Blockade of α1 subtype GABAA receptors attenuates the development of tolerance to the antinociceptive effects of midazolam in rats

Adding intrathecal midazolam to local anesthetics improves sensory and motor block and reduces pain score without increasing side effects in lower limb surgeries: A meta-analysis and systematic review

This meta-analysis was done to investigate the role of intrathecal midazolam in lower limb surgeries regarding prolongation of spinal block, postoperative pain control and associated side effects. The included studies reported onset and duration of sensory and motor block, time to first request analgesia, 24h opioid consumption, postoperative pain control, and associated side effects following use of intrathecal midazolam for lower limb surgeries. This review was performed following the PRISMA guidelines and using the online databases, Medline, Science Direct, Google scholar and Cochrane library. We registered this review with the PROSPERO database (ID-CRD42022346361) in August 2022. A total of 10 randomised controlled trials were included in this meta-analysis. Our results showed patients receiving 1mg intrathecal midazolam showed significantly faster onset of sensory block [P=.001 (CI: -0.98, -0.31)]. Duration of sensory and motor block were also significantly prolonged in intrathecal midazolam group [P<.00001 (CI: 18.08, 39.12), P=.002 (CI: 0.45, 2). Intrathecal midazolam also increased the time to first request analgesia [P=.0003, (CI: 1.22, 4.14)]. Pain scores at 4 and 12h postoperatively were significantly lower in patients receiving intrathecal midazolam [P=.00001 (CI: -1.20, -0.47) and P=.05 (CI: -0.52, -0.01) respectively]. In conclusion, the addition of intrathecal midazolam to local anesthetics in lower limb surgeries results in early onset of sensory and motor block. It also increases the duration of sensory and motor block. The time to first request analgesia is increased. VAS pain scores at 4 and 12h postoperatively were also lower without any increased side effects.