| In recent years,adductor canal block has been gradually used to replace the femoral nerve block for for postoperative analgesia for knee joint operation.Adductor canal block can provide considerable analgesic effect to that of femoral nerve block,what's more,it can can better maintain the muscle strength of musculi quadriceps femoris,thus promoting the early rehabilitation of the knee joint.Midpoint horizontal approach and adductor canal distal approach are two most frequently used adductor canal block approaches under ultrasound guidance,however,there are no systematic comparisons between these two approaches in terms of success rate,analgesic effect and effects on strength of musculi quadriceps femoris after arthroscopic knee surgery.Ultrasound guided adductor canal block can provide a good analgesic effect for knee arthroscopy,but there is dispute about the capacity of local anesthetics.In this experiment,we investigate the minimum local anesthetic capacity of ultrasound guided adductor canal used for effective analgesia after knee arthroscopy,in order to provide reference for clinical analgesia.Part 1,Comparison on approaches of two ultrasound guided adductor canal blocksObjective:To look for a better approach of adductor canal block with better postoperative analgesia of knee joint operation by comparison on success rate of nerve block,the score of analgesia and the muscle strength of musculi quadriceps femoris of two approaches of midpoint horizontal approach and adductor canal distal approach of adductor canal block under ultrasound guidance.Methods:40 patients undergoing medial meniscus resection under knee arthroscopy from December 2016 to May 2017 are selected as objects.Aged at: 18 years old to 60 years old.ASA Grading: ?~?,BMI<35kg/m2,reoperative VAS score of motion state:?3,the motion state is defined as 45 degrees of knee joint flexure,method of VAS scoring:0 ~ 10 points,0 for painlessness,10 for unbearable pain.Those 40 patients are randomly divided into 2 groups: midpoint horizontal approach group(M group)and adductor canal distal approach(D group),each has 20 patients.And the VAS score of the patient's motion state is measured before nerve block.In M group,midpoint adductor canal block is performed under ultrasonic guidance: high frequency linear ultrasonic probe is placed horizontally at the midpoint level of the thigh,femoral artery under ultrasound is located under sartorius muscle,showing pulsating low-level echo.On the lateral of the femoral artery,the small,circular hyperechoic structure is the saphenous nerve.The needle is punctured in by In-plane Technology to connect the nerve stimulator.The tip of the needle points to the saphenous nerve at the lateral of the femoral artery under ultrasound.When the needle is approaching the saphenous nerve,the stimulator is opened.The current is adjusted to 1.0m A to observe if there is any positive sign.The positive sign means contractile muscles of the distal part of the thigh or numbness in saphenous nerve distribution region.After the positive signs,the current of the stimulator is reduced to0.6m A,if there is still positive sign,20 ml of 0.5% ropivacaine is injected into.In D group,distal adductor canal block is performed under ultrasonic guidance:the high frequency linear ultrasound probe is placed horizontally at the 1/3 position of the distal thigh,femoral artery under ultrasound is located under sartorius muscle,showing pulsating low-level echo.Continue to scan to the distal thigh along the long axis,until the arteria cruralis approaches to the popliteal space to be the continuation of the popliteal artery,the changing area of the femoral artery position is known as hiatus adductorius,and nerve block is performed at its proximal 2-3cm position.The needle is punctured in by In-plane Technology to connect the nerve stimulator.The tip of the needle points to the saphenous nerve at the lateral of the femoral artery under ultrasound.When the needle tip is close to the saphenous nerve,the stimulator is opened and the current is adjusted to 1.0m A to observe whether there is positive sign,the positive signs are same as above.After positive sign appears,the current of the stimulator is reduced to 0.6m A,if there is still positive sign,20 ml of 0.5%ropivacaine is injected into.After the nerve block is completed,the medial cutaneous sensation of the medial calf is measured every 1min,the method of measuring is the combination of cold stimulation and acupuncture;the degree of sensory block is classified as 4 grades,if?2,it means effective block.The time needed to produce effective block in this area is recorded as the onset time of nerve block.30 min after nerve block is completed,the above method is also used to evaluate the degree of sensory block in three skin distribution areas(respective anterior medial patellar,medialis of the middle of the calf and around the medial malleolus)of the saphenous nerve.After effective block found in all three areas,saphenous nerve block is regarded as effective,otherwise,it is considered as a failure of block.1h after nerve block,VAS score of patients' motion state and muscle strength of musculi quadriceps femoris will be measured,the definition of motion state is same as that before operation,and the muscle strength of musculi quadriceps femoris is classified as 6 grades: 0-5,0 for no muscle strength,5for normal muscle strength.All patients receive subarachnoid block anesthesia.8h after operation,the quiescent condition VAS score,the motion state VAS score,and the muscle strength of musculi quadriceps femoris are measured.24 h after operation,follow-up is required to ask if there is any anaesthesia associated complication.Indexes recorded: 1,the operation time,offset time and maintenance time of nerve block in two groups of patients;2,stimulation rate of two groups of patients with nerve stimulator;3,success rate of nerve block in two groups of patients;4,VAS score of motion state before nerve block,VAS score of motion state after 1 h of nerve block;5,the quiescent condition VAS score,the motion state VAS score after operation for 8 h;6,the muscle strength of musculi quadriceps femoris of patients in two groups after 1 h of nerve block and 8 h of operation;7,use of oral analgesics by patients in the two groups;8,whether there is nerve block related adverse reactions of the patients in the two groups.Statistical analysis is carried out by the statistical software SPSS16.0,and P < 0.05 means it statistically significant.Results:1.Comparison of general data There is no significant difference in gender,age,weight,BMI,ASA classification and operation time of patients between the two groups(P>0.05).2.Comparison of operation