BBI Contributing Writer

SAN JOSE, California – The biggest news at the annual meeting of the Association for the Advancement of Medical Instrumentation (AAMI; Arlington, Virginia) here in early June were the pending Federal Communications Commission (FCC) rule changes that will affect the entire U.S. patient-worn telemetry market.

The rules were changed by the FCC on June 8, effectively make all existing telemetry systems prematurely obsolete, and requiring a relocation over the next three years from both existing bands used currently – the UHF PLMR (450-470 MHz band) and the VHF TV band (174-216 MHz) – to new bands. This was discussed in a special, one-day presentation at the AAMI gathering.

Even though medical users of the UHF private land mobile radio (PLMR) band are licensed, they transmit much less power than other licensed users, which makes them susceptible to interference from other in-band users. The characteristics of the transmissions by the primary users in these bands have a profound impact on their safety for medical use. Neither the UHF nor VHF band has been ideal for medical use because of interference from other users. In the future, neither of the bands will support medical use with existing transmitters, and, while medical use is "grandfathered" by the FCC, it may become more dangerous in these existing bands due to the rule changes.

The series of recent FCC actions was the culmination of several years of work behind the scenes by the American Hospital Association (AHA; Chicago, Illinois) task force that included representatives from both large and small telemetry vendors. The task force was established after the well-publicized disruption of 50% of the telemetry beds in one ambulatory unit at Baylor Medical Center (Houston, Texas) due to HDTV testing at a nearby television station. That incident prompted the FCC to take a series of temporary actions to freeze the current situation in order to buy time for a more permanent solution. To help hospitals, the FCC took the steps summarized in Table 1 on page 153. However, these were intended as a short-term fix, not as a long-term solution for medical users. The creation of the new Wireless Medical Telemetry Spectrum (WMTS; 608-614 MHz) band was reported a year ago and became final at the June 8 meeting. The full text of the FCC action can be found at www.fcc.gov/Bureaus/ Engineering-Technology/ Orders/2000.

In the VHF TV band, additional high-definition transmitters for existing TV stations are being assigned. New low-power community TV stations also are being assigned. Both of these use frequency spectrum that hospitals may currently be using for patient-worn telemetry monitoring. The FCC support for community programming, and assignment of additional low-power TV stations in various communities, further consumes the VHF band previously available for telemetry use. While these community TV stations are "low power" from the FCC perspective, at 5,000 watts they are high power from the point of view of patient-worn medical telemetry systems, which are limited to a few thousandths of one watt, or 2,500 times less power than the new low-power stations.

In the past, medical telemetry was designed to use space between VHF TV channels, which worked because the standard TV signals did not occupy the full 6 MHz they were allotted for each channel. With HDTV, however, that will no longer be possible either. The new HDTV signals consume the entire 6 MHz spectrum assigned to each TV channel, leaving no room for medical telemetry.

Interference issues in the UHF band

The UHF PLMR band has many mobile users who transmit signals 1,000 times stronger than medical telemetry signals. Because these are mobile, the interference they cause is transitory, somewhat unpredictable, and difficult to deal with. Because it is in-band interference by licensed users of the UHF PLMR band, medical users have no recourse in preventing it. Rather, they must find ways to work around this problem. In rural areas, where there are not as many UHF users, this problem occurs less frequently. But in large, metropolitan areas like New York, Chicago, Atlanta, Los Angeles, Dallas, Houston, or any other big city, this is a serious problem without an acceptable or permanent solution. However, what will make the UHF PLMR band unusable for medical telemetry is FCC-announced "refarming" to accommodate more users. Refarming is the process of changing the width of the channels used from the current 25 kHz-wide channels to four times as many 6.25 kHz-wide channels. The new, narrower channels are too narrow for current telemetry transmitters to use, and it will not economically feasible to modify existing medical transmitter designs to use such narrow channels. When complete, the band will grow to have up to four times as many mobile users, and therefore up to four times more interference from these extra users.

Why 'refarm' the PLMR band?

The FCC needed to address the overcrowding of the existing UHF PLMR band. It made these changes in the operating rules, some of which are unfavorable to current medical users of the PLMR band. The FCC did not feel the new rules would be an issue for medical users, as it was acting simultaneously to create the new, protected WMTS (608-614 MHz) band the American Hospital Association and vendor task group had requested. The implication is that the FCC expects medical use of the existing UHF PLMR band to cease soon, as medical users move to new spectrum provided for them in the WMTS band or in other bands, like the Industrial, Scientific and Medical (ISM) 2.4 GHz band. This is stated under item 57 of the FCC order.

To create the opportunity for more UHF PLMR commercial users, the FCC mandated a change in the channel width used in that band, to be instituted over a phase-in period. Instead of the current 25 KHz-wide channels, a new channel width of 6.25 kHz would be used. With this backdrop, virtually every supplier of telemetry is affected, as shown for selected vendors in Table 2. Once fully phased in, these refarmed narrower channels would allow four times as many users in the same radio spectrum. The FCC has made it clear that it wants medical telemetry out of the UHF PLMR band.

