An Observation Of The Effect Of Different Local Anesthetic Doses In Ultrasound-guided Axillary Brachial Plexus Block

Objective:This study was to investigate the effect of different doses of0.5%ropivacaine inultrasound-guided axillary brachial plexus block, and to explore the impact of the effect ofdose on the innervations of the upper arm aiming at finding the optimal dose ofropivacaine in axillary brachial plexus blockMethods:75qualified upper extremity surgery cases wereselected, aging16~70years old,weighing40~90kg, ASA I~II.The patients were randomly divided into A, B, C threegroups with25patients each, of which the dose of local anesthetic was20ml for group A,30ml for group B, and40ml for group C.0.5%ropivacaine was used in ultrasound-guided axillary brachial plexus block for all groups. A four-point method was establishedwith a needle sending one quarter of the total local anesthetics doses in each target group tothe four main branches of axillary brachial plexus..Operation time, sensory and motoronset time were recorded every5minutes within30minutes. Quality of the block wasassessed at the beginning of surgery (Better, Good, Bad). Any complication during orafter the operation and the duration of blocked time was also recorded.Results:There were no significant difference in operation time and anesthesia excellent rate (P>0.05) among the three groups. The blockade efficiency of each nerve branch wasclose to 100%. The onset time of superior lateral brachial cutaneous nerve, medial cutaneous nerveof the arm and forearm medial cutaneous nerve block were significantly longer for group Athan group C (P<0.05).The ulnar nerve motor block onset time in group B wassignificantly longer than that of group C. Among the cutaneous nerve of the upper arm, thesensory onset time was obviously longer in the superior lateral brachial cutaneous nerve.Significant difference had obtained between the axillary nerve and the others on motoronset time. The duration time was shorter for group A than the other two groups.Complications such as nerve damage were not seen, except nausea and vomiting. Therewere no significant differences considering the complications among the groups. But wefound that it was more often for females than males to have this complication. None of thegroups needed to convert to a general anesthesia.Conclusions:Ultrasound-guided axillary brachial plexus block can obtain satisfactory blockadeoutcome. With the dose increasing, duration time has been extended and a better blockeffect of axillary nerve can be achieved. However, the incidences of nausea and vomitingand other complications also increase. Considering the blocking effect, duration time andthe incidence of complications, our study suggests that30mL0.5%ropivacaine areprobably more appropriate.