BACKGROUND: There have been recent reports on the effects of the addition of intrathecal midazolam to bupivacaine on spinal anesthesia. Therefore, the effects of the addition of intrathecal midazolam to bupivacaine on spinal anesthesia and peri-operative sedation were investigated.

METHODS: Thirty one ASA class 1 and 2 patients, scheduled for transurethral resection of the bladder or prostate (TURB or TURP), were randomly divided into two groups. Group B (n = 15) received bupivacaine 12 mg, and normal saline 0.6 ml, whereas group BM (n = 16) received bupivacaine 12 mg, midazolam 2 mg, and normal saline 0.2 ml. The blood pressure (BP), heart rate (HR), arterial oxygen saturation (SaO₂), bispectral index (BIS) and Observer's Assessment of Alertness/Sedation Scale (OAA/S scale) scores were recorded every 5 minutes, both before and during the spinal anesthesia. The sensory blockade was measured using a pin-prick test, and motor blockade evaluated using the Bromage motor scale. In addition, the side effects, including pruritus, nausea, vomiting, and headache, and so on, were observed for a period of 24 hours.

RESULTS: There were no differences in the motor and sensory block and recovery between the two groups. However, a difference was found in the time to first recognition of pain and the BIS scores between the two groups.

CONCLUSIONS: Intrathecal midazolam did not, itself, affect the spinal anesthesia, but was found to have a statistically prolonged postoperative analgesic and more sedative effects.