Comparison of Efficacy of Midazolam and Fentanyl as Adjuvants to Intrathecal Bupivacaine in Patients Undergoing Elective Gynaecological Surgeries

Background and Aims Spinal anaesthesia is most commonly used for gynaecological surgeries, but it is often criticized due to its short action. Various adjuncts are being used to prolong the duration of analgesia. This study aims to compare analgesic efficacy of midazolam and fentanyl as an adjunct to intrathecal hyperbaric bupivacaine. We studied total duration of postoperative analgesia as primary outcome variable and the characteristics of the block, hemodynamic variable and adverse effects as secondary outcome variable. Material and Methods The present prospective, randomized, double-blind study was undertaken on ninety American Society of Anaesthesiologists (ASA) I-II patients, 2050 yrs. of age, undergoing elective lower abdominal gynaecological surgeries under spinal anaesthesia. Patients were randomized into three group of 30 each using chit in box method. In group B, patients received 15 mg hyperbaric bupivacaine 0.5 % with 0.4 ml normal saline, group M, received 15 mg hyperbaric bupivacaine 0.5 % with 2 mg (0.4 ml) midazolam and in group F, 15 mg hyperbaric bupivacaine 0.5 % with 20 g fentanyl (0.4ml) intrathecally. Results Time to onset of sensory and motor block in all the three groups was comparable. However, duration of sensory block and postoperative analgesia was significantly prolonged in groups M and F in comparison to group B (P less than 0.0001) and it was the longest in Group F. The duration of motor blockade was similar in all the three groups. Intra- and post-operative hemodynamic parameters, as well as side effects, were comparable. Conclusion Addition of midazolam and fentanyl as adjuvants to intrathecal 0.5 % bupivacaine prolongs postoperative pain relief without causing hemodynamic variations and adverse effects but fentanyl is superior as compared to midazolam.