A Comparative Study On The Effects Of Ultrasound-guided Axillary Nerve-assisted Axillary Brachial Plexus Block Versus Supraclavicular Brachial Plexus Block

Background and ObjectiveBrachial plexus block is a common method of local anesthesia for upper limb surgery.The approaches of brachial plexus block include intermuscular groove,supraclavicular,subclavian,and axillary routes.In the axillary brachial plexus block,the terminal branches of the brachial plexus are blocked to produce anesthesia of the distal upper extremities including the distal humerus,elbow joint,radius,and ulna,and hand.However,unlike supraclavicular brachial plexus block,it cannot provide anesthesia and analgesia for the area below the shoulder joint.We hypothesize that combined axillary nerve block may complement the narrow range of axillary brachial plexus block,and achieve similar blocking range as supraclavicular brachial plexus block with fewer complications.This randomized controlled trial aimed to determine whether the anesthesia effect of axillary nerve-assisted axillary brachial plexus block（ANA block）is equivalent to that of the supraclavicular brachial plexus block（S block）.MethodsA total of 60 cases of upper arm,elbow,and forearm surgery were selected from ASA I to ASA III and divided into 2 groups（the ANA block group and the S block group）according to the random number table method.The ANA block group（n=30）received 0.4%ropivacaine 20ml for axillary brachial plexus block（median nerve,ulnar nerve,radial nerve,musculocutaneous nerve,5ml each）and 0.4%ropivacaine5ml for axillary nerve block.The S group（n=30）received 0.4%ropivacaine 25ml for supraclavicular brachial plexus block.The primary results were the effects of sensory and motor block at 30 minutes after the injection of local anesthetic.The parameters are as followed.（1）The effects of sensory block and motor block on the median nerve,ulnar nerve,radial nerve,musculocutaneous nerve,and axillary nerve at 10min,20min and 30min after administration.（2）Evaluation of anesthesia quality during the perioperative period,including sensory function score,motor function score,patient subjective feeling score,and postoperative analgesia maintenance time score at the time of skin incision,30min after skin incision,and at the end of operation.The secondary results are as followed.（1）The indicators related to the block:the total time of the block operation（sec）,the total time of sensory block（h）,and the total time of motor block（h）.（2）Hemodynamic related indicators:vital signs（SBP,DBP,HR,and SPO₂）at the time that the two groups of patients entered the operation room（T₀）,5min before administration（T₁）,30 min after administration（T₂）,at skin incision（T₃）,30min after skin incision（T₄）and immediately after operation（T₅）.（3）The Ramsay’s score and visual analog scale（VAS）score at 2h,6h,24h,and 48h post-operation.（4）Auxiliary drug related indicators,including the number of cases using sufentanil（%）,the number of cases using propofol（%）,and the dosages of Dexmedetomidine（μg）,and the number of cases using postoperative salvage analgesia（%）.（5）Related adverse events in the two groups,such as Horner’s syndrome,phrenic nerve block,dyspnea,pneumothorax,local anesthetic toxicity,vascular injury,nerve injury,and sinus bradycardia.ResultsPrimary indicators Regarding the pain blockade,at 10 minutes post-administration,the number of cases（%）in which the neuralgia disappeared completely was comparable between the two groups（P>0.05）.However,the number of cases（%）that reported complete disappearance of pain in the median nerve,ulnar nerve,musculocutaneous nerve,and axillary nerve in S block group was higher than ANA block group at 20 minutes post-administration,（P<0.05）.At 30 minutes post-administration,no difference was observed between the two groups regarding the number of cases（%）that reported complete disappearance of pain in the median nerve,ulnar nerve,radial nerve,and musculocutaneous nerve;however,the number of cases（%）that reported complete disappearance of axillary nerve pain in the S block group was higher than the ANA block group（P<0.05）.Regarding the motor blockade,at 10 minutes post-administration,there were similar cases（%）in the two groups that reported complete motor blockade of the median nerve,ulnar nerve,radial nerve,and musculocutaneous nerve;however,compared with the ANA block group,the S block group had more cases（%）with complete motor blockade of the axillary nerve（P<0.05）.At 20min post-administration,compared with the ANA block group,more cases in the S block group reported complete motor blockade of the median nerve,ulnar nerve,radial nerve,musculocutaneous nerve,and axillary nerve.At 30min post-administration,the S block group had higher cases（%）of the complete motor blockade of axillary nerve than the ANA group（P<0.05）.The ratio of good anesthesia quality in the ANA block group and the S block group reached 80%and 76.7%,respectively.There were no cases of anesthesia failure in either group.Both groups met the requirements for anesthesia and analgesia.Secondary indicators Compared with the ANA block group,the total operation time of the S block group was shorter（P<0.05）.The duration of sensory and motor blockade was similar between the two groups（P>0.05）.The proportion of salvage analgesia in the two groups was similar（36.7%）.The proportion of additional analgesia required in 48 hours after operation in both groups was greater than 50%（P>0.05）.In the ANA block group,compared with the values at the T₀,the values of the RR at T₂,T₃,T₄,and T₅,the values of HR at T₄and T₅,and the values of DBP at T₅were significantly different（P<0.05）.In the S block group,the values of RR at T₃,T₄,and T₅,the values of HR at T₄and T₅,and the values of SBP at T₅were significantly different compared with the values at the T₀.No significant difference was observed between the two groups regarding the values of SBP,DBP,RR,and SPO₂at T₀,T₁,T₃,T₄,and T₅（P>0.05）except for the values of HR at T₂（P<0,05）.Ramsay’s scores and VAS scores in the two groups at 2h,6h,24h,and 48h post-operation were comparable（P>0.05）.Compared with the ANA block group,the incidences of Horner’s syndrome and phrenic nerve palsy were higher in the S block group（P<0.05）.There were 9 cases（30%）and 10 cases（33.3%）of sinus bradycardia during operation reported in the ANA group and the S block group,respectively（P>0.05）.Both groups reported 1case（3.3%）with vascular and nerve injury and 1 case（3.3%）with nerve injury（P>0.05）.ConclusionThe ultrasound-guided axillary nerve-assisted axillary brachial plexus block shows similar anesthesia quality as supraclavicular brachial plexus block without increasing the use of sufentanil or adverse reactions,which may be valuable in clinical practice.