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UCSD Medical Center Expands Its RFID Deployment
The teaching hospital estimates the technology has saved it $70,000 annually by merely enabling it to locate its IV pumps more quickly.
Oct 29, 2008—For about two years, the University of California, San Diego (UCSD) Medical Center has employed an RFID-enabled real-time location system (RTLS) to track a variety of assets at its Thornton, Calif., campus. The teaching hospital estimates it has saved approximately $70,000 annually on IV pumps alone, because it can easily locate the pumps with a click of a button, thereby eliminating the need to rent pumps on a daily basis in order to meet demand. Now, UCSD is expanding the RTLS to its other campus in Hillcrest.
The medical center is using an RTLS from Awarepoint that employs active RFID tags operating at 2.48 GHz. The tags transmit their unique IDs over the 802.15.4 (ZigBee) communications protocol, to small receivers (which Awarepoint refers to as sensors) that plug directly into standard 120-volt AC wall outlets. These tags and sensors also function as transceivers, communicating with each other via the ZigBee mesh networking protocol. A tag or sensor can pass data to a main access point (known as a bridge) by first sending it to another tag, which then forwards the information to a third tag or sensor, or to the main access point, depending on whether the second tag is in range of the main access point. In the Awarepoint network, a tag can transmit data to a bridge through up to five other tags and receivers. The receivers employ the ZigBee protocol to forward a tag's ID number and signal strength to a bridge, along with its own ID number and the time it read the tag and the ID of the transceiver that may have previously picked up the tag's signal.
The bridges link, via an Ethernet cable, to a central Awarepoint server that calculates the locations of all tagged assets, then displays that information on a map of the facility. Any computer linked to the system's local area network (LAN) can access the map and then employ Awarepoint's software to search for a specified type of asset. The software can provide the asset's location to an accuracy level of 1 to 3 meters (3 to 10 feet). Awarepoint utilizes a proprietary algorithm to determine asset locations, based on the tags' RF signal strength.
Generally, Awarepoint's RTLS requires one sensor per every 1,000 square feet, and one bridge per every 20,000 square feet, according to Matt Perkins, the company's CTO. The recently renovated Hillcrest campus is a 386-bed hospital that measures nearly 1,000,000 square feet. Thornton, meanwhile, is a 119-bed, 238,800-square-foot general medical-surgical facility. UCSD and Awarepoint decline to reveal the number of sensors and bridges the hospital has actually deployed to date.
The Thornton facility has currently tagged approximately 650 to 700 assets, including IV pumps, headlights worn by surgeons, and wheelchairs, according to Tom Hamelin, UCSD's director of perioperative services and the initiator and overseer of the RFID project. At Hillcrest, Hamelin says, he and his team have been "furiously tagging" assets. So far, 400 items have been tagged, and he soon expects to have a total of about 800. Each tags' unique ID number is correlated with information specific to that item (including the item's serial number, the manufacturer, the model number, and an internal asset number assigned by the biomedical department) in a database that's part of Awarepoint's software.
Awarepoint's RTLS does not operate on a Wi-Fi network, as do other RTLS systems currently on the market. That feature was important to UCSD. "When I started this project, there were two things that the head of IT asked of me," Hamelin says. "He told me not to bring in a system that would mess with the hospital's wireless network, and he asked me for a solution that would determine the location of assets."
Prior to implementing the RTLS, first at Thornton and later at Hillcrest, UCSD had no method for tracking its assets, other than simple pen and paper. "We had inventory lists from the biomedical engineering department," Hamelin says, "and did our best to keep track of things that way." But, he explains, as often happens in hospitals, caregivers would stash items so they could access them when needed, which often resulted in items missing for days on end. Every so often, the hospital would have to put together a "SWAT team" to hunt down all of the various assets and bring them to a vacant storage room. "We'd go from an empty room to a room full of equipment," he adds.
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