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Medical Devices

September 29, 1999 M.D.A. No. 111

To: Hospital and Nursing, Home Administrators

Attention: Clinical and Biological, Engineering ICU, CCU staff

Subject: Interference Between Digital TV Transmissions and Medical Telemetry Devices

The purpose of this Alert is to inform you of the potential risk of electromagnetic interference from digital television (DTV) transmissions to medical telemetry devices that operate in frequency bands allocated to television broadcasting.

Certain medical telemetry devices, such as cardiac patient monitors, are allowed to operate on television channels that are currently unoccupied in their geographic area. As television services are starting to use the formerly unoccupied channels for digital television (DTV) broadcasts, the potential for interference to the telemetry devices is now substantially higher. Two cases of interference with hospital telemetry have already occurred in the US.¹, ²

The latest information on the channels that are allotted to DTV stations is listed by geographic location in the Industry Canada DTV Transition Allotment Plan (external link).

New DTV stations in the US may also cause interference to telemetry devices that operate near the border. The US Plan is posted at the FCC Web site at www.fcc.gov/Bureaus/Engineering_Technology/News_Releases/1998/nret8002.html (external link).

The US Federal Communications Commission has recently proposed that alternative frequency bands be reserved for medical telemetry (FCC Docket 99-255). Industry Canada intends eventually to harmonize these frequency bands with the US for such use. Medical telemetry devices operating in these bands would be protected from interference. Until such allocations are approved, the potential interference to medical telemetry monitoring devices should be addressed and rectified.

Recommended Course of Action

It is therefore recommended that you:

1. Contact the supplier or the manufacturer of your telemetry devices to determine the channels or frequencies used by the devices;
   
   
2. Consult the DTV Transition Allotment Plan posted on Industry Canada's web site (external link) and, if necessary, the US DTV Allotment Plan at: www.fcc.gov/Bureaus/Engineering_Technology/News_Releases/1998/nret8002.html (external link) to determine which currently vacant TV channels in your area are allotted to DTV broadcasts in the near future;
3. If your medical telemetry devices are transmitting on channels that are scheduled to be used by local TV stations, you should:
   1. contact your local television stations to determine when they plan to begin broad-casting on those channels; and,
   2. work with your supplier or manufacturer to change your telemetry channels to unused TV channels prior to the expected broadcast date to avoid interference.

If your telemetry devices are transmitting on channels that will remain unused, you should not experience interference from DTV transmissions. However, you should periodically check the DTV Transition Allotment Plan to insure that those channels remain available.

Inquiries or reports regarding electromagnetic interference with medical equipment may be made by calling the toll-free Medical Devices Hotline at 1-800-267-9675, or by contacting:

Director,
Medical Devices Bureau,
Therapeutic Products Programme,
Room 1605,
Main Statistics Canada Building,
Tunney's Pasture,
Address Locator 0301H1,
Ottawa, Ontario, K1A 0L2.

Tel: 613-957-4786,
fax: 613-957-7318.

Dr. J.Z. Losos
Assistant Deputy Minister

References

¹ US FDA Public Health Advisory: Interference Between Digital TV Transmissions and Medical Telemetry Systems, March 20, 1998.

² "TV Station Interferes with Hospitals", Wireless Week, March 16, 1998.