Evaluation of effect of midazolam added to bupivacaine on postoperative pain in cesarean section

Regional anesthesia is the preferred technique for cesarean section. In this regard spinal anesthesia with bupivacaine is the most prevalent, but this method has only 2 to 2.5 hours duration of analgesia, therefore different additives has been used in order to prolong its analgesic duration. In this study efficacy of Midazolam, added to bupivacaine, studied on postoperative pain. This study was a double blinded clinical trial on 54 parturients with ASA I, II candidate for elective cesarean section. The parturients assigned into two groups: 27 in each one. Before spinal anesthesia, 1000 ml ringer solution infused, then spinal anesthesia was done in sitting position through L3-L4 or L4-L5. Bupivacaine group (B), received 3 ml of 0.5% bupivacaine, and bupivacaine + midazolam group (BM), received 3ml of 0.5% bupivacaine + 0.4 ml of midazolam (2mg). Hemodynamic status including systolic, diastolic, and mean arterial pressure and heart rate were measured each 2 minute post spinal until child bearing, then every 15 minute till 30 minutes and finally every 1 hour for 5 hours. Pain score measured by numerical analog pain score (NAS) during postoperative period every hour for 5 hours. The data analysis was done by t-test. There was no significant difference between two groups concerning demographic data and length of operation. Systolic blood pressure at 4th and sixth minute, third hour and fourth hour; diastolic blood pressure at second and third hours; and heart rate at fourth minute until fifth hour was significantly lower in BM group compared with B group. Mean arterial blood pressure showed decrement within both groups yet were not significant in comparison with the base line. Both groups were painless during first two postoperative hours, while BM group had less pain score in third hour (p<0.05); moreover, BM had less pain score at fourth and fifth postoperative hours, it was not statistically significant.(P> 0.05) Addition of midazolam to bupivacaine in spinal anesthesia was effective in lowering the pain score during first postoperative hour and is recommended.