Proposed Medical Implant Rule Changes

401-406 MHz

During 1996 and 1997 a manufacturer of medical devices petitioned the
FCC to establish rules allowing the operation of data telemetry links
(Medical Implant Communications or MICS) in the band 401-406 MHz for
communication with implants within the human body. At the time the most
prevalent planned use was pacemakers, where the pacemaker could be
programmed in a hospital or clinic environment. The band 401-406 MHz
offered many advantages due to propagation characteristics of flesh and
a relatively quiet operating environment. The links were only intended
to be operated at a range of less than 10 to 15 feet. Studies were
conducted within the U.S. and internationally that led to the
development of International Telecommunications Union-
Radiocommunication Sector (ITU-R) Recommendation SA. 1346. The studies
showed the potential for interference to radiosonde systems was very
low, but without appropriate mitigation techniques, the MICS link could
receive interference from radiosondes. Interference to an implant during
a programming session could potentially harm a patient. ITU-R SA.1346
recommended mitigation techniques to ensure radiosondes would not cause
harm to patients through interference caused to the MICS operating on a
non-interference basis. The primary concern from the meteorological
community was ensuring patient harm could not occur, even though MICS
was operating on a non-interference basis (NIB). Radiosonde operations
in the band clearly have priority over the MICS, but concern existed
over the potential perception and emotional response if radiosonde
transmissions were to cause harm.

The current FCC rules allowing the operation of MICS within the band
401-406 MHz require implementation of the mitigation techniques defined
in ITU-R SA.1346. Over the last several years the FCC has received two
waiver requests asking for relief from some of the mitigation techniques
intended to protect patients from interference. The medical implant
devices for which the waivers were requested were of a nature that
interference would cause delay in transmission of data from the implant
to a body-worn receiver, but no patient harm could result from the
delay. The FCC, with NTIA concurrence, has granted both devices waivers
based on the conclusion that patient harm could not occur, if
interference was to occur from radiosondes. Each one of these waiver
approvals required careful analysis to ensure patient harm would not
occur. Based on these two waivers, a medical implant manufacturer has
petitioned the FCC for creation of new set of rules that do not require
the mitigation techniques for patient protection. The new rules would
apply to Medical Data Services (MEDS), devices the manufacturers
determine are not performing a function where interference could cause
harm or loss of life.

While other Federal agencies are the primary users of radiosondes in the
401-406 MHz band, NTIA has been looking to DOC/NOAA for advice on this
issue. As with MICS, the potential for interference from MEDS to
radiosondes is small, though greater than MICs due to a higher intended
proliferation of the MEDS devices and the fact they will transmit
outside the hospital/clinic environment. The primary concern is allowing
the manufacturers to determine whether a radiosonde interference event
could cause a life-threatening issue. In many cases the manufacturers do
not understand radiosonde operations or how those operations could
impact a MEDS user. The agencies using the 401-406 MHz band for
radiosonde operations should evaluate the proposed rules and work with
their frequency management offices to raise issues, concerns or
agreement to the proposed new rules. Attention should given to the
potential for radiosondes to cause interference to MEDS, and the
resulting impact if it was shown radiosonde transmissions were harming
MEDS patients. Sharing of information on agency views would also be of
value to all WG-FM members.