time,onset time and maintenance time of two groups of patients with nerve block:The operation time and the onset time of nerve block in group M are significantly shorter than that in group D(P<0.05),and there is no significant difference in nerve block maintenance time between the two groups(P>0.05).3.Comparison of the elicitation rate of two groups of patients with nerve stimulator:The rate of muscle contraction in the medial femoral muscle of nerve stimulator in group M is significantly higher than that in group D(P<0.05).There is no significant difference in the total extraction rate of muscle contraction and numbness between the two groups(P>0.05).4.Comparison of the success rate of nerve block in two groups of patients:There is no significant difference in the success rate of nerve block in the two groups(P>0.05).5.Comparison of VAS scores in two groups of patients at different times:There is no significant difference in VAS score of motion state between the two groups before nerve block(P>0.05).The VAS score of motion state after 1h of nerve block,quiescent condition VAS score after 8 h of operation,and motion state VAS score after 8 h of operation are significant lower than those of D group(P<0.05).6.Comparison of the muscle strength of musculi quadriceps femoris There is no significant difference in the muscle strength of musculi quadriceps femoris in patients of two groups after 1h of nerve block and 8h of operation(P>0.05).7.Comparison of the dosage of oral analgesics in two groups of patients:No oral analgesics are used in the rest of the patients except for nerve block failure patients.8.Adverse reactions:There is no significant difference in the incidence of nausea and vomiting between the two groups(P>0.05),and the two groups did not report other anaesthesia related adverse reactions.Conclusion:Compared to adductor canal distal approach,the midpoint horizontal approach of adductor canal block under ultrasound guidance can shorten the operation time and offset time of nerve block,provide better analgesic effects,and have no decline in muscle strength of musculi quadriceps femoris.Part 2: The ED50 of ultrasound guided adductor canal used for knee arthroscopyObjective:To discuss the minimum effective block capacity of adductor canal block under ultrasound guidance used for effective analgesia after knee arthroscopy,that is,the capacity of 0.5% ropivacaine for effective analgesia of 50% patients after knee arthroscopy,and the capacity of 0.5% ropivacaine for effective analgesia of 95%patients after knee arthroscopy.Methods:25 patients undergoing medial meniscus resection under knee arthroscopy are selected as objects.Among them,17 male cases and 8 female cases.Aged at: 30~60years old,body weight: 58~85kg.The sequential test method is used in this study.1hour before the operation,the patients are taken to the anesthesia recovery room.After routine disinfection,midpoint horizontal approach adductor canal block under ultrasound guidance is performed,the block method is same as that in first part of this study.30 min after nerve block is completed,the method of combination of cold stimulation and acupuncture is used to evaluate the degree of sensory block in three skin distribution areas(respective anterior medial patellar,medialis of the middle of the calf and around the medial malleolus)of the saphenous nerve.The degree of sensory block is classified to 4 grades,0 for no block;1 for mild block(cold irritation hyposensation);2 for moderate block(feeling needling puncturing but not feeling cold stimulation);3 for severe block(no sensation of cold stimulation and acupuncture);the degree of sensory block ?2 means effective block.After effective block found in all three areas,saphenous nerve block is regarded as effective,otherwise,it is considered as a failure of block.1h after nerve block,VAS score of patients' motion state and muscle strength of musculi quadriceps femoris will be measured,the definition of motion state is defined as 45 degrees of knee joint flexure;the muscle strength of musculi quadriceps femoris is classified as 6 grades: 0 for no muscle strength;1 for muscle contraction but not shift;2 means muscle can be shifted but not resistant to gravity;3 means muscles can resist gravity but do not resist resistance;4 means muscle can resist resistance but not reach normal muscle strength;5 for normal muscle strength.All patients receive subarachnoid block anesthesia.8h after operation,the quiescent condition VAS score,the motion state VAS score,and the muscle strength of musculi quadriceps femoris are measured.Definition of adductor canal successful block: effective block is observed in three test areas of the saphenous nerve,and the quiescent condition VAS score,the motion state VAS score after 8h of operation are all ?1.The initial dose of local anesthetic is set as 20 ml of 0.5% ropivacaine.Under the condition of the successful case of adductor canal block,the local anesthetic will be reduced 2ml for next patient; If the adductor canal block is not successful,the local anesthetic will be increased 2ml for next patient based on agreement.Indexes recorded: 1,Local anesthetic volume and sensory scores of three test regions corresponding to saphenous nerve block;2,The volume of local anesthetic and quiescent condition VAS score,motion state VAS score 8 h after operation;3,Volume of local anesthetic and muscle strength of musculi quadriceps femoris 1h and8 h later;4,Dosage of oral analgesic drugs;5,adverse reactions such as blood vessels,hematoma,nausea and vomiting,infection and so on.The data are statistically analyzed with SPSS 16,and the ED50 and ED95 of the required local anesthetics are calculated by using Probit probability analysis method.Results:1.ED50: 10.81 ml,95%CI(9.13 ml,11.91ml)used for effective analgesia after knee arthroscopy of adductor canal block under ultrasound guidance.2.ED95: 13.23 ml,95%CI(11.98 ml,15.31ml)used for effective analgesia after knee arthroscopy of adductor canal block under ultrasound guidance.3.All patients in this study have no oral taking of analgesic drugs.4.In this study,the scoring on muscle strength of musculi quadriceps femoris of all patients with nerve block after 1h and operation after 8h is 5.Only 5 of the patients have nausea and vomiting,and the rest did not report any anaesthesia associated adverse reactions.Conclusion:The capacity of 0.5% ropivacaine used for effective analgesia for 50% patients after knee arthroscopy under adductor canal block is 10.81 ml,and the capacity of0.5% ropivacaine used for effective analgesia for 95% patients after knee arthroscopy under adductor canal block is 13.23 ml. |
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