PatrickMD.net

A JAMA article out this week from investigators in Amsterdam reports that RFID tags induced “potentially hazardous incidents in medical devices” in the ICU room used for testing. Ventilators and infusion pumps just shut down due to interference in some cases. Their website includes a full catalog of the observed bad behavior.

The image here is from the article and demonstrates the test protocol used. Both active (145 Mhz) and passive (868 Mhz) RFID tags were tested, and the passive tags caused more incidents. Median distance between the reader and device was 30 cm over all incidents, with a range of 0.1 to 600 cm.

The passive RFID tag and reader were the OBID UHF model from Feig Electronic. The article states that a 2-4W reader was used, which indicates one of the long-range models. The power can be brought down as low as 100 mW with a corresponding range reduction. The active RFID tag and reader was from Eureka RFID. The reader was 125 kHz and the tag was at 868 Mhz at 2 µW. Active tags can be read at 50-100m.

I point out the power issues because all readers were used at maximum output power to mimic a worst-case scenario. The authors defend this as realistic since hospital building effects may require maximum power in order for a RFID system to be usable. This study was conducted in the context of a project to track blood products and expensive supplies in ORs and ICUs. I imagine that for that purpose one might need a range of 50-100m, but that seems excessive to me.

I was surprised to read that 2G and 3G cell phones can cause hazardous interference also. I had thought most of those issues were due to the high power output of analog phones. An article in Critical Care from the same team reports a median range of only 3 cm for interference events. The 2G signals (GPRS at 900 Mhz, 2W) caused more interference than the 3G signals (UMTS at 1,947.2 MHz, 0.2 W.)

van der Togt R, van Lieshout EJ, Hensbroek R, et al. Electromagnetic Interference From Radio Frequency Identification Inducing Potentially Hazardous Incidents in Critical Care Medical Equipment
JAMA. 2008;299(24):2884-2890.

van Lieshout EJ, van der Veer SN, Hensbroek R, Korevaar JC, Vroom MB, Schultz MJ. Interference by new-generation mobile phones on critical care medical equipment. Crit Care. 2007;11(5): R98. PMID 17822524.

(Thanks to the WSJ Health Blog for the link.)

Tags:   interference · jama · phone · rfid1 Comment