMI malfunction is summarized in a simple equation. A few solutions to minimize the risk of medical device EMI malfunctions are also proposed.
Subjects: What is the Risk of EMI Malfunction?; Potential Sources of EMI; Which Sources Have the Greatest EMI Potential?; Measurement of the Electromagnetic Environment of Hospitals: Fixed and Portable Sources; Medical Device Immunity to EMI; Minimizing the Risk of EMI Malfunctions; Source - Device Separation Distance; Current and Future EMI Potential Risk; EMI Risk Minimization: The Next 5 to 10 Years and the Next 10 to 20 Years
Note: Also in Chapter 1 and Chapter 4
Abstract: Many medical devices have significant interference problems due to radiofrequency interference (RFI) in the non clinical environment. This paper discusses the measurement performed by the Center for Devices and Radiological Health (CDRH) to determine the field strengths of common RF sources in this area. The study showed that the field strength of distant transmitters, user handheld transceivers, and local transmitters exceeded the 3V/m RFI immunity level specified in the IEC 601-1-2 international medical device electromagnetic compatibility standard.
Subject: Introduction; Methods; Results; Conclusions
Note: Also in Chapter 1
Abstract: This paper describes the effects of electromagnetic interference (EMI) on medical devices. It discusses the various sources of electromagnetic interference such as power lines, radio stations, cellular phones and walkie-talkies, while presenting examples of hospital policies on the usage of transmitting devices. It also provides excerpts of different standards dealing with EMI and EMC by radio frequency fields and medical devices.
Subjects: Sources of Electromagnetic Interference; Susceptible Devices; Portable Telecommunication Devices; Hospital Policies; Electromagnetic Compatibility; National and International Standards
Abstract: The numerous reports on EMI in electronic medical devices have triggered investigations into the susceptibility of specific devices, the realization that EMI is a potential hazard for electronic medical devices, and the development of a CDRH plan to assure EMC in medical devices. An on-line version of reporting EMI problems in medical devices is currently under consideration at CDRH. Until then, EMI problem reports can best serve to raise the awareness of the medical device community about the kind of malfunctions that could arise and to identify medical devices and use them in environments for which further investigation on EMI is needed.
Subjects: Medical Device Problem Reporting; Are Problem Reports Verified?; What Is Actually EMI?; The Changing Electromagnetic Environment; How Much Of A Problem Is EMI?; What Has the FDA Done About EMI?; Accessing FDA Problem Reports; Suggestions for Medical Device Manufacturers; Suggestions for Health-Care Facilities; Examples EMI Problem Reports
Note: Also in Chapter 4
Abstract: Due to the increasing use of high power FM radio and VHF television, the Center for Devices and Radiological Health (CDRH) conducted an experiment to determine the radiofrequency (RF) susceptibility of an apnea monitor. The experimental method include connecting the monitor to a saline-filled, full-size model of an adult human and conducting measurements at an outdoor electromagnetic (EMC) test facility. The results showed that the RF susceptibility of an apnea monitor increased by approximately 8 to 15 dB when its leads and electrodes were connected to the model.
Subject: Introduction; Exposure System; Human Model; Medical Devices; Diagnostic System; RF Interference Test Methods; Results; Conclusions
Abstract: This report discusses a study performed to collect data for radiated EMI and conducted EMI in different hospital environments in two major hospitals. The radiated measurements were taken using a Model 2712 spectrum analyzer, calibrated EMI antenna, and a Model 3004 RF field intensity meter. The conducted measurements were taken using a single-phase power disturbance analyzer. The results showed that the main sources of radiated EMI were intentional radiators such as telemetry and paging devices, handheld radios, and wireless phones. The study also found the electrosurgical units (ESUs) to be a main source of radiated EMI. However, low levels of EMI was found to be emitted from lasers, x-rays, and other high-energy equipment. There was also minimal conducted EMI resulting from power disturbances.
Subjects: The Elements of EMI; Test Methods; Test Results; Discussion
Abstract: The possibility of disruption of hospital equipment due to interference from cellular mobile phones is a matter of grave concern. Increasingly, several hospital policies restrict the usage of phones in areas such as Intensive Care Units. Though there is no concrete evidence to prove that the interference is due to phones, the potential damage is undeniable. Since cellular phones are highly mobile and can be brought to the near vicinity of sensitive equipment, any disruption caused may not be correctly attributed to them. This article discusses the testing of analog and digital cellular phones on medical equipment like syringe pump, infusion pump, pulse oximeter, and monitor.
