Back ground: In spinal anesthesia various additive drugs have been tried with 0.5%hyper baric bupivacaine to look for the improvement in the quality and the duration of blockade like midazolam & 2-agonists. We designed a prospective, randomized, double blind study to compare the efficacy of midazolam and dexmedetomidine with 0.5% hyperbaric bupivacaine when given intrathecally in terms of effect and maximum level of sensory and motor blockade, overall duration and quality of analgesia, hemodynamic effects during intraoperative periods and any side effects.
Aim of the study: A comparison between the effect of adding dexmedetomidine and midazolam as adjuvant to intrathecal Bupivicaine on the quality of spinal block for orthopedic surgery
Patients and Methods: Sixty six of American Society of Anesthesiologists physical status classes I and II patients scheduled for lower limb orthopedic surgery were enrolled in this study. According to the received intrathecal drug mixture, these patients were randomly divided into 3 equal groups (22 in each group). Group I (control group) received 2.5 ml heavy bupivacaine (0.5%) plus 0.5 ml normal saline intrathecally. Group II (dexamedetomedine group) received 2.5 ml heavy bupivacaine (0.5%) plus 5 μg dexamedetomedine in 0.5 ml normal saline intrathecally. Group III (midazolam group) received 2.5 ml heavy bupivacaine (0.5%) plus 2 mg midazolam in 0.5 ml normal saline intrathecally.
Results: Patients in group II (Dexmedetomidine group) had a significantly longer sensory and motor block time than patients in group III (Midazolam group). The time of sensory block regression to S1 in group II (248.8±32.4 min) was significantly longer than the time in and in group III (208.3±21.7 min) (P=0.000). The time of motor block regression to reach Bromage score 0 in group II (235.6±32.4 min) was significantly longer than the time in group III (191.4±14.8 min) (P=0.000).
Conclusions: Although both dexmedetomidine (5μg) and midazolam (2mg), when added to intrathecal heavy bupivacaine lead to prolongation of the motor and sensory block with hemodynamic stability and lack of sedation but dexmedetomidine was superior to midazolam in prolongation of the motor and sensory block.