Unhooking Medicine

Wireless networking sets staff free, but settling on a frequency is tricky

7 min read
Unhooking Medicine

This is part of IEEE Spectrum's special report: Always On: Living in a Networked World.

photo of person using PatientNet, the medical telemetry system

Photo: Vitalcom Inc.
Mission control: PatientNet, the medical telemetry system developed by VitalCom Inc., Tustin, Calif., feeds all patient vital signs to a central monitoring station.

Hospitals might blame their wireless technology woes on digital television. Two years ago, a TV station in Dallas, Texas, accidentally crippled the Baylor University Medical Center when it began testing digital TV signals. Part of Baylor's wireless patient monitoring telemetry, which operated in the same band, experienced interference. No patients were injured, but the event prodded the Federal Communications Commission (FCC), Washington, D.C., to find a dedicated chunk of spectrum for medical telemetry.

Last summer the hospitals got it. The FCC allocated 14 MHz for the Wireless Medical Telemetry Service, or WMTS. The new service is broken into three bands: 608-614, 1395-1400, and 1429-1432 MHz. The old bands (ultra-high frequency and very high frequency) will become increasingly troublesome to use in medicine. Those frequencies will be used for digital television, set for a 2003 launch, and by police and fire departments and other so-called Private Land Mobile Radio uses, which are scheduled to move to those bands at about the same time.

Not everyone is cheering the new allocation. The ruling is forcing medical device firms to come up with fixes for their old devices and new technologies for the next generation of wireless telemetry. Industry majors, including GE, Agilent Technologies, Siemens, and SpaceLabs Medical, are rolling out solutions in the new band. Hospitals are not applauding for another reason: return on investment.

"This is a first-class mess," noted Arthur Gasch, president of Medical Strategic Planning (MSP), a market research and publishing firm in Lincroft, N.J. "The FCC effectively accelerated the normal replacement cycle. Starting in 2000, the average age of telemetry systems was only 4.2 years. So hospitals won't even be able to depreciate what they've already invested in before they have to replace it."

In effect, the new band allocation has pushed cash-strapped hospitals in the United States to the brink of an unwanted technology makeover. Hospitals are being forced to reengineer their patient-worn and bedside wireless systems, which could mean the purchase of new transmitters, receivers, and antennas. At the same time physicians and other health care workers are confronted with a whole raft of new wireless technologies, many involving accessing patient data through a personal digital assistant (PDA) or a wireless phone.

While the WMTS offers a safe haven for telemetry signals, it has some technical limitations that may diminish its importance. For instance, because the FCC did not specify transmission standards, it is up to hospitals to prevent interference within the WMTS from competing technology. Another potential problem is that the FCC barred voice and video data from the new bands because video would eat up too much of the spectrum, and it deemed that voice was inappropriate for monitoring devices. (Electrocardiogram and other physiological waveforms are not considered to be video.) But the increasing use of wireless phones and other handheld devices by nurses may call for wireless medical networks that can handle both voice and medical waveforms.

Other sore spots center on the availability of the allotted frequencies. In some regions, hospitals must still share the new frequencies. The upper two bands of the WMTS, for instance, are not completely freed up yet, limiting the amount of spectrum that is immediately available to 6 MHz rather than 14 MHz. Several U.S. government radar sites use the upper and middle bands, 1395-1400 MHz and 1429-1432 MHz, and those installations will not go off-line until 2004 and 2009, respectively.

The topmost band is also coveted for use by low-earth orbiting satellites. And even the lowest 6 MHz must share its bandwidth with radio astronomy, though the overlap between medical centers and radio astronomy zones is minimal.

The U.S. frequency allocation is prompting other nations to consider such a move as well. Beth Pieterson, acting director of the Canadian health system's medical devices branch, said that device makers in Canada recently began discussing a dedicated band in that country. Also, she said that a uniform medical telemetry band might be a future topic of discussion for the Global Harmonization Task Force, a group set up to standardize medical device requirements across Japan, Australia, the United States, Canada, and the European Union. Pieterson is the task force's current chairperson.


Hospitals are faced with a difficult choice: move their telemetry out of the frequency it is currently operating in, or face the risk of patient injury when interference occurs. But where that telemetry should be parked is not obvious. While many companies are planning systems for the new WMTS band, others say hospitals should skip WMTS altogether and move to the unprotected but much larger industrial, scientific, and medical (ISM) band--an 83 MHz chunk of spectrum centered at 2.4 GHz that is home to devices using IEEE 802.11 wireless Ethernet standards.

The competition is fierce, with companies on both sides of the WMTS divide trying to woo hospitals with their technology while deriding competitors' strategies. As hospitals sort out their wireless telemetry needs, at least two systems are expected to get much of the attention. Both are frequency hopping spread spectrum (FHSS) schemes. One, developed by VitalCom Inc. of Tustin, Calif., is a proprietary local-area network (LAN) in the 608-614 MHz band of the WMTS. In the other corner are 802.11-based technologies operating at 2.4 GHz and championed by telemetry makers Welch Allyn Protocol and Criticare Systems.