Subjects: Problem; Equipment Tested; Test Procedure
Abstract: This paper reports a study conducted to test the effect of EMI from wireless telecommunication devices on fifty medical devices chosen from fourteen medical device groups. The study utilized four two-way radios and one analog cellular phone. The results showed that these wireless telecommunication devices can cause some medical devices to malfunction. The malfunctions due to EMI were grouped into five different categories.
Subjects: EMI Problems Reported in Canada; EMI Screening Tests; Results; Discussion; Conclusion
Abstract: Degradation of medical devices due to electromagnetic interference can be harmful for patient safety. Additional information is needed regarding circumstances in health care environments in which electromagnetic field strengths are expected to be high, such as emergency/transport. In ambulances, the requirement that medical devices and communications equipment function properly in close proximity is extremely critical. This study focuses on EM fields in and around ambulances under realistic conditions. The results indicate that the ambulance environment presents a considerable challenge to medical devices specifically used for emergency medical care.
Subjects: Ambulance Specifications; Methods; Results and Discussions; Ambient Field Strength Measurements; Ambulance Field Strength Measurements; Human Exposure Considerations
Abstract: This paper describes the results of a survey which has been done by the Medical Devices Bureau. Eight monitoring and therapeutic medical devices were tested. The susceptibility of these devices to EMI was determined by any change in device function, including failure, distortion of displayed information, erroneous readout or activation of an alarm. The tests were done using the IEC standard 801-3 (1984) and the frequency range was extended to 2000 MHz to take into account the wide range of radio transmitters and radio stations in use today. All medical devices tested were found to be susceptible to radiated electric fields of varying strengths and frequencies.
Subjects: Biomedical Equipment; Equipment Testing; Radio Frequency Spectroscopy; Electromagnetic Wave Interference; Monitoring; Calibration; Amplitude Modulation; Electric Field Effects; Frequencies; Cellular Telephone Systems; Radio
Abstract: A study was conducted to assess the effects of electromagnetic environmental (EME) potential hazard due to fixed external sources on medical devices in five Montreal hospitals. Field strength was measured inside and outside the five hospitals using industry standard techniques at frequencies 30 MHz to 1000 MHz, and the field measurement was then compared to fields predicted using line-of-sight and hybrid methods. The result found that electromagnetic interference (EMI) caused medical device malfunction although the measured fields were below 3 V/m. For field prediction, the line-of sight method predicted fields to within 20 dB of the measured fields while hybrid method predicted fields to within 10 dB.
Subject: Introduction; Methods; Results; Discussion and Summary
Abstract: This paper discusses the interference caused by analog and digital cellular phones on implantable cardiac pacemakers. The details of a study conducted to ascertain the interference of cellular telephones on cardiac pacemakers are described. In vitro testing was employed and the phones were placed in the close vicinity of four pacemakers. It was found that all four pacemakers exhibited some kind of interference. Seven different types of cellular phones, operating in the frequency range of 800-900 MHz were employed in the study.
Subjects: Introduction; Materials and Methods; Experimental Setup; Results and Conclusions
Abstract: This report summarizes the results of the large-scale in vitro investigation interaction between wireless phones and cardiac pacemakers conducted by the Center for the Study of Wireless Electromagnetic Compatibility at the University of Oklahoma. The research focused on testing 29 pacemaker models with 5 different phone standards to evaluate the amount of interaction between wireless phones and pacemakers as well as to identify those factors which had a significant influence on the level of interaction.
Subjects: Background; Method; Conclusions, Future Directions; Order Form
Abstract: This report summarizes the results of the phone-pacemaker planar separation study which is an extension of earlier research conducted by the Center for the Study of Wireless Electromagnetic Compatibility at the University of Oklahoma. This second phase of testing was conducted to further define the minimum planar separation distance of the phone and pacemaker needed to avoid interaction.
Subjects: Background; Method; Conclusions
Abstract: This paper is a concise version of a study done to investigate the interference of implanted cardiac pacemakers with wireless communication devices. The objective of the study was to determine the interference effects which occur at different spatial positions from the surface of a pacemaker and to ascertain if filtering technology can reduce these interference effects. This article also provides the methodology and results of this study.
