Background: Spinal anaesthesia is safe, reliable and inexpensive technique of providing surgical anaesthesia. The intrathecal use of clonidine is shown to be effective and safe. Several studies indicate that clonidine extends duration of local anaesthetics action and can decrease the dose of local anaesthetic drug. Midazolam, a benzodiazepine when added to local anaesthetic bupivacaine has significant synergistic effect in terms of quality of spinal anaesthesia, duration and prolong post-operative analgesia without having any significant side effects.

Aims: To evaluate the synergistic effect and safety of adding 50µg clonidine to intrathecal 0.5% hyperbaric bupivacaine in spinal anaesthesia compared to 2mg of midazolam to intrathecal 0.5% hyperbaric bupivacaine for infra-umbilical surgeries. 

Material and Methods: Mean onset of sensory blockade in Group A was 151.8±36.8 sec and in Group B was 170±53.5 sec. Mean time taken for two segment regression in Group A was 210.5±62.1 min and in Group B was 162.7±54.9 min which was statistically significant. Mean Duration of analgesia in Group A was 312.4±53.8 min and in Group B was 404.5±63.6 min.

Results: Mean onset of sensory blockade in Group A was 151.8±36.8 sec and in Group B was 170±53.5 sec. Mean time taken for two segment regression in Group A was 210.5±62.1 min and in Group B was 162.7±54.9 min which was statistically significant. Mean Duration of analgesia in Group A was 312.4±53.8 min and in Group B was 404.5±63.6 min.

Conclusions: Midazolam as an additive to intrathecal bupivacaine prolongs the duration of analgesia with minimal side effects when compared to clonidine.