The delivery of health care is an inherently mobile activity, with patients moving though the care delivery process and almost all health care workers in constant motion. So it's no wonder that wireless technologies have been adopted with gusto.

Electromagnetic interference (EMI) has been a concern with medical devices since their inception. This EMI can be divided into intentional and unintentional interference. Intentional interference typically comes from radio frequency (RF) radiators like walkie-talkies, wireless phones, WiFi radios, and cell phones that use frequencies and specified power levels that may interfere with the operation of other radios or electronic devices. Unintentional interference is caused by things like paper shredders, bad florescent light ballasts, and noisy electric motors (from blow dryers to elevators).

Any electronic device can be affected by EMI, including medical devices. The wireless features of medical devices (or any other wireless device, for that matter) can also be affected. The larger medical device vendors have dedicated engineers and techs who do EMI testing and troubleshoot interference problems at customer sites.

In an effort to promote best practices regarding the use of mobile wireless communications and computing technologies in health care facilities, standards committees TC 215 and ISO 35.240.80 have created recommendations for
electromagnetic compatibility (management of unintentional
electromagnetic interference) with medical devices. Here's the abstract:

ISO/TR 21730:2007 provides
guidance for the deployment, use and management of mobile wireless
communication and computing equipment in healthcare facilities in a way
that promotes effective electromagnetic compatibility (EMC) among the
wireless technology and active medical devices through mitigation of
potential hazards due to electromagnetic interference (EMI). The
recommendations given recognize the different resources, needs,
concerns and environments of healthcare organizations around the world,
and provide detailed management guidelines for healthcare organizations
that desire full deployment of mobile wireless communication and
computing technology throughout their facilities. In addition,
suggestions are included for selective restrictions in cases where
healthcare organizations have decided that comprehensive management
procedures are not feasible, practical or desirable at the present
time. The recommendations herein distinguish between wireless
technology controlled by the facility and used by doctors and staff for
healthcare-specific communication and health informatics transport
versus non-controlled (personal) mobile wireless equipment randomly
brought into the facility by visitors, patients or the healthcare
organization workforce.

You can buy your copy of the standard for a mere 132.00 Swiss Francs here. The Medicines and Healthcare products Regulatory Agency (the Brit's equivalent to the FDA) has free recommendations based on the standard here. And you can read a paper on cell phone use in hospitals from last fall here.