Acute Extremity Compartment Syndrome and (Regional): Anesthesia: The Monster Under the Bed

Acute compartment syndrome (ACS) is a potential orthopedic emergency that leads, without prompt diagnosis and immediate treatment with surgical fasciotomy, to permanent disability. The role of regional anesthesia (RA) for analgesia in patients at risk for ACS remains unjustifiably controversial. This critical review aims to improve the perception of the published literature to answer the question, whether RA techniques actually delay or may even help to hasten the diagnosis of ACS. According to literature, peripheral RA alone does not delay ACS diagnosis and surgical treatment. Only in 4 clinical cases, epidural analgesia was associated with delayed ACS diagnosis.

Bilateral brachial plexus block as alternative to general anaesthesia in high-risk patient; a case report and literature review

Introduction

Bilateral brachial plexus blocks can be an alternative to general anaesthesia in the surgery of arm, forearm, wrist, or hand. This study aims to report a case in which a risky patient underwent amputation surgery under regional anaesthesia.

Case presentation

A 64-year-old male was admitted to the hospital for an amputation operation. Ultrasonography revealed normal findings regarding internal organs, aside from grade II increased echogenicity of both kidneys and a small bladder cyst. Echocardiography revealed mildly left ventricular dilation, moderate systolic left ventricular dysfunction, ejection fraction 38%, left ventricular wall hypokinesia with left ventricular dilation. The amputation was performed under a bilateral supraclavicular brachial plexus block with the guidance of ultrasound.

Discussion

Theoretically, there are some advantages to regional anaesthesia in comparison to general anaesthesia, such as decreasing the ordinary body response to stress in the presence of low levels of cortisol and catecholamines, increasing blood flow and peripheral vasodilatation, decreasing hypercoagulability, lower risk of arterial and venous thrombosis and it aids to prevent endotracheal intubation and mechanical ventilation.

Conclusion

Bilateral brachial plexus blocks, as a type of regional anaesthesia under ultrasound guidance, can be depended upon as a reliable substitute for general anaesthesia in perilous conditions.

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Bilateral brachial plexus blocks (BBPB) are a kind of regional anaesthesia that can be used instead of general anaesthesia.

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Several complications may be encountered during the process of BBPB, including diaphragmatic paralysis.

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In this study, BBPB has been discussed with literature review.

What Is the Minimum Effective Volume of Local Anaesthetic Applied in Brachial Plexus Blockage With an Axillary Approach Under Ultrasonography Guidance?

Peripheral nerve blocks with the use of ultrasonography (USG) allow visualisation of both the structures and nerves and make the block administrations safe, quick, and comfortable. However, few publications concerning the minimum local anesthetic (LA) volume are capable of providing blocks. This study aimed to find the minimum effective LA volume in brachial plexus blockage administrations with an axillary approach accompanied by ultrasonography in hand, elbow, and forehand operations. Materials and Method The study included a total of 55 patients (classified as American Society of Anesthesiologists (ASA) I-II) who underwent hand surgery by administering USG-guided axillary brachial plexus blockage. The ulnar, median, and radial nerves were located, and the minimum effective LA volume was investigated starting with a total of 21 ml of bupivacaine 0.5%. After accomplishing the blockage, the volume was decreased by 0.5 ml for each nerve. Block administration time, block onset times, anesthesia times, and time to first analgesic requirement were recorded. Results The minimum effective LA volume for each nerve was 2.5 ml for a total of 7.5 ml. In comparing block administration times, there were no differences between high or low volume groups. It was found that sensory block onset time was 17 minutes for 7.5 ml and 11 minutes for 21 ml; sensory block regression time was six hours for 7.5 ml and 10.4 hours for 21 ml, respectively. This regression was statistically significant. The first analgesic requirement was 5.8 - 16.6 hours, respectively, for each group. Conclusion In the administration of an USG-guided axillary block, sufficient anesthesia can be achieved by administering 2.5 ml of bupivacaine 0.5% for each nerve. However, it might be kept in mind that motor and sensory block onset time will be extended and regression time and time to the first analgesic requirement will be shorter with this volume. In addition, more advanced studies must be done for the determination of the optimum volume which can be used.

