Wireless Patient Monitors, WMTS or ISM?

The FCC and FDA designated two portions of spectrum for wireless telemetry, WMTS (wireless medical telemetry service) and ISM (the Industrial, Scientific and Medical band).  Since the inception of WMTS in June of 2000, and the release of WMTS and ISM based medical devices, there has been a lot of talk about one band being more “protected” from interference than the other.

There are two kinds of RF interference, intentional, and unintentional. In the previous string, the talk has been about intentional interference from HDTV, TV, and PLMR (but NOT ham radios).

By far the most frequent (and troublesome) form of interference is unintentional. Bad fluorescent light ballasts, elevator motors, microwave ovens and other RF radiators in and around hospitals.

Vendors have made a lot of hay about how WMTS is “protected.” It is protected, but only from intentional interference. And even then, you must identify the source and go through a formal process to resolve the situation. This could take weeks or months to resolve.

WMTS is a designation of frequency ranges, a piece of RF real estate. Vendors can develop any kind of communications schemes within that band that they want. There are no standards built into WMTS to ensure coexistence, maximize capacity or minimize the impact of interference, intentional or otherwise.

The ISM band (approved by the FDA and FCC for medical telemetry) is also a piece of RF real estate, but it includes standards that everyone must follow to ensure (or at least facilitate) coexistence, enhance capacity and minimize the effect of interference (either power level restrictions or protocols like 802.11a/b/g). This is why GE (and soon Philips) is employing ISM-like protocols (spread spectrum frequency hopping) in their WMTS products.

ISM has many times more bandwidth than WMTS, thus providing greater theoretical capacity, and more room to avoid interference. In larger facilities, this may be an issue. Also, WMTS coexistence between two or more vendors is a big issue. I’ve seen a GE system hop all over a channelized Philips system, rendering the Philips system ineffective. WMTS infrastructure, i.e., access points, are proprietary — although the network cable pulled to them is not.

In the real world of patient monitoring and surveillance, WMTS and ISM are substantially equivalent. Which is best depends on the details of your particular situation, and the vendor(s) involved.

The real criteria come into product features like scalability, reliability, ease of use, and support for your clinical workflow. Oh ya, and the devices that hang off the network.

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Engineers to Improve Patient Flow at LA County/USC Hospital

Patient flow is getting so hot, that engineering schools are getting into the act.  A team of engineers at the USC Viterbi School of Engineering are analyzing patient flow throughout LA County/USC Hospital.

In the first study of its kind for USC's Viterbi School of Engineering, Hall and a team of engineers in the Epstein Department of Industrial and Systems Engineering partnered with Los Angeles County/USC Hospital to model the entire hospital, from top to bottom, as an integrated system. The objective was to identify the most significant bottlenecks, as well as the highest payoff strategies, for improving patient flow.

As Randolph Hall, principal investigator and professor of industrial and systems engineering in the Viterbi School says,

“ To keep up with the demand,  patients must be transferred without delay from emergency room triage to ancillary services, such as radiology departments, for x-rays, CT scans, MRIs and other diagnostic tests, or on to operating rooms for surgery. Those who need to be admitted to the hospital must further wait for a bed to be freed up, which depends on the speed at which patients are discharged, rooms are prepared and patients are transferred among locations.

“All of these departmental activities are interdependent as patients flow through the emergency care system,” Hall said. “It's like a domino effect. If there is a delay in any one of those steps, every other department down the line will experience a delay.” 

No patient flow secrets are revealed, just the basics:  timely results reporting, efficient discharges, and good communications between Admitting, Environment Services and nursing units (did he forget timely orders?).  The focus of their efforts is to apply systems process engineering from manufacturing, distribution and transportation.  After interviewing more than 100 administrators and physicians, and developing a computer model for patient flow in the hospital, I can only imaging the cost if this was a commercial consulting engagement!

In parallel with new and improved procedures to manage patient flow, engineers in the Viterbi School are also developing a collaborative educational program with County/USC Hospital, which will include student placement in the hospital and a new course in industrial engineering on patient flow improvement.

Architectural firms that specialize in hospitals frequently offer services that include equipment and management consulting.  I'm sure these guys would love to hire graduates from the Viterbi School.

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