A Prospective Study Of Low Dose Local Anesthetic For Ultrasound Guided Supraclavicular Brachial Plexus Targeting Block

Objectives: To estimate the possibility and effectiveness of low-dose local anesthetic for ultrasound guided supraclavicular brachial plexus block and analyse whether there is a difference between age、gender and BMI in the dose of local anesthetic and effect of block.. Methods: Part one:100 patients, ASA physical status I to III, scheduled for elective upper extremity surgery were recruited. Inclusion criteria were age between 16~80y and weight 30kg~90kg.After inclusion, patients were randomly divided into two groups each with 50 patients: low dose experimental group and 20 ml local anesthetic(LA) control group. A ultrasound guided supraclavicular brachial plexus block method was performed with 0.5% ropivacaine. Intraneural injection method was used by transfusing the LA into a particular place between the epineurium and the perineurium. The volume of LA used in low dose group was calculated while each buddle of the nerve was surrounded by LA. Operation time, sensory and motor onset time were recorded every 5 minutes within 30 minutes. The quality of sensory block was assessed at the beginning of surgery(Better, Good, Bad).Any complication during or after the operation and the duration of blocked time were also recorded. Part two: Using the same criteria and blocking strategy, the sample of low dose group was increased to 130 cases, in which patients were divided into several groups depending on their age(youth group:16≤age≤44, middle-aged group:45≤age≤59,elder group: age≥60), gender(male and female) and BMI(lean group: BMI ≤ 18.5,normal group:18.5 < BMI≤23.9, overweight group:24≤BMI≤27.9,obesity group: BMI≥28). After that the effects of those factor on local anesthetic volume and block effect was analized. Results: Part one: The average volume used for low dose group was 9.4±2.0ml. The success block rate was almost 100% for each branches of supraclavicular brachial plexus. The effectiveness had no significant difference between low dose group and 20 ml group(P>0.05).The operation time and sensory block onset time of the ulnar nerve were longer in low dose group(P<0.05).There was no significant difference in motor onset time between the two group(P>0.05). There were no significant difference concerning the duration of block time and complications such as vomit and nausea occurred in both groups(P>0.05). Additional axillary brachial plexus block was needed for two patient in low dose group and one in 20 ml group. Part two:there were no significant difference among different age(youth group:16≤age≤44, middle-aged group:45≤age≤59,lder group:age≥60, gender(male and female) and BMI(lean group:BMI≤18.5,normal group:18.5 <BMI≤23.9, overweight group:24≤BMI≤27.9, obesity group:BMI≥28)concerning consumption of LA, block time and effects(P > 0.05). The duration of block time was longer in youth group than that in middle-aged group(P < 0.05). Between different gender, male’s radial and musculocutaneous nerve motor block onset time was longer than female’s(P<0.05).Among different BMI, the medial antebrachial cutaneous nerve block onset time was shorter in lean group than that in overweight and obesity group.Besides, medial brachial cutaneous nerve block onset time was shorter in lean group than overweight and obese group. The posterior antebrachial cutaneous nerve block onset time was shorter in normal group than obesity and overweight group, but maintain time of block was shorter than the other two groups(P<0.05).Conclusions 1.Ultrasound guided supraclavicular brachial plexus block can also achieve a satisfied effect with low dose local anesthetic via accurate injection to each of the branches, while the incidence of complications related didn’t increase.2. No difference occurred considering age、gender and BMI in the dose of local anesthetic and effect of block...