European Society of Anaesthesiology and Intensive Care Guidelines on peri-operative use of ultrasound for regional anaesthesia (PERSEUS regional anesthesia): Peripheral nerves blocks and neuraxial anaesthesia

Nowadays, ultrasound-guidance is commonly used in regional anaesthesia (USGRA) and to locate the spinal anatomy in neuraxial analgesia. The aim of this second guideline on the PERi-operative uSE of UltraSound (PERSEUS-RA) is to provide evidence as to which areas of regional anaesthesia the use of ultrasound guidance should be considered a gold standard or beneficial to the patient. The PERSEUS Taskforce members were asked to define relevant outcomes and rank the relative importance of outcomes following the GRADE process. Whenever the literature was not able to provide enough evidence, we decided to use the RAND method with a modified Delphi process. Whenever compared with alternative techniques, the use of USGRA is considered well tolerated and effective for some nerve blocks but there are certain areas, such as truncal blocks, where a lack of robust data precludes useful comparison. The new frontiers for further research are represented by the application of USG during epidural analgesia or spinal anaesthesia as, in these cases, the evidence for the value of the use of ultrasound is limited to the preprocedure identification of the anatomy, providing the operator with a better idea of the depth and angle of the epidural or spinal space. USGRA can be considered an essential part of the curriculum of the anaesthesiologist with a defined training and certification path. Our recommendations will require considerable changes to some training programmes, and it will be necessary for these to be phased in before compliance becomes mandatory.

Onset times and duration of analgesic effect of various concentrations of local anesthetic solutions in standardized volume used for brachial plexus blocks

Visualization of the nerve structures of brachial plexus allows anesthesiologists to use a lower dose of local anesthetics. The content of this low dose is not unequivocal, consequently, the pharmacokinetics of local anesthetics used by various authors are difficult to compare. In this study, the onset times and duration of the analgesic effect of local anesthetic mixture solutions used for brachial plexus blocks are investigated and the quality of anesthesia is compared. 85 unpremedicated American Society of Anesthesiologist physical status I-III, 19-83-year-old patients scheduled for upper limb trauma surgery are assigned to four groups for the axillary-supraclavicular block with lidocaine 1% and bupivacaine 0,5% 1:1 mixture (Group LB) or bupivacaine 0.33% (Group BS) or lidocaine 0,66% (Group LS) or bupivacaine 0.5% and lidocaine 1% 2:1 mixture (Group BL). 0.4 ml/kg was administered to the four groups. The onset time was significantly shorter in the lidocaine group (LS 13.0 ± 1.02) than in the other study groups (LB 16.64 ± 0.89; BS 17.21 ± 0.74; BL 16.92 ± 0.51 min ±SEM, p = 0.002). No differences were observed in the onset times between LB, BS, and BL groups (p > 0.05). Statistical differences were found in the duration of local anesthetics between LB (392.9 ± 20.4), BS (546.4 ± 14.9), LS (172.85 ± 7.8), and BL (458.7 ± 11.9 min ±SEM, p = 0.001). Lidocaine does not shorten the onset times, but significantly decreases the duration of action of bupivacaine when used in mixture solutions. Lidocaine exhibits a good quality of block in the applied dose, while other solutions have excellent quality. Bupivacaine without lidocaine has the longest duration of action to achieve the longest postoperative analgesia.

A fluoroscopic assessment of brachial plexus block by the supraclavicular approach: Have we been overmedicating?

Background

Ultrasonography-guided supraclavicular brachial plexus block has demonstrated safety as compared with landmark or nerve stimulation techniques. However, the minimum effective analgesic volume (MEAV) necessary for adequate blockade has not been determined. This study was undertaken to assess under fluoroscopy the postinjection spread of different drug volumes with clinical correlation. Secondary outcome measures included correlation of onset of block, block quality, and incidence of side effects.

