Evaluation of two different doses of intrathecal midazolam with bupivacaine for lower abdominal surgery.

ABSTRACT

Midazolam has a synergistic effect when added to intrathecal bupivacaine. This prospective controlled study compared the effect of addition of two different doses of midazolam [1 mg and 2 mg] to intrathecal bupivacaine for patients undergoing lower abdominal surgery. Fifty six adult patients undergoing lower abdominal surgery were randomly allocated to receive intrathecal 3 ml of hyperbaric bupivacaine [0.41%] alone or in combination with one or two mg of midazolam. The duration and quality of sensory and motor block, postoperative analgesia, perioperative hemodynamic changes, sedation levels and neurological dysfunction were noted. The difference in the level of sensory block or the motor block between patients in the three groups was not statistically significant. The time elapsed for the sensory block to regress to S2 was significantly longer in the M1 [4.4+/-0.44 hours] and M2 [5.9+/-0.37 hours] groups than the control group [2.3+/-0.58 hours] [p <0.05]. Also, the duration of effective analgesia for patients in M1 group [4.6+/-0.22 hours] and M2 group [6.3+/-0.21] was significantly longer than the control group [2.2+/-0.49 hours] [p<0.05]. None of the patients developed perioperative respiratory depression, excessive sedation or neurological dysfunction at discharge. Other perioperative vital parameters were comparable between patients in the three groups. We conclude that the addition of 1-2 mg midazolam to intrathecal bupivacaine did not produce a higher level of sensory or motor block. It increased the duration of postoperative analgesia without increased perioperative complications. Further dose-response studies are required to define the dose of intrathecal midazolam necessary to elicit an optimal effect