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Background: A wide variety of additives have been used in a mixture with local anesthetics in PBA to fasten the onset, increase the potency and prolong the duration of the block to cover the long viteroretinalsurgeries. Dexmedetomidine, magnesium sulphateand rocuronium bromidehave been added to local anesthetics to achieve such goal.
Patients and methods: This randomized double-blind prospective study was carried out on 96 ASA I and II patients aged 40 to 65 years who were scheduled for elective vitreoretinal surgery in Tanta university. Patients were divided randomly allocated into three groups, 32 patients in each group. Group C received the combination of 3.5 ml bupivacaine 0.5%, 3.5 ml lidocaine 2%, 0.5 ml rocuronium bromide (5 mg) plus 0.5 ml Normal saline (0.9% NaCl), group D received the same local anesthetic rocuronium mixture supplemented plus with plus 0.5 ml Dexmedetomidine (5 Group M group received the same local anesthetic rocuronium mixture plus 0.5 ml MgSO4 5% (50 mg). the onset of corneal anesthesia, time to adequate condition to begin surgery, the score and duration of akinesia, number of patients requiring supplementary injection, IOP, sedation scores, intraoperative pain, patients and surgeon’s satisfaction and incidence of complication were assessed.
Results: There was no statistical significance in the onset of corneal anesthesia between all groups with p value>0.05 (Group M 2.00 ± 0.70, Group M, 2.04 ± 0.77 and Group C 2.26 ± 0.62 min). However, the time adequate to start the surgery was significantly shorter (p<0.0001) in group M than in group D and group C (7.05 ± 1.54, 7.86 ± 1.61 and 8.63 ± 1.65 min respectively); also, it was significantly shorter in group D than group C. The duration of akinesia was significantly longer (p<0.0001) in group M compared with other groups (200.55 ± 7.55,180.11 ± 1.61 and 140.44 ± 13.04 min in group M, D and C respectively). IOP comparison was statistically insignificant between all groups with p value>0.05. No significant difference was noticed between the 3 groups regarding sedation score HR and MAP at all-time measures. As regards the akinesia score Mg group had the least akinesia score (p<0.0001) compared with the other groups in all measurement times. The VAS score and the need of supplemental dose were much higher in the control group. Patient satisfaction (p<0.0001) was best achieved in the D Group while surgeon satisfaction (p=0.01) was the best in M Group.
Conclusion: Adding Mg to local anesthetic mixture in peribulbar anesthesia resulted in a fast onset, long duration and better akinesia score while Dexmedetomidine supplementation offered more patient satisfaction.