Methods

This randomized, multiarm, cross-sectional, observational study was conducted at a single tertiary care center. A total of 549 patients were randomly allocated to 3 groups (20 ml, 30 ml, and 40 ml of drug mixture). A local anesthetic drug mixture with a radiopaque dye was administered under ultrasonographic guidance, and postinjection fluoroscopic drug spread was studied.

Results

Surgical anesthesia was achieved in 494 (89.98%) patients with 85.25%, 92.97%, and 91.71% in 20-, 30-, and 40-ml groups, respectively, being significantly low (p = 0.0317) in the 20-mL group. Cephalad and infraclavicular spread was higher in the 40-mL group than in other two groups (p = 0.103). Horner syndrome (HS) was seen in 51.18% of patients. First, ipsilateral superficial cervical plexus block was also observed in 40.22% of patients. Among patients who developed both, ∼60% of patients (99/167) belonged to the 40-mL group.

Conclusions

Optimal MEAV appears between 20 and 30 mL. Higher drug volumes are associated with more cephalad spread and side effects. Drug spread can predict block efficacy as well. It is postulated that loss of sensation in the ipsilateral neck can be used to predict development of hemidiaphragmatic paresis similar to HS.

A Comparative Clinical Study of Ultrasonography-Guided Perivascular and Perineural Axillary Brachial Plexus Block for Upper Limb Surgeries

Background:

Axillary brachial plexus block (ABPB) is safest among other methods of brachial plexus block because of its ease and reliability. The two approaches of ultrasonography-guided ABPB are perivascular (PV) and perineural (PN).

Aims:

This study was conducted to compare primary outcomes such as performance time, onset of the block, number of needle passes, block success rate, duration of sensory and motor block, and complications between ultrasound-guided PV and PN ABPB in patients posted for upper limb surgeries.

Settings and Design:

This prospective randomized study was conducted on 106 patients American Society of Anesthesiologists Class I and II posted for forearm, wrist, and hand surgeries, who were allotted into Group PV and Group PN 53 each.

Materials and Methods:

In both methods, 20 mL of the drug was used. To start with, musculocutaneous nerve was blocked with 5 mL of the drug. In the PV technique, remaining 15 mL of the drug was deposited anterior and posterior to axillary artery, and in PN technique, 5 mL of the drug was injected around radial, ulnar, and median nerve.

Statistical Analysis:

Mann–Whitney and Chi-square test were used for statistical analysis.

Results:

Significant difference was observed between the two groups in performance time (PV – 8.647 ± 0.54 min and PN – 14.53 ± 0.20 min), onset time (PV – 19.48 ± 2.83 min and PN – 13.86 ± 1.81 min), and number of needle passes (PV – 2.30 ± 0.50 and PN – 4.91 ± 0.66). Other parameters were comparable in both the groups.

Conclusions:

Ultrasound-guided PV axillary plexus block is better than PN axillary plexus block with respect to performance time and number of needle passes; but onset time was shorter in PN block, with precaution eliminating the risk of complications.

Pharmacokinetic and clinical effects of two bupivacaine concentrations on axillary brachial plexus block

Introduction

The risk of systemic bupivacaine toxicity is a persistent problem, which makes its pharmacokinetic study fundamental for regional anesthesia safety. There is little evidence of its influence on plasma peak at different concentrations. The present study compares two bupivacaine concentrations to establish how the concentration affects this drug plasma peak in axillary brachial plexus block. Postoperative latency and analgesia were also compared.

Methods

30 patients were randomized. In the 0.25% Group, 0.25% bupivacaine (10 mL) was injected per nerve. In the 0.5% Group, 0.5% bupivacaine (5 mL) was injected per nerve. Peripheral blood samples were collected during the first 2 h after the blockade. For sample analyses, high performance liquid chromatography mass spectrometry was used.

