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Back To Vidyya FDA Public Health Advisory:

Risk Of Electromagnetic Interference With Medical Telemetry Systems

Existing wireless medical telemetry systems may be at increased risk of electromagnetic interference (EMI) if they continue to operate in the range of frequencies in which most medical telemetry devices are currently operating. To address this risk, the Federal Communications Commission (FCC) has created a new Wireless Medical Telemetry Service (WMTS) that will allow medical telemetry systems to operate on an interference-protected basis. It is recommended that practioners evaluate whether their medical telemetry systems are at risk and take appropriate measures to reduce that risk. It is believed that the best way to accomplish this is to use telemetry systems operating in the new WMTS frequency bands.

Background

Currently, most wireless medical telemetry devices operate as secondary users in commercial broadcast TV bands and in the private land mobile radio service (PLMRS) band. As secondary users, medical telemetry must accept interference from, and not interfere with, primary licensed users. Typically, if there is interference from a primary user, the medical telemetry system will be unusable. This happened in 1998 when DTV transmissions disrupted medical telemetry systems in two Texas hospitals. These frequency bands will be used more extensively by digital TV and high power PLMRS operators, which is likely to result in an increased risk of interference with medical telemetry. (For details of these actions, see the Additional Detailed Information Section at the end of this notification.)

Recommendations

It is recommended that health care professionals determine whether their wireless medical telemetry systems are at risk of EMI and to take appropriate action, if necessary, to reduce that risk. Practioners may wish to consult with the telemetry equipment manufacturer to discern the level of risk. This action should include, at a minimum, determining at which frequencies particular telemetry systems are currently operating (i.e., what frequency band, channel) and comparing that data with the frequencies allocated to digital television (DTV) in the general area and the PLMRS band. A list of all DTV allocations can be found on the FCC web site http://www.fcc.gov/healthnet/dtv.html.

  • If it is determined that medical telemetry equipment is at risk of EMI from other in-band radio frequency (RF) sources (e.g., DTV or PLMRS transmitters), the system should either be replaced with equipment that operates in the WMTS bands (608-614 MHz, 1395-1400 MHz, and 1429-1432 MHz), when this equipment is available, or modify it to operate in the WMTS band.
  • If you and/or the telemetry equipment manufacturer determine that your medical telemetry equipment is not at risk of EMI from other in-band RF sources (e.g., DTV or PLMRS transmitters), then no change is necessary.

Risks should be assessed and necessary changes made to equipment as soon as reasonable because licensed TV stations are authorized to begin testing and transmitting in DTV channels as soon as they are ready, and because the FCC will begin accepting applications for high-powered users in the 450-460 MHz band January 29, 2001. Again, it is recommended by the FDA that medical telemetry systems operate within the WMTS bands, particularly for new purchases, to minimize the risk of EMI with wireless medical telemetry.

Reporting Adverse Events to FDA

The Safe Medical Devices Act of 1990 (SMDA) requires hospitals and other user facilities to report deaths and serious illnesses and injuries associated with the use of medical devices. This means that if interference with a medical device results in a death or serious injury, you must report that event.

If a telemetry system fails to function due to electromagnetic interference or any other reason, it is a device malfunction. Such malfunctions should be reported to the manufacturer. Alternatively, they can be reported directly to MedWatch, the FDA's voluntary reporting program. Submit reports to MedWatch by telephone at 1-800-FDA-1088, by FAX at 1-800-FDA-0178, or by mail to MedWatch, Food and Drug Administration, HF-2, 5600 Fishers Lane, Rockville, MD 20857.

Getting More Information

If you have any questions regarding this notice, please contact Nancy Pressly, FDA, CDRH, Office of Surveillance and Biometrics, 1350 Piccard Drive, HFZ-510, Rockville, MD 20850, fax 301-594-2968, or by e-mail at phann@cdrh.fda.gov.


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Editor: Susan K. Boyer, RN
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