Jun 25, 2008This article was originally published by RFID Update.
June 25, 2008—Electromagnetic interference (EMI) caused by RFID systems interfered with medical devices in intensive care unit testing, according to a study published today in the Journal of the American Medical Association (JAMA). The study, performed by researchers at the Academic Medical Center at the University of Amsterdam in the Netherlands, tested 41 medical devices three times each. It documented 34 incidents of electromagnetic interference for the 123 tests. The study tested passive 868 MHz (the UHF band used in Europe) and active 125 KHz RFID technologies.
The report sparked extensive coverage by mainstream and IT media, including several reports that sensationalize the danger. The actual study summary reported by JAMA is much less alarmist. It said the danger to medical devices from RFID is comparable to that from cell phones and documented potential problems RFID devices can cause, but did not call for a ban on RFID in hospitals. The report ends with the following statement:
"In conclusion, in a controlled nonclinical trial setting, RFID technology is capable of inducing potentially hazardous incidents in medical devices. Implementation of RFID in the ICU and other similar health care environments should require on-site EMI tests in addition to updated international standards."
Pacemakers, defibrillators, dialysis machines, infusion/syringe pumps, and ventilators were among the tested devices that experienced interference. There were incidents recorded for all three external pacemakers tested, and for eight out of nine infusion/syringe pumps. No pacemakers stopped completely, but six out of nine infusion/syringe pumps did, as did both renal replacement devices tested.
The 41 medical devices tested included 17 categories of equipment from 22 manufacturers. Passive UHF signals created interference for 26 of the devices (63 percent), and active 125 KHz signals caused interference for eight devices (19.5 percent). All eight devices that experienced interference from 125 KHz signals also experienced interference from 868 MHz signals.
Researchers developed an adverse events scale to rate the severity of interference. Of the 34 instances of EMI, 22 were classified as hazardous, two as significant, and ten as light. Incidents were defined as "every unintended change in function of a medical device." "Hazardous" incidents were defined as a direct physical influence on the patient because of an unintended change in equipment function, such as an IV pump or pacemaker stopping. "Significant" incidents required additional patient monitoring or events that caused significant distractions from patient care, such as incorrect device alarms. Finally, "light" incidents referred to events that did not require a significant level of attention.
Tags and readers were tested in a patient room. The median distance between RFID tags and readers and affected medical devices was 30 centimeters. For comparison, report authors cited research into cell phone safety that found the median distance for harmful incidents in hospitals was 3 centimeters. The researchers reported that the incidence rate increased as the power output of RFID devices increased. RFID devices caused EMI incidents on medical devices that were up to 600 centimeters away.
The article said electromagnetic interference caused by RFID had never previously been reported. The study was developed out of research into the suitability for using RFID to track blood products and expensive medical supplies. Researchers at the University of Wisconsin-Madison RFID Lab are also currently investigating RFID's uses for blood tracking, which would require FDA approval (see RFID Holds Promise for Blood Supply Chain). In 2004 the FDA approved a class of RFID chips for human implant (see VeriChip RFID Technology Gets FDA Approval; Stock Surges).
