Anesthesia − use brain monitors?
Anesthesia − use brain monitors?
Source: http://sci.tech−archive.net/Archive/sci.med/2005−10/msg00353.html
• From: Steve
• Date: Tue, 25 Oct 2005 05:41:41 −0700
Excerpts from
http://online.wsj.com/article/SB113020303501978376.html?mod=todays_us_marketplace
A rare phenomenon in which patients wake up during surgery, but are
unable to communicate their pain or fear, has caused a rift in the
anesthesia community.
At issue is whether doctors should use brain−monitoring machines
during operations to help them give patients the proper level of
anesthesia.
Aspect Medical Systems' Bispectral Index monitor has become a
flashpoint in the controversy. The company has about a 90% share of
the market for the devices, which some doctors attribute to aggressive
marketing rather than scientific and clinical evidence.
There's no dispute that awareness, ranging from fuzzy memories of
sound during surgery to explicit recall of painful procedures, does
happen − but it occurs in only about one or two cases in every 1,000,
according to several widely cited medical studies. Finding a precise
way to measure consciousness during surgery − and therefore perfect
the dose of anesthesia given − has long been regarded as the field's
holy grail.
Aspect's BIS machine, as the monitor is generally called, tracks
brain−wave activity during surgery and, using a proprietary computer
algorithm, assigns a numerical value to the probability of
consciousness. Zero indicates no electrical brain activity, and 100
means the patient is wide awake. A "BIS number" between 40 and 60 is
supposed to indicate an adequate depth of unconsciousness, in which a
patient neither perceives nor recalls unpleasant or painful
stimulation.
Aspect maintains that its device is a critical tool in the operating
room and has been lobbying to make brain−monitoring devices the
standard of care for the 20 million surgeries under general anesthesia
each year. Members of the American Society of Anesthesiologists are
scheduled to vote today on a report on the issue, which could give a
Anesthesia − use brain monitors? 1
Anesthesia − use brain monitors?
boost to Aspect and other brain−monitoring device makers.
A draft of the report assessing the BIS technology and five competing
monitors concludes that evidence doesn't support making the technology
standard care but suggests clinicians use the machines at their
discretion.
Brain−monitoring devices have been around for decades, but never has
awareness been such a hot topic. Many doctors pinpoint the recent
heightened focus to the fall of 2003, when the FDA approved a labeling
change that allowed Aspect to use a new phrase in its marketing
materials that said its monitor "may be associated with the reduction
of the incidence of awareness with recall in adults during general
anesthesia and sedation."
The JCAHO issued an "alert" in October 2004 about the problem, calling
it a "frightening phenomenon" that is "underrecognized and
undertreated." Stories in the Washington Post and other major
publications warned of the "nightmare" of intraoperative awareness.
But many anesthesiologists say Aspect's machine − already installed in
about 40% of U.S. operating rooms − doesn't always produce reliable
results.
Those opposing routine use of the monitors say it's still best to rely
on clinical signs like physical movement and blood pressure to gauge
anesthesia levels. Experienced doctors worry that junior
anesthesiologists might be distracted by the devices, ignoring other
important signs.
In the final analysis, many doctors believe the monitors should be
more widely adopted. Harold Goll, chairman of the anesthesiology
department at the Greater Baltimore Medical Center, which has 37 BIS
machines, says, "It's not 100% reliable, but it is a very helpful
technology and it probably should be used on the majority of cases."
******************************************************
A great many people think they are thinking,
when they are merely rearranging their prejudices.
....Edward R. Murrow
.
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