Comparison of the effects of intravenous Dexmedetomidine with intravenous Midazolam on the characteristics of Bupivacaine spinal block

Introduction: Different adjuvants have been used to extend spinal anesthesia, with probable benefits of late commencement of postoperative pain and reduced analgesic requirements. Midazolam has only sedative property. However, dexmedetomidine has both analgesic and sedative properties that may prolong the duration of sensory and motor block obtained with spinal anesthesia. This study was designed to compare intravenous dexmedetomidine with midazolam and placebo on spinal block duration, analgesia and sedation. Method: Single blinded randomized study was carried out on 75 patients undergoing surgeries in spinal anesthesia at General Surgery 0T in Civil hospital Ahmedabad. Patients were randomly divided into 3 groups D-received Dexmedetomidine 0.5 µg/kg i.v. M-received Midazolam 0.05 mg/kg i.v. S-received Normal Saline i.v. After 5 min all patients were induced under spinal anesthesia with 0.5%bupivacaine heavy 3 ml intrathecaly. Time taken for highest level and duration of sensory and motor block of bupivacaine spinal block was noted. Duration of analgesia and sedation were recorded. Result: Highest upper level of sensory block were higher in D(T560±1.73)than in M(T784±1.99) (p<0.001) or with S( T8.48±1.75) (p<0.001). Time for sensory regression of two dermatomes was 154±9.89 min in D while 112±10.31 min in M (p<0.001) and 96.4±10.94 min in S (p<0.001). Duration of motor block was higher in D(194±9.94 min) compared to M(169±11.38 min) and S(169±18.38 min) Patients in D had 24 hrs mean VAS score <3 while patients in M and S needed rescue analgesic after 12 hr and 8 hr respectively as their VAS score were >3.The median of RAMSAY sedation score was 2(2-5) in D,3 (2-5) for M and 1(1-2) for S. Conclusion: Dexmedetomidine prolonged highest upper level, duration of sensory blockade of bupivacaine induced spinal anesthesia with effective analgesia and sedation compared to intravenous midazolam.