Apr 14, 2009The University of Michigan Health System, with six facilities and 60 surgical rooms, is employing an RFID-based system for tissue tracking as the first step in a push toward automating and better securing its many assets, medical devices and laboratory items. The system, provided by Mobile Aspects, enables the hospital to control which personnel retrieve tissue products for surgical procedures, which patient receives each product, and if they are utilized or returned unused. For items requiring refrigeration, the system also monitors the length of time they remain out of cold storage.
With that data, the hospital can provide regulatory agencies with better records of the human, animal and synthetic tissues it stores and uses in surgery. The facility can also reduce wastage, as staff members are held responsible for all items they remove from storage.
The hospital stores as many as 190 different tissue products, including skin and bone fragments, some of which can be valued as high as $10,000. All have an expiration date, beyond which the hospital must dispose of any item not used. To manage the tissues in the hospital's adult surgical area, employees previously stored items in a variety of locations distributed around 26 operating rooms. The nursing staff would manually record, on paper, each time they took an item out of storage, by writing down for whom that product was destined, then doing so again if they returned it unused. Despite the items' high value, the hospital was unwilling to lock the cabinets and cooling units that housed them, because they needed to be accessible to the nursing staff at any hour of the day, often with short notice. Frequently, multiple products are removed from storage in various sizes prior to a particular surgical procedure, so that the surgeon could determine the best size during the operation. The unused tissue products would then be returned to storage.
All of this, says Patricia Silverman, the hospital's business systems leader for operating rooms, was a poor use of the medical staff's time, and the removal of tissue from storage simply wasn't always recorded.
The Mobile Aspects system offers benefits on several layers, Silverman says. Not only is the movement of tissue items tracked by RFID, but the cabinets, freezer and refrigerator doors are locked until workers scan proximity badges and select a patient, thus indicating who has taken which items, as well as for which patient they are destined, thereby reducing tissue theft or wastage.
Each tissue item is tagged with a Texas Instruments 13.56 MHz high-frequency (HF) passive RFID tag, complying with the ISO 15693 standard, attached to the bottom of the cardboard box or plastic bag containing that tissue. The hospital prints the item's serial number printed on the front. Mobile Aspects software, running on a server housed within the hospital, contains the unique RFID number encoded to each item's tag, and associates it with that item's serial and lot numbers, description, expiration date, temperature requirements and other data.
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.