Results

Plasma peak occurred 45 min after the blockade, with no difference between groups at the assessed time-points. Plasma peak was 933.97 ± 328.03 ng.mL⁻¹ (mean ± SD) in 0.25% Group and 1022.79 ± 253.81 ng.mL⁻¹ in 0.5% Group (p = 0.414). Latency was lower in 0.5% Group than in 0.25% Group (10.67 ± 3.71 × 17.33 min ± 5.30, respectively, p = 0.004). No patient had pain within the first 4 h after the blockade.

Conclusion

For axillary brachial plexus block, there was no difference in bupivacaine plasma peak despite the use of different concentrations with the same local anesthetic mass. The concentration inversely influenced latency.

Comparing Electrical Stimulation With and Without Ultrasound Guidance for Phenol Neurolysis to the Musculocutaneous Nerve

BACKGROUND

Ultrasound guidance is increasingly being used for neurolytic procedures that have traditionally been done with electrical stimulation (e-stim) guidance alone. Ultrasound visualization with e-stim-guided neurolysis can potentially allow adjustments in injection protocols that will reduce the volume of neurolytic agent needed to achieve clinical improvement.

OBJECTIVE

This study compared e-stim only to e-stim with ultrasound guidance in phenol neurolysis of the musculocutaneous nerve (MCN) for elbow flexor spasticity. We also evaluated the ultrasound appearance of the MCN in this population.

DESIGN

Retrospective review.

SETTING

University hospital outpatient clinic.

PARTICIPANTS

Adults (N = 167) receiving phenol neurolysis to the MCN for treatment of elbow flexor spasticity between 1997 and 2014 and adult control subjects.

METHODS

For each phenol injection of the MCN, the method of guidance, volume of phenol injected, technical success, improved range of motion at the elbow postinjection, adverse effects, reason for termination of injections, and details of concomitant botulinum toxin injection were recorded. The ultrasound appearance of the MCN, including nerve cross-sectional area and shape, were recorded and compared between groups.

MAIN OUTCOME MEASURES

The volume of phenol injected and MCN cross-sectional area and shape as demonstrated by ultrasound.

RESULTS

The addition of ultrasound to e-stim-guided phenol neurolysis was associated with lower doses of phenol when compared to e-stim guidance alone (2.31 mL versus 3.69 mL, P < .001). With subsequent injections, the dose of phenol increased with e-stim guidance (P < .001), but not with e-stim and ultrasound guidance (P = .95). Both methods of guidance had high technical success, improved ROM at elbow postinjection, and low rates of adverse events. In comparing the ultrasound appearance of the MCN in patients with spasticity to that of normal controls, there was no difference in the cross-sectional area of the nerve, but there was more variability in shape.

CONCLUSIONS

Combined e-stim and ultrasound guidance during phenol neurolysis to the MCN allows a smaller volume of phenol to be used for equal effect, both at initial and repeat injection. The MCN shape was more variable in individuals with spasticity; this should be recognized so as to successfully locate the nerve to perform neurolysis.

LEVEL OF EVIDENCE

IV.

Ultrasound-guided perineural injection for nerve blockade: Does a single-sided injection produce circumferential nerve coverage?

PURPOSE

Our current clinical technique for sonographic-guided perineural injection consists of two-sided perineural needle placement to obtain circumferential distribution of the injectate. This study aimed to determine if a single-side needle position will produce circumferential nerve coverage.

METHODS

Fresh-frozen cadaveric specimens were used for this study. In six upper extremities, a needle was positioned along the deep surface of median, radial, and ulnar nerves in the carpal tunnel, radial tunnel, and cubital tunnel, respectively, and 2 ml of contrast was injected for each nerve. In three pelvic specimens, a needle was positioned deep to the sciatic nerves bilaterally, and 5 ml of contrast was injected. An additional four median nerve injections were performed using superficial surface needle position. The specimens then underwent CT scanning to assess the distribution of the perineural contrast medium.

