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.     

Applying ultrasound imaging to interscalene brachial plexus block

OBJECTIVE: Previous studies have examined ultrasound-assisted brachial plexus blocks, but few have applied this imaging technology to the interscalene region. We report a case of interscalene brachial plexus block using ultrasound guidance to show the clinical usefulness of this technology. CASE REPORT: A nerve stimulator-guided interscalene block was attempted for arthroscopic shoulder surgery but failed. Subsequent nerve localization was accomplished by ultrasound imaging using a high-frequency probe (5-12 MHz) and the Philips ATL HDI 5000 unit. Ultrasound showed nerves between the scalene muscles, block needle movement at the time of advancement, and local anesthetic spread during injection. Interscalene block was successful after 1 attempt of nerve localization and needle placement. CONCLUSIONS: Advanced ultrasound technology is useful for nerve localization and can generate brachial plexus images of high resolution in the interscalene groove, guide block needle placement and advancement in real time to targeted nerves, and assess adequacy of local anesthetic spread at the time of injection. Ultrasound imaging guidance can potentially improve success during interscalene brachial plexus block.     

Ultrasound-guided supraclavicular brachial plexus block

In this study, we evaluated state-of-the-art ultrasound technology for supraclavicular brachial plexus blocks in 40 outpatients. Ultrasound imaging was used to identify the brachial plexus before the block, guide the block needle to reach target nerves, and visualize the pattern of local anesthetic spread. Needle position was further confirmed by nerve stimulation before injection. The block technique we describe aligned the needle path with the ultrasound beam. The block was successful after one attempt in 95% of the cases, with one failure attributable to subcutaneous injection and one to partial intravascular injection. Pneumothorax did not occur. Our preliminary data suggest that a high-resolution ultrasound probe can reliably identify the brachial plexus and its neighboring structures in the supraclavicular region. The technique of real-time guidance during needle advancement can quickly localize nerves. Distinct patterns of local anesthetic spread observed on ultrasound can further confirm accurate needle location. IMPLICATIONS: Real-time ultrasound imaging during supraclavicular brachial plexus blocks can facilitate nerve localization and needle placement and examine the pattern of local anesthetic spread.     

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.     

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.     

Ultrasound-guided nerve block: brachial plexus block

Ultrasonographic guidance has been introduced as an aid to nerve localization, for brachial plexus blockade in the interscalene and infraclavicular regions. Ultrasound-guided interscalene approach and infraclavicular approach were established as an excellent method to provide good analgesia during surgery and relieve post-surgical pain after shoulder or upper arm surgery and forearm or hand surgery respectively. Single shot injection and continuous catheter approach in both nerve blocks were described together with clinical key points based on the ultrasound images.     

Severe respiratory failure after infraclavicular block with 0.75% ropivacaine: a case report

Upper extremity surgery is usually performed with an axillary block. There is a risk of pneumothorax and phrenic nerve block when interscalene or supraclavicular block are used in day case surgery, or in patients with chronic obstructive pulmonary disease. The infraclavicular block is a simple, reliable, and easy to learn method to block the brachial plexus. No clinically relevant respiratory effects have been reported with infraclavicular block. Nonetheless, we report a case of a chronic obstructive pulmonary disease patient who developed severe respiratory failure requiring tracheal intubation after an infraclavicular block.     

Needle placement and injection posterior to the axillary artery may predict successful infraclavicular brachial plexus block: a report of three cases

PURPOSE: The combined use of ultrasound and nerve stimulation for localization of the brachial plexus during infraclavicular block has not been evaluated. We describe three cases of infraclavicular block where we used ultrasound to place the needle and catheter, observe type of muscle twitch obtained and local anesthetic spread after injection. CLINICAL FEATURES: Injection of local anesthetic after obtaining proximal muscle stimulation was associated with local anesthetic spread between the axillary artery and pectoral muscle. This resulted in block failure (case 1).In case 2, proximal stimulation was associated with anterior spread after a test injection. The needle and subsequently the catheter were repositioned posterior to the axillary artery and distal muscle stimulation obtained. Injection through the catheter resulted in local anesthetic spread posterior to the artery and successful block.In case 3, no distal twitch could be obtained but in light of previous experience the needle and then the catheter were placed posterior to the axillary artery. Posterior local anesthetic spread was observed and successful block ensued despite absence of any muscle stimulation. CONCLUSION: Ultrasound guidance during infraclavicular brachial plexus block enables direct visualization of needle/catheter tip location and confirmation of appropriate local anesthetic spread. Our early experience suggests that spread of injectate posterior to the second part of the axillary artery is associated with successful block.     

