Supraclavicular brachial plexus blocks: review and current practice

This article reviews the possible revival of the supraclavicular brachial plexus blockade due to the use of ultrasound guidance. The brachial plexus is a complex network of nerves, extending from the neck to the axilla, which supplies motor and sensory fibers to the upper extremity. Understanding the complexities of the formation and structure of the brachial plexus remains a cornerstone for effective regional anaesthesia. On the level of the supraclavicular fossa, the plexus is most compactly arranged. The supraclavicular approach of the brachial plexus has a high success rate including blockade of the ulnar and musculocutaneous nerve, which can be missed respectively with the interscalene and axillary approach. However, because of the proximity of the pleura, most anaesthesiologists have been reluctant to perform this supraclavicular approach. The introduction of ultrasound guidance techniques not only reduces the possible risk of pneumothorax but also allows a faster onset time of the block with a reduction of the local anaesthetic dose. This makes the supraclavicular approach a valuable alternative to the axillary, interscalene and infraclavicular approach for upper limb surgery.     

末梢灌注指数评估臂丛神经阻滞的效果

目的 观察末梢灌注指数(tip perfusion index,TPI)的变化能否客观评估臂丛神经阻滞的效果.方法 臂丛神经阻滞下行上肢手术患者70例,ASA1～Ⅱ级,予以连续监测心电图、无创血压、双上肢脉氧饱和度和TPI,手术室温度控制在24℃～26℃2,阻滞前10 min静脉注射咪达唑仑0.06 mg/kg镇静,记...     

三种常用定位方法肌间沟臂丛阻滞的比较

目的 比较筋膜突破(facial pop,FP)、异感(paresthesia,PAR)、外周神经刺激(peripheral nerve stimulation,PNS)3种定位法应用于肌间沟臂丛阻滞的临床效果以及局麻药在臂丛鞘内的分布与扩散状况.方法 90例拟行上肢手术的患者,采用随机数字表法分为筋膜突破组(FP组)、异感组(PAR组)和外周神经刺激组(PNS组),每组30例.评估感觉和运动神经的阻滞程度、手术过程中的麻醉效果,观察和记录并发症的发生情况,每组6例行C_4～T_3的横断面及注药侧肌问沟的冠、矢状面计算机体层摄影(computed tomography,CT).结果 3组患者中腋神经、肌皮神经、正中神经、桡神经的感觉及运动评分差异均无统计学意义;前臂内侧皮神经的感觉评分和尺神经的感觉及运动评分FP组明显高于PAR组(P<0.05)和PNS组(P<0.01),PAR组明显高于PNS组(P<0.05);损伤血管发生率PAR组明显高于FP组(P<0.01)和PNS组(P<0.05). CT结果显示局麻药在臂从鞘内呈不均匀扩散,仅在肌间沟水平似乎有鞘的特征,其以下有明显的分隔及囊袋,并有伪足.PNS组的总体麻醉效果高于FP组(P<0.05);尺侧手术麻醉效果FP组低于PAR组(P<0.05)和PNS组(P<0.01).结论 上臂及前臂桡侧手术采用3种定位均可,但FP法更安全简便;偏向尺侧的手术宜采用PAR或PNS定位法,以PNS定位为佳.     

