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April 4, 2005

Wireless Worry? — Radio Frequency Interference Is an Issue, But Widely Considered a Manageable One
By Robbi Hess
Radiology Today
Vol. 7 No. 7 P. 20

“Can you hear me now?” The catchphrase made popular in cellular telephone commercials is probably not something you want to hear when you are in a hospital. But the jury is out on the potential for—and severity of—radio frequency (RF) interference caused by wireless technology, whether from cellular phones, personal digital assistants (PDAs), or laptop computers.

RF Interference: Fact or Fiction?
Urban legends abound with horror stories of people who have died while in the operating room because someone in the hallway flipped open his or her cell phone and started making calls. The tales have it that because someone flagrantly disregarded warnings to not operate a cell phone inside a hospital, it caused the failure of medical telemetry and ultimately the untimely demise of the individual on the operating table.

While cellular phones may be an annoyance to some, they are a convenience that many individuals have come to believe they cannot live without—even within a hospital setting.

According to an article published in the British Medical Journal in March 2003, “Mobile phones in hospitals are not as hazardous as believed and should be allowed in nonclinical settings.”

So how dangerous are they? The evidence for harm is limited. Anecdotal reports of interference with medical electrical equipment led to studies that showed that 4% of medical devices suffered from electromagnetic interference from digital mobile phones at a distance of 3 feet. This compared with 41% from emergency services’ handsets. Most of the interference related to disturbance of the signal on monitors, such as electrocardiographs, according to 2001 data from the Mayo Clinic.

Chris Kent, director of infrastructure services at Daou Systems, says RF interference from mobile telephones or other wireless devices, while a possibility, is infrequent. “There is documented research and studies that show if you have a cardiac monitoring system that is transmitting data back via radio frequency, you can interfere with that by taking a regular wireless local area network [LAN] and placing it next to the monitor,” he says. “But there hasn’t been any documentation to support harm that has occurred in a patient setting.”

Daou Senior Consultant Russ Michel says there is little information on documented incidents where RF interference affected patients. “Studies were done by heavyweights in the networking environment, and they found if equipment has been properly installed, that there is virtually no risk from interference to patients,” he explains. “To ascertain proper implementation, that’s where experts come in and help the hospital coordinate their RF systems and help to predict any potential interference.”

Michel says Intel Corporation conducted a study in 2002 and found that there were absolutely no confirmed incidents in which RF affected patient health.

Interference With Each Other
What is more of a concern within hospitals today is the manner in which their wireless equipment interacts with each other.

Jim McCoy, chief technology officer and vice president of InnerWireless, likened the internal wireless networks in a hospital to an airport. “An analogy I can use is if we think of each of the wireless systems within a hospital as an airport and the hospital as a city. If the city suddenly has many, many small airports operating within it, the task of managing all the take-offs and landings would be monumental,” he explains.

McCoy continues his analogy by saying that in a well-managed city, there are several large airports that take off from a central point. “The same thing is true for a wireless network in a healthcare system,” he says. “A hospital needs to have its wireless medical infrastructure handled through a common platform.”

Michel explains that if wireless systems in a hospital aren’t compatible, patient monitoring telemetry systems could be degraded or interrupted. He likens the RF interference to walking next to a microwave oven while on a home cordless telephone. “The interference could cause static, poor performance, or loss of connectivity,” he warns.

Faruq Ahmed, a principal with the national architecture and engineering firm Burt Hill Kosar Rittelmann Associates, wrote a paper that cautions that the “inexpensive wireless equipment proliferating in hospitals has the potential to interfere with sensitive electronic components in medical devices such as patient monitors, ventilators, neonatal infant warmers, etc.” He writes that healthcare information technology managers need to take prompt action to correct existing interference problems and prevent future ones.

Kent explains that when a healthcare system is looking to deploy a wireless infrastructure, it must perform due diligence. “Physicians and clinicians are aware of the radio frequency issue as it’s been in the healthcare environment for many years,” Kent says. “Hospitals have had at least ancillary pockets of wireless technologies and they’ve become accustomed to dealing with the inherent challenges of wireless environments. I think most healthcare professionals are cognizant of what must be taken into consideration when making electronic wireless upgrades.”

Preventative Planning
McCoy says there is always some level of risk when it comes to interference, but the degree depends on how wireless is managed and handled inside the hospital. “If it’s unmanaged, then risk is moderate to possibly high,” he says. “If, on the other hand, all of the departments—clinical, biometric, information technologies, facilities, outside emergency responders, and visitors—are contemplated and appropriate policies and procedures are put in place and if wireless systems are operated and coordinated from those policies, then the risk is small to almost nonexistent.”

In most cases, McCoy explains, “modern medical devices and wireless devices have shielding mechanisms that help prevent radiated signal levels from causing problems and potentially catastrophic failures. The wave form might get a little noisy, but the equipment keeps functioning normally.”

It’s estimated that a wireless device such as a cell phone has to be within 1 foot of medical equipment to possibly cause interference.

