As a response to the mounting concerns about interference resulting from new digital television transmitters, low television transmitters, and greater use of Private Land Mobile Radio equipment, in 2000 the Federal Communications Commission (FCC) took the following actions:
> Established the Wireless Medical Telemetry Service (WMTS), dedicating bands of frequencies to promote interference-free operation of medical telemetry systems;
> Appointed ASHE as the Frequency Coordinator for the WMTS bands;
> Mandated that all transmitters operating in the WMTS bands must be registered with ASHE to ensure interference-free operation.
Wireless Medical Telemetry Service (WMTS) is the remote monitoring of a patient's health, in which the RF communication occurs between a patient-worn transmitter and a central monitoring station. The FCC has allocated interference-protected spectra for use by licensed physicians, healthcare facilities and certain trained and supervised technicians in the 608-614 MHz, 1395-1400 MHz and 1427-1432 MHz frequency bands. All types of communications except voice and video are permitted on both a bi-directional and unidirectional basis, provided that all communications are related to the provision of medical care.
WMTS equipment may be used only within a health care facility. FCC at present does not permit home use of WMTS equipment because of a concern that temporary use of such equipment at many dispersed locations would make it difficult to coordinate the operating frequencies, resulting in harmful interference. The FCC has, however, mentioned that it may revisit the issue of home use of WMTS equipment in the future if experience suggests that home use can be effectively coordinated to avoid interference.
According to the FCC, the same interference concerns that led it to exclude WMTS equipment from home-use also led it to prohibit the use of WMTS equipment in vehicles, including ambulances. This is due to the inherent difficulty of ensuring that WMTS equipment operated in ambulances or other vehicles would not interfere with WMTS equipment operating on the same or adjacent frequencies at fixed sites such as hospitals and other health care facilities within the area traversed by the ambulance.
Since June 2000, when the FCC issued its initial guidance regarding telemetry transmission protection, the healthcare industry has been in a dilemma - whether to upgrade or to replace existing systems. In addition, there is concern about replacement timeframes and whether to use the new Wireless Medical Telemetry Spectrum band or the Industry Scientific and Medical (ISM) band.
With regard to predictability, security and infrastructure reliability, both the WMTS and the ISM bands provide protection against the types of interference that brought about the FCC’s intervention. The future of telemetry broadcasts is much more secure now, regardless of whether the telemetry systems purchased are based on WMTS or on the ISM broadcasting platform. Interference from Public Land Mobile Radio (PLMR) and High Definition Television (HDTV) interference is accounted for and eliminated within both broadcast realms.
Some might argue that the WMTS offers a more secure solution because it is primarily a medical broadcast arena. The counter-argument to this is that the WMTS is also a much smaller broadcast arena compared to the ISM band. Likewise, the Ethernet Network Standard of 802.3 and the Local Area Network Standard of 802.11x are ISM band standards with a proven path of reliability and security within the global information system market. In reality, many vendors use both bands and some even use both bands as part of their telemetry solution package.
What this implies to the average purchasing agent or telemetry replacement committee with the responsibility of identifying a new telemetry system solution for their hospital or patient care setting is that they need to look for a telemetry replacement system that has all the features, functions and benefits needed to service the patient population while making sure that the selection is primarily based on quantifiable differences instead of marketing hype.
The brighter side of the restructuring of the telemetry industry is that the number of new functions and capabilities that have emerged from the required R&D efforts in telemetry technology. The market has never had so many patient-friendly and nurse-friendly solutions to address the perennial problems of telemetry.
FCC Order 00-2111 created the Wireless Medical Telemetry Service in direct response to the growing concern for potential interference from other legally operating devices in the same spectrum. This issue affected both Part 15 approved users of VHF and UHF broadcast spectrum, as well as Part 90 Business Band users operating in the UHF PLMRS bands (450 to 470 MHz). Given the widespread impact of this decision, it is important to consider both the near and long term implications for medical telemetry.
Manufacturers continue to voice their concerns regarding the long-term practicality of supporting the growing needs of medical telemetry within the limited bandwidth supported by WMTS. Therefore, to complement the available bandwidth allocated under WMTS, the telemetry architecture of certain companies like Spacelabs Medical provides multi-band RF solutions for integration within other companies' telemetry systems. Additional ISM solutions lie outside of the VHF/UHF bands and are specifically allowed for use by medical telemetry under Part 15, in accordance with the FCC’s recent order.
The multi-band approach does away with the current concern for potential interference from external sources, such as digital television, and also provides for long-term expansion, enabling the monitoring of many more patients within the same facility. Prior to issuance of the FCC order, multiple industry leaders had voiced their concerns about limited bandwidth availability and the inability easily to reach the assumed spectral efficiency metric. Using the additional ISM bands, as well as the bandwidth provided for by WMTS, augments the total available bandwidth and hence the amount of patient data that can be transmitted in any given facility. The multi-band approach also deals with what will be a future interference dilemma for healthcare providers and device manufacturers: the issue of internal interference. Internal interference is likely to result from internal sources such as other medical telemetry systems operating in the 608 MHz band within the same facility.
The FCC’s drive to promote the WMTS standard is resulting in wide-scale migration to the WMTS band. Early adopters opted for replacements as early as 2001-2002. The fact that the FCC has extended its freeze until the end of 2005 will further drive hospitals to migrate, most likely by the early part of 2006 at the latest. Thereafter, the market is expected to experience steady growth. According to Frost & Sullivan’s study, “U.S. Medical Wireless Ambulatory Telemetry Monitoring Equipment Market,” the market is expected to grow at a compound annual growth rate of 11.5 percent over the period 2005-2011. WMTS migration is eventually expected reach market saturation levels, ultimately leading to a decline in unit shipments. However, telemetry is also poised for growth in other areas of the hospital, though ECG monitoring is still expected to experience the greatest demand.
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