RESULTS

One hundred percent of the radial, ulnar, and sciatic nerves demonstrated circumferential distribution on CT. Only 50% of the median nerve injections with the needle placed deep to the nerve produced circumferential coverage, whereas 100% of median nerves injected with the needle between the nerve and retinaculum demonstrated circumferential coverage. The average length of spread of perineural injectate was 11.6 cm in the upper extremity and 10.3 cm for the sciatic nerves.

CONCLUSIONS

Using clinical volumes of fluid, needle positioning at the deep surface of upper extremity and sciatic nerves was sufficient to produce circumferential coating of the nerve, except in the carpal tunnel, where placement of the needle between the nerve and flexor retinaculum is recommended. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 44:465-469, 2016.

Effect of dexamethasone in low volume supraclavicular brachial plexus block: A double-blinded randomized clinical study

BACKGROUND AND AIMS

With the use of ultrasound, a minimal effective volume of 20 ml has been described for supraclavicular brachial plexus block. However achieving a long duration of analgesia with this minimal volume remains a challenge. We aimed to determine the effect of dexamethasone on onset and duration of analgesia in low volume supraclavicular brachial plexus block.

MATERIAL AND METHODS

Sixty patients were randomly divided into two groups of 30 each. Group C received saline (2 ml) + 20 ml of 0.5% bupivacaine and Group D received dexamethasone (8 mg) + 20 ml of 0.5% bupivacaine in supraclavicular brachial plexus block. Hemodynamic variables and visual analog scale (VAS) score were noted at regular intervals until 450 min. The onset and duration of sensory and motor block were measured. The incidence of "Halo" around brachial plexus was observed. Student's t-test and Chi-square test were used for statistical analysis.

RESULTS

The onset of sensory and motor block was significantly earlier in dexamethasone group (10.36 ± 1.99 and 12 ± 1.64) minutes compared to control group (12.9 ± 2.23 and 18.03 ± 2.41) minutes. The duration of sensory and motor block was significantly prolonged in dexamethasone group (366 ± 28.11 and 337.33 ± 28.75) minutes compared to control group (242.66 ± 26.38 and 213 ± 26.80) minutes. The VAS score was significantly lower in dexamethasone group after 210 min. "Halo" was present around the brachial plexus in all patients in both the groups.

CONCLUSION

Dexamethasone addition significantly increases the duration of analgesia in patients receiving low volume supraclavicular brachial plexus block. No significant side-effects were seen in patients receiving dexamethasone as an adjunct.

Minimum effective volume of mepivacaine for ultrasound-guided supraclavicular block

BACKGROUND

The aim of this study was to estimate the minimum effective volume (MEV) of 1.5% mepivacaine for ultrasound-guided supraclavicular block by placing the needle near the lower trunk of brachial plexus and multiple injections.

METHODS

Thirty patients undergoing forearm and hand surgery received ultrasound-guided supraclavicular block with 1.5% mepivacaine. The initial volume of local anesthetic injected was 24 ml, and local anesthetic volume for the next patient was determined by the response of the previous patient. The next patient received a 3 ml higher volume in the case of the failure of the previous case. If the previous block was successful, the next volume was 3 ml lower. MEV was estimated by the Dixon and Massey up and down method. MEV in 95, 90, and 50% of patients (MEV95, MEV90, and MEV50) were calculated using probit transformation and logistic regression.

RESULTS

MEV95 of 1.5% mepivacaine was 17 ml (95% confidence interval [CI], 13-42 ml), MEV90 was 15 ml (95% CI, 12-34 ml), and MEV50 was 9 ml (95% CI, 4-12 ml). Twelve patients had a failed block. Three patients received general anesthesia. Nine patients could undergo surgery with sedation only. Only one patient showed hemi-diaphragmatic paresis.

