Application of the Doppler ultrasound bloodflow detector in supraclavicular brachial plexus block

Celebrating the state of the art and innovations in regional anaesