Modulation of Bupivacaine-Induced Spinal Anesthesia by Intrathecal Midazolam: A Pharmacodynamic Analysis

Abstract

 Background: Subarachnoid Block remains a widely utilized neuraxial technique in contemporary anesthetic practice, offering distinct clinical advantages compared to general anesthesia. Objective: The present investigation aims to evaluate the impact of incorporating either 1 mg or 2 mg of midazolam adding to hyperbaric bupivacaine upon the sensory and motor blockade durations, as well as intraoperative circulatory fluctuations, during spinal anesthesia for cesarean delivery. Patient and method: A total of 180 parturient, classified according to American Society of Anesthesiologists (ASA) physical status I or II and aged between 18 and 40 years, were distributed randomly in to three groups planned for elective cesarean section under neuroaxial anesthesia (spinal anesthesia) at AL Basra teaching hospital, Iraq. Group Ⅰ (n = 60) received an intrathecal combination comprising 12.5 mg of bupivacaine supplemented with 0.4 ml of isotonic saline, whereas group Ⅱ (n = 60) was administered 12.5 mg of bupivacaine combined with 1 mg of midazolam, and group Ⅲ (n = 60) received 12.5 mg of bupivacaine together with 2 mg of midazolam. The three groups displayed similarity regarding maternal age and baseline hemodynamic parameters, both before and immediately after initiation of the spinal intervention. Results: Patients in Groups Ⅱ and Ⅲ experienced significantly extended pain relief durations, regarding motor block times of 190 and 187 minutes versus 145.00 minutes in Group 1 (P value< 0.0001). Similarly, sensory block durations were 219.00, 217.00, and 149.00 minutes, respectively (P value < 0.0001). No notable variations in hemodynamic stability were observed across the cohorts. Conclusion: Among women receiving spinal anesthesia, combining midazolam as an adjuvant with bupivacaine provides a prolonged analgesic effect compared to using bupivacaine alone without an additive.