The big advantages of ISM-based wireless local-area networks are cost savings and interoperability. They allow a single wireless architecture to carry patient record data, voice, and telemetry. In fact, Welch Allyn Protocol Inc., Beaverton, Ore., is offering such a system, FlexNet, connecting its wireless monitors with off-the-shelf hand-held devices such as PDAs and phones as well as the Internet. In addition, MSP's Gasch points out that 802.11 transceivers are likely to cost less than proprietary systems for the WMTS band because of the high volume of the other markets for the transceivers.

In the medical arena, Welch Allyn Protocol, Criticare Systems, and others have allied themselves with Symbol Technologies of Holtsville, N.Y., a maker of wireless LANs. Meanwhile, Agilent Technologies Inc., of Palo Alto, Calif., and SpaceLabs Medical Inc., of Redmond, Wash., have partnered with another 802.11-based wireless firm, Proxim Inc., Sunnyvale, Calif. Proxim, an early player in wireless LANs in hospitals and clinics, has been installing LANs that handle patient charting, emergency admitting, and other functions performed by handheld or other wireless devices.

In the face of competition, VitalCom is thinking big, claiming it can handle 1000 patients' worth of data with its system, PatientNet [photo at top of page]. It recently installed PatientNet at Saint Luke's-Shawnee Mission Health System in Kansas City, Mo., an eight-hospital group with facilities at a distance of as much as 240 km. In each hospital, patient-monitoring devices are tied into VitalCom's wireless LAN, which in turn connects to the hospital's wired network.

Instead of patient waveforms being monitored at the nursing station of each ward, VitalCom uses a more efficient method. All patient data is fed to a single "mission control" center, where it is processed, monitored, and archived by technicians. At the same time, the data can be routed to any nursing station in the system and is also available to physicians outside the hospital network through the Internet. [For more on the Internet in health care, see "Shortliffe's Prescriptions for the Internet"

The prime selling point for PatientNet over ISM technologies is the WMTS spectrum it operates in, said VitalCom's vice president for research and development, Steve Hannah. "If integrity of that signal is important, you should be in what the FCC has defined as the only protected airspace," he said.

Hospitals won't even be able to depreciate what they've invested in before they have to replace it

The suggestion that operating in the ISM band is unsafe rankles Jim Welch, general manager of the systems business unit at Welch Allyn Protocol. The 802.11 standard's ability to handle real-time and mission-critical data has already been proven in other applications such as voice-over Internet protocol, he counters. "It's the application of standards in the ISM that allows you to provide robust, interoperable systems," he said. Welch also points to rapid U.S. Food and Drug Administration approval of ISM products as the seal of that technology's approval in medicine.

Free-range physicians

While patient telemetry schemes are receiving more attention than ever, the proliferation of handhelds and phones is prompting companies to consider other wireless technologies beyond the proprietary WMTS and ISM-band 802.11. Medical suppliers are eyeing wide-area networks for third-generation cell phones, as well as the short-range Bluetooth technology. Though phones are banned in certain patient wards for fear of interference with medical equipment, physicians are increasingly comfortable using them as part of their practice outside the hospital. [For a new patient-monitoring scheme that uses cell phones, see " Detecting a Heartbeat with a Cell Phone"]

The move to hand-held devices in doctors' offices--and between the office and the hospital--is being driven by the need for easy and mobile access to patient records, lab results, and drug information, as well as for the ability to order prescriptions on-line. For instance, next month Data Critical, of Bothell, Wash., is launching a wireless service called UnwiredDr.com to connect physicians outside the hospital with patient data through handheld devices such as PDAs and cell phones.

Bluetooth, with its low output power, could also play a role in this area. Dr. Tom Giannulli, Data Critical's vice president of advanced research, said that Bluetooth might allow physicians to use its patient data service even in hospitals. A cell phone or a hand-held computer would connect to the Internet through Bluetooth when inside the hospital and through a wide-area wireless network when outside.

But Giannulli has little hope of this happening any time soon. Bluetooth, he said, would be much more useful to physicians who are looking up patient records or drug interaction precautions while in their offices. In contrast to hospitals, office networks would need fewer transceivers, and fewer users would be on the network at any one time.

According to financial services firm W.R. Hambrecht & Co., based in San Francisco, by 2004 about 20 percent of U.S. physicians will be using handheld devices for daily medical transactions. This activity could generate over $2 billion for firms in that market. "Practitioners need to access large volumes of information quickly, and they can't keep running back to centralized computers while they're taking care of their patients," said Roy Hays, vice president of product development at SpaceLabs Medical. "So wireless communication and the ability to bring needed information basically to wherever you happen to be is important."

Sometimes a wireless phone would be appropriate, and sometimes a PDA, with its somewhat larger display and easier system for entering data. Other times, because of the data density and the complexity of the interaction, a full-sized PC would be required. "I see all of those playing out and having a role in the future," Hays said.

To Probe Further

The U.S. Federal Communications Commission (FCC) ruling that set up the Wireless Medical Telemetry Service can be found at https://www.fcc.gov/Bureaus/Engineering_Technology/Orders/2000/fcc00211.pdf.

A more detailed analysis of the FCC rules appears in MSP Industry Alert, Vol. 2, no. 2, published by Medical Strategic Planning, Inc. of Lincroft, N.J.

The U.S. National Research Council's findings regarding the role of the Internet in health care can be found in Networking Health: Prescriptions for the Internet (National Academy Press, Washington D.C., 2000).

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