The Effect Of Different Doses Of Intrathecal Dexmedetomidine On Spinal Anesthesia: A Meta Analysis

Background: Some studies indicated dexmedetomidine had synergistic effect on spinal anesthesia when using intrathecally. Several studies also compared the effect of different doses of dexmedetomidine on spinal anesthesia. However, the results were inconsistent. We performed this meta-analysis to investigate the safety and efficacy of different doses of dexmedetomidine on spinal anesthesia. Methods: Pubmed, Embase and Cochrane library were searched. All randomized controlled trials that compared the effect of different doses of dexmedetomidine on spinal anesthesia were included. Sensory and motor block onset times, block durations, duration of analgesia, postoperative anesthetic consumption, and side effects were analyzed. Sensory block duration was our primary outcome. Meta-analysis was performed using a random effects model. Results: Nine randomized controlled trials were included in our meta-analysis. Compared with low-dose dexmedetomidine group, high-dose dexmedetomidine group prolonged sensory block duration by 36.06 min [95% CI: 33.90, 38.22, P<0.00001], decreased sensory and motor block onset times by 0.69 min [95% CI: 0.25, 1.13, P=0.002] and 0.62 min [95% CI: 0.22, 1.02, P=0.002], respectively, and prolonged motor block duration by 54.27 min [95% CI: 23.18, 85.36, P=0.0006]. High-dose dexmedetomidine also prolonged the duration of analgesia by 108.13 min [95% CI: 52.77, 163.50, P=0.0001], and decreased postoperative anesthetic consumption was decreased by 60.1 mg [95% CI: 7.83, 112.36, P<0.00001]. However, the risk of bradycardia was increased [OR, 1.91, 95% CI: 1.06, 3.43; P=0.03] in high-dose intrathecal dexmedetomidine group. Conclusion: Increasing the dose of intrathecal dexmedetomidine may prolong the action of spinal anesthesia. However, the risk of bradycardia was increased at the same time.