| The aim of this study is to investigate the 50%Effective Volume(EV50)of low concentration ropivacaine for ultrasound-guided Serratus Anterior Plane Block(SAPB)in modified radical mastectomy for breast cancer.This study was divided into two parts.In the first part,the clinical effect of ultrasound-guided SAPB with different concentrations of ropivacaine in modified radical mastectomy was observed to determine the optimal concentration.On this basis,the second part uses the sequential method to explore the EV50 of SAPB with this concentration of ropivacaine for ultrasound-guided SAPB through different approaches,so as to provide a reference for the selection of ropivacaine volume when SAPB is used in this kind of surgery.Part I:Clinical effects of ultrasound-guided anterior serratus plane block with different concentrations of ropivacaine in modified radical mastectomy for breast cancerObjectiveTo investigate the clinical effect of different low concentrations(0.2%,0.25%,0.3%)of ropivacaine for SAPB in modified radical mastectomy for breast cancer,and to determine the optimal concentration.MethodsWe chose one hundred and two female patients undergoing unilateral modified radical mastectomy in our hospital and randomly divided them into three groups:0.2%ropivacaine group(group A,n=34),0.25%ropivacaine group(group B,n=34)and 0.3%ropivacaine group(group C,n=34).Groups A,B,and C received ultrasound-guided SAPB with 30ml ropivacaine at different concentrations(0.2%,0.25%,0.3%).In all three groups,general anesthesia was induced 20 minutes after the completion of block according to uniform standards.We recorded VAS scores at 1h,3h,6h,12h and 24h after operation,the QoR-15 at 24 hours after operation,the amount of analgesics used during and after operation,and the onset time and block range of nerve block.Mean arterial pressure(MAP)and heart rate(HR)were recorded 5min after calm entering the room,before skin incision,1 min after skin incision,during axillary dissection and at the end of surgery.The occurrence of postoperative nausea and vomiting,dizziness and drowsiness,pruritus,and dyspnea was recorded,too.Results1.Postoperative pain scores:The resting and active state VAS scores of patients in all three groups gradually increased with the postoperative time(P<0.05).There was no significant difference between the resting and active state VAS scores of the three groups at 1h and 3h postoperatively(P>0.05);compared with group A,the resting and active state VAS scores of groups B and C were significantly lower at 6h,12h and 24h postoperatively(P<0.05);there was no statistical difference between the resting and active state VAS scores of groups B and C at 6h.12h and 24h postoperatively(P>0.05).2.24-hour postoperative QoR-15 scores:compared with group A,group B and C had higher postoperative QoR-15 scores at 24 hours,and the difference was statistically significant(P<0.05);the difference in QoR-15 scores between groups B and C was not statistically significant(P>0.05).3.Intraoperative and postoperative analgesic drug dosage:compared with group A,the total intraoperative and postoperative analgesic drug dosage in groups B and C was significantly reduced(P<0.05);there was no significant difference in the total intraoperative and postoperative analgesic drug dosage in groups B and C(P>0.05);there was no significant difference in the intraoperative analgesic drug dosage in the three groups(P>0.05);compared with group A,the postoperative analgesic drug dosage in groups B and C was significantly There was no statistically significant difference in the amount of postoperative analgesic drugs used in groups B and C compared with group A(P<0.05).4.Nerve block onset time:compared with group A,the block onset time was significantly shorter in groups B and C(P<0.05);compared with group B,the block onset time was shorter in group C(P<0.05).5.Nerve block range:There was no statistical difference in the comparison of nerve block ranges between the three groups(P>0.05).The nerve block range was concentrated at the T2-T7 level,with the cephalic range up to the T2 level and the caudal range up to the T9 level.6.Haemodynamics:As time progressed,MAP and HR showed a trend of decreasing and then increasing in the three groups(P<0.05),and there was no statistical difference between the three groups in the comparison of MAP and HR at each time point(P>0.05).7.Adverse reactions:There was no significant difference in the incidence of postoperative nausea and vomiting,dizziness and drowsiness,pruritus and dyspnea among the three groups(P>0.05).ConclusionsThe analgesic effect and prognostic impact of ultrasound-guided SAPB with ropivacaine at 0.25%or 0.3%were similar.Based on the principle of minimum dose to meet the anaesthetic requirements,this study recommends the use of ropivacaine at 0.25%for SAPB.Part Ⅱ:Half effective volume study of ultrasound-guided anterior serratus plane blocks with 0.25%ropivacaine on different approachesObjectiveWe use the sequential method to explore the half effective volume(EV50)of 0.25%ropivacaine for different approaches to SAPB under ultrasound guidance,to provide a reference for the selection of ropivacaine volume for SAPB for modified radical surgery of breast cancer.MethodsWe selected female patients who were to undergo modified radical unilateral breast cancer and divided them into 6 groups using the random number table method,namely group A1(superficial SAPB at the 4th rib level),group A2(deep SAPB at the 4th rib level),group B1(superficial SAPB at the 5th rib level),group B2(deep SAPB at the 5th rib level),group C1(superficial SAPB at the 6th rib level)and group C2(deep SAPB at the 6th rib level).The first patient in each group received 30 ml of 0.25%ropivacaine injection in a ratio of 1:1.2 between adjacent volumes,and depending on the effect of the block in the previous patient,the volume of ropivacaine received by the next patient was increased or decreased by a gradient until 7 inflection points(blocking effect from ineffective to effective)were obtained,i.e.the end of the trial.Probit regression analysis was used to calculate the half effective volume(EV50)and 95%confidence interval(CI)of ropivacaine for each group.ResultsA total of 145 patients completed the trial,including 24 patients in group A1,22 patients in group A2,27 patients in group B1,26 patients in group B2,24 patients in group Cl and 22 patients in group C2.20.74 ml);group B1 ropivacaine EV50 was 14.58 ml(95%CI 11.94 to 17.73 ml);group B2 ropivacaine EV50 was 15.95 ml(95%CI 13.93 to 17.92 ml);group C1 ropivacaine EV50 was 14.89 ml(95%CI 12.99 to 16.65 ml);The EV50 of ropivacaine in group C2 was 16.75ml(95%CI 12.50 to 19.80ml).There was no statistical difference in the EV50 of ropivacaine between the six groups(P>0.05).ConclusionThe half effective volumes of 0.25%ropivacaine at the 4th,5th and 6th rib level for ultrasound guided superficial anterior serratus plane blocks for modified radical breast cancer were 15.40ml,14.58ml and 14.89ml respectively,and the half effective volumes of ultrasound guided deep anterior serratus plane blocks at the 4th,5th and 6th rib level were 17.71ml,15.95ml and 16.75ml. |
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