A comparison of stimulation patterns in axillary block: part 2

BACKGROUND AND OBJECTIVES: Radial plus musculocutaneous nerve stimulation may have a predominant role in the success of an axillary block, producing more extensive anesthesia of the upper limb than median plus musculocutaneous nerve stimulation. However, no comparison has been made with ulnar plus musculocutaneous nerve stimulation. We compared the extent of both sensory and motor block after ulnar plus musculocutaneous nerve stimulation or radial plus musculocutaneous nerve stimulation. METHODS: Sixty patients were randomly assigned to receive an axillary block using either radial plus musculocutaneous or ulnar plus musculocutaneous nerve stimulation with 40 mL plain 1.5% mepivacaine. Patients were assessed for sensory block by the pinprick method at 5 and 20 minutes. RESULTS: No statistically significant differences were found in the rates of anesthesia at 20 minutes in the cutaneous nerve distributions of the upper limb between radial plus musculocutaneous and ulnar plus musculocutaneous nerve stimulation except for the following nerves: radial (90% and 63.3%, respectively), medial cutaneous of the forearm (83.3% and 100%, respectively), and medial cutaneous of the arm (73.3% and 93.3%, respectively). Global sensory score (minimum: 0; maximum: 12 points) at 20 minutes was significantly higher after radial plus musculocutaneous than after ulnar plus musculocutaneous nerve stimulation: 12 (11-13) and 11 (10-12), respectively. The rates of median nerve blockade were 50% and 53%, respectively. CONCLUSIONS: Radial plus musculocutaneous nerve stimulation produced more extensive anesthesia of the upper limb than did ulnar plus musculocutaneous nerve stimulation. However, there is not an optimal combination of 2 responses in axillary brachial plexus block.     

Mépivacaïne à 1 % et bloc axillaire: durée du bloc sensitif et moteur

ObjectivesTo assess the duration of both sensory and motor blockade of brachial plexus with 40 mL 1% mepivacaine after axillary or midhumeral approach.Study designProspective, open, non-comparative, multicentric study.PatientsOne hundred and eighty patients, ASA physical class 1 and 2, scheduled for hand or forearm surgery under brachial plexus block were included.MethodsA midhumeral or axillary brachial plexus block using a nerve stimulator was performed with 40 mL of 1% mepivacaine. Sensory blockade was tested for each cutaneous area (median, radial, ulnar, musculocutaneous and medial cutaneous nerve of the forearm) using pin-prick. Motor blockade was assessed by grip strengh of the hand. Incidence and duration of analgesia, anaesthesia and motor blockade were assessed. The incidence of tourniquet pain and the time when pain occurred were determined.ResultsAccording to the nerve area tested, analgesia and anaesthesia were obtained in 98% and 85% of cases respectively; duration of anaesthesia was between 150 ± 40 to 167 ± 49 minutes and duration of analgesia was from 184 ± 50 to 205 ± 51 minutes. Duration of paralysis was 144 ± 40 minutes and duration of paresis was 190 ± 51 minutes. Pain occurred in three out of 138 patients at tourniquet inflation and in six patients after completion of surgery.ConclusionsMid humeral or axillary block with 40 mL of 1% mepivacaine is highly successful and provides efficient surgical anaesthesia for various surgical procedures of intermediary duration.     

Painful paresthesiae are infrequent during brachial plexus localization using low-current peripheral nerve stimulation

BACKGROUND: Considerable controversy exists over the relationship of paresthesia to nerve stimulation. The purpose of this study was to determine the frequency with which patients report paresthesia at the point that an acceptable motor response is obtained to low-intensity current electrical stimulation. METHODS: Low-intensity current nerve stimulation (0.6 mA, 200 microseconds, 2 Hz) was used to identify the brachial plexus in 64 consecutive patients having shoulder or arm surgery with an interscalene block. During nerve localization and while maintaining a motor response (0.20 mA-0.40 mA), the patients were queried regarding any radiating sensation or pain (paresthesia) in the shoulder or extremity on the side of the blockade. Sensory distribution of the block, motor strength of the arm muscles, and adequacy of anesthesia were used to assess the extent of blockade. RESULTS: Ninety-five percent of patients had satisfactory surgical anesthesia. None of the patients spontaneously reported having a paresthesia during nerve stimulation. However, on careful questioning, half of the patients (55%) reported electrical paresthesia, defined as dull tingling sensation traveling down to their hands and coinciding with the motor response. In addition, most patients (71%) spontaneously reported having a mild, radiating paresthesia on initial injection of local anesthetic. CONCLUSIONS: Painful paresthesiae should be infrequent when a low-stimulating current is used to identify the neural components of the brachial plexus and when the block needle is advanced slowly. Low-current intensity nerve stimulation can be used to achieve successful interscalene block with minimal discomfort to the patient.     

