Objectives: In this prospective, randomized, double-blind, placebo-controlled study, we investigated the postoperative analgesic efficacy of 2 doses of intrathecal midazolam as an adjunct to bupivacaine for spinal anesthesia.

Methods: Sixty patients undergoing elective cesarean delivery under spinal anesthesia were allocated randomly to 3 groups: group B, 2 mL hyperbaric bupivicaine 0.5%; group BM1, 2 mL bupivacaine plus midazolam 1 mg (preservative free); and group BM2, 2 mL bupivicaine plus midazolam 2 mg.

Results: The mean duration of postoperative analgesia (determined by request for rescue medication) was 3.8 ± 0.5 hours in group B compared with 4.3 ± 0.7 hours in group BM1 (P = .18), and 6.1 ± 1.0 hours in group BM2 (P = .001). Supplemental analgesic requirements with diclofenac were significantly less in group BM2 (93 ± 29 mg) compared with group B (145 ± 12 mg) and group BM1 (148 ± 16 mg, P < .001). Time to block regression was longer in group B (182 ± 30 minutes) compared with group BM1 (152 ± 32 minutes) and group B (126 ± 20 minutes) (both P < .001). Arterial pressure, heart rate, oxygen saturation, sedation score, and time to first void were comparable between groups. Group B had a significantly higher incidence of nausea and vomiting than groups BM1 and BM2 (P = .02). No neurologic deficits were observed.

Conclusions: Intrathecal midazolam 2 mg provided a moderate prolongation of postoperative analgesia when used as an adjunct to bupivacaine in patients undergoing cesarean delivery. Intrathecal midazolam, 1 mg and 2 mg, decreased postoperative nausea and vomiting.