Comparison of dexmedetomidine and clonidine as adjuvants to local anesthetics for intrathecal anesthesia: A meta-analysis of randomized controlled trials.

The authors performed a meta-analysis to compare the characteristics of clonidine and dexmedetomidine as adjuvants to local anesthetic in intravertebral anesthesia. Four investigators independently searched electronic databases for randomized trials comparing the characteristics of clonidine vs dexmedetomidine as adjuvants to local anesthetic on adults. The endpoints were onset of analgesia, sensory and motor block, and duration of analgesia. A random-effects model was used to perform quantitative analysis. Seven studies comprising 354 subjects were included in this meta-analysis. The onset of sensory block was significantly 40 seconds shorter when dexmedetomidine was added as an adjuvant in the intrathecal injection. The duration of stable sensory block, duration of overall sensory block, and the time before the need for analgesic requirements were significantly extended, 10.8 minutes, 22.3 minutes, and 38.6 minutes, respectively, when dexmedetomidine was used as an adjuvant to local anesthetics (bupivacaine or ropivacaine). No significant differences were detected in the motor block characteristics and the time to achieve peak sensory level between dexmedetomidine and clonidine as adjuvants to local anesthetics. Compared to clonidine, the addition of dexmedetomidine as an adjuvant to local anesthetics is associated with earlier, prolonged sensory block characteristics and later need for analgesic requirements.