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Pre-Surgical Information
Spaying or neutering your pet is a big step! There is a lot to consider
when we are planning your pet’s surgery. Here is some information to help
you make wise decisions.
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Special LibraryOur Special Library
is a collection of informative articles on a variety of health topics.
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Discharge InstructionsClick here for
information on how to care for your pet at home.
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Intra-Op Hypotension
Anesthesiology News
| ISSUE: APRIL,
2006 | VOLUME: 32:04
|
y
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Intra-op Hypotension,
Tachycardia Linked to Poor
Outcome
Michael Vlessides
|
AtlantaLow
intraoperative blood pressure is
associated with a significantly
greater number of negative
outcomes after surgery,
according to preliminary results
of an ongoing investigation.
Researchers at the University of
Michigan Medical School, Ann
Arbor, said the study showed
that patients whose systolic
blood pressure drops below 90 mm
Hg are more likely to die than
are their counterparts whose
systolic blood pressure remains
above this level; however,
additional analysis is required
to determine whether hypotension
is an independent predictor and
to evaluate other predictors of
adverse outcomes.
"Several years ago, Terri
Monk showed that patients who
are kept at a deep level of
anesthesia during surgery
experience higher mortality [
Anesth Analg 2005;100:4-10],"
commented Michael O'Reilly, MD,
MS, Associate Professor of
Anesthesiology at the University
of Michigan Medical School. "But
if you look closely at the data,
it also turned out that these
individuals had low
intraoperative blood pressure."
Using data compiled as part
of the National Surgical Quality
Improvement Program (NSQIP), in
addition to data from the
University of Michigan
computerized anesthesia records,
Dr. O'Reilly and his
co-investigators were able to
examine physiologic and other
variables associated with
anesthesia care and correlate
them with the outcomes recorded
in the NSQIP database. "I
decided to look at the blood
pressures and see if they're
correlated with outcomes," he
said.
Dr. O'Reilly and his
colleagues studied the
computerized anesthesia records
of 2,383 patients who were also
included in the NSQIP database.
The anesthesia database was
scanned for systolic blood
pressure values between 70 and
90 mm Hg; cases were considered
positive when the low values
lasted for more than five
minutes or were recorded during
three consecutive measurements
in patients wearing a
noninvasive blood pressure cuff.
Co-investigators with Dr.
O'Reilly were Kevin K. Tremper,
PhD, MD, Amy Shanks, MS, Sachin
Kheterpal, MD, and Darrell A.
Campbell Jr, MD.
The investigators also
searched the database for
patients with tachycardia
(defined as a heart rate of >110
or >120 bpm) of at least 10
minutes' duration. The
association between
intraoperative low blood
pressure, tachycardia and
outcomes (as reported in the
NSQIP database) was then
examined.
As Dr. O'Reilly reported at
the 2005 annual meeting of the
American Society of
Anesthesiologists, 24.7% of
patients with a systolic blood
pressure 80 mm Hg had at least
one negative outcome, compared
with 13.9% of those who did not
have low blood pressure
(P=0.0001). Patients with
systolic blood pressure
measurements <90 mm Hg were more
likely to develop septic shock
or infections away from the site
of surgery. In addition, a clear
relationship was found between
blood pressure measurements 90
mm Hg and 30-day mortality.
Similarly, patients whose
intraoperative heart rate
exceeded 110 bpm were more
likely to die within 30 days and
experience septic shock than
were those who did not have
tachycardia.
Despite these results, Dr.
O'Reilly was quick to point out
that the study is in its early
stages. "We're not done with the
analysis yet; this is very
preliminary," he said in an
interview with Anesthesiology
News. "The trick is, we have to
risk-adjust the data. It may
turn out that the patients with
low blood pressure didn't do
well because they have sick
hearts to begin with."
"But I bet that's not the
case," he added. "I bet when we
risk-adjust the data, it's going
to turn out that the low blood
pressure was responsible for the
negative outcomes and death."
Co-moderator Lucinda L.
Everett, MD, saw the potential
for such data to ultimately help
anesthesiologists. "Hypotension
is not uncommon in anesthetized
patients," she commented.
"In general,
anesthesiologists are probably
more aggressive in treating
hypotension either if the
hypotension is severe or if the
patient has underlying coronary
or cerebrovascular disease," she
continued. "If further analysis
shows that hypotension is an
independent predictor of adverse
outcomes and perhaps better
defines threshold blood pressure
values, it would help to guide
our practice." Dr. Everett is
Chief of Pediatric Anesthesia at
Massachusetts General Hospital,
Boston, and President of the
Society for Ambulatory
Anesthesia.
Based on a poster
presentation (Abstract A-648) at
the 2005 annual meeting of the
American Society of
Anesthesiologists and interviews
with Michael O'Reilly, MD, MS,
and Lucinda L. Everett, MD.
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