Anatomical study of the brachial plexus using surface ultrasound

The aim of this study was to define the anatomy relevant to brachial plexus regional anaesthesia and to identify the extent of variation between individuals. Surface ultrasound examination of the brachial plexus was performed on twenty volunteers. In the axilla there was considerable individual variation in the location of the median, radial and ulnar nerves in relation to the axillary artery. There was often more than one venous structure in this region, which was easily compressed by surface palpation. In the supraclavicular region, neural elements were located inferiorly to the subclavian artery in two volunteers. In one volunteer, a vein was identified between nerve trunks in the interscalene region. These findings indicate that the anatomical variation is considerable, even within the relatively small sample studied. For this reason, use of surface ultrasound may lead to increased success of brachial plexus regional anaesthesia and a decreased risk of intravascular injection.     

A comparison between double-injection axillary brachial plexus block and midhumeral block for emergency upper limb surgery

In this prospective and randomized study, we compared a double-injection axillary (median and radial nerves) block with a midhumeral block in 90 patients undergoing emergency upper limb surgery. Time to perform the block, success rate, and patient tolerance were evaluated. The time to perform the block was 5 min longer in the midhumeral group. The success rate was similar in both groups (80% and 91% in groups axillary and midhumeral respectively), except for the musculocutaneous nerve. Patient tolerance was better in the axillary group. Double-injection axillary brachial plexus block is superior to midhumeral block for emergency hand surgery.     

The pharmacokinetics of ropivacaine after four different techniques of brachial plexus blockade

Arterial plasma concentrations of ropivacaine were measured after brachial plexus blockade using four different approaches: lateral interscalene (Winnie), posterior interscalene (Pippa), axillary and vertical infraclavicular. Four groups of 10 patients were given a single 3.75 mg.kg(-1) injection of ropivacaine 7.5 mgxml(-1). The pharmacokinetics of ropivacaine were evaluated for 1 h after local anaesthetic injection. The supraclavicular techniques (lateral and posterior) were associated with earlier and higher peak plasma concentrations of local anaesthetic than the infraclavicular techniques (axillary and vertical infraclavicular): mean (SD) values = 3.30 (0.65) microgxml(-1) vs 2.55 (0.62) microgxml(-1) (p = 0.001) in 13.4 (6.9) min vs 25.0 (10.8) min (p = 0.0002). More ropivacaine is taken up by the systemic circulation in the first hour after the supraclavicular approaches; the mean (SD) area under the concentration-time curve was larger: 2.63 (0.51) microgxml(-1).h vs 2.10 (0.49) microgxml(-1).h (p = 0.002). These results show that the technique used for brachial plexus blockade significantly influences the systemic uptake of ropivacaine.     

Repair of isolated axillary nerve lesions after infraclavicular brachial plexus injuries: case reports

Stretch injuries of the infraclavicular brachial plexus have a much better prognosis for spontaneous recovery than do their supraclavicular counterparts. We present three patients with stretch injuries of the infraclavicular brachial plexus who had spontaneous restoration of function in all muscles except the deltoid. Decreased shoulder abduction was a serious handicap to these individuals. At surgical exploration, each patient had an isolated, complete axillary nerve disruption at the quadrilateral space. Deltoid muscle function was restored in all three patients by repair of the axillary nerve with sural nerve grafts across the quadrilateral space.     

Lateral infraclavicular plexus block vs. axillary block for hand and forearm surgery