Subjects: Abstract; Objectives; Test Protocol; Results; Recommendations
Abstract: EMI-induced degradation of medical devices could adversely affect medical diagnosis and patient treatment and at times can be fatal. This paper provides information concerning engineering design of commonly used medical electronic devices in India, and their performance within the hospitals electromagnetic environment. It also focuses on the sources of EMI and its effects on the commonly used medical equipment.
Subjects: Electromagnetic Environment; Electromedical Equipment Causing EMI; Electromedical Equipment Susceptible to EMI; EEG; EMG; Cardiac Pacemaker; Design Aspects to Achieve EMC; Power Supply Considerations; EMC Standard for Medical Equipment
Abstract: This executive summary presents the results of the clinical trials of the Hearing Aid - Wireless Phone Interaction study completed by the University of Oklahoma Wireless EMC Center. To date in the United States, this study is the most comprehensive scientific effort to involve a diverse group of hearing aid users to determine the degree of interaction between hearings aids and wireless phones.
Subjects: Background; Scope of the Clinical Trials; Results; Future Research; Order Form
Abstract: This study presents the results of a study done at the University of Oklahoma to develop a standard interference signal that can be used to test all hearing aids. It was shown that the IRIS signals had similar pattern defined by the phone technology for all hearing aids. In this experiment, five IRIS signal levels for each of the three phone technologies were mixed with speech at 65 dB SPL (L) to test the speech intelligibility of 24 hearing-impaired people subjected to wireless phone interference.
Subjects: Executive Summary; Order Form
Abstract: The purpose of this research was to evaluate the interaction of digital wireless telephones with hearing aids at various distances. Four behind-the-ear (BTE) and four in-the-ear (ITE) hearing aids were tested with five different types of digital wireless phones (GSM, PCS-1900, NADC, CDMA, TDMA). The study found that all the phones tested produced similar interference level within 2 cm of hearing aids. It also proved that the interference-induced sound pressure level (SPL) from code division multiple access (CDMA) based system reduced rapidly with distance as compared to those from the division multiple access (TDMA) based system.
Subject: Introduction; Methods; Results; Discussion
Abstract: This report summarizes the results of an in vitro investigation of the interaction between wireless phones and implantable cardioverter defibrillators (ICDs) by the Center for the Study of Wireless Electromagnetic Compatibility at the University of Oklahoma. This study comprised Phase I of the Centers ICD research, and focused on determining the amount of interaction between wireless phones and ICDs, and identifying those factors which had a significant influence on the level of interaction.
Subjects: Background; Method; Scope of This Study; Conclusions; Future Research; Order Form
Abstract: Sensitive patient cables are susceptible to electromagnetic interference. This article focuses on radiated interference issues surrounding patient cable terminations. Most of the traditional solutions are not effective with such terminations. Suppressing EMI at the patient connection can be complicated and requires a lot of experimentation. This article discusses the challenges and possible solutions to the problem.
Subjects: Challenge; Solutions; Filters; Shields; Chassis Ground; Conclusion
Abstract: This paper addresses the issue of a radiant heater, a critical-care medical device that malfunctioned "silently" and discusses its implications. The malfunction occurred within 1-2 m. of a 146 MHz walkie-talkie (100mW). A more complete test-chamber assessment of EMI susceptibility proved that the heater malfunctioned at electric field strengths above 0.3 -1 V/m over four roughly 50 MHz bands between about 10 and 600 MHz. The malfunction was due to EMI from near-by fixed source FM transmission antennas. The device had probably been malfunction for months but was not detected. Due to the difficulty of detecting such malfunction, awareness, vigilance and understanding of "silent" malfunctions are essential to prevent serious consequences.
Subject: Malfunction History; Methods; Results - Device Function in Repair Shop, Partial Susceptibility Testing, More Complete Susceptibility Testing, Malfunction-Site Electromagnetic Environment; Discussion, Discussion - Patterns of EMI Malfunctions Not Recognized, Unfamiliarity With Electromagnetic Environment, Alarms Misinterpreted, Unawareness of, and Non-Vigilance for, EMI Malfunctions, Significance
Abstract: There have been several incidents related to unintended movement of powered wheelchairs and scooters for the last two years. This article discussed the study done by the Center for Devices and Radiological Health (CDRH) to investigate the susceptibility of those devices to electromagnetic interference (EMI). The study proved that the powered wheelchair and scooter exhibited some degree of susceptibility to exposure fields.
Subject: Introduction; Methods; Results