Comparative study between the effect of intrathecal midazolam versus intrathecal midazolam plus magnesium sulfate on the efficacy and duration of analgesia in patients undergoing cesarean section

Background Regional techniques using either epidural or intrathecal routes are currently the most popular methods of pain relief during labor and delivery. Aim The aim of the study was to compare efficacy and duration of analgesia produced by adding magnesium sulfate to intrathecal bupivacaine (10 mg) plus midazolam (1 mg) in patients undergoing cesarean section. Patients and methods In our study, 60 patients aged 18–35 years of American Society of Anesthesiologists (ASA) class I and II were scheduled for a cesarian section under an intrathecal block and divided randomly into two groups: midazolam group (group M): A total of 30 patients received 10 mg/2 ml intrathecal 0.5% hyperbaric bupivacaine, midazolam (1 mg/0.2 ml), and 0.8 ml normal saline and magnesium midazolam group (group MM): A total of 30 patients received 10 mg/2 ml intrathecal 0.5% hyperbaric bupivacaine, midazolam (1 mg/0.2 ml), magnesium sulfate (50 mg/0.5 ml), and 0.3 ml normal saline. The onset and duration of both sensory and motor block, the total dose of analgesia, and adverse effects were recorded. Results The onset of sensory block was significantly delayed in the MM group compared with the M group (6.05 ± 1.1 vs. 3.5 ± 0.45 min, P = 0.024); the duration of sensory block was longer in the MM group compared with the M group (132.4 ± 7.8 vs. 115.3 ± 6.60 min, P = 0.018). In addition, the onset of motor block was delayed in the MM group (7.05 ± 1.3 min) compared with the M group (5 ± 0.65 min, P = 0.028) as well as its duration (149.9 ± 8.67 vs. 126.3 ± 5.35 min, P = 0.005). Conclusion The addition of magnesium sulfate to intrathecal bupivacaine plus midazolam led to a significant delay in the onset of both sensory and motor blockade, and also prolonged their duration without side effects.