Can We Fix Wireless in Health Care?

Awareness is growing about the challenges of developing and maintaining safe and effective wireless medical devices. What with IEC80001 moving forward (due to be finalized next year) and the recent series of wireless medical device workshops, people in hospitals and among vendors are asking more of the hard questions about wireless. Amongst the turmoil, participants are jostling for position. This post looks at common problems with Wi-Fi, a report from U.K. alliance ERBI, and some alternatives to Wi-Fi.

Problems with Wireless

Those of us who are old enough, think back to the golden age of wireless medical devices — channelized analog telemetry. These systems were so basic and limited in scope (a couple dozen transmitters typically covering just a single 30 bed unit) that they had few problems and required little maintenance.  Today, larger hospitals are pushing the envelope with a few hundred patient monitors and a thousand or more wireless infusion pumps. These wireless devices are using sophisticated client radio/access point (AP) communications protocols to maximize capacity, whether using Wi-Fi or WMTS. We’ve since left the golden age far in the past.

Radio frequency (RF) spectrum is a shared resource. There’s no getting around that fact, even with “dedicated” spectrum. The ether in which wireless signals move is like gases in the atmosphere or chemicals in water. There are no ways to practically segregate RF signals to specific areas, except for a Faraday cage. In a health care facility, some shielded rooms in Radiology qualify as Faraday cages, but little else. Much of the rest of a health care facility consists of objects and structures that seem to perversely confound and obstruct RF communications in  ways like partially blocking and attenuating signals, creating multipath interference, and radiating both intentional and unintentional interference. Intentional interference is where two or more users of a portion of wireless spectrum get in each others way, disrupting or degrading the communications of one or both parties. When there are problems with two or more wireless devices using the same spectrum, this is intentional interference, often referred to as coexistence problems. Unintentional interference comes from electromechanical devices that accidentally spew RF signals as a consequence of some degradation or failure. Common sources of unintentional interference are florescent light balasts, blow dryers, paper shredders, elevator motors, or faulty microwaves. You can see a bunch of examples of RF interference on a spectrum analyzer (which everyone doing wireless medical devices should have, and know how to use) here.

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Awarepoint RTLS Installed at UCSF


Awarepoint was chosen for asset tracking at University of California San Francisco Medical Center (UCSF). The vendor selection team looked at 6 different systems and selected Awarepoint. The story in Healthcare IT News highlights the technology’s use for improving productivity in the surgery department.

Here’s what jumped out at me:

Installation and the tagging of 700 assets throughout UCSF Medical Center took under 48 hours.

Whoa. The 700 tags is not much for a 500+ bed hospital; what got my attention was the 48 hour installation time. A brief blurb on the product explains:

Awarepoint’s RTLS needs no hardwiring or fixed infrastructure due to
wireless sensors, which plug into electrical outlets. Assets are
attached with small, battery-powered tags, which are tracked using the
Web-based Searchpoint search engine.

Pictured at right is an Awarepoint ZigBee receiver, shot in the wild.

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