BACKGROUND: In the last few years infraclavicular plexus block has become a method of increasing interest. However, this block has been associated with high complication incidences and without advantage in the quality of blockade over the axillary approach. We prospectively studied 40 patients (ASA I-III) undergoing surgery of the forearm and hand, and investigated the performance of the lateral infraclavicular plexus block against an axillary paravascular block to evaluate the success rate as well as the extent and quality of blockade. METHODS: Patients were randomized into two groups: group I (lateral infraclavicular approach; n=20) and group A (axillary approach; n=20). The lateral infraclavicular approach is a technique with the coracoid process (CP) as landmark. Alone the sagittal plane, the needle is inserted until contact with the CP. The needle is then withdrawn 2-3 mm and reinserted directly under the CP, until it contacts the brachial plexus sheath. Plexus blockade was performed using 40 ml of mepivacaine 1%. Quality of sensory and motor block was recorded selectively for each nerve distribution at close intervals for 6 h. RESULTS: Successful block according to Vester-Andersen's criteria was achieved in 100% of group I and 85% of group A. In group I, a pronounced sensory and motor blockade of the musculocutaneous nerve was observed, while patients of group A had a weak block of this nerve. In group I, an additional spectrum of nerves (thoracodorsal, axillary and medial brachial cutaneous nerves) was involved compared to group A. There was no difference among groups in onset and duration of block. CONCLUSION: Based on the safe landmark and feasibility of this procedure and the additional spectrum of nerve block achieved, the application of lateral infraclavicular technique has to be reconsidered in clinical practice.     

Evaluation of brachial plexus block. Comparison between supraclavicular and interscalene approach (author's transl)]

A scheme for evaluating brachial plexus block was developed, which is based on anatomical structures and which utilizes simple neurological examination techniques. It facilitates the localization of the tip of the cannula near the plexus, gives an idea of the spread of the local anesthetic in the region of the trunks and cords, gives well timed judgement on the success of the block and allows a comparison of the development of the block when using various techniques. Using this scheme, the development of the block was examined following use of the supraclavicular and interscalene approach. With the supraclavicular technique, motor as well as sensory blockade of all nerves of the brachial plexus occurred with about the same frequency; with the interscalene technique, the centre of the block affected the caudal nerves of the cervical plexus and the cranial nerves of the brachial plexus. Following both approaches, the blockade developed from proximal to distal areas, the motor blockade preceding the sensory blockade.     

Ultrasound-guided infraclavicular brachial plexus block: an alternative technique to anatomical landmark-guided approaches

BACKGROUND AND OBJECTIVES: Infraclavicular brachial plexus block has been used less than other approaches because of its less uniform landmarks and the necessity of a longer needle, which increases the patient's discomfort. To overcome these drawbacks, we applied ultrasound guidance to infraclavicular approach and prospectively evaluated its feasibility and usefulness in 60 patients undergoing upper extremity surgery. METHODS: A 7.0-MHz ultrasound probe was placed near the lower edge of the clavicle, and a transverse view of the subclavian artery and vein was visualized. Using a needle guide, a 23-gauge needle was advanced under real-time ultrasound guidance, and 1.5% lidocaine with 1:200,000 epinephrine was injected near the subclavian artery, 15 mm medially and 15 mm laterally to the artery. The extent of sensory and motor block was evaluated at 30 minutes after the injection. RESULTS: An adequate ultrasound image was obtained for all the patients. In 57 patients (95%), surgery was performed without supplementation of any other anesthetics or analgesics. The complete sensory block was obtained in 100% of patients for the musculocutaneous and medial antebrachial cutaneous nerves, 96.7% for the median nerve, and 95% for the ulnar and radial nerves. The complete motor block was achieved in 100% of patients for the musculocutaneous nerve, 96.7% for the median nerve, 90% for the ulnar nerve, and 93.3% for the radial nerve. No evidence of any complications was identified. CONCLUSIONS: Real-time ultrasound guidance facilitates accurate infraclavicular approach to the brachial plexus. It could be used as an alternative to the landmark-guided techniques.     

逆行锁骨下臂丛神经阻滞的临床应用

目的探讨逆行锁骨下臂丛神经阻滞(BPB)的效果。方法择期行上肢手术的患者90例随机分为三组,每组30例。在外周神经刺激器引导下行逆行锁骨下(A组)、肌间沟(B组)或锁骨上(C组)BPB穿刺,注入0.5%罗哌卡因40ml。记录感觉神经阻滞完善时间、不良反应。A组记录穿刺针进针深度,与矢状面、冠状面角度。结果A组感觉神经阻滞效果优于B、C组(P<0.05或P<0.01)。A组臂内侧皮、前臂内侧皮、正中、尺神经阻滞完善时间快于B组(P<0.01)。A组颈浅神经阻滞完善时间较B组慢(P<0.01)。A组不良反应与并发症明显少于B、C组(P<0.01)。结论逆行锁骨下BPB的感觉神经阻滞效果优于肌间沟法或锁骨上法。     