CONCLUSIONS

MEV95 was 17 ml, MEV90 was 15 ml, and MEV50 was 9 ml. However, needle location near the lower trunk of brachial plexus and multiple injections should be performed.

Comparison of ultrasound-guided supraclavicular block according to the various volumes of local anesthetic

Background

The ultrasound guidance in regional nerve blocks has recently been introduced and gaining popularity. Ultrasound-guided supraclavicular block has many advantages including the higher success rate, faster onset time, and fewer complications. The aim of this study was to examine the clinical data according to the varied volume of local anesthetics in the ultrasound-guided supraclavicular block.

Methods

One hundred twenty patients were randomized into four groups, according to the local anesthetic volume used: Group 35 (n = 30), Group 30 (n = 30), Group 25 (n = 30), and Group 20 (n = 30). Supraclavicular blocks were performed with 1% mepivacaine 35 ml, 30 ml, 25 ml, and 20 ml, respectively. The success rate, onset time, and complications were checked and evaluated.

Results

The success rate (66.7%) was lower in Group 20 than that of Group 35 (96.7%) (P < 0.05). The average onset times of Group 35, Group 30, Group 25, and Group 20 were 14.3 ± 6.9 min, 13.6 ± 4.5 min, 16.7 ± 4.6 min, and 16.5 ± 3.7 min, respectively. There were no significant differences. Horner's syndrome was higher in Group 35 (P < 0.05).

Conclusions

In conclusion, we achieved 90% success rate with 30 ml of 1% mepivacaine. Therefore, we suggest 30 ml of local anesthetic volume for ultrasound-guided supraclavicular block.

Minimum effective volume of ropivacaine 7.5 mg/ml for an ultrasound-guided infraclavicular brachial plexus block

BACKGROUND

Ultrasound guidance has been shown to reduce the minimum effective volume (MEV) of local anaesthetics for several peripheral nerve blocks. Although the lateral sagittal infraclavicular block (LSIB) is a well-established anaesthesia method, MEV for this technique has not been established. Our aim with this study was to determine the MEV using ropivacaine 7.5 mg/ml for the LSIB method.

METHODS

Twenty-five adult American Society of Anesthesiologists physical status I-II patients scheduled for hand surgery received an ultrasound-guided LSIB with ropivacaine 7.5 mg/ml. A successful block was defined as anaesthesia or analgesia for all five sensory nerves distal to the elbow, 30 min after local anaesthetic injection. The MEV for a successful block in 50% of the patients was determined by using the staircase up-and-down method introduced by Dixon and Massey. Logistic regression and probit transformation were applied to estimate the MEV for a successful block in 95% of the patients.

RESULTS

The patients received ropivacaine 7.5 mg/ml volumes in the range of 12.5-30 ml. The MEVs in 50% and 95% of the patients were 19 ml [95% confidence interval (CI), 14-27] and 31 ml (95% CI, 18-45), respectively.

CONCLUSIONS

For surgery distal to the elbow, the MEV in 95% of patients for an ultrasound-guided LSIB with ropivacaine 7.5 mg/ml was estimated to be 31 ml (95% CI, 18-45 ml). Further studies should determine the factors that influence the volume of local anaesthetic required for a successful infraclavicular block.

Ultrasound-guided peripheral nerve blockade of the upper extremity

PURPOSE OF REVIEW

Is ultrasound guidance changing the practice of upper extremity regional anesthesia? This review will aim to describe the findings published in the literature during the previous 18 months.

