RRadio Frequency Identification (RFID) tagging is a much discussed technology that sounds to be a panacea for inventory tracking. And RFID is an appropriate technology especially for supply chain management. However, RFID is not the appropriate solution for tracking sponges in the human body. No company currently offers a RFID solution, viable or not, for the myriad of reasons listed below.

Technology Review

• Passive tags are the inexpensive RFID tags that are talked about in the news and are being used by retailers and for supply chain management. In its simplest form, a small silicon chip is attached to a small flexible antenna to create a tag. The chip is used to record and store information. When a tag is to be read, the reader (which also uses an antenna) sends it a radio signal. The tag absorbs some of the RF energy from the reader signal and reflects it back as a return signal delivering information from the tag's memory. The range of a passive tag depends on the size of the tag and reader – the smaller the tag, the closer and more powerful the reader has to be. The typical passive tag range is 6-12 inches.
• Active tags are battery powered and send out on their own, unlike passive tags, a strong signal constantly, much like the transponder attached to the windshield of a car going through the express lane at a toll plaza. Active tags can work up to several feet away from a reader but typically are the size of a credit card due to the power constraints of the tag.

Suitability of RFID to Sponge Counting

Read rate/failure rate:

• Right now the healthcare industry is having a problem with their 99.9996% accuracy counting. No RFID tag manufacturer can or will offer the same accuracy guarantee.
• RFID manufacturers do not release their machines' read rates, most likely due to the general accepted fact that they are all less than 80% outside of laboratory environments.
• In mid-2005, UPS abandoned research into implementing RFID to track their packages while moving through their system. If UPS doesn’t think RFID is worth the ease and cost in comparison to losing a box, then it surely can’t be worth losing a life.

Cost

• Cost is the biggest hurdle to RFID tags being implemented in any field that requires item-level tracking of low-cost products, such as sponges. Data matrix tags and its siblings typically cost between 1-5 cents. The most optimistic proponents of RFID are still “hoping” for 5-10 cent passive RFID tags sometime in the future (this may be years away). To overcome the blocking of weak passive radio signals passing in and back out of the body and through bodily fluids, active tags would be needed to make an RFID sponge work. Generally speaking, an EPC tag costs from 20-40 cents at very high volume. If the tag is embedded in a thermal transfer label on which companies can print a bar code, the price rises to 40 cents and up.

Should a Tag Fail:

• Imagine a scenario where the RFID tag becomes detached from its sponge and is entangled inside another sponge. Using an RFID wand to “read” the kick bucket to count the sponges would result in a false correct count – physically the sponge is still in the body but the wand is reading the tag in the bucket. Scanning the body to see if a sponge remained would also result in similar false results – either the nurse would not realize that a sponge remained, since in this case the tag is in the bucket and there is no “response” indicating that the sponge remains, or because the RFID reader could not pick up a tag deep inside the abdomen.
• With a line-of-sight system, everything must be scanned in by hand. It is rather unreasonable to believe that a nurse would scan in only the ½" by ½" squared label were it to detach (an extremely improbable event since the polymer is fused into the sponge) and claim that it was the entire sponge. In any case, the nurse would automatically know that something was amiss and there was a sponge missing since the label was in her hand. And there lies the benefit of a line-of-sight system: even if it fails to read, it is already in the nurse’s hands, and thus, can’t be forgotten and left behind.

Responsibility

• Though none currently exists, using an RFID solution shifts the responsibility for the count from the hospital’s staff to the manufacturers of the sponges and readers. Our line-of-sight system simply aids nurses in counting faster and more accurately within the confines of their established counting protocol. An RFID system shifts the burden to the manufacturer to guarantee that it read/scanned everything correctly since it is now solely the RFID system’s role to count the sponges. This has several implications:
  
  • These manufacturing companies will face enormous insurance indemnity fees – to a point that they will be unsustainable.
  • Should one single sponge be lost, the companies already-high insurance fees will skyrocket to unaffordable levels and the companies will be bankrupted quickly or will discontinue manufacturing the products.

• Should sponges be lost, the technology would have to be abandoned, at tremendous sunk costs to hospitals.

Other Technical problems with an RFID retained sponge solution

1. RFID tags can fail. Yes, bar codes can fail too, but again, they are designed to be handled by the staff with the code visibly printed on the label. And much like at a grocery store, a failed tag results in a ½ second manual entry of the ID code. Were an RFID tag to fail, how would a nurse know the difference between a missing tag and a failed tag? When it comes to life and death, out of sight is not out of mind.
2. RFID does not work well with water, blood, and bodily fluids. Radio waves are absorbed by liquids at ultra-high frequencies making implementation of RFID tags into the bodies full of variably viscous fluids extremely difficult and pernicious. RFID tags can be tuned to deal with specific fluids, but the body has water, bile, fecal matter, acids, the whole gamut. This leads to higher RFID read failure rates.
3. RFID is not directional. It will read all tags within a circular range, unknowingly and indiscriminately. And since either active tags or very powerful passive tag readers would be required, an unopened pack of sponges sitting on a shelf in the room would be read and counted as well as an opened pack sitting on the mayo stand. RFID tags cannot be turned on or off. Bar coding permits the selective reading of labels. Imagine a janitor walking down the hall with some new supplies throwing off every reader in every OR.
4. The phenomenon of tag collision occurs when more than one tag reflects back a signal at the same time, confusing the reader. Having a 10 pack of sponges with 10 RFID tags on top of each other is a far different cry than having one RFID tag on the outside of an entire crate of sponges in a warehouse. Again, having a line-of-sight, one at a time, reading system prevents this read failure issue from occurring.
5. Read collision. This occurs when the signal from one reader can interfere with the signal from another where coverage overlaps. Again, imagine someone walking down a hall with a reader on the way to maintenance. That reader could interfere with the RFID reader inside another OR.
6. Sterilization. The battery in an active tag would need to survive both the sterilization process and sitting on a shelf for months. So far, batteries are unable to sustain much power after sterilization, let alone sit on a shelf awaiting use.

A solution with this many problems and pitfalls is not the right solution to a problem with a error rate of .0004%.