AAMI members weigh in: survey sheds light on use of wireless technology.

Richard Kosmala is a strategic marketing manager for systems and connectivity at Mindray North America. E-mail: [email protected] Since the first wireless patient telemetry systems were introduced in the 1970s, the technology used to transmit real-time patient information over the airwaves has gone through a number of generations. Initially, the radio frequency (RF) technology was purely analog, typically using frequency modulation. The electrocardiogram (ECG) waveform would get “noisier” as the patient moved out of range, but nurses became quite adept at making out the ECG even in the midst of considerable noise. In the 1990s there was a transition to digital signal transmission. This approach had the advantage of allowing user channel programming (previously they had to be set up at the factory), the possibility of using diversity to improve reception, and very clean signals when the patient was in range—but no signal when the patient was out of range. This took some getting used to and much more attention was required for antenna placement. These systems operated mostly in the very high frequency(VHF)/ultra high frequency (UHF) TV bands, making use of unused channels in a given locale. Sometimes, a new TV station would come online, creating an issue for a hospital that had telemetry systems using that channel and necessitating that the devices be reprogrammed. In the late 90s, the testing of the new digital television technology in the Dallas area interfered with the telemetry systems at Baylor Health Care. This incident was the impetus behind the Federal Communications Commission (FCC) creating the wireless medical telemetry system (WMTS) bands, currently used by many patient telemetry systems in the United States. The UHF/VHF bands are still used in the rest of the world. Currently, we are seeing a wide expansion in the number of technologies that can be and are used for patient ambulatory telemetry and medical device instrument wireless. Vendors have released systems that operate in the WMTS bands (typically using proprietary technology), the industrial, scientific, and medical (ISM) bands using 802.11a/b/g, Zigbee, Bluetooth technology, and there are even potential uses of cellular technology. Given all the possibilities, we thought it would be interesting to see what members of the AAMI community had installed and how they thought things might change. To that end, we created a survey that was distributed to AAMI members.