Comparison of the onset and duration of analgesia with intrathecal hyperbaric bupivacaine and intrathecal hyperbaric bupivacaine plus midazolam for lower limb orthopaedic surgeries.

Abstract

Various additive drugs have been added to bupivacaine to modify its onset and duration of analgesia; these include among others the use of midazolam, tramadol, morphine and fentanyl. This study, therefore, was aimed at comparing the onset and duration of analgesia during intrathecal hyperbaric bupivacaine 0.5% alone and intrathecal hyperbaric bupivacaine 0.5% with midazolam for lower limb orthopaedic surgeries. Methodology: This was a prospective randomized double-blinded controlled study that recruited one hundred and thirty-eight (138) ASA I and II patients scheduled for elective lower limb orthopaedic surgeries. The patients were allocated into two groups. Group BA (n=69) received 12.5mg(2.5mls) of 0.5% hyperbaric bupivacaine with 0.5mls normal saline intrathecally at L3-L4 or L4-L5 inter-space, and group BM that received 12.5mg (2.5mls) of 0.5% hyperbaric bupivacaine with 2.5mg
(0.5mls) of preservatives-free midazolam at L3-L4 or L4-L5 intrathecally, no premedicants were given. Standard monitoring of the vital signs was done. The onset and duration of analgesia were documented and analysed. Results: Results showed that the mean onset time of analgesia was 37.04±4.53min and 25.65±4.84min in groups BA and BM respectively, with statistically significant difference (P < 0.01). While the mean duration of analgesia were151.43 ± 58.84 min and 323.4 ± 22.55 min in groups BAand BM respectively, P<0.01. Conclusion: The addition of 2.5mg (0.5ml) of midazolam to hyperbaric bupivacaine for subarachnoid block shortens the onset and prolonged the duration of analgesia when compared to bupivacaine alone.