Terry Roumayah RN, BSN, SRNA, CCRN
Oakland University/Beaumont Hospital
Graduate Program of Nurse Anesthesia
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Gaszynski, T., Gaszynski W.,
Strzelczyk. (2004). Post-anesthesia
recovery after infusion of propofol
with remifentanil or alfentanil or
fentanyl in morbidly obese patients.
Obesity Surgery, 14, 498-504
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Location: Barlicki University
Hospital, Lodz, Poland.
Approval obtained from the local
University Ethics Committee.
(Allegedly!) ---->
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The type of opioid used during general
anesthesia in the morbidly obese influences
recovery and the postoperative period.
The use of modern anesthetics and methods of
anesthesia has increased safety of general
anesthesia in high-risk patients, i.e. the
morbidly obese.
The postoperative recovery period becomes a
major concern because of the safety and costs
of possible complications.
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It has been suggested that the intraoperative
use of opioids during general anesthesia may
determine the development of post-anesthetic
complications among morbidly obese patients.
Fentanyl, Alfentanil and Remifentanil will be
compared in terms of post op recovery in the
morbidly obese.
Not many studies have been done comparing
these drugs in relation to morbidly obese post
op recovery.
Fentanyl
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Potency – 100 X Morphine
Onset 1-2 min, Peak 3-5
min, Duration 0.5-1 hours
Metabolized in liver and
excreted in urine
Elimination half-life 3.1-6.6
hours
Alfentanil
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Potency – 10-20 X Morphine
Onset 60-90 sec, Peak 2-3 min,
Duration 15-30 min
Metabolized in liver and
excreted in urine
Elimination half-life 1.4-1.5
hours
Remifentanil
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Potency – 100 X Morphine
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Ultra rapid and short acting
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Metabolized by nonspecific
esterases
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Randomized control study
The study was double blind for the
patient and PACU staff.
Anesthesiologist preforming general
anesthesia was aware of the opioid
used.
Inclusion
Criteria
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BMI range of 36-49
Elective Roux-en-Y
gastric bypass
ASA class 2 or 3
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Morbidly obese subjects with BMI >50 or with
co-morbidities influencing the respiratory drive
(sleep apnea syndrome, Pickwickian
syndrome) were excluded from the study.
3 patients in the Alfentanil group were
excluded because of incompletely collected
data.
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60 morbidly obese patients were randomly
allocated into 3 groups.
Remifentanil (R) - 20 patients
Fentanyl (F) – 22 patients
Alfentanil (A) – 18 patients
The three opioids were administered
intravenously per kg of Ideal Body Weight
(IBW).
Male = 50 + (height - 150) X 0.7
Female = 50 + (height - 150) X 0.6
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Rates of infusion was changed based on
cardiovascular parameters.
Fentanyl 5 mcg/kg then 0.05 mcg/kg/min
Remifentanil 1.0 mcg/kg/min
Alfentanil 1.5 mcg/kg/min
All other anesthetics were given in all 3 groups
following the same pattern (propofol gtt, 50%
Nitrous Oxide in oxygen, Cisatracurium for
muscle relaxant).
Monitors used were NIBP, pulse ox, ETc02,
Propofol titrated to BIS level between 40 and 60.
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Morphine was given in the Remifentanil group.
Fentanyl infusion was stopped 20 minutes
before the end of the operation.
Alfentanil was stopped 10 minutes before the
end of the operation.
Zofran was given. Neostigmine and Atropine
were used for reversal.
Textbook extubation criteria used.
Post op analgesia using morphine 2mg/hour.
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Post op period up to 6 hours was evaluated.
Incidence of post op N/V was recorded.
Verbal scale for post op pain (1 – Small, 2 mild, 3 - disturbing, 4 – strong, 5 – severe).
What Was
Measured
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Response to verbal
commands
Spontaneous respirations
Adequate respiration
Safe extubation
Pain (no pain, small, mild,
disturbing, strong, severe)
No nausea or vomiting
Nausea
Vomiting
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Analysis included the Shapiro-Wilk test,
Student t-test, Cochrane-Cox test and the
Wilcoxon test (AKA the Brandon Wilcox test).
To confirm the differences between the groups,
ANOVA test was preformed.
The results of statistical analysis were
presented as mean values with two-sided P
values. P <0.05 were considered significant .
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Group R had the best “recovery
profile”(duration to achieve required stages of
post-anesthesia recovery and discontinuation
of Propofol) and Group A and F were similar.
Duration to spontaneous respiration, adequate
respiration and safe extubation were
significantly shorter in group R compared with
group F.
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Evaluation of early postoperative pain and
requirement for analgesics revealed that right
after anesthesia, more patients in group R felt
disturbing pain (25%) than group F (4.5%).
The number of patients who felt mild pain was
similar in all groups (range 45-46.7 %).
None of the groups felt strong or severe pain.
Post op N/V occurred more often in group R
(30% compared to 20% in group A and 14% in
group f).
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Cardiovascular parameters (heart rate and BP)
during the post-anesthesia period remained
within acceptable limits and did not differ from
levels before operation.
Blood oxygenation > 94%, p02 > 60mmHg, and
pC02 stayed between 35 and 45 mmHg
No respiratory complications were observed in
the postoperative period.
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Obese patients are sensitive to all central
depressant drugs, with upper airway obstruction
or respiratory arrest occurring with minimal doses
of opioids.
Remifentanil dosage is more flexible than fentanyl
and Alfentanil and can be based on changes in
cardiovascular parameters.
This allows for immediate reaction and increase in
doses that does not lead to accumulation and
prolonged action which is accompanied by
residual respiratory depression.
This makes Remifentanil the choice opioid for
patients at high risk for respiratory complications.
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Fentanyl effects lasts longer and
influence post operative pain control
positively.
Alfentanil is similar to Fentanyl in terms
of PONV and post op pain.
The higher rate of PONV is probably
related to the higher doses of post op
Morphine.
Strengths
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The studied groups
were similar in
demographic profiles
and duration of the
procedure.
Randomized double
blind study
The anesthetics given
in all three groups
followed the same
pattern.
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Small sample size of only 60 patients.
Doses of Morphine could have
influenced results especially in the
Remifentanil group.
More research needs to be completed
related to higher ASA classes with comorbidities influencing the respiratory
drive.
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Morbidly obese patients with BMI <50 and
without co-morbidities influencing respiratory
drive can be safely anesthetized with Alfentanil
or Fentanyl.
The advantage of Remifentanil, which is the
better recovery profile, is altered by the higher
rate of PONV and more difficult post op pain
management.