Study On The Suitable Dosage Of Dexmedetomidine Combined With Ropivacaine For Brachial Plexus Block

Background and objectiveUpper limb surgery is one of the common surgical methods.postoperative incision pain and adverse reactions such as nausea and vomiting caused by opioid analgesia are still instrumental factors affecting the postoperative recovery and the process of discharging from hospital for patients.During this period of upper limb surgery,the employment of brachial plexus block anesthesia can significantly improve the degree of comfort for patients in hospital,and in the mean time,it can reduce the side effect of postoperative analgesia and enhance degree of the satisfaction for patients.Brachial plexus block is usually performed by a single injection of local anesthetics around the nerve or by continuous infusion of local anesthetics by placing a catheter around the nerve.When nerve block is carried out by catheterization,a series of complications can be caused by the catheter including drug leakage,catheter shedding,or infection and so forth would accompany along with,at the same time,due to the high requirements for operating technology,the clinical application of indwelling catheter is limited.When nerve block is carried out by single injection of local anesthetics around the nerve,although the incidence of the complications above is lower than that after placing a catheter around the nerve,but the duration of nerve block analgesia is shorter than the one of the latter,and this can not introduce long-term effective postoperative analgesia.In order to make up for the listed shortcomings.A variety of adjuvants have been applied clinically for nerve block,such as clonidine,dexamethasone,opioids,magnesium,and neostigmine.However,these adjuvants also have their own drawbacks in the application of nerve block.Recent studies suggest that dexmedetomidine is as much efficient in brachial plexus block as an adjuvant.When it is employed as adjuvant in brachial plexus block,it can significantly prolong the period of nerve block and improve the condition of patients after postoperative analgesia.However,it has also been reported that when dexmedetomidine is applied with a large number as an adjuvant in nerve block,there may be adverse reactions including bradycardia,hypotension and respiratory depression etc.Recently,with the increasing application of dexmedetomidine as an adjuvant in the process of nerve block,the purpose of this study was to explore and evaluate the appropriate dosage of dexmedetomidine combined with ropivacaine for brachial plexus block,so as to provide some reference of dexmedetomidine for clinical work.MethodsA total of 100 patients who undergoing upper limb surgery in the daytime surgery department of the first affiliated Hospital of Zhengzhou University were selected.They were randomly divided into 5 groups: 0.5% ropivacaine group(R)group,dexmedetomidine 1?g/mL + 0.5% ropivacaine(RL)group,dexmedetomidine 1.5?g/mL + 0.5% ropivacaine(RM)group.dexmedetomidine 2?g/mL + 0.5% ropivacaine(RH)group and dexmedetomidine 2.5?g/mL + 0.5% ropivacaine(RE)group holding 20 patients respectively in each group.Comparing the general conditions of the patients in the five groups before anaesthesia.The duration of operation and nerve block were documented.the mean arterial pressure(MAP),heart rate(HR),percutaneous oxygen saturation(SpO2)and BIS were recorded before the onset of nerve block(T0),15 minutes after the nerve block(T1),the beginning of operation(T2),30min(T3)after the beginning of the surgery,the end of the surgery(T4).Meanwhile,the onset time of nerve block and postoperative duration of sensory and motor nerve block in the five groups were observed and recorded.Additionally,the degree of postoperative satisfaction and the adverse reactions of brachial plexus block of the patients in the five groups were documented.Results1.The comparison of general data between five groups : There was no significant difference in aspects of sex,age,BMI,ASA grade and the duration of nerve block among the five groups(P > 0.05).2.The comparison of intraoperative hemodynamic parameters in five groups: MAP comparison: compared with T0 at different time,MAP in DL,DM,DH and DE groups decreased at T2,T3 and T4 in varying degrees(P < 0 05).Compared with R group,MAP in DM group decreased at T2 and T3,and MAP decreased at T2,T3 and T4 in DH and DE group(P < 0 05).HR comparison: compared with T0 at different time,HR in DL,DM,DH and DE groups decreased at T2,T3 and T4 in varying degrees(P < 0 05).Compared with R group,HR in DH group decreased at T2 and T3,and HR decreased at T2,T3 and T4 in DE group(P < 0 05).3.The comparison of BIS values in five groups: Compared with T0 of each group,the BIS values of DM,DH and DE groups were decreased at T2,T3 and T4,and those of DM,DH and DE at T2 and DH and DE at T3 and T4 were significantly lower than those of R group(P < 0 05).The BIS values of DH and DE groups at T3 and T4 were significantly lower than those of R group(P < 0 05).Compared with DM group,DE group was at T2 and T2.The BIS value decreased at T3 and T4(P < 0.05).4.Comparison the degree of nerve block in five groups: Compared with group R,the onset time of nerve block was shortened and the duration of nerve block was prolonged in DL,DM,DH and DE groups.Compared with DL and DM groups,the onset time of nerve block in DH and DE groups was shorter.The duration of postoperative nerve block was prolonged,and the difference was statistically significant(P < 0 05).There was no significant difference in the onset time of nerve block and the duration of postoperative nerve block between the two groups(P < 0.05).There was no significant difference in the onset time of nerve block and the duration of postoperative nerve block between);DH and DE groups(P > 0 05).5.The comparison of postoperative complications and the degree of satisfaction of patients among the five groups: bradycardia occurred in 6(30%)patients in DE group,compared with other groups,which the difference with other groups was statistically significant(P<0.05),In DH group,there was only 1(5%)patient developed bradycardia.All patients with bradycardia were relieved atropine i.v.There were no postoperative nausea and vomiting,excessive sedation,skin pruritus,respiratory inhibition and other adverse reactions related to brachial plexus block in intermuscular sulcus.The comparison of the degree of satisfaction in five groups: the data in DH group and DE group was higher than that in R group and DL group(P < 0.05).Conclusion1.Employing dexmedetomidine combined with ropivacaine has obvious sedative and anti-anxiety effects during brachial plexus block,and the mixed drugs can also enhance the analgesic effect of ropivacaine and shorten the onset time of nerve block in a dose-dependent effect.2.When dexmedetomidine reaches a certain concentration(2.0ug/mL),it may have a capping effect on enhancing the analgesic effect of local anesthetics.3.Applying 2?g/mL dexmedetomidine mixed with local anesthetics group has a better effect,and in the same time,there are higher level of satisfaction and lower adverse reaction rate in this group,so 2.0?g/mL dexmedetomidine mixed with local anesthetics may have more advantages in clinical application.