RECENT FINDINGS

In some approaches to brachial plexus blockade, local anesthetic volumes may be reduced without deterioration of analgesic effect. However, even 10 ml of local injected into the interscalene space may result in diaphragmatic paresis. High-resolution ultrasonography has revealed anatomical variations of C5, C6 and C7 nerve roots in almost half of the patients examined, without negative block effectiveness. The addition of dexamethasone may prolong analgesia after single-shot interscalene and supraclavicular blocks. Insertion of brachial plexus perineural catheters using ultrasound guidance can be successful and provides better postoperative analgesia than single-shot blocks for up to 24 h postoperatively. Infraclavicular catheters provide superior analgesia when compared with supraclavicular catheters. Multiple-site injections of local offer no advantage over a single-site injection during an infraclavicular block. Ultrasound guidance compared with neurostimulation may reduce patient discomfort during axillary blocks compared with neurostimulation. Intra-epineural injections are common during an interscalene blockade, but the incidence of neurological injury remains low. There is an ongoing debate on the effectiveness and safety of ultrasound-guided intra-epineurial injections.

SUMMARY

Current literature suggests a reduction of the volume of local anesthetics used for ultrasound-guided upper extremity blockades. Dexamethasone may prolong duration of brachial plexus blocks and more frequent use of perineural catheters is encouraged. Controversy over intra-epineurial injections exists and requires additional large-scale studies.

A peptidomimetic tight junction modulator to improve regional analgesia

The paracellular flux of solutes through tissue barriers is limited by transmembrane tight junction proteins. Within the family of tight junction proteins, claudin-1 seems to be a key protein for tightness formation and integrity. In the peripheral nervous system, the nerve fibers are surrounded with a barrier formed by the perineurium which expresses claudin-1. To enhance the access of hydrophilic pharmaceutical agents via the paracellular route, a claudin-1 specific modulator was developed. For this purpose, we designed and investigated the claudin-1 derived peptide C1C2. It transiently increased the paracellular permeability for ions and high and low molecular weight compounds through a cellular barrier model. Structural studies revealed a β-sheet potential for the functionality of the peptide. Perineurial injection of C1C2 in rats facilitated the effect of hydrophilic antinociceptive agents and raised mechanical nociceptive thresholds. The mechanism is related to the internalization of C1C2 and to a vesicle-like distribution within the cells. The peptide mainly colocalized with intracellular claudin-1. C1C2 decreased membrane-localized claudin-1 of cells in culture and in vivo in the perineurium of rats after perineurial injection. In conclusion, a novel tool was developed to improve the delivery of pharmaceutical agents through the perineurial barrier by transient modulation of claudin-1.

Ultrasound brachial plexus anesthesia and analgesia for upper extremity surgery: essentials of our current understanding, 2011

PURPOSE OF REVIEW

Ultrasound-guidance is gaining tremendous popularity. There is growing evidence of value with emphasis on clinical relevance, but can ultrasound-guidance scientifically warrant changing the practice of upper extremity regional? The literature is searched to describe findings where ultrasound may reduce complication rates, reduce block performance times, and improve block efficacy and quality.

RECENT FINDINGS

Ultrasound examination identified variations in anatomical positioning of C5-C7 roots in approximately half of all patients despite no deleterious effects on block efficacy. Anesthetic volumes in brachial plexus blockade may be reduced without compromise of effectiveness. However, even with reduced volumes injected into the interscalene space, respiratory compromise from effect(s) on the phrenic nerve may result in hemi-diaphragmatic paresis. Ultrasound-guidance may reduce discomfort during axillary block placement compared with neurostimulation or parasthesia. Nerve catheters may be highly effective and provide prolonged analgesia compared with single-shot injections. Infraclavicular catheters result in improved analgesia compared with supraclavicular catheters and multiple injections of local provide no advantage over single-shot infraclavicular blockade. Dexamethasone combined with local may extend analgesia following a single-injection interscalene or supraclavicular block. During interscalene blockade, intraepineurial injections may occur, but incidence of nerve injury remains low. Therefore, debate continues about intraepineurial injections.

SUMMARY

Intraepineurial injection requires additional investigation. Conclusions have suggested reducing typical volumes (40  ml) of local with ultrasound-directed upper extremity blockade. Increased use of perineural catheters is being advocated for prolonged analgesia, but risk-to-benefit consequences need to always be considered.