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University of Michigan Health System Tags Surgical Tissue

The hospital is using passive high-frequency RFID tags to secure and manage up to 190 different tissue products, including bone fragments and skin for grafting.
By Claire Swedberg
The items are then placed in one of three interconnected cabinets, two of which are RFID-enabled, or in the refrigerator or freezer. The interior of each of the two master cabinets (the auxiliary cabinet lacks an interrogator) has one HF RFID reader installed on a shelf, while an additional HF RFID interrogator is installed outside the cabinets, to tracks items placed in or removed from the refrigerator or freezer, or the auxiliary cabinet. The system is managed by a computer that captures information from the readers and sends it along to the Mobile Aspects software on the hospital's back-end system, while also managing the locking units and a separate low-frequency (LF) reader for scanning staff ID cards, each of which contains an HID 125 kHz RFID tag with a proprietary air-interface protocol.

A nurse requiring a tissue item first scans his or her proximity card at the central reader. A list of patients scheduled for surgery that day is displayed on a touch-screen monitor, and the nurse selects the patient for whom he or she is taking the tissue. The doors of all storage units then unlock. When a cabinet, refrigerator or freezer door is closed, it locks automatically. Shelf readers inside that cabinet capture the ID numbers of items remaining within, and the Mobile Aspects software determines which ID numbers are no longer being read, then associates those items with the patient name selected by the nurse, as well as the identification of the nurse who took those items. When any items are returned, they are placed in a return bin and eventually put back in the appropriate cabinet, refrigerator or freezer. Because there are no readers inside the freezer or refrigerator, the staff uses the external HF RFID interrogator outside the cabinet to read a product's tag whenever that item is removed from or returned to cold storage.

Mobile Aspects developed this technology, known as the Intelligent RF Identification System Secure (iRISecure), approximately 18 months ago, says Bryan Christianson, the company's VP of marketing, to manage tissue implants for surgical procedures. The system is also being used at Children's Hospital Boston, as well as at other hospitals within the United States.

For the University of Michigan, Mobile Aspects provided three cabinets measuring 7 feet tall by three feet wide by three feet deep that store items at room temperature. "They needed to know not just the quantity on hand, but what they did with each item," says Gino N. Iasella, Mobile Aspects' director of new product development. The software enables the hospital to run reports showing which items were used for each patient, as well as which staff member removed them, and how quickly unused items were returned to a refrigerator or freezer. The system can indicate, on the report, which items have spent too much time out of cold storage, Iasella says, or which are nearing their expiration dates. The software also allows the hospital to track which items have been used on a daily basis, and the reordering of those items.

Simply alerting the hospital to use an item before it expires, Christianson says, can justify the cost of the technology. According to Silverman, the system has already saved the surgical unit money in the three weeks during which it has been in operation, simply by making the nursing staff more accountable. In the past, she says, tissue items would simply disappear. Now, with the Mobile Aspects installed, staff members are recorded as having removed specific items. "No matter how tired they are [at the end of a surgical procedure]," she adds, "we've made it easy for them to return everything," rather than discard an unused tissue item.

The technology still has some kinks to work out, Silverman says, noting, "It's finicky technology." Because the shelf readers do not operate at the cold temperatures within the refrigerator and freezer—which can drop to as low as -86 degrees Fahrenheit (-66 degrees Celsius)—the items need to be scanned at an RFID reader outside the units. And because the tags do not read well on foil (which, according to Silverman, approximately half of the items are packed in), the hospital requires only select staff members to replace returned items in storage from the return bin, in order to ensure the RFID tags are read properly. If, for instance, the items were replaced upside down, Silverman explains, they would be difficult to interrogate. To make the tags able to be read on foil, she says, the hospital first attaches a piece of cardboard to the item, then applies the tag to the cardboard's surface.

The hospital intends to roll out the system to all of its surgical areas, Silverman says, and is also considering an asset-tracking system, though the requirement of active RFID tags for such an application, as well as the heavy presence of RF-absorbing lead in the walls, makes that solution more challenging.

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