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May 2002
Volume 66 |
Number 5
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| Wireless Devices
Improving Communications in the Operating Room |
Roy G. Soto, M.D.
Ira J. Rampil, M.D.
Committee on Electronic Media and Information Technology
Scope of the Problem
Efficient, rapid and reliable communication in acute medical and
surgical care settings is vital to patient safety. Overhead audio
pages and small wireless beepers have been the standard for communications
for several decades now, and although more efficient methods of
communication exist, fears of electromagnetic interference have
prevented the widespread dissemination of wireless technology.
The problem with current systems is that they allow only one-way
communication; therefore, it is not known to the sender of the
message when or even if a particular message arrives. Newer technologies
such as two-way beepers, cellular telephones and wireless handheld
computers like the Palm Pilot allow for essentially instant two-way
communication so that not only does the sender know the message
is delivered, an answer may be delivered equally as quick. It
would be difficult to find an experienced clinician who does not
know of a serious near-miss or worse in patient care due to a
delayed beeper message.
| "Detailed in vitro studies of the interaction of
cellular telephones with commonly available implantable pacemakers
have revealed little in the way of interference with most
brands being completely insensitive to the cellular telephone
and one requiring the telephone to be placed less than six
inches from the pacer to induce interference." |
Electromagnetic Interference – Is It an Issue?
Our environment is replete with electromagnetic radiation, and
there are not many places on the surface of the earth where one
can effectively escape exposure to radio waves. Principally, there
are two factors that determine the interaction of a radio signal
and an object: frequency and field strength. The higher the field
strength (a measure of power and distance), the more likely there
will be a detectable interaction. Frequency is a more complex
variable, but generally speaking, the higher the frequency of
a signal, the more effectively its energy can be mitigated or
shielded. The trend in personal telecommunications devices has
been to higher frequencies and lower power, thus causing less
interaction with mechanical or biological systems. For example,
a 30-year-old electrosurgical unit would generate several hundred
watts of energy widely spread over low frequencies (mostly below
5 MHz), whereas a 30-year-old mobile telephone (precellular technology)
might generate 5 watts at about 50 MHz. A typical modern digital
cellular telephone uses a frequency close to 2 GHz and might generate
only 100 milliwatts when close to a cell transmitter. Wireless
computer networks also operate near the 2 GHz range but at even
less power output.
Based on several anecdotal reports, including cellular telephone
tower interference with an electrocardiography (ECG) telemetry
system and a broadcast station-induced uncommanded movement of
a motorized wheelchair and interference with apnea monitors, several
industry consultants began to recommend the banning of cellular
telephones in hospitals. (Curiously, a documented case where an
ECG telemetry transmitter caused a factitious pulse oximeter reading
in a dead patient did not lead to a call for banning telemetry
systems.) Since 1994, the U.S. Food and Drug Administration (FDA)
has required medical device manufacturers to incorporate radio
frequency shielding in their products. Detailed in vitro studies
of the interaction of cellular telephones with commonly available
implantable pacemakers have revealed little in the way of interference
with most brands being completely insensitive to the cellular
telephone and one requiring the telephone to be placed less than
six inches from the pacer to induce interference.
Thus recently manufactured medical devices, as mandated by FDA,
are sufficiently shielded to make interference highly unlikely,
and indeed neither FDA nor the Federal Communications Commission
(FCC) has banned any transmitters from hospital environments.
Further, Health Devices, a prominent medical consulting company,
recently softened its recommendation on banning cellular telephones
to exclude only visitors, not staff.
Three large epidemiologic studies within the past five years
also have examined the effects of electromagnetic interference
on biological systems. The first, published as a report titled
"Electromagnetic Compatibility of Medical Devices With Mobile
Communications" by the British National Health Service, concluded
that no significant levels of interference were detected from
either cellular telephones or cellular base stations. The second,
published in the Journal of the Canadian Medical Association,
summarized findings of the Health Canada medical devices roundtable.
They recommended that a total ban on radio-frequency transmitters
in hospitals was not justified and that rational management of
telecommunications devices was suitable. The final study, published
online and conducted by the University of Oklahoma in conjunction
with the FDA and FCC, concluded that the problems occurred with
a very low frequency and only at very close distances (less than
six inches) from the devices.
Anticipating the Future
Future efficiencies and improvements in practice are likely to
evolve from incorporating selected parts of the great technological
wave of innovation that has already deeply penetrated many other
parts of our daily lives. In particular, immediate access to medical
records, laboratory results, reference material and colleagues
via wireless networks has obvious appeal. Access to these resources
should come via very low-powered networks and microcellular base
stations placed within the health care facility itself to minimize
blacked-out areas with the lowest possible transmitter power and
to facilitate security of the information being transmitted. As
anesthesiologists, we must be at the table when implementation
of these systems is considered in order to present our case and
to see that history does not repeat itself with administrative
technological illiteracy and failure to consider evidence-based,
risk-benefit assessment.
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In an attempt to better understand the frequency
of problems with communications in the operating
suite, we have created a brief online survey. Please
take a few moments to fill out the questionnaire
at hsc.usf.edu/anest/survey.
Results will be posted online and reported in a
future issue of the NEWSLETTER.
For more information, refer to the FDA's Center
for Devices and Radiologic Health at <www.fda.gov/cdrh/phones>.
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Roy G. Soto,
M.D., is Assistant Professor of Anesthesiology, University
of South Florida, Tampa, Florida. |
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Ira
J. Rampil, M.D., is Professor of Anesthesiology and Neurological
Surgery, State University of New York at Stony Brook, Stony
Brook, New York. |
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