RFID EMI poses medical equipment hazard.

A recent study published in the June 24 edition of the Journal of the American Medical Association (JAMA) shows findings of possible patient risk due to interference between radio frequency identification devices (RFID) and some medical devices. The study was co-authored by two physicians at the Academic Medical Centre of the University of Amsterdam, the Netherlands. The study, which was conducted in a controlled non-clinical setting, was designed to assess and classify incidents of electromagnetic interference (EMI) by RFID on critical care equipment.

The assessment was made in proximity to 41 different medical devices spanning some 17 different categories and 22 manufacturers. The researchers utilized two types of RFID systems--one passive (868 MHz), which must be activated and powered by an EMI field generated by a reader in order to transmit information, and an active system (125 kHz), which is powered by batteries and can collect, store and broadcast the information without reader activation.

Some 123 tests were conducted with devices such as external pacemakers, infusion/syringe pumps, dialysis devices, defibrillators, mechanical ventilators, monitors and anesthesia devices. The 41 medical devices were submitted to three EMI tests each, constituting the total of 123. Out of that total, there were 34 incidents of EMI interference with 22 categorized as hazardous; two labeled as significant in that they influenced monitoring to a degree, causing a distraction from patient care; and, 10 were defined as light in that they influenced monitoring without requiring a significant level of attention.

Hazardous incidents included: ventilation rate changes and total switch-offs of mechanical ventilators; complete stoppage of syringe pumps; external pacemaker malfunctions; complete stoppage of renal replacement devices; and, electrocardiogram interference in atrial and ventricular electrogram curves read by the pacemaker programmer. Results showed that the passive RFID systems produced a significantly greater proportion of interference (44 percent difference) and hazardous incidents (27 percent difference) than the active systems. The median distance between reader and device where all instances occurred was 11.9 inches while hazardous incidents occurred at a median distance of 9.8 inches.

The authors acknowledge that the study was limited by the generalization of the incidents and applied only to the two types of RFID systems evaluated. The systems were also tested at full power to evaluate worst-case scenarios and no patients were involved in the study.

Peper Long, a Food and Drug Administration (FDA) spokesperson acknowledged that the agency was aware of potential problems but had received no reports of injuries directly caused by EMI with hospital devices. The FDA is testing some medical devices to determine vulnerability to EMI and the extent that the vulnerability may pose to public health. This is the first safety study dealing with RFID, which is widely used by hospitals to wirelessly tag medical equipment and even patients. The Dutch Ministry of Health, Welfare and Sport, the Ministry of Economic Affairs, the Academic Medical Center, Capgemini, Geodan, Oracle and Intel funded the study.