Thursday, November 1, 2007

Bar codes, RFID, and Patient Safety

Like most hospitals, Beth Israel Deaconess Medical Center is focused on maximizing patient safety, quality and value. Over the past few years, we've implemented Provider Order Entry, Guidelines/Care Plans, and Electronic Medical Records. However, a great puzzle remains - how do we positively identify our patients so that we are confident they are receiving the correct medications, have the correct blood samples sent to the lab and receive the right blood products during a transfusion? For example, with perfect identification, we can create an electronic medication administration record that documents that the right patient received the right medication from the right person at the right time.

To accomplish the goal of positive identification of our patients, our staff and our medications, we spent the past year investigating two major kinds of technology - bar codes and radio frequency identification (RFID). In different use cases, each technology has its pros and cons. Based on our early work, we have implemented these technologies in various production settings in the hospital with positive results.

Bar Codes have been used successfully in industry for decades. The technology is stable and well standardized. Bar codes come in two basic forms, simple linear bar codes and more complex two dimensional bar codes. Linear bar codes encode a few characters or numbers, such as the 12 digit UPC symbols found on grocer's shelves. Linear bar codes can be used in a healthcare setting to encode a medical record number placed on a patient wristband. Two dimensional bar codes can encode more complex information such as patient name, age, gender that could be used to provide details about the patient without requiring a lookup in a hospital information system, which helps provide redundancy in case of hospital system downtime.

Many vendors offer wrist bands and printers which facilitate easy bar coded wrist banding of each patient upon admission or registration. Bar codes are inexpensive, highly reliable and generally already used in hospitals. Hence existing hospital bar code readers can be used.< However, bar codes do have limitations. Reading bar codes requires line of sight scanning which means that patients need to be awakened/repositioned each time the bar code needs to be scanned. Linear bar codes must be relatively flat to be read properly, so a wristband wrapped around a premature baby's wrist is problematic. Bar codes generally do not read well when wrinkled, wet or torn. One positive aspect of this characteristic is that bar codes rarely yield an inaccurate read, but simply do not read at all when damaged.

In our case, we believe that putting both linear and two dimensional bar codes on wrist bands enables us to take advantage of linear bar code readers already in use in the hospital, while also preparing us for purchases of future bar code reading equipment which will read both two dimensional and linear bar codes. For employees, our security badging software produces a linear bar code on employee badges. For medications, an informal survey of our supply chain revealed that 70% of all medication containers are already bar coded. Although this may help with drug distribution, it does not help us identify unit doses of medications since pills are not yet bar coded. Repacking pills into bar coded bags is required for positive identification of unit dose medications.

Radio Frequency Identification is an evolving technology that is widely speculated to replace bar codes over the next few years. However, RFID in healthcare requires careful examination, because separating reality from hype can be challenging. RFID comes in two basic forms, active and passive.

Active RFID tags contain a battery and transmitter which can be used as a geo-location, constantly providing information about the physical location of the active tag in the hospital. Current active tags are about the size of the pager, require battery replacement every 6 months and cost $50 each. As with many new technologies, the size is decreasing, the battery life is lengthening and the cost per tag is dropping significantly. Active RFID transmitters generally use one of two frequencies - either 802.11b/WiFi (2.4 Ghz) or a proprietary frequency (488 Mhz). The advantage of using WiFi is that the existing hospital wireless network can be used to read tag location. Our experience is that Active RFID over WiFi can be rapidly and cost effectively deployed for use cases which require room level tag location. Proprietary systems that use an Active RFID specific network, such as 488 Mhz or infrared receivers in each room can provide location to the level of the square meter, but do require the installation of dedicated wiring to support the RFID system. >In our case, we believe that Active RFID tags are a robust technology for applications which can utilize a pager size device such as tracking equipment, tracking patient beds, and tracking staff who are willing to wear an extra pager-sized device. For tracking staff, we specifically worked with managers to ensure that tags would not be used in a punitive way i.e. to record minutes in the lunch room, trips outside to smoke etc. Our application of active RFID is currently for equipment tracking in the Emergency Department and has reduced the time to search for ventilators, IV pumps, and EKG devices to near zero.

Passive RFID tags contain an antenna and a chip, but no battery. They can be as flat as piece of paper and as small as a grain of rice. When a reader provides RF energy which is absorbed by the antenna, the chip is stimulated to broadcast its data. This data could be simple such as a medical record number or complex such as name/gender/date of birth. Examples of passive RFID tags are the Mobil Speedpass used for gasoline purchases, product identification tags used on retail products such as Gillette Razors at Walmart and tags used in libraries to track books.

RFID tags have several advantages over bar codes. They do not require line of sight reading, hence an RFID reader can be brought near a sleeping patient or a swaddled NICU baby and can easily read the patient identifier. RFID tags are resistant to moisture, crushing and tearing.

However, passive RFID is not a panacea. Tags are more expensive than simple printed bar codes. Standards for passive RFID are still in evolution and many different frequencies are used to read different tags i.e. 125 Khz, 134.2 Khz, and 13.56 Mhz. RFID tags typically have up to a 20% failure rate in manufacture and thus can result in a non-readable wrist band. RFID tags are much harder to read if a metal barrier such a aluminum foil exists between the reader and the tag.

Existing passive RFID products include wrist bands and implantable chips such as those used to track pets. Human use has been limited and I am one of the early evaluators of the technology (see Straight from the Shoulder in New England Journal of Medicine, July 28, 2005, page 331). My body is RFID enabled and when scanned, I emit my medical record identifiers which can be used by authorized physicians to retrieve my medical records via a secure web application.

In our case, we use Passive RFID to track NICU babies via RFID wristbands and to track mother's milk stored in tagged containers. A software application and RFID scanner is used to ensure the right infant receives the right milk and to automatically create an audit trail.

Our early work with positive patient identification can be summarized as

For identification of most patients, we believe linear and two dimensional bar codes on wrist bands is robust, cost effective and standardized. For staff badges, linear bar codes work well. For NICU babies passive RFID enables scanning of swaddled infants without disturbing them.

For identification of medications, we believe linear bar codes of NDC numbers on heat sealable plastic bags provides a practical means to positively identification medications.

For identification of equipment, specifically for tracking location in real time, active RFID works well. Because of the size and expense of tags, we do not believe active RFID should be used for patient identification at this time.

Thus, a combination of bar codes, passive RFID and active RFID is working well in our various pilots. No one technology meets the needs of all use cases. Although we favor bar codes over passive RFID in the short term, we do expect to eventually replace bar codes with RFID once the technology is more robust, standardized and cost effective.

1 comment:

Kevin said...

Any thoughts on ultrasound technologies - like Sonitor?