Now, they have been found to interfere with medical devices. This includes critical items such as mechanical ventilators and external pacemakers.
The study was published in JAMA ($ for full access):
Electromagnetic Interference From Radio Frequency Identification Inducing Potentially Hazardous Incidents in Critical Care Medical Equipment
Remko van der Togt, MSc; Erik Jan van Lieshout, MD; Reinout Hensbroek, MSc; E. Beinat, PhD; J. M. Binnekade, PhD; P. J. M. Bakker, MD, PhD
JAMA. 2008;299(24):2884-2890.
Context Health care applications of autoidentification technologies, such as radio frequency identification (RFID), have been proposed to improve patient safety and also the tracking and tracing of medical equipment. However, electromagnetic interference (EMI) by RFID on medical devices has never been reported.
Objective To assess and classify incidents of EMI by RFID on critical care equipment.
Design and Setting Without a patient being connected, EMI by 2 RFID systems (active 125 kHz and passive 868 MHz) was assessed under controlled conditions during May 2006, in the proximity of 41 medical devices (in 17 categories, 22 different manufacturers) at the Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands. Assessment took place according to an international test protocol. Incidents of EMI were classified according to a critical care adverse events scale as hazardous, significant, or light.
Results In 123 EMI tests (3 per medical device), RFID induced 34 EMI incidents: 22 were classified as hazardous, 2 as significant, and 10 as light. The passive 868-MHz RFID signal induced a higher number of incidents (26 incidents in 41 EMI tests; 63%) compared with the active 125-kHz RFID signal (8 incidents in 41 EMI tests; 20%); difference 44% (95% confidence interval, 27%-53%; P < .001). The passive 868-MHz RFID signal induced EMI in 26 medical devices, including 8 that were also affected by the active 125-kHz RFID signal (26 in 41 devices; 63%). The median distance between the RFID reader and the medical device in all EMI incidents was 30 cm (range, 0.1-600 cm).
Conclusions In a controlled nonclinical setting, RFID induced potentially hazardous incidents in medical devices. Implementation of RFID in the critical care environment should require on-site EMI tests and updates of international standards.
Note that the "passive" devices are not really passive. They still emit radio waves, despite being called passive. They are called passive because they don't have an internal battery; rather, they are powered by a capacitor that is connected to a coil.
A little more detail about the study can be seen openly in a USA Today article, here.
Out of 123 tests for electromagnetic interference between RFIDs and medical devices, 34 instances of interference occurred. In those cases, the midpoint between reader and device was less than a foot. Among the hazardous incidences, a mechanical ventilator switched off, a syringe pump stopped, and an external pacemaker malfunctioned.
The language is a little muddled in that section. They meant median distance, not midpoint. The median distance was 20cm (8 inches) The range is also important to note: up to 600cm (20 feet).
I once read about a patient who died, when a housekeeper unplugged a ventilator in order to use a floor buffer. That was bad. But imagine being able to have the same effect, just by walking by with a package or other item.
It would not be difficult to set up detectors in hospitals, to warn if potentially hazardous RFIDs are brought in. Better yet, it would be possible to shield devices so that this cannot happen, or can happen only from a specified direction. Or, critical devices could be designed so they won't shut off without a specific intervention from a human.
The galling thing is, it has been known for years that UHF RFIDs operate in the ISM (Industrial, Scientific, Medical) part of the spectrum, specifically the passive 868-MHz RFIDs. So it seems that the potential for this kind of thing should have been obvious.
Technology
Medicine & Health
Comments
Passive tags are not a danger in the absence of a reader: there's no EM to activate them. So the point is that if, say, medicine bottles are tagged, the presence of a bottle in someone's room is not a worry. But if someone was planning to install a reader at the patient's bed, say, to warn that the wrong drug was just brought within range... that could be a problem.
Posted by: Barry Leiba | June 25, 2008 10:29 AM
I am not surprised. A lot of medical equipment is poorly shielded: its circuitry incorrectly picks up radio-frequency radiation and treats it as a real signal, causing misoperation. You would think that life-critical equipment would be shielded to hell and gone, but this feature is often sorely lacking.
"The galling thing is, it has been known for years that UHF RFIDs operate in the ISM (Industrial, Scientific, Medical) part of the spectrum, specifically the passive 868-MHz RFIDs."
Spectral overlap is not the major problem. The medical device circuitry erroneously picks up signals over a wide range of frequencies. The RFID equipment might jam wireless telemetry systems that operate in the ISM band, but the central monitor would simply signal an alarm due to loss of contact.
Anyway, I question the utility of RFID in a hospital, since RFID cannot positively track the exact location of an item. E.g., giving the prescription computer a list of all the ampoules in a room is not nearly as useful as have a nurse barcode scan them one at a time as they are dosed.
Posted by: Daniel Newby | June 25, 2008 1:48 PM