Intrathecal midazolam added to bupivacaine improves the duration and quality of spinal anaesthesia.

BACKGROUND: The antinociceptive action of intrathecal midazolam is well documented. In this prospective study, we investigated the addition of midazolam to intrathecal bupivacaine on the duration and quality of spinal blockade.

METHODS: Forty ASA I or II adult patients undergoing lower abdominal surgery were selected for the study. The patients were randomly allocated to receive 3 ml of 0.5% hyperbaric bupivacaine intrathecally either alone or with 1 mg of midazolam using a combined spinal epidural technique. The duration and quality of sensory and motor block, perioperative analgesia, haemodynamic changes, and sedation levels were assessed.

RESULTS: The duration of sensory block (i.e. time to regression to the S2 segment) was significantly longer in the midazolam group than the control group (218 min vs. 165 min; P < 0.001). The duration of motor block was also prolonged in the midazolam group as compared with the control group (P < 0.01). In 90% of the patients in the midazolam group, the quality of block was adequate during the intra-operative period as compared with only 65% of the patients in the control group (P < 0.05). The duration of effective analgesia was longer in the midazolam group than in the control group (199 vs. 103 min; P < 0.001). Blood pressure, heart rate, oxygen saturation and sedation scores were comparable in both groups. No neurological deficit or other significant adverse effects were recorded.

CONCLUSION: The addition of intrathecal midazolam to bupivacaine significantly improves the duration and quality of spinal anaesthesia and provides prolonged perioperative analgesia without significant side-effects.