Efficacy and safety of dexmedetomidine as an additive to local anesthetics in peribulbar block for cataract surgery.

BACKGROUND AND OBJECTIVES: We evaluated the effect of adding dexmedetomidine to lidocaine and bupivacaine for peribulbar block in two different doses. The primary endpoints were the onset and duration of corneal anesthesia, globe akinesia, and duration of analgesia.

MATERIALS AND METHODS: A randomized controlled clinical trial was conducted on 90 ASA I-II patients scheduled for elective cataract surgery under peribulbar anesthesia. Patients were randomly allocated to one of three groups of 30 each; group C (control) received 3 ml of 2% lidocaine with 3 ml of 0.5% bupivacaine; group D50 received 3 ml of 2% lidocaine with 3 ml of 0.5% bupivacaine and 50 ug of dexmedetomidine; and group D25 received 3 ml of 2% lidocaine with 3 ml of 0.5% bupivacaine and 25 μg of dexmedetomidine.

RESULTS: The onset of corneal anesthesia and globe akinesia was significantly shorter in group D50 (P < 0.001) as compared to group C; however, in Group D25 onset of corneal anesthesia was significantly faster, but not onset of globe akinesia (P = 0.45). The duration of corneal anesthesia and globe akinesia was significantly longer (P < 0.001) in both Group D50 and Group D25 in comparison to Group C. Decrease in IOP was observed in both group D50 and group D25 at 5 minutes and 10 minutes following peribulbar block which was significant (P < 0.05) compared to group C.

CONCLUSION: Addition of dexmedetomidine to lidocaine and bupivacaine in peribulbar block shortens the onset time and prolongs the duration of the block and postoperative analgesia. It also provides sedation which enables full cooperation and potentially better operating conditions.