Effects Of Dexmedetomidine And Dexamethasone Adjuvant On Anaesthesia And Postoperative Analgesia Of Popliteal Sciatic Nerve Block In Ankle And Foot Surgery

Objective:To discuss the effects of dexmedetomidine or dexamethasone alone and in combination as an adjuvant on anaesthesia and postoperative analgesia of foot and ankle surgery under popliteal sciatic nerve block of ropivacaine.Methods:A total of 120 patients,including 59 males and 61 females,aged 30-65 years,with a body mass index(BMI)of 19.57-29.73kg/m2,were enrolled in our hospital for calcaneal,lateral or posterior malleolus surgery from September 2017 to June 2018.They were rated I-II by the American society of anesthesiologists(ASA)and voluntarily signed the informed consent for anesthesia.Ultrasound combined with nerve stimulator guided femoral nerve block combined with popliteal sciatic nerve block was selected for anesthesia.All patients were given 20 m L 1% lidocaine for femoral nerve block and 30 m L 0.5% ropivacaine for popliteal sciatic nerve block.Patients were randomly divided into 4 groups(n=120)according to the addition or absence of two adjuvants in 0.5% ropivacaine local anesthetic for popliteal sciatic nerve block by the random numbers table: Group C(no two adjuvants);DD group(containing 1ug/kg dexmedetomidine adjuvant);DM group(containing 10 mg dexamethasone adjuvant);DD+DM group(containing 1ug/kg dexmedetomidine,10 mg dexamethasone adjuvant).All patients were treated with patient-controlled intravenous analgesia(PCIA)by sufentanil after surgery.The onset time of sensory and motor block,duration,postoperative analgesia and postoperative sufentanil dosage after popliteal sciatic nerve block and the cases of nausea,vomiting,itching,drowsiness,hypotension,bradycardia,respiratory depression and neurological symptoms within 72 h after block were monitored.To evaluate the effect of two adjuvants alone or in combination on anesthesia and postoperative analgesia of popliteal sciatic nerve block with ropivacaine and to explore the interaction between the two adjuvants.Results:1 General information: there was no significant difference in age,BMI and operation time(P>0.05).2 The time of complete onset of sensory block and the time of complete onset of motor block: compared with the C group,the DD,DM and DD+DM groups were all prolonged,and the DD+DM compared with the DD and DM groups were all prolonged,the difference was statistically significant(P<0.05).There was no significant difference between DD and DM groups(P>0.05).The two adjuvants have synergistic effect(P<0.05).3 The duration of narrow sense sensory block Ta,broad sense sensory block Ta ’,narrow sense motor block Tb,broad sense motor block Tb ’:3.1 The duration of narrow sense sensory block Ta,broad sense sensory block Ta ’: compared with the C group,the DD,DM and DD+DM groups were all prolonged,with statistically significant differences(P<0.05).The differences between DD,DM and DD+DM groups were statistically significant(P<0.05).The two adjuvants have synergistic effect(P<0.05).3.2 The duration of narrow sense motor block Tb,broad sense motor block Tb ’: compared with the C group,DD,DM and DD+DM groups were all prolonged,and DD+DM was prolonged compared with DD and DM groups,with statistically significant difference(P<0.05).There was no significant difference between DD and DM groups(P>0.05).The two adjuvants have synergistic effect(P<0.05).4 Duration and interaction of analgesia:compared with the C group,all groups of DD,DM and DD+DM were prolonged(P<0.05).The differences between DD,DM and DD+DM groups were statistically significant(P<0.05).The two adjuvants have synergistic effect(P<0.05).5 Analgesic pump dosage for 24 h,48h and 72 h after block:5.1 Dosage of analgesic pump after 24 h of block: DD+DM group is not open,is 0;Compared with the C group,DD,DM and DD+DM groups were all decreased(P < 0.05).The differences between DD,DM and DD+DM groups were statistically significant(P < 0.05).The two adjuvants have synergistic effect(P<0.05).5.2 Dosage of analgesic pump after 48 h of block: compared with the C group,DD,DM and DD+DM groups were all decreased(P < 0.05).The differences between DD,DM and DD+DM groups were statistically significant(P<0.05).The two adjuvants have synergistic effect(P<0.05).5.3 Dosage of analgesic pump after 72 h of block: compared with the C group,DD,DM and DD+DM groups were all decreased(P<0.05).Compared with DD and DM groups,DD+DM group decreased(P<0.05).There was no significant difference between DD and DM groups(P>0.05).The synergistic effect of the two adjuvants was not shown(P>0.05).6 Only 4 patients in group C experienced nausea within 72 h after the block.No itching,drowsiness,significant hypotension,bradycardia,respiratory depression,or neurological symptoms occurred in each group.Conclusion:The application of 1ug/kg dexmedetomidine adjuvant or 10 mg dexamethasone adjuvant could both extend the time of complete onset of popliteal sciatic nerve sensory block and motor block with 0.5% ropivacaine,and the duration of sensory block and motor block was prolonged,the duration of analgesia was prolonged,the dosage of sufentanil in analgesic pump were reduced and does not increase side effects.All of the above effects were enhanced and synergistic effects were observed when the two adjuvants were applied together.It can be inferred that the combined use of 1ug/kg dexmedetomidine and 10 mg dexamethasone adjuvant with local anesthetics such as ropivacaine can be promoted as a safe and effective optimization scheme for nerve block adjuvant.