Patient monitoring vendors without either a transmitter in the new 608-614 MHz or ISM band are not going to be seen as viable telemetry suppliers. If they do not have core RF capabilities themselves to build systems for other bands, they will have to look to Vitalcom (Tustin, California) or other OEM suppliers, or seek assistance from an RF supplier outside of the medical industry, such as Proxim (Mountain View, California), Breezecom (Tel Aviv, Israel), or Symbol Technologies (Holtzville, New York).

Ch 13-46 opened for medical secondary use

In October 1997, the FCC opened up unused TV channels 14-47 for secondary use by medical telemetry. This is not to be confused with PLMR UHF frequencies (450-470 MHz), where police, firefighters, taxicabs, and delivery trucks now operate. The UHF-TV band starts right above the private land mobile radio commercial UHF band and covers the 470-668 MHz frequency spectrum. The new Wireless Medical Telemetry Spectrum (WMTS) is right in the middle of this band at 608-614 MHz.

Siemens (Danvers, Massachusetts) has adopted these frequencies as its interim solution. However, as they too fill up with HDTV and new low-power TV users, Siemens and other companies offering telemetry in this band will have to focus into a single 6 MHz slice at Ch-37, which is the new, protected WMTS band for medical telemetry operations.

Hospitals are confused about all of these changes and many don't understand the long-term implications. The magnitude of this confusion was apparent from simply looking at their buying patterns over the last two years. The FCC and the AHA conducted a nationwide survey in 1998 and found that 61% of medical telemetry users were operating in the PLMR band, while 31% were operating in the VHF TV bands. They also found that the useful life of telemetry systems was 10 years, but that the mean and median ages of the installed base of patient-worn telemetry systems were only three and five years, respectively. This meant that the installed base of equipment was relatively new, not yet fully depreciated or ready for replacement.

Medical Strategic Planning (Lincroft, New Jersey) also conducted a survey of the purchases of telemetry during the last two years, after the 1997 announcements of proposed new bands. In spite of this information and the relative new age of the installed telemetry base, about 25% of all units currently installed were replaced during the last 15 months, and they were replaced with essentially obsolete UHF PLMR transmitters. Where these hospitals will find the capital funds, after their previous Y2K spending and faced with spending for Healthcare Insurance Portability and Accountability Act compliance, to again prematurely replace all of this new telemetry within the next three years, is anyone's guess.

In response to medical telemetry interference issues at Baylor, the AHA and a group of industry telemetry vendors formed a task group to explore, with the FCC, various options for additional spectrums that would be dedicated to medical telemetry use, and which would be free from non-medical interference. Letters of invitation to participate were sent to both large and small vendors, so they knew what was happening.

Creation of the WMTS band

The FCC worked with the AHA task group to find a frequency spectrum that could be used on a co-primary basis for medical purposes. For this purpose, it was assumed that 0.8 bits/second/Hz of bandwidth would be required for medical signals, an assumption used widely across several industries.

If voice or additional high-frequency parameters (such as heart sounds, or additional leads of ECG waveforms) are transmitted, the spectrum required would be increased proportionally. Realizing this, the FCC prohibited voice and video signals from being transmitted in the new band. To actually squeeze all of this data allowed for 1,000 patients/devices into a 6 MHz band, newer, more-efficient transmitter designs (that use only 6 KHz per patient) would be required, yet no leading vendor offers such a transmitter. The only one that claims to currently offer such a radio is Vitalcom, which is offering a radio that it claims has bidirectional transmission in 5 KHz-wide channels. This radio hops frequencies across the entire 6 MHz-wide WMTS band, but only is useful for devices that do not require more than three leads of ECG transmission continuously. Moreover, Vitalcom makes no vital signs monitors itself, but simply interfaces to other vendors' already-installed monitors. This is fine for portable bedside monitors, but is not a good solution for patient-worn monitors – which are not available from vendors to which Vitalcom is interfaced.

Possible acquisition target

The fact that Vitalcom, with limited resources, has been able to provide interesting technology is a credit to its new management. However, it also may be a do-or-die situation for this company, which is in the midst of a continuing trend of declining revenues and losses on operations. Should the market not accept the Vitalcom approach, or become concerned about its direction, the company's continued stand-alone existence could be in question. Having been "burned" by the larger vendors offering essentially obsolete products already, hospitals' sensitivity to the potential financial instability issues of an alternate supplier may come more into play than it otherwise would, particularly for the kind of large orders Vitalcom is going to need to win in order to reverse its declining revenues. Assuming its new technology works, Vitalcom may be better off being acquired by another firm which is larger and perceived as more stable, rather than continuing to attempt to market its solution directly. Some industry watchers think this might be a good play for a Mennen Medical (Clarence, New York) or Invivo Research (Orlando, Florida), which have the monitors to go along with the telemetry Vitalcom brings to the party. Criticare Systems (Waukesha, Wisconsin) or Welch Allyn (Skaneateles Falls, New York) might also be interested.