Restricted infraclavicular distribution of the local anesthetic solution after infraclavicular brachial plexus block

BACKGROUND AND OBJECTIVES: The distribution of local anesthetic after different approaches for brachial plexus anesthesia could be responsible for the varying rates of side effects, such as phrenic block, hoarseness, and Horner's syndrome associated with each approach. We compared the distribution of local anesthetic within the neurovascular space in infraclavicular block with that of interscalene and supraclavicular block. METHODS: In a prospective analysis using fluoroscopy, we studied the distribution of a solution of local anesthetic containing radiologic contrast medium in 18 patients. Six patients received an interscalene block, another 6 patients received a perpendicular supraclavicular block, and another 6 patients, a perpendicular coracoid block. RESULTS: Distribution of the anesthetic solution in the interscalene and supraclavicular groups extended to both supraclavicular and infraclavicular spaces in all patients. This distribution was significantly different (P <.05) compared with that of the infraclavicular group. In this group, the solution remained below the clavicle in every patient. CONCLUSIONS: Spread of the local anesthetic from the infraclavicular space after infraclavicular coracoid block appears to be limited to below the level of the clavicle. Conversely, local anesthetic solution passes below the clavicle in all patients given interscalene or supraclavicular blocks.     

Ultrasound-guided regional anesthesia for upper limb surgery

Purpose

The purpose of this module is to review the main ultrasound-guided approaches used for regional anesthesia of the upper limb.

Principal findings

The anatomical configuration of the upper limb, with nerves often bundled around an artery, makes regional anesthesia of the arm both accessible and reliable. In-depth knowledge of upper limb anatomy is required to match the blocked territory with the surgical area. The interscalene block is the approach most commonly used for shoulder surgery. Supraclavicular, infraclavicular, and axillary blocks are indicated for elbow and forearm surgery. Puncture techniques have evolved dramatically with ultrasound guidance. Instead of targeting the nerves directly, it is now recommended to look for diffusion areas. Typically, local anesthetics are deposited around vessels, often as a single injection. Phrenic nerve block can occur with the interscalene and supraclavicular approaches. Ulnar nerve blockade is almost never achieved with the interscalene approach and not always present with a supraclavicular block. If ultrasound guidance is used, the risk for pneumothorax with a supraclavicular approach is reduced significantly. Nerve damage and vascular puncture are possible with all approaches. If an axillary approach is chosen, the consequences of vascular puncture can be minimized because this site is compressible.

Conclusions

Upper limb regional anesthesia has gained in popularity because of its effectiveness and the safety profile associated with ultrasound-guided techniques.     

Ultrasound-guided infraclavicular brachial plexus block

Background. Peripheral nerve blocks are almost always performedas blind procedures. The purpose of this study was to test thefeasibility of seeing individual nerves of the brachial plexusand directing the block needle to these nerves with real timeimaging. Methods. Using ultrasound guidance, infraclavicular brachialplexus block was performed in 126 patients. Important aspectsof this standardized technique included (i) imaging the axillaryartery and the three cords of the brachial plexus posteriorto the pectoralis minor muscle, (ii) marking the position ofthe ultrasound probe before introducing a Tuohy needle, (iii)maintaining the image of the entire length of the needle atall times during its advancement, (iv) depositing local anaestheticaround each of the three cords and (v) placing a catheter anteriorto the posterior cord when indicated. Results. In 114 (90.4%) patients, an excellent block permittedsurgery without a need for any supplemental anaesthetic or conversionto general anaesthesia. In nine (7.2%) patients local or perineuraladministration of local anaesthetic, and in three (2.4%) conversionto general anaesthesia, was required. Mean times to administerthe block, onset of block and complete block were 10.0 (SD 4.4),3.0 (1.3) and 6.7 (3.2) min, respectively. Mean lidocaine dosewas 695 (107) mg. In one patient, vascular puncture occurred.In 53 (42.6%) patients, an indwelling catheter was placed, butonly three required repeat injections, which successfully prolongedthe block. Conclusion. The use of ultrasound appears to permit accuratedeposition of the local anaesthetic perineurally, and has thepotential to improve the success and decrease the complicationsof infraclavicular brachial plexus block. Br J Anaesth 2002; 89: 254–9