“I don’t want to downplay the risk because it is well worth the time of the hospitals’ executive and management staff to go through the process of inventorying systems and usages and creating wireless policies,” McCoy says.

The good news, McCoy says, is that over the past 10 years, the topic of RF interference is raised periodically. Because of that, equipment vendors of sensitive medical devices have taken additional steps in the designing of their equipment and are making it more resistant to interference. “Many device vendors are using technologies that operate at lower levels of power that offer less of a chance of disruption or interruption,” he says.

He says the bottom line is that healthcare institutions have to take the risks down to an acceptable level, and that’s something that requires coordination and planning. “There simply has to be a unified approach to wireless technologies, not only at the policy and procedure level but [also during] the installation and distribution of those wireless signals within the physical building itself,” McCoy explains.

Piecemeal Standards
Wireless technology has evolved in a piecemeal fashion in the healthcare setting. Unfortunately, that has made it difficult to establish standards for RF, according to McCoy.

The evolution from LANs to wireless LANs has all proceeded incrementally. As a consequence, healthcare officials have adopted these technologies and deployed them independently to serve their purposes—one at a time as they are installed into the physical hospital.

“InnerWireless advocates taking wireless usages and providing them over a fully coordinated infrastructure so any potential interference issues can be mitigated and the reliability of services maximized,” McCoy says. “What we do for WiFi [wireless fidelity] systems, cell phones, two-way radios, and paging devices is to start with vendors of the wireless telemetry systems and look to move as many wireless systems as practical into an integrated infrastructure.”

Kent agrees that most hospitals don’t have a cohesive inner working when it comes to deploying RF equipment within the physical building. “Some hospitals have a single point of contact when bringing in an RF device when they should be doing spectrum analysis to see how the equipment fits in with the whole infrastructure,” he says. “Administrators and IT people need to be looking long-term, not taking a snapshot in time of the situation.”

Bringing in new equipment and upgrades needs to be approached proactively, Michel says. “As part of due diligence, coordination should be taken up with departments like emergency and ICU [intensive care unit],” he says. “Patient equipment that may move throughout the hospital must be analyzed also to see if there will be any conflict.”

Sensitive Equipment
As equipment moves throughout a hospital, it is possible to track it through the use of RF devices. This tracking capability makes it possible for caregivers to quickly locate needed medical devices and also prevents incompatible equipment from being in the same location.

Richard Barnwell, the chief technology officer of PanGo Networks, Inc., a supplier of active RF tracking technology, says PanGo’s system operates on the core radio frequency of 802.11. This allows companies to capitalize on their existing WiFi infrastructure.

Hospitals are making significant wireless investments to improve quality and operations and, above all, save lives. PanGo is helping with this initiative by providing RF tracking devices that help staff locate lifesaving pieces of equipment.

“In the event that a doctor or nurse needs a crash cart to help someone who is suffering a heart attack, our RF tracking tags help them locate it quickly,” Barnwell says. “Time—even seconds—spent looking for a piece of equipment could mean the difference between life and death for a patient.”

Because equipment usage in a hospital doesn’t remain static, the tracking tags also help technicians locate it when it is time to perform maintenance to keep the equipment in compliance. “A technician could receive a work order to service equipment but could spend valuable time wandering the hospital looking for it. But once the tracking tags are attached, equipment is easily locatable,” he says.

The tags also provide information on how many times a medication cabinet has been opened and how often a piece of equipment is utilized. This type of information can help hospitals manage valuable resources.

RFID Issues
While many department stores utilize passive radio frequency identifications (RFIDs) to track shipments, PanGo’s RFID applications are active tracking devices. Passive RFIDs need a tag and a scanner in close range to track items, while active RFIDs are networked with existing systems. “We track, in real time, where equipment is,” Barnwell says.

Because PanGo’s software operates on the standard 802.11 platform, it minimizes RF interference as it is integrated into existing systems.

Ahmed points out that although RFIDs have helped hospitals operate more efficiently, administrators need to have a clear understanding of the potential for interference with medical equipment.

Before a deployment of wireless technologies, he says hospitals should evaluate the following equipment and their locations to avoid RF interference problems:

• radio communications equipment;

• wireless equipment such as nurse calls, PDAs, cell phones, etc;

• patient monitoring equipment;

• medical equipment such as MRI scanners; and

• electrical and mechanical equipment such as high-frequency electronic ballasts, light-dimming devices, variable frequency motor drives, etc.

To maintain a stable RF environment, Ahmed says a hospital must do the following:

• avoid the indiscriminate use of all kinds of radio equipment on the premises;

• pay careful attention to the choice of electrical and mechanical equipment and avoid equipment that produces excessive RF interference; and

• perform intermodulation studies at least annually or whenever major equipment changes occur.

— Robbi Hess, a journalist for more than 20 years, is a writer/editor for a weekly newspaper and a monthly business magazine in western New York.

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