Study On Multimodal Analgesia With Sufentanil Dexmedetomidine And Ketamine

Objective: To compare the analgesic effects of three different analgesic drugs,nam ely sufentanil,dexmedetomidine and ketamine,on the formalin-induced inflammatory pain and to explore the mechanism of their analgesic effect.Methods: Fourty-eight adult male SD rats were randomly divided into eight groups:Control group(Con group): saline(100 μl)was injected into the left hind plantar,and saline(20 μl)was injected into the intrathecal space 10 minutes later.The remaining groups were injected with 5% formalin(100 μl)into the left hind plantar and intrathecal injection of the same volume(20 μl)after 10 min.Formalin group(For group):saline(20 μl);Sufentanil group(Suf group): sufentanil 1μg;Dexmedetomidine group(Dex group): dexmedetomidine 2 μg;Ketamine group(Ket group): ketamine 100μg;Sufentanil + dexmedetomidine group(Suf+Dex group): sufentanil 0.5 μg+ dexmedetomidine 1 μg;Sufentanil + ketamine group(Suf+Ket group): sufentanil 0.5 μg + ketamine 50 μg;Ketamine+dexmedetomidine group(Ket+Dex group): ketamine 50 μg+ dexmedetomidine 1 μg.The time of formalin-induced pain-related behavior at 5、10、15、25、35、45、55、60 min each time point after formalin injection was observed and recorded,and the pain score was calculated.The expression levels of c-Fos and SP in the spinal dorsal horn of each group were detected by immunohistochemistry and Western blotting.Results: Compared with group Con,the pain score and the expressions of c-Fos,SP of group For were significantly increased at each time point(P < 0.05)in For group.Compared with For group,the expression of c-Fos,SP and the pain score decreased significantly(P < 0.05)in experimental group at each time point 15 min after the injection of formalin.Compared with Suf+Dex group,the pian scores in group Ket+Dex increased significantly(P < 0.05)at 15 min,45 min and 55 min time point,while no difference(P > 0.05)was found in the group Suf+Dex.The expression of c-Fos protein in the Suf+ Dex group and Suf+ Dex group was higher than that in the Suf+Ket group(P < 0.01).No difference was shown in SP expression level among Suf+ Ket group,Suf+ Dex group and Ket+ Dex group(P > 0.05).Conclusion: 1)Intrathecal injection sufentanil combined with dexmedetomidine or sufentanil combined with ketamine had the best analgesic effect on formalin-induced pain in rats.2)Intrathecal sufentanil combined with ketamine was the most effective decrease c-Fos expression in the spinal dorsal horn.For sufentanil,dexmedetomidine and ketamine combined intrathcally use either two of them had similar inhibitory effects on SP.