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Ultrasound's Unique Use

December 1, 2007
by Michelle Grey
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Seton Medical Center is using ultrasound to do more than image the heart; it's tracking clinical assets and patients

Gerry lewis

Gerry Lewis


Using ultrasound for a range of diagnostic processes such as monitoring fetuses, imaging the heart, and evaluating blood vessel flow is not new.

However, in April, Austin, Texas-based Seton Medical Center, part of the Seton Family of Hospitals, a not-for-profit organization owned by Ascension Health, began testing the use of ultrasound technology for a unique set of goals — to track clinical assets and patients.

Sounding out the competition

Utilizing ultrasound for location services is clearly an emerging technology, says Barry Hieb, senior analyst, Gartner Industries, Stamford, Conn. He maintains that Sonitor Technologies (Oslo, Norway) is the only company that uses sound waves to track medical devices and patients, and that the company has only carried out a “handful” of deployments in U.S.-based hospitals.


Jeffrey falwell

Jeffrey Falwell


Why then would a 471-bed hospital such as Seton select a technology with so few proven implementations? It was the only solution that guaranteed 100 percent room-level accuracy, touts Seton Medical Center's CIO, Gerry Lewis. However, Lewis claims to have only taken a “calculated risk,” which was minimized by carrying out several pilots in small areas of the hospital. “We call it the ‘toe-dipper’ approach — dip your toe in the water before you jump in,” he explains.

Interestingly, Jeffrey Falwell, a Dell (Round Rock, Texas) senior project consultant who serves as Seton's director of its program management office, alleges the medical center was initially in favor of using active RFID (radio frequency identification) to track medical devices and patients. Falwell says, “When I came on board to manage the asset tracking venture, it was called the RFID Equipment Tracking project.”

Originally, Seton was interested in running active RFID tags off the existing WiFi (wireless fidelity) network, Lewis explains. “We'd just put a lot of money into implementing a WLAN (wireless local area network), so my great idea was to just leverage off that infrastructure. However, I soon found out going down that road would be woefully inadequate,” he says. Lewis claims even RFID vendors recommended he would need to double the amount of access points to achieve the accuracy and granularity the organization was looking for, and that meant infrastructure costs would “skyrocket.”

After jettisoning the plan to use Seton's existing wireless network, Falwell says the hospital identified a vendor that used RFID tags in the 303-MHz space, which gave “a good level of accuracy,” but again required the installation of a large number of access points. Another problem with using RFID-based technology is that it bleeds through walls, he says. “It may give 5-10 feet accuracy, which is relatively good, but walls are only 6-8 inches thick,” says Falwell.

According to Hieb, in order to circumvent the problem of “wall bleeding” and to gain more accuracy, many RFID vendors will use algorithms that calculate the distance of the tag from the access point, based on factors such as the amount of time elapsed between the issuance of the signal and its receipt, he explains. Three or more access points can be used to locate a tag through triangulation. Of course, “You still run into the problem of increased infrastructure costs and hassle with the implementation of extra access points,” Hieb says.

Falwell claims his team also looked at a company using the 620-MHz spectrum, which had “very good location accuracy,” but was in the same bandwidth as some of the hospital's clinical equipment, and could potentially cause interference. Although Falwell says he briefly looked at passive RFID, it was clear early on that this technology would not fulfill Seton business requirements. To achieve room level accuracy with passive RFID, every door needs to be fitted with detectors. “And there is still the concern that it's not 100 percent accurate because these detectors can't tell which direction a device is travelling,” he says. “You don't know whether something has left or entered the room.”

Notably, Falwell says Sonitor, the sole ultrasound vendor, was an outlier. “We didn't really know how well the technology had been adopted, but we were impressed with its level of accuracy.”

After careful analysis of the different types of asset tracking technologies, Seton chose five vendors to submit proposals. The hospital conducted a two and a half day demonstration in which each leading candidate deployed its system throughout 16 rooms. Clinicians, nurses, and executives were then asked to test and rate the different solutions, explains Falwell.

The clear frontrunners were Sonitor Technologies and Radianse (Andover, Mass.), an RFID vendor using the 433 MHz spectrum — both gave excellent accuracy levels, says Falwell, although Sonitor is the only vendor that guarantees 100 percent room-level accuracy. Sonitor required the installation of a reader in each room.”We were concerned about the added cost of adding a reader in each room with the Sonitor solution,” Falwell stated. However, because Radianse had to add extra readers to its normal solution to provide close to room level accuracy, “essentially it became a commodity buy, and the ultrasound readers, which are just little microphones, were cheaper,” claims Falwell.

Utilizing ultrasound

Sonitor's ultrasound-based indoor positioning solution works relatively simply, says Terry Aasen, president and CEO of Sonitor USA. Tags are attached to the devices or people that are to be tracked. The tags then send out ultrasound waves to microphones installed in various locations throughout the facility. Each tag communicates the serial number of the item to which it is attached via sound waves — each tag has its unique “chirp,” explains Aasen. The microphones then send this information — either via WiFi or cabled Ethernet (which is what Seton chose) — to the system's server, which matches the serial number to the piece of equipment and displays it on the chosen application. Because it's only sending 200 bytes per location signal over the network, it places only a very small burden on the infrastructure, he says.



Illustration, J. Gouijn-Stook


Ultrasound tags are thicker than the tags used with RFID or WiFi-based tracking systems because they contain a speaker, but can be attached to most items via double-sided tape, explains Falwell. He says that Seton helped to redesign Sonitor's tags. “Initially they had a tag that I think looked like a Sharpie pen, but it didn't fit on some of the equipment because of the curved surfaces and weird angles. So we redesigned one to look like a little piece of chocolate — it was more ergonomic,” he explains. The new design, he claims, allows more flexibility, especially when it's attached to smaller devices such as thermometers.

Hieb contends that a significant benefit of using ultrasound technology over RFID is that it provides better coverage. “If you put a microphone in a room, it should be able to hear any ‘chirp’ that's in the room because ultrasound travels very well,” he explains. However, when antennas receive radio wave signals, if someone is standing next to a metal door frame, the signal may suddenly become weaker, or momentarily lost, says Hieb. Large metal objects such as X-Ray machines don't interfere with ultrasound, he says.

Knowing where to place readers — either ultrasound or RFID — and how many to use poses a challenge for many institutions, says Jim Dachelet, CIO of RadiantWave, an asset tracking consulting firm based in Nacogdoches, Texas. Seton hired Dachelet to help design, integrate and implement Sonitor's system, which included determining how many microphones to install. Seton currently has 985 microphones hanging in patient rooms, hallways and equipment closets, he says. But it plans to install half a dozen more after noticing that some equipment was being hoarded in other locations, such as the nurses break room.

To visualize the location of its assets, Seton chose Waukesha, Wis.-based RedPrairie's Mobile Resource Solution asset-management software. The Web-based application has a mapping function, allowing it to illustrate digitally all rooms containing a specific device, explains Dachelet.

RedPrairie's application is easy to use — it only takes 10 minutes of training, and users can see where a device is located within a couple of clicks, says Falwell. Some other solutions provide “fantastic” information about the asset, such as whether it's ready for maintenance, or whether it needs to be cleaned or upgraded, he says, “but all we want to know is where a device is.” One software competitor called it the ‘Where's Waldo’ application, he chuckles.

Dachelet notes that Seton chose its software application first, even before selecting the type of technology it wanted to use for asset tracking. According to Dachelet, the hospital wanted to make sure the software had the ability to visualize assets and patients throughout its multiple sites. It didn't want to have to link five or six different applications together. Most hospitals will look for hardware solutions first, and then backtrack to try and find a software application to tie all the hardware together — and not all applications work with all types of hardware. Some applications don't have the capability of linking several sites together, so each facility can be left with separate silos of information, he says. “Seton was very forward thinking in that respect,” Dachelet touts.

Tracking the future

Seton Medical Center is using Sonitor's ultrasound-based technology to track assets such as IV pumps, pain-medication pumps, bloodpressure monitors, specialized wheelchairs and thermometers. However, beginning this winter, the facility plans on rolling out the technology to track patients.

Falwell explains that although the infrastructure is in place, there are a number of processes that need to be ironed out. For instance, he claims the placement of tags on patients is an issue. He says they've looked into putting tags on wrist bands, but if a patient leaks bodily fluid onto the tag it can pose significant infection control problems, and the tag would need to be sterilized or replaced. “Some companies are selling disposable wrist bands, but last time I checked they were $8 a piece, and that's not acceptable for a hospital that's treating over 80,000 patients a year,” Falwell maintains.

Seton's Infection Control Department has begun working with Sonitor to design a unique reusable tag that will have a plastic cover that can be thrown away, but with the expensive part remaining intact, explains Falwell. He says the key driver behind tracking patients is the ROI Seton expects to see with regards to the discharge process. “If we can get beds ready as soon as a patient leaves, we can increase our capacity,” he says.

When asked about ROI studies that Seton has carried out, Falwell says he “can't give specific details.” However, in order to tag the equipment, Seton needed to create a comprehensive equipment inventory, which allowed it to see which devices had gone “missing” over the past five to seven years, he explains. “We're assuming that by putting this solution in place it's going to prevent loss, and hopefully the system should pay for itself in about a year,” he contends. Lewis also stresses the importance of “soft returns” such as clinician satisfaction, streamlining workflow, and reducing the amount of time nurses spend searching for equipment.

Lewis advises that if a facility wants to implement a successful asset or patient tracking solution, it needs to spend a significant amount of time defining its business requirements. “A lot of times we have a solution in our head and we go out and get it without meticulously planning how we're going to use it,” he says.

Hieb echoes this sentiment. “Healthcare facilities need to define which technology is best for which type of function before they run out and deploy an entire system.” For example, it's probably not appropriate to put an RFID or ultrasound tag on an aspirin — not only because the tablet is too small, but the cost of the tag is too high — so in this case bar coding might be a good choice for drug administration, he explains. “Asset tracking is not an ‘all inclusive’ proposition; different technologies are suited to tracking different items,” he says. Ultrasound is great for tracking items where 100 percent room-level accuracy is needed — patients are a good example of this, Hieb contends.

However, one of the obvious downsides of implementing Sonitor's technologies is that it's so new, claims Hieb. Often with new technology there are no defined standards, so if a second company shows up with an ultrasound tracking application, it will almost certainly use different hardware, he says.

It's unlikely Sonitor's tags could be used on another system, “which means you're kind of tied to that particular company,” Hieb explains. There aren't many clients out there that a hospital can talk to about how well the technology works, or how well a particular vendor supports its system, he says. “If the company dissolves, a hospital's investment is at risk — and these solutions aren't cheap.”


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