COMPARISON OF THE ANALGESIC EFFECT OF INTRATHECAL FENTANYL AND MIDAZOLAM

Abstract

The spinal route of analgesia has consolidated its place as a major modality
in the treatment of acute, chronic and cancer pain because the spinal cord
represents a principal target in the modulation of pain impulses from the periphery
as well as the brain. This makes it important in the management of pain. The use
of 0.5% heavy bupivacaine in combination with fentanyl or midazolam has been
reported to provide excellent and superior analgesia of longer duration during
surgical procedures.1,2 This combination has the added advantage of reduced side
effects in the perioperative period compared to when any of these drugs is used
singly as monotherapy.
This study is designed to determine the quality of analgesia provided by the
intrathecal administration of fentanyl 25µg or midazolam 2mg in combination
with 10mg of 0.5% heavy bupivacaine compared with single administration of
10mg 0.5% heavy bupivacaine alone as control in adult patients undergoing open
reduction and internal fixation of lower limb fractures. The total post operative
analgesic consumption of patients in 24 hours following surgery as well as the
incidence and severity of any undesirable effect were studied
The study groups comprise patients receiving intrathecal fentanyl 25µg
with 10mg 0.5% heavy bupivacaine(FB group) or midazolam 2mg with 10mg
0.5% heavy bupivacaine(MB group) for analgesia in adult patients undergoing
open reduction and internal fixation for lower limb fractures .The control group(B
group) were patients receiving neuraxial 10mg 0.5% heavy bupivacaine alone. A
total of fifty (50) patients, American Society of Anaesthesiologists (ASA) I and II
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status requiring open reduction and internal fixation of lower limb fracture under
subarachnoid blocks were studied.
The mean duration of analgesia / neural blockade in the control group (B)
was 2.37(±0.30) hours; 4.73(±0.89) hours in the fentanyl – bupivacaine (FB)
group and 5.04(±0.99) hours in the midazolam – bupivacaine (MB) group. Two
patients (11.8%) in the fentanyl – bupivacaine( FB ) group had pruritus (p = 0.132)
while pruritus was absent in the other two groups. Two patients (11.8%) in the
fentanyl – bupivacaine (FB ) group, one patient in the control group (5.9%) and
none in the midazolam – bupivacaine ( MB ) group vomited (p = 0.364 )
It was found from this study that both intrathecal midazolam and fentanyl
potentiate the analgesic effect of 0.5% hyperbaric bupivacaine. Midazolam
bupivacaine combination however offers a better side effect profile than fentanyl –
bupivacaine