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.
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.