WMTS frequencies for medical use

The AHA task force ultimately asked the FCC for 14 MHz of frequency for medical use. Based on that request, the FCC created the Wireless Medical Telemetry Spectrum at what was previously UHF TV Ch-37 (608-614 MHz) in June. This action also will add 8 MHz of spectrum from that being vacated by the U.S. military. This additional spectrum is broken into two pieces: One is from 1.395-1.40 GHz and the second from 1.429-1.432 GHz. These two frequencies will become available in 2003 and 2006, respectively. They currently are being used for U.S. military (radar) purposes.

The lowest-frequency 6 MHz part of the WMTS spectrum, covering the 608-614 MHz band, is the only one immediately available for hospitals. One advantage of this band is that the FCC designated medical as co-primary users (with a limited number of radio astronomy sites) in the final rule. The clear message from the FCC is this: We have created additional spectrum suited to medical use, and we need to take back both the UHF PLMR and VHF TV spectrum you are now using, so continue to operate in the VHF or UHF PLMR bands at your own risk.

The creation of the WMTS band was a remarkable achievement for the medical industry. The FCC gave to the medical industry RF spectrum that it usually sells for millions of dollars to other users. It also elevated the status of medical to co-primary users, essentially protecting medical use from interference outside of the band for the first time. It also left the band wide open as to operations, at the industry's request, and imposed no standards for interoperability on the spectrum. It did specify the notion of four, 1.5 MHz wide sub-channels within the 6.0 MHz spectrum. As a result, hospitals should not assume that the WMTS is automatically free of interference from users inside of the band – sometimes referred to as "friendly interference."

Co-primary status in the new WMTS band does not protect hospitals from vendors offering incompatible modulation schemes legally operating inside of the WMTS band. The WMTS band has only the most rudimentary mechanism to help multiple users on the band to coexist without interference in a single institution. This mechanism is the notion of four 1.5 MHz-wide channels. These channels allow different telemetry vendors offering conflicting solutions to share the spectrum by operating within one or more channels. Interference is prevented by limiting the frequency within the band that each vendor can use, and it is the hospital's responsibility to coordinate this, not the vendor's or the FCC's. By failing to specify standards for how the new WMTS band would be used, the FCC left it to each hospital to assure that it doesn't allow vendors with conflicting or interfering systems to be installed in its facilities.

While all of these vendors' WMTS devices will work well by themselves, they may not all work well together, or co-exist well in one hospital. This has become a hospital issue to resolve. The approach already announced by Vitalcom potentially conflicts with the approach taken by Agilent Technologies (Andover, Massachusetts) and Spacelabs (Redmond, Washington). It is made to co-exist by carving up the small 6 MHz slice of spectrum into four smaller slices and restricting each vendor to operate in one of these smaller slices. Whether this is an advance from the hospital's perspective, compared to the uses of IEEE standards available in other bands, is uncertain. If hospitals want to use products from different vendors operating in this new WMTS band, they must make sure they have not adopted interfering transmission methodologies or allowed overlapping spectrum in the WMTS band.

Winner take all?

This could lead to a "winner take all" situation, in which hospitals could restrict the vendors selling systems to one vendor, presumably a large one. Such a move, if adopted on an industrywide basis, could cause the demise of many smaller vendors of telemetry systems, stifle competition and innovation, and result in a serious stagnation in the U.S. telemetry market.

Should this scenario develop, Vitalcom could be adversely affected, unless it turns out to be the one vendor that "takes all." It is certainly at risk. Since it went public in 1995 with revenues of almost $24 million and a $1.5 million profit, it has experienced declining revenues and losses every year thereafter. Q100 revenues continued this trend, and were below 1999 levels.

WMTS frequency coordinator

While the FCC did not specify transmission rules, it nonetheless created a resource to assist hospitals in getting their wireless acts together. It mandated the creation of a "frequency coordinator" to whom hospitals must report installation of new WMTS devices. To do this, hospitals must have an inventory of devices now being used and their frequencies, as well as any future WMTS devices installed. There will be a fee to register with the coordinator, which is an extra cost to the hospitals that purchase new units operating in the WMTS band.

Additional telemetry channels also will be required for wireless local area networks that portable, bedside monitors use to communicate data back to central stations. Additional channels could be required for networks of infusion pumps, ventilators, and other patient care devices that are not interfaced to bedside monitors. All of these needs won't be accommodated by a single slice of 6 or 14 MHz, using currently available devices designed to operate in the new WMTS band. One reason is that the products announced so far by industry leaders like Agilent Technologies, Spacelabs, and GE Medical/Marquette for the WMTS band all maintain the notion of 25 kHz-wide channels. If installed in the entire 6 MHz-wide WMTS spectrum, a maximum of 240 patients could be monitored. This is far fewer than the 1,000 projected by the AHA as required by hospitals in 10 years.

To meet all wireless frequency needs of the hospital, additional spectrum will be needed. The WMTS band alone will not provide the entire wireless spectrum hospitals will need today or in the future. While the promise of the WMTS band is exciting for the future, the present reality of the band is another matter. That question will be explored in Part 2 of this AAMI report in BBI's August issue.