Effect of low‐dose dexmedetomidine or clonidine on the characteristics of bupivacaine spinal block

TLDR

The study compares the onset and duration of sensory and motor block, hemodynamic changes, and sedation when intrathecal bupivacaine is supplemented with dexmedetomidine or clonidine. In a prospective, double‑blind trial of 60 patients undergoing transurethral resection, patients were randomized to receive bupivacaine alone, bupivacaine plus 3 µg dexmedetomidine, or bupivacaine plus 30 µg clonidine, and onset and regression times of sensory and motor block, as well as hemodynamics and sedation, were recorded. Dexmedetomidine and clonidine both shortened motor block onset and prolonged sensory and motor regression compared with bupivacaine alone, with no significant difference between the two additives, and all groups maintained similar hemodynamics and sedation.

Abstract

Background: The purpose of this study was to compare the onset and duration of sensory and motor block, as well as the hemodynamic changes and level of sedation, following intrathecal bupivacaine supplemented with either dexmedetomidine or clonidine. Methods: In a prospective, double‐blind study, 60 patients undergoing transurethral resection of prostate or bladder tumor under spinal anesthesia were randomly allocated to one of three groups. Group B received 12 mg of hyperbaric bupivacaine, group D received 12 mg of bupivacaine supplemented with 3 µg of dexmedetomidine and group C received 12 mg of bupivacaine supplemented with 30 µg of clonidine. The onset times to reach peak sensory and motor levels, and the sensory and motor regression times, were recorded. Hemodynamic changes and the level of sedation were also recorded. Results: Patients in groups D and C had a significantly shorter onset time of motor block and significantly longer sensory and motor regression times than patients in group B. The mean time of sensory regression to the S1 segment was 303 ± 75 min in group D, 272 ± 38 min in group C and 190 ± 48 min in group B (B vs. D and B vs. C, P < 0.001). The regression of motor block to Bromage 0 was 250 ± 76 min in group D, 216 ± 35 min in group C and 163 ± 47 min in group B (B vs. D and B vs. C, P < 0.001). The onset and regression times were not significantly different between groups D and C. The mean arterial pressure, heart rate and level of sedation were similar in the three groups intra‐operatively and post‐operatively. Conclusions: Dexmedetomidine (3 µg) or clonidine (30 µg), when added to intrathecal bupivacaine, produces a similar prolongation in the duration of the motor and sensory block with preserved hemodynamic stability and lack of sedation.