cell phoneSimilar to the controversy about whether cellular phones can cause brain cancer, there is brewing debate about whether these phones also affect medical devices. In two earlier articles discussing research findings from the Tan Tock Seng Hospital (Singapore) and Mayo Clinic (Rochester, Minnesota), I reported that mobile phone use was not detrimental to medical equipment. Similar studies have prompted the reversal of cell phone bans in many hospitals throughout the United States.

Just as we have become comfortable chatting on the phone while walking from patient room to the cafeteria, a new Dutch study presents a caveat to the earlier reports. While it is true that newer generation mobile phones may generate less electromagnetic interference (EMI) due to better shielding and signal downregulation, there is limited information characterizing the risks of using Internet-capable phones around medical devices.

To explore this question, researchers from the University of Amsterdam utilized wireless signal generators to mimic data transmission on modern mobile phones. The generators were placed in proximity of medical devices commonly found in the ICU, such as telemetry monitors, mechanical ventilators, and infusion pumps. The group detected 48 incidents in 26 devices (43%). Sixteen (33%) were classified as hazardous, 20 (42%) as significant, and 12 (25%) as light. The median distance of effect was 3 cm (range: 0.1 to 500 cm). Some hazardous effects included ventilator shutdown, restart, and setting adjustment. A syringe pump also stopped without an accompanying alarm. These were not trivial events.

One limitation of the study is that the group used signal generators at maximum power to assess the potential risk of cell phone use. Since mobile phones frequently regulate its power output based on the carrier network’s signal strength, we would expect lower EMI in real-world conditions. On the other hand, since the group’s aim was to characterize possible worst-case scenarios, this criticism is moot. Besides, deep inside the behemoth of a hospital, signal strength is usually weaker and EMI inversely stronger.

In brief, although newer generation Internet-capable smartphones present new challenges of electromagnetic interference, a one-meter buffer between phone and medical device still seems reasonable. Now to publish this article via my CrackBlackberry before I get too close to Mr. Johnson’s ventilator.