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Bupivacaine is the frequently used anaesthetics for the subarachnoid block in parturients undergoing the cesarean section.
For
patients undergoing a cesarean section, 10 or 15 μg of intrathecal fentanyl
with 10 mg of bupivacaine provided adequate surgical anaesthesia and analgesia
with minimal side effects.
Bupivacaine is the frequently used anaesthetics for the
subarachnoid block in parturients undergoing the cesarean section. It is
noticed that intrathecal bupivacaine alone is inadequate to provide entire
anaesthesia. Therefore, to improve the duration and quality of subarachnoid
block, surgeons commonly add opioids such as fentanyl.
It is reported that intrathecal fentanyl is associated with
the number of side effects such as pruritus, nausea/vomiting, and respiratory
depression. The appropriate and safe dose of fentanyl is still unclear.
Previous studies assessed the adequate doses of intrathecal fentanyl for
clinical efficacy but did not have sufficient ability to identify the
differences in secondary outcome variables such as pruritus, respiratory
depression, nausea, and vomiting. In this investigation, 25 μg of fentanyl is
used with bupivacaine for spinal anaesthesia during cesarean section.
Rationale behind research:
The previous studies which
assessed the varying doses of intrathecal fentanyl for clinical efficacy were
not sufficient to detect the differences in secondary outcome variables such as
pruritus, respiratory depression, nausea, and vomiting.
Therefore, this study was conducted to
compare 25 μg of intrathecal fentanyl with 10 and 15 μg doses in parturients
undergoing a cesarean section.
Objective:
To compare 25 μg intrathecal
fentanyl with 10 and 15 μg doses in parturients undergoing cesarean section
under spinal anaesthesia with intrathecal bupivacaine to assess:
Study outcomes:
In addition, neonatal APGAR score,
patients' hemodynamics, need for vasopressors, onset and duration of sensory,
and motor block was measured.
Time period: NA
Outcomes
Baseline: No significant differences observed at baseline
Study
outcomes:
In the present study, there was no significant difference
among the three groups in the quality of surgical anaesthesia. Most of the
patients (95–96%) reached to a great level of surgical anaesthesia with all
three doses of fentanyl, with only 6 (2.46%) requiring intravenous rescue
analgesia and none requiring conversion to general anaesthesia. Previous
studies have shown the significantly higher number of failed blocks at a dose
of 7.5 μg. As per the survey conducted by Chu et al. all the patients receiving
12.5 and 15 μg of intrathecal fentanyl with 0.5% hyperbaric bupivacaine
experienced excellent analgesia as compared to 7.5 μg of fentanyl.
Moreover, in a study conducted by Goel et al. it was found that the patients receiving 7.5 μg of fentanyl in combination with low-dose bupivacaine had a significantly higher number of failed blocks (27%) than those receiving 10 or 12.5 μg of fentanyl. Therefore, most of the researchers favour using doses of intrathecal fentanyl higher than 10 μg. In this study, the lowest dose of intrathecal fentanyl was 10 μg, and no difference in the anaesthesia was observed provided by 10μg dose and the higher doses of fentanyl (15 and 25 μg). Therefore, it can be deduced that increasing the dose of intrathecal fentanyl more than 10 μg does not add to the quality of surgical anaesthesia.
The opioid is added to the local anaesthetic not only to
improve the quality of surgical anaesthesia but also for the onset and duration
of the block. Therefore, combining an opioid with a local anaesthetic may add
local anaesthetic sparing effects and lead to a shorter onset time and
prolonged duration for the sensory block. In this study, the time of achieving
the sensory block of T5 and motor block was similar in all the three groups,
indicating that it is the presence of opioid and not the dose of opioid that
affects the onset of the block. However, it was observed that the duration of
motor and sensory block increased with an increase in the dose of fentanyl.
The incidence of pruritus was found to be highest in the
patients from Group 25 among all the study groups. Some studies have shown
nonsignificant pruritus in patients receiving 25 μg and less of intrathecal
fentanyl. One of the possible reasons might be that as none of these studies
has measured pruritus as the main outcome. This study was designed with a
sample size large enough to detect the differences in pruritus, respiratory
depression, nausea, and vomiting.
The incidence of nausea was the highest in the patients from
Group 25, while no difference was seen in the frequency of vomiting among the
three groups. The high incidence of nausea observed in this study is not
comparable to other studies, which showed either less or no differences. The
higher incidence of nausea could be due to the variation in surgical technique,
including uterine exteriorization in some patients, as well as variations in
the level of anxiety among patients.
APGAR score of the babies remained the same in all groups and also compatible with other studies.
In conclusion, out of all three examined
doses of intrathecal fentanyl, 15μg determined as the safer and optimal dose
used with 10 mg bupivacaine for cesarean section under spinal anaesthesia.
The present study has indicated the use of 10 or 15 μg of intrathecal
fentanyl with 10 mg of bupivacaine in patients undergoing a cesarean section.
The combination of 10 or 15 μg of intrathecal fentanyl with 10 mg of
bupivacaine can be helpful in providing adequate surgical anaesthesia and
analgesia with a lower incidence of side effects.
J Anaesthesiol Clin Pharmacol 2018;34:221-6
A double-blind randomized control trial to compare the effect of varying doses of intrathecal fentanyl on clinical efficacy and side effects in parturients undergoing cesarean section
Muhammad Asghar ali et al.
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