Brachial plexus anatomy

The brachial plexus may be visualized simply as beginning with five nerves and terminating in five nerves. It begins with the anterior rami of C5, C6, C7, C8, and the first thoracic nerve. It terminates with the formation of the musculocutaneous, median, ulnar, axillary, and radial nerves. The intermediate portions are displayed in sets of threes: three trunks are formed, followed by three divisions, then three cords. Each trunk gives rise to two divisions and each cord gives rise to two branches. The lateral cord divides into the musculocutaneous nerve and the lateral branch of the median nerve. The medial cord divides into the medial branch of the median nerve and the ulnar nerve. The posterior cord divides into the axillary and the radial nerves. The anatomy of the brachial plexus can be confusing, especially because of frequent variations in length and caliber of each of its components.     

全身麻醉下小儿皮肤温度变化对臂丛神经阻滞效果的评估

目的 通过观察小儿全身麻醉复合超声引导腋路臂丛神经阻滞下的阻滞区域内皮肤温度变化与阻滞效果之间的关系,探讨温度变化对阻滞效果评估的准确性. 方法 选择小儿手部手术30例,全身麻醉喉罩通气,行超声引导下腋路臂丛神经阻滞,在靠近肌皮神经、桡神经、尺神经和正中神经周围各注入1 ml/kg总量1/4的0.25％罗哌卡因.随机在阻滞的各个神经分支支配的皮肤区域内取一个测量点,记录神经阻滞前、阻滞后15 min皮肤温度的变化值.以阻滞效果作为评判的标准,通过受试者工作特征(receiver operator characteristic,ROC)曲线分析阻滞区域内温度变化对阻滞效果反应的敏感度和特异性,寻找诊断临界值(cutoff值);Spearman相关分析两者的相关性. 结果 阻滞区域内温度变化对阻滞效果反应的ROC曲线下面积(area under roc curve,AUC)为0.886[95％置信区间(confidence interval,CI):0.815～0.957];阻滞区域内温度变化幅度为0.65℃时,敏感度与特异性之和值最大,其敏感度为86.4％,特异性为94.1％;Spearman相关系数:r=0.773(95％CI:0.656-0.840). 结论 皮肤温度变化对评估阻滞效果有较高的准确性,可以用于全身麻醉下小儿腋路臂丛神经阻滞后阻滞效果的评价.     

Brachial plexus examination and localization using ultrasound and electrical stimulation: a volunteer study

BACKGROUND: Current techniques of brachial plexus block are "blind," and nerve localization can be frustrating and time consuming. Previous studies on ultrasound-assisted brachial plexus blocks are mostly performed with scanning probes of 10 MHz or less. The authors tested the usefulness of a state-of-the-art, high-resolution ultrasound probe (up to 12 MHz) in identifying the brachial plexus in five locations of the upper extremity and in guiding needle advancement to target before nerve stimulation. METHODS: In this prospective observational study, 15 volunteers underwent brachial plexus examination using an L12-L5 MHz probe and a Philips-ATL 5000 ultrasound unit in the interscalene, supraclavicular, infraclavicular, axillary, and midhumeral regions. Thereafter, an insulated block needle was advanced under direct ultrasound guidance to target nerves before confirmation by electrical nerve stimulation in five volunteers in each of the interscalene, supraclavicular, and axillary regions. The quality of brachial plexus images, anatomic variations, and the technique of needle advancement for nerve localization were recorded. RESULTS: The brachial plexus components were successfully identified in the transverse view as round to oval hypoechoic structures with small internal punctuate echos in all regions examined except the infraclavicular area (visualized in 27% of the cases). The authors' technique of advancing the needle in-line with the ultrasound beam allowed moment-by-moment observation of the needle shaft and tip movement at the time of nerve localization. Hypoechoic structures were stimulated electrically and confirmed to be nerves. CONCLUSIONS: These preliminary data show that the high-resolution L12-L5 probe provides good quality brachial plexus ultrasound images in the superficial locations i.e., the interscalene, supraclavicular, axillary, and midhumeral regions. The needle technique described here for ultrasound-assisted nerve localization provides real-time guidance and is potentially valuable for brachial plexus blocks.     

超声引导下不同入路臂丛神经阻滞在桡骨远端手术中效果的比较

目的 比较超声引导下不同入路臂丛神经阻滞(肌间沟、腋路、锁骨上)在桡骨远端手术中的麻醉效果. 方法 90例择期行“桡骨远端骨折切开复位内固定术”或“桡骨远端骨折术后内固定取出手术”的成年患者,在超声引导下行臂丛神经阻滞,按照随机数字表法分为3组(每组30例):肌间沟入路臂丛神经阻滞组(A组)、腋路臂丛神经阻滞组(B组)、锁骨上入路臂丛神经阻滞组(C组).记录操作时间、镇痛持续时间,测定桡神经、尺神经、正中神经、前臂外侧皮神经和前臂内侧皮神经分布区的痛觉消失时间,评价感觉阻滞效果、麻醉效果及并发症的发生情况. 结果 3组患者基本资料与操作时间比较,差异无统计学意义(P＞0.05).3组的镇痛持续时间差异无统计学意义(P＞0.05).3组桡神经、正中神经、前臂外侧皮神经痛觉消失时间差异均无统计学意义(P＞0.05).A组和C组患者尺神经痛觉消失时间比较[(21±6) min比(20±5) min],差异无统计学意义(P＞0.05),但均长于B组[(8±5)min](P＜0.05);A组和C组前臂内侧皮神经痛觉消失时间比较[(18±6) min比(17±6) min],差异亦无统计学意义(P＞0.05),但与B组[(10±6) min]比较,差异均有统计学意义(P＜0.05).B组麻醉效果优秀率最高(90％).A组和C组分别有2例和1例患者出现膈神经阻滞,B组有1例患者止血带不耐受. 结论 超声引导下腋路臂丛神经阻滞时尺神经及前臂内侧皮神经痛觉消失时间短,在桡骨远端手术中麻醉优秀率高、并发症少.     

Block of the brachial plexus branches by the humeral route. A prospective study in 503 ambulatory patients. Proposal of a nerve-blocking sequence

BACKGROUND: Brachial plexus is usually approached by the supraclavicular or axillary route. A technique for selective blockade of the branches of the plexus at the humeral canal using electrolocation has recently been proposed. The aim of the present study was to assess the feasibility of this technique in the ambulatory patient and to determine the optimal sequence of nerve-blocking. METHODS: The nerves originating from the brachial plexus were located in the humeral canal, at the junction of the proximal and the middle third of the arm, with a stimulator and blocked using either lidocaine or a mixture of lidocaine and bupivacaine, depending on the anticipated duration of surgery. The minimal stimulating intensity eliciting an adequate response, type of local anaesthetic and injected volume, and time of onset of surgical anaesthesia were collected. RESULTS: The study included 503 consecutive ambulatory patients due to undergo surgery of the elbow, wrist or hand in one year. Suitable anaesthesia was obtained with the humeral blockade in 82.1% of cases. In the remaining 17.9%, an additional block at the elbow was required, mainly for ulnar and median nerves. The onset times of sensory blocks were the longest for the median nerve, similar for the radial and ulnar nerves, shorter for the musculocutaneous nerve and the shortest for the medial brachial and antebrachial cutaneous nerves. The difference was more significant with the lidocaine-bupivacaine mixture, than with lidocaine alone (P<0.001 vs P<0.05, respectively). The onset times of motor blocks were the longest for the median nerve (P<0.05) and the shortest for the musculocutaneous nerve (P<0.001). Neither nervous nor vascular complications occurred. CONCLUSION: This study shows that the nerve block at the humeral canal is an efficient and safe technique. Considering the onset times of nerve blocks, the following sequence for blockade can be recommended: median, ulnar, radial, musculocutaneous, medial (brachial and antebrachial) cutaneous nerves. The selective blockade of the main nerves of the upper limb at the humeral canal can be recommended for surgery of the forearm and the hand in the ambulatory patient.     

Interscalene brachial plexus block with a continuous catheter insertion system and a disposable infusion pump

Continuous interscalene brachial plexus blockade traditionally requires a hospital stay for local anesthetic infusion, and achieving consistent catheter insertion may be difficult. Incorporating long-acting pain relief from a continuous peripheral nerve block, with a reliable method of catheter insertion, and a self-contained infusion system would be a valuable asset for short-stay care. We compared the efficacy of single injection interscalene brachial plexus blockade to a continuous peripheral nerve block, with an insulated Tuohy system and a disposable infusion pump. Forty adult patients scheduled for open rotator cuff repair were entered in this randomized, double-blinded, placebo-controlled study. Patients received an interscalene brachial plexus blockade and a continuous peripheral nerve catheter as their primary anesthetic and then, were assigned to receive one of two different postoperative infusions: either 0.2% ropivacaine at 10 mL/h via a disposable infusion pump or normal saline at 10 mL/h via a disposable infusion pump (n = 18-20 per group). Visual analog pain scores and postoperative morphine consumption were measured for 24 h. The ropivacaine group showed less pain than the placebo group (P: = 0.0001) between 12 and 24 h after the initial injection of local anesthetic. In addition, initial interscalene blockade was successful in all patients and all redosed catheters were functional after 24 h with the continuous catheter insertion system. We conclude that it is possible to achieve a high rate of successful catheter placement and analgesia by using the continuous catheter insertion system and a disposable infusion pump in the ambulatory setting. This method of analgesia may offer improved pain relief after outpatient rotator cuff repair.     

Effect of transcutaneous electrical nerve stimulation on onset of axillary plexus block

We examined the effect of high frequency transcutaneous electrical nerve stimulation on the onset of brachial plexus block. Three groups of patients scheduled for surgery of the hand had a local anaesthetic block performed with 40 ml mepivacaine 1.5% using the axillary approach. After injection of the local anaesthetic transcutaneous electrical nerve stimulation was applied for 15 min either to the median nerve or the ulnar nerve; no stimulation was applied in the control group. Before and for 45 min after, the injection of local anaesthetic touch perception, pin prick, motor strength andskin temperature were tested by a blinded investigator in the areas supplied by the median, musculocutaneous, radial and ulnar nerves. There were no differences in the onset of block between the groups. Thus, the frequency-dependent action of local anaesthetics could not be demonstrated.     

皮肤温度对评定锁骨下臂丛神经阻滞效果的有效性

背景尽管有报道说皮肤温度的变化比针刺痛或冷温度感觉对阻滞效果的评定更具敏感性和特异性,但以前应用的方法是计算机辅助的红外温度记录法,该技术花费大且需要一定的人员培训.在这项前瞻性的观察研究中,我们评估简易的红外温度计是否能可靠地预测锁骨下臂丛神经的阻滞效果.方法30例在锁骨下臂丛神经阻滞下行上肢手术的患者纳入本研究.局...     

The use of a "reverse" axis (axillary-interscalene) block in a patient presenting with fractures of the left shoulder and elbow.

IMPLICATIONS: A patient presented for surgery to repair a fractured left shoulder and elbow and requested regional anesthesia. Most upper extremity operations require a single brachial plexus nerve block. The position of the two fractures however required the use of two separate approaches, an interscalene and an axillary approach.     

The neurostimulator for brachial plexus blockade by the axillary approach: a metaanalysis on its efficacy to increase the success rate

OBJECTIVE: To evaluate the effectiveness of the neurostimulator to improve the success rate of a brachial plexus blockade by the axillary approach. STUDY DESIGN: Metaanalysis. METHODS: Ten prospective randomized studies comparing a neurostimulating technique (NST) of brachial plexus blockade performed by the axillary approach to another technique were kept for analysis. A successful block was defined as blockade of the four following nerves: radial, median, ulnar and musculocutaneous. Data were entered on an intention to treat basis and were analyzed with a random model. A p<0.05 was considered significant. RESULTS: Data were heterogenous (p < 0.001) and the Cochran-Mantel-Haenzel test showed that the neurostimulator does not improve the success rate of brachial plexus blocks performed by the axillary approach when all available studies are considered as a whole (p = 1). For the subgroup of studies where four nerves were stimulated however, the NST decreases the incidence of failed block by 25% (95% CI = 7-42%) (p < 0.0001). There were 12 patients with systemic signs of local anesthetics toxicity when a NST was used compared to 28 when it was not (p = 0.04), relative risk of 0.7 (95% CI= 0.6-0.8). CONCLUSION: This study shows that the neurostimulator improves the success rate of brachial plexus blocks performed by the axillary approach only when three nerves or more are stimulated and its use decreases the incidence of systemic local anaesthetics toxicity.     

Brachial plexus blocks: a review of approaches and techniques

PURPOSE: The purpose of this narrative review is to summarize the evidence derived from randomized controlled trials (RCTs) regarding established approaches and techniques for brachial plexus anesthesia. SOURCE: Using the MEDLINE (January 1966 to November 2006) and EMBASE (January 1980 to November 2006) databases, key words "brachial plexus", "nerve blocks", "interscalene", "cervical paravertebral", "suprascapular", "supraclavicular", "infraclavicular", "axillary", "brachial canal" and "humeral canal" were searched for full text articles pertaining to the evaluation of recognized approaches and techniques for brachial plexus anesthesia. The search was limited to RCTs involving human subjects and published in the English language. Seventy-six RCTs were identified. PRINCIPAL FINDINGS: Many of the published studies were underpowered and contained various methodological limitations. We found that, for shoulder and proximal humeral surgery, interscalene and cervical paravertebral approaches to the brachial plexus appear to provide equally effective surgical anesthesia. Intersternocleidomastoid supraclavicular blocks are not associated with improved postoperative analgesia despite eliciting more complete anesthesia of the brachial plexus. For surgery at or below the elbow, an infraclavicular block may result in decreased performance time and block-related pain while providing similar efficacy compared to (multiple-stimulation) axillary and brachial canal approaches. With respect to technique, it is unclear if nerve stimulation provides a more effective interscalene block than elicitation of paresthesiae. For supraclavicular blocks, nerve stimulation with a minimal threshold of 0.9 mA is recommended, whereas a double-stimulation technique is optimal for infraclavicular blocks. For the axillary approach, a triple-stimulation technique, involving injections of the musculocutaneous, median and radial nerves, is the most effective option. CONCLUSIONS: Published reports of RCTs provide evidence to formulate limited recommendations regarding optimal approaches and techniques for brachial plexus anesthesia. Further well-designed and meticulously executed RCTs are warranted, particularly in light of new techniques involving ultrasound or combining neurostimulation and echoguidance.     

Infraclavicular block with lateral approach and nerve stimulation: extent of anesthesia and adverse effects.

BACKGROUND AND OBJECTIVES: The infraclavicular approach to the brachial plexus is little used despite theoretical advantages of the technique. Using a vertical paracoracoid approach, we assessed the extent of the sensory block and the incidence of adverse effects. METHODS: After obtaining informed consent, 100 patients undergoing surgical procedures distal to the elbow were evaluated. The block was performed using a peripheral nerve stimulator. The puncture site was located in the infraclavicular fossa; the direction of the insulated needle was perpendicular to the skin. Motor response was sought in the hand or wrist at < or = 0.6 mA. A total of 40 mL of 1.5% mepivacaine was administered as a single injection. The sensory block was evaluated every 5 minutes for 30 minutes before surgery in the cutaneous distribution of terminal branches of the brachial plexus. RESULTS: When one considers the cutaneous distributions of the median, ulnar, radial, and musculocutaneous nerves, the success rate was 89% for surgery without need for additional peripheral nerve blocks or general anesthesia. In contrast, cutaneous areas innervated by the axillary and medial cutaneous nerves were rarely anesthetized. We were unable to demonstrate a correlation between the intensity of the stimulation and the success of the block. On the other hand, a correlation was found between tourniquet sensation and the absence of anesthesia of the medial cutaneous nerve of the arm. Local anesthetic toxicity, Horner's syndrome, and vascular puncture were respectively observed in 1%, 4%, and 5% of cases. The depth of the needle introduction was correlated with the body mass index (P <.001; r =.63). CONCLUSION: Single injection infraclavicular block, using a vertical paracoracoid approach, appears suitable for surgery distal to the elbow. Selective anesthesia of the medial cutaneous nerve is useful in improving tolerance of the tourniquet.