Comparative study of the effect of adding two different doses of dexmedetomidine to levobupivacaine/hyaluronidase mixture on the peribulbar block in vitreoretinal surgery

Background Many additives have been added to local anesthetics in PBA to decrease the time of onset and increase the duration of analgesia to suit the relatively long vitreoretinal surgery with limited success. Dexmedetomidine has been added to local anesthetics for such purpose. Patients and methods Sixty consented ASA I–II adult patients undergoing vitreoretinal surgery were enrolled in this randomized, double blind, controlled study. Patients were randomly and evenly assigned to three groups to receive one of three anesthetic solutions for PBA: group C, group D25, and group D50. Patients in group C received 6 ml of 0.5% levobupivacaine with 10 IU/ml hyaluronidase in addition to 1 ml of normal saline. Patients in groups D25 and D50 received the same mixture but with replacement of the normal saline with 25 and 50 mcg dexmedetomidine, respectively. Intraoperative recordings included onset and duration of corneal anesthesia and globe akinesia, hemodynamics, intraocular pressure (IOP), and Ramsay sedation score. Postoperative recordings included time to first rescue analgesia and number of doses required, pain score, and patient and surgeon satisfaction score. Results The onset of corneal anesthesia and globe akinesia was significantly shorter in group D50 than in group C (1.05 ± 0.50 and 6.90 ± 1.94 vs. 1.68 ± 0.78 and 9.10 ± 2.14); in group D25 the onset was insignificantly shorter. Duration of anesthesia was significantly longer in both groups compared with control, as was the time to first rescue analgesia. IOP was also significantly lower in both groups compared with control. Conclusion Addition of two different doses of dexmedetomidine (25 and 50 mcg) to levobupivacaine/ hyaluronidase mixture shortened the onset and prolonged the duration of peribulbar block in patients undergoing vitreoretinal surgery. It also lowered the IOP and provided sedation with patient’s cooperation, leading to better patient and surgeon satisfaction.