About Wireless Medical Telemetry
- What is it?
- FCC order establishing WMTS
- Authorized users
- Service rules for equipment and use
- Use of WMTS
Wireless medical telemetry is generally used to monitor patient physiological parameters (e.g., cardiac signals) over a distance via radio-frequency (RF) communications between a transmitter worn by the patient and a central monitoring station. These devices have the advantage of allowing patient movement without tethering the patient to a bedside monitor with a hard-wired connection
On June 8 the FCC voted to adopt new rules establishing a service for wireless medical telemetry devices. (http://www.fcc.gov/Bureaus/Engineering_Technology/Orders/2000/fcc00211.doc) [Word Doc].
The Wireless Medical Telemetry Service (WMTS) report and order sets aside the frequencies of: 608 to 614 MHz, 1395 to 1400 MHz, and 1429 to 1432 MHz for primary or co-primary use by eligible wireless medical telemetry users. This action creates frequencies where medical telemetry will enjoy protection against interference from other in-band RF sources. A key feature of the new WMTS is the provision for establishment of a Frequency Coordinator to maintain a database of user and equipment information to facilitate sharing of the spectrum and to help prevent interference among users of the WMTS. The FCC order also provides a definition for wireless medical telemetry, which is consistent with recommendations made in April 1999 by the American Hospital Association (AHA) Task Group on Wireless Medical Telemetry. The FCC will now define wireless medical telemetry as:
"the measurement and recording of physiological parameters and other patient-related information via radiated bi- or unidirectional electromagnetic signals"
The FCC order also describes the requirements for users of the new WMTS.
Eligible WMTS users are limited to authorized health care providers, which includes licensed physicians, healthcare facilities, and certain trained and supervised technicians. The healthcare facilities eligible for the WMTS are defined as those that offer services for use beyond 24 hours, including hospitals and other medical providers. Ambulances and other moving vehicles are not included within this definition.
The service rules for the equipment and use of the WMTS include limitations on transmitter output power, out-of-band emissions, and protection of other services. Users of the WMTS will be co-primary with the radio astronomy service operating in the 608 - 614 MHz frequency range and must not disrupt radio astronomy operations. WMTS devices are required to obtain written permission to be used for transmitting within 80 km of some radio astronomy facilities and within 32 km of other radio astronomy facilities. In addition, users of the upper frequency bands of the WMTS will have to coordinate with the current government (primarily military) users of these bands. The government uses of these frequencies are being phased out over the next few years. Information on these sites can be found in the appendices of the FCC Report and Order. The Frequency Coordinator will maintain information to help the WMTS co-primary users avoid conflicts.
Because of concerns for interference with the present wireless medical telemetry systems, and the introduction of the WMTS, CDRH has issued a public health advisory to hospital administrators, risk managers, directors of biomedical/clinical engineering, and nursing home directors. In general, CDRH encourages manufacturers and users of medical telemetry devices to move to the new spectrum because of its protections against interference from other intentional transmitters and because frequency coordination will be provided.
CDRH believes that the appropriate use of the WMTS will significantly reduce the risk of EMI with vital medical telemetry signals. The FDA is committed to working with device manufacturers and users to facilitate migration to the WMTS frequencies in a least burdensome manner. Devices utilizing alternative technologies or RF frequencies may be acceptable, provided the device's safety and effectiveness is addressed in terms of immunity to EMI from licensed primary users of RF spectrum in which these devices operate. The Office of Device Evaluation has developed a guidance document to assist wireless medical telemetry manufacturers in meeting any FDA regulatory requirements that may apply to devices that utilize a new WMTS. Manufacturers of wireless medical telemetry utilizing existing technology, such as those operating in the TV or PLMRS bands, should consider conducting a risk assessment to determine the likelihood that their existing, installed telemetry equipment is at risk from other in-band RF sources. In the meantime, FDA will continue to inform wireless medical device manufacturers of any significant developments regarding EMI and wireless medical telemetry.
Users of wireless medical telemetry devices should assess the potential vulnerability of their own equipment to EMI as a result of changes in the use of the RF spectrum presently used by medical telemetry devices. Because of the protection afforded by the WMTS, users are encouraged to consider using medical telemetry devices that are capable of transmitting and receiving in the new WMTS bands. Although the AHA recommended t hat the use of the present secondary frequencies be maintained for an extended period of time, starting two years from the effective date of the final rules on WMTS, the FCC will not approve new medical telemetry equipment that operates in the TV or PLMRS bands. There is no cutoff on the sale or use of equipment approved before that date to operate in the TV and PLMRS bands. However, the FCC will begin accepting high-power land mobile user applications for the 450-460 MHz band January 29, 2001, and high-power user applications for the 460-470 MHz band within three years. At the same time, TV broadcasters are under FCC mandated deadlines to begin testing and transmitting in their allocated DTV channel. These actions will continue to increase the risk of interference to medical telemetry systems operating in the TV and PLMRS bands. For these reasons, the FDA and the FCC strongly encourage medical telemetry users to migrate out of the TV and PLMRS bands and into the WMTS as soon as reasonable, and cooperate fully with the designated Frequency Coordinator to minimize potential EMI with medical telemetry devices.