(Circulation. 1998;98:492.)
© 1998 American Heart Association, Inc.
High-Definition Television and Telemetry
Ruth SoRelle, Circulation Newswriter
In March 1998, WFAA-TV in Dallas became the first
television station in the United States to venture into the future of
digital broadcasting. But as the broadcast signal went into the
airwaves, medical telemetry units on the 13th floor at nearby Webb
Roberts Hospital at Baylor University Medical Center went blank.
It was 24 hours before engineers at the television station and Baylor
put 2 and 2 together to figure out that the heart monitors were on the
same frequency as the station's new signal. There was a good chance
that theirs was not the only conflict. As a result, the US Food and
Drug Administration (FDA) sent out an advisory warning hospitals and
healthcare providers of the potential conflict. The situation, the
agency warned, could occur in other parts of the country because of a
quirk in the way television channels are assigned.
Several years ago, the Federal Communications Commission (FCC) decided
to allow medical telemetry devices to use part of the broadcast
spectrum that was also used by television stations. The medical
telemetry units were assigned a television channel that was not being
used in a particular area. However, the agency warned that television
stations had priority and medical devices had to be able to tolerate
television signal interference. Putting the 2 different kinds of users
on separate channels originally alleviated the problem.
But the advent of digital broadcasting forced the FCC to give stations
an additional channel during the transition to the newer form of
broadcasting. The FCC was apparently unaware that some of the channels
it assigned were already being used for medical telemetry.
Fortunately, the Dallas case resulted in no harm to patients, said
Baylor spokeswoman Jamie Rambo. The hospital was already planning to
replace its heart telemetry units with updated multifrequency versions,
Rambo said. WFAA turned off its test broadcast signal, the hospital
expedited installation and training on the new monitors, and the
problem seemed to be solved.
However, several weeks later, the Dallas station began testing its
signal again, and once more, a Baylor hospital—a different one this
time—had problems, Rambo said. Again, the hospital went through the
equipment updating procedures while the television station waited.
Since that time, the FDA has required television stations to warn
hospitals and nursing homes about the possible conflict in signals. Now
the agency is working with medical equipment manufacturers on labeling
that warns of the problem.
To prevent a similar mishap, the FDA advises that hospitals and
healthcare institutions determine the channels/frequencies that their
telemetry systems use and consult with the FCC for the digital
television channels that will be coming on line in their area. If there
is a conflict, the healthcare institutions should find out when the
television stations plan to begin their test digital broadcast and
change telemetry channels before that time.
The FCC and FDA are cooperating to determine the needs of such medical
devices in the future in hopes of avoiding a similar blackout of
information.
