Prolonged analgesia by adding midazolam and hyperbaric bupivacaine in subarachnoid block for lower uterine caesarian section

Antinociceptive effect and safety of sub-arachnoid (SAB) midazolam is well established in animals and human beings. In this randomized, prospective placebo control clinical study, we investigated the addition of 2.5mg midazolam to bupivacaine on the quality of surgical anaesthesia and duration of first analgesic in the post operative period after lower uterine caesarean section (LUCS). Sixty ASA I or II pregnant women scheduled for elective lower uterine caesarean section were selected for the study. The patients were randomly allocated to receive 2ml of 0.5% hyperbaric bupivacaine with either 0.5ml of 5% dextrose in aqua or 2.5 mg (0.5ml) midazolam. The duration of first analgesic demand, quality of anaesthesia, haemodynamic changes and neonatal condition were assessed. The duration of analgesia (the time interval in minutes between the sub-arachnoid injection and the first analgesic demand by the patient) was significantly longer in the Group II than Group I (197min vs. 112min; p<0.001). The quality of surgical anaesthesia was excellent or good throughout the surgical procedure in 90% (n = 27) of the patients in Group II (p = 0.01). Systolic Blood pressure was significantly lower in the group I at 10 min and 20 min after administration of SAB than group II (p = 0.005 and p = 0.007) but comparable at other times. Sedation level, Apgar score was comparable in both groups. No neurological deficit or other significant adverse effects were recorded. The addition of midazolam with hyperbaric low dose bupivacaine in SAB significantly improves the quality of surgical anaesthesia and prolongs the duration of analgesia without any adverse effects.