ID Number		732
Study Type		Engineering & Physics
Model		28-470 MHz (CW) radios, 400 MHz (AM-17Hz TETRA), 900 MHz (GSM), 2.4 GHz (802.11b / LAN) exposure to medical devices and analysis of electromagnetic interference
Details		Medical Devices were tested using emergency service and security radios (28-450 MHz CW), GSM mobile phones (900 and 1800 MHz), Tetra mobile phones (400 MHz), cordless phones (400 MHz DECT), 802.11b / LAN systems, and 2-way pagers. Transmitters were operated at full / higher power when possible. High powered devices (1-5 watt radios) caused the largest amount of significant EMI (40% of devices tested). GSM mobile phones contributed to less EMI (4% of devices tested), but on some occasions the EMI could be potentially hazardous. For Tetra mobile phones, interference effects were observed at 0 meters on some infusion & delivery pumps, pacemakers, and on one defibrillator model, but the effects at 1 meter were similar to GSM phones. The report suggests that overall, TETRA system handsets would be similar to GSM mobiles in terms of EMI risk and that personnel using TETRA handsets on hospital premises should comply with hospital policy. The authors recommend user education and managed use in hospitals (including restrictions of unmanaged wireless equipment in sensitive areas) as a way to avoid the possibility of full power emissions in close proximity to critical medical devices. No mention is made of alternative strategies designed to control and decrease transmission power as an alternative to manage EMI.
Findings		Not Applicable to Bioeffects
Status		Completed With Publication
Principal Investigator		Medical Device Agency, UK
Funding Agency		MHRA, UK
Country		UNITED KINGDOM
References		Med. Device Agency, MDA Bulletin (MDA DB 9702), (1997) :- Med. Device Agency, MDA SN2001 (06) at http://www.medical-devices.gov.uk/sn2001(06).htm , (2001) :-
Comments		Some tests appear to have been performed during hookup and not during a more quantitative test mode. Data given at 0 meter (directly touching the medical devices) is not normal user conditions and not recorded at 25 & 50 cm where more useful information on a distance threshold might have been obtained. The field strengths as determined in the study (TETRA = 148 V/m at 0 meters, GSM = 41 V/m at 0 meters) could not be accurately measured using a Holiday E-field probe. The study did not look at ventilators which are probably one of the more important devices that can be critically affected by EMI events. Finally, the definition of "severe" EMI was not provided, and many of the effects listed may have been categorized as a nuisance, but not a loss of critical device function.