| Part 1Effect of different doses of dexamethasone on up-regulation of p H of ropivacaine for lower limb nerve blockObjective: To observe the effect of different doses of dexamethasone on lower limb nerve block by up-regulating the p H value of ropivacaine,and to determine the optimum dose of dexamethasone combined with ropivacaine.Methods: Different doses of dexamethasone sodium phosphate injection and ropivacaine hydrochloride injection were used to form a ropivacaine mixture with a concentration of 0.25%,and the volume was fixed at 40 ml with normal saline.The characteristics of different mixtures were observed at room temperature and the p H values of ropivacaine,dexamethasone and local anesthetic mixtures were measured by p H meter.According to the p H value,the appropriate anesthetic formula was selected and the next clinical trial was carried out.A total of 63 patients,ASA Ⅰ-Ⅱ and aged 40-65 years,were selected for unilateral total knee arthroplasty in the First People’s Hospital of Yunnan Province from February 2021 to August 2021.The participants were randomly divided into three groups: group C(n=21): 0.25% ropivacaine;group Ds1(n=21):0.25% ropivacaine+10mg dexamethasone;and group Ds2(n=21): 0.25% ropivacaine + 20 mg dexamethasone.Under the guidance of ultrasound(Navi S),the femoral nerve(15ml),sciatic nerve(15ml)and obturator nerve(10ml)were blocked successively.The mean arterial pressure(MAP)and heart rate(HR)were observed and recorded at different times(T0 before nerve block,T1 10 min after nerve block,T2 before intubation,T3 at the beginning of operation,and T4 when leaving the operating room).The block time of sensory and musle of each innervation area was observed and recorded.Endotracheal intubation was then performed under general anesthesia and maintained by total intravenous anesthesia during the operation.The recovery time of sensation and movement in each innervated area and the occurrence of adverse reactions in all patients 48 hours after operation were observed and recorded.Results: In this study,a total of 60 patients completed the experiment,20 patients in each group.(1)The results of p H value: The p H values of ropivacaine and dexamethasone were 5.13 and8.05,respectively.The p H values of the 4 groups of local anesthetic formulations were as follows: The p H value of 0.25% ropivacaine was 5.22,the p H value of 0.25% ropivacaine +10mg dexamethasone was 6.66,the p H value of 0.25% ropivacaine + 20 mg dexamethasone was6.86,0.25% ropivacaine + 30 mg dexamethasone mixture was crystallization.(2)Comparison of general condition: There was no significant difference in preoperative ASA,sex,age,BMI among the three groups(P > 0.05).(3)The time of sensory and muscle block in each innervated area: Compared with group C,the sensory and muscle block time of femoral nerve,obturator nerve and sciatic nerve was shortened in group Ds1 and group Ds2,and the time of sensory and myodynamic block in Ds2 group was significantly shorter than that in control group(P < 0.05).(4)Recovery time of sensory and muscle strength in each innervated area: Compared with group C,the sensory time of femoral nerve,obturator nerve and sciatic nerve in group Ds1 and group Ds2 was prolonged,and the muscle strength time of femoral nerve and sciatic nerve was prolonged in group Ds1 and group Ds2(P > 0.05),but there was no significant difference in the recovery time of muscle strength of obturator among the three groups(P < 0.05).(5)Comparison of intraoperative adverse reactions: There was no local anesthetic poisoning and nerve injury after nerve block in the three groups.There was no hyperglycemia occurred among the three groups.Some patients in group C developed nausea,vomiting and vertigo after operation,but there was no significant difference in the incidence of adverse reactions among the three groups(P > 0.05).Conclusion: In certain dose range,dexamethasone increased the p H value of ropivacaine in a dose-dependent manner;compared with 10 mg dexamethasone,20 mg dexamethasone alkalinized ropivacaine was more effective;20mg dexamethasone combined with ropivacaine could significantly shorten the onset time of lower limb nerve block and prolong the maintenance time of nerve block to a certain extent.Part 2Effect of different local anesthetic formulations under the guidance of p H value in patients undergoing total knee arthroplastyObjective: To observe the effect of different pH values of local anesthetic formulations on nerve block in patients undergoing total knee arthroplasty.Methods: A total of 125 patients who were scheduled for unilateral total knee arthroplasty in the First People’s Hospital of Yunnan Province from September 2021 to September 2022,ASA Ⅰ-Ⅱ,aged 40-65 years old,were randomly divided into four groups: Group C(n=31): 0.25%ropivacaine;Group Ds(n=32): 0.25% ropivacaine + dexamethasone 20mg;Group Dm(n=31):0.25% ropivacaine + dexmetomidine 20ug;Group Ds + Dm(n=31): dexamethasone 20 mg +dexametholidine 20 ug + 0.25% ropivacaine.All formulations were fixed at 40 ml with normal saline.Observing the properties of different mixtures at room temperature and using a p H meter to measure the p H value of each group of local anesthetic mixtures.Under the guidance of ultrasound(Navi S),the femoral nerve(15ml),sciatic nerve(15ml)and obturator nerve(10ml)were blocked,and the block time of sensory and musle in each innervation area was observed and recorded.Followed by rapid induction of general anesthesia and endotracheal intubation,total intravenous anesthesia was maintained during the operation.The MAP and HR of patients at different times(T0,T1,T2,T3 and T4)were observed and recorded.The duration of operation,the dosage of propofol and remifentanil in each group were recorded.The recovery time of sensation and muscle strength in the innervated area was observed and recorded.At 4h,6h,12 h,24h and 48 h after operation,the numerical rating scale(NRS),postoperative analgesia and adverse reactions were recorded.Postoperative hospitalization days,patient satisfaction and surgeon satisfaction were recorded.Results: In this study,a total of 120 patients completed the experiment,with 30 patients in each group.The main results were as follows:(1)The results of p H value: The p H values of the four groups were 5.22 in ropivacaine group,6.86 in ropivacaine + 20 mg dexamethasone group,5.24 inropivacaine + 20 ug dexametholidine group,and 6.88 in ropivacaine + 20 mg dexamethasone +20ug dexametholidine group,respectively.(2)Comparison of general condition and the operation condition: There was no significant difference in ASA,sex,age,BMI,propofol dosage,remifentanil dosage and operation time among the four groups(P > 0.05).(3)The onset and recovery time of nerve block: Compared with group C,the disappearance time of sensation and muscle strength in group Dm was not significantly different from that in group C(P > 0.05),but it was significantly shortened in group Ds and group Ds + Dm,especially in group Ds,which was significantly shorter than that in the other two groups(P < 0.05).Compared with group C,there was no significant difference in sensory recovery time and muscle strength recovery time in group Ds(P > 0.05),but significantly prolonged in group Dm and group Ds +Dm,and there was no significant difference between the two groups(P < 0.05).(4)Comparison of NRS scores: there was no significant difference in NRS scores between resting and active in all patients within 4 hours after operation(P > 0.05),but NRS scores in group C began to increase at 6 hours after operation(compared with 4 hours after operation)and reached the peak at 48 hours after operation,and the NRS scores in group C were significantly higher than those in the other three groups(P < 0.05).The NRS scores at rest and activity in group Ds began to increase at 12 hours after operation(compared with 6 hours after operation),and the NRS scores at 24 hours after operation were higher than those in group Dm and group Ds + Dm(P < 0.05),but there was no significant difference among group Ds and group Dm and group Ds + Dm within 48 hours after operation(P > 0.05).There was no significant difference in NRS scores within 48 hours between group Dm and group Ds + Dm(P > 0.05).(5)Comparison of postoperative analgesia: Compared with group C,the first time of postoperative analgesia in group Ds,group Dm and group Ds + Dm was shortened,and the total dosage of analgesics was reduced(P < 0.05).But group Dm and group Ds + Dm required the longest postoperative analgesia time for the first time,and the total amount of analgesic drugs was the least(P < 0.05).Compared with group C,the analgesic pump pressing times and effective pressing times of group Ds,group Dm and group Ds + Dm were decreased,and there was no significant difference among the three groups(P > 0.05).(6)Comparison of adverse reactions: There were not nerve injury or local anaesthesia occurred in all the four groups after nerve block.There were no bradycardia and hyperglycemia among the four groups,nausea and vomiting occurred in some patients in group C.Some patients in group C and group Ds had vertigo,and there was no significant difference in the incidence of adverse reactions among the four groups(P > 0.05).(7)Comparison of other indicators: The hospitalization days of group C were significantly longer than those of the other three groups,and the hospitalization days of group Dm and group Ds + Dm were the shortest(P < 0.05).The patient satisfaction of group C was lower than that of the other three groups,and the patient satisfaction of group Dm and group Ds + Dm was the highest(P < 0.05).The satisfaction of surgeons in group Ds was significantly higher than that among the other three groups(P < 0.05).Conclusion: Dexmedetomidine 20 ug cannot significantly change the p H value of ropivacaine,but it can significantly prolong the action time of lower extremity nerve block and provide patients with a long-term analgesic effect.Ropivacaine combined with dexamethasone 20 mg and dexmetomidine 20 ug has an advantage in prolonging postoperative analgesia.It is used in total knee replacement has an obvious advantage. |
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