Biomedical Engineering Reference
In-Depth Information
Biomedical Engineering and possible resolutions of the
problem are analyzed and reviewed.
There is not always an ideal solution to an
interference problem. Many factors may contribute to
device victimization, some of which are not easily or
practically resolved. For example, if a recently added
high-power paging transmitter were installed on an
adjacent building, the additional energy radiated could
affect devices that exhibited no previous EMI-related
reactions. Historically, if the licensed transmitter is
installed on a building over which the institution has no
control, it will be difficult to remove. Such transmitters
are licensed by the Federal Communications Commis-
sion and the medical device has no statutory protection;
a one-way street.
Modifications to the environment are recommended
if they are practical. These might include screening an
area or relocating a device within an area. If modification
of a medical device appears to be the only solution to the
problem, then the manufacturer of the device is advised
of the problem. The biomedical engineering department
can and does advise the manufacturer. Ad hoc modifica-
tions of medical devices to mitigate susceptibility or
egress are improper and should not be attempted. Per-
forming such modifications would, in most cases, be a
violation of FDA regulations and would increase the
institution's risk for liability.
Summary
Despite gains in spectrum protection for some categories
of patient monitoring devices through the development
of standards, the overall electromagnetic environment is
becoming increasingly hostile to the safe operation of
clinical devices. The establishment and maintenance of
a safe environment for the operation of clinical devices
requires a multidisciplined approach. There must be
a program of education involving technical, clinical,
maintenance, and management personnel and staff. A
clinical engineer experienced in RF and EMI, as well as in
appropriate test and measurement equipment, must be
available
A proactive testing and evaluation program that in-
cludes ongoing measurements of plant and incoming
devices must be established. Maintained devices
d
especially those that have demonstrated a potential for
electromagnetic waves
d
be
spot-tested periodically
using the fingerprint method.
This chapter has presented the need for a proactive
EMI management program designed to limit the de-
structive effects of EMI on clinical devices. Some of the
previously mentioned causes of EMI and methods used
to test both the environment and the devices within it are
based on experiences at Texas Children's Hospital.
References
ANSI. American National Standard for
Methods of Measurement of Radio-
Noise Emissions from Low-Voltage
Electrical and Electronic Equipment in
the Range of 9 KHz to 40 GHz. C63.4.
New York, American National
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Bennett WS. Making OATS Measurements
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CBS. Haywire. Eye-to-Eye with Connie
Chung. CBS, December 1, 1994.
US Government. CFR 47; Part 15.103
(c,e). Code of Federal Regulations of
Telecommunications. Code of Federal
Regulations, 1991.
David Y. Safety and Risk Control Issues:
Biomedical Systems. In Dorf RC (ed).
The Electrical Engineering Handbook .
Boca Raton, FL, CRC Press, 1993.
ECRI. Patient-Owned Equipment. Health
Devices 17:98, 1988.
ECRI. Ventilators, High Frequency. Health
Device Alert p. 2, December 18, 1992.
ECRI. Guidance Article: Cellular
Telephones and Radio Transmitters-
Interface with Clinical Equipment.
Health Devices 22(8,9):416, 1993.
Knudson T, Bulkeley WM. Stray Signal,
Clutter on Airwaves Can Block
Workings of Medical Electronics.
The Wall Street Journal , p. 1, June 15,
1994.
Paperman WD, David Y, McKee KA.
Electromagnetic Compatibility: Causes
and Concerns in the Hospital
Environment. ASHE Health care
Facilities Management Series. Chicago,
IL, ASHE, 1994
Southwick R. EMI Signal Measurements at
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