"The clinical and histopathological effects of perineural dexmedetomidine in combination with bupivacaine in sciatic nerve block in rabbits undergoing sevoflurane anesthesia"

Abstract

Many drugs or additives have been tried as adjuvants in the blocking of nerve blocks with local anesthetics, and it is aimed to increase the duration of action and analgesia quality of local anesthetics in this way. In this study, we aimed to see the adjuvant efficacy of Dexmedetomidine [Dex] added to bupivacaine and its effect on analgesia and histopathological effects in rabbits by administering sevoflurane anesthesia. Twenty-four rabbits were randomly allocated to 3 groups; Group S: sham [0.5 ml saline], Group B: perineural bupivacaine [0.5 mg/kg] [0.5 ml] and Group BD: perineural bupivacaine [0.5 mg/kg] combined with Dex [20 µr/kg] [0.5 ml]. Analgesia measurement was evaluated by hotplate test, the paw withdrawal response was performed for sensorial and motor blockades also were recorded at baseline, 30, 60, 90, and 120 min after drug administration. Dissected nerve tissue was also examined for histopathologic evaluation. In the hot-plate test applied for the measurement of acute thermal pain; when compared to Group S, significant prolongation was found in Group B and Group BD at 0, 30, 60, 90, and 120 minutes [p<0.05]. When Group BD was compared with Group B, a significant prolongation was found at 60 minutes [p=0.012]. No significant difference was found in other times. No significant differences were found between the groups in sensory and motor block tests. In the BD group, compared to the B group, edema and inflammation in the epineurium and surrounding tissues were significantly reduced on the 1st day [p<0.05]. On the 14th day, there was no difference in terms of edema. In rabbits administered sevoflurane anesthesia, the mixture of bupivacaine and Dex applied to provide analgesia in the application of sciatic block prolongs the delay time and increases the quality of analgesia in the hot-plate test evaluating acute thermal pain. Dex added to bupivacaine contributed positively when the analyzed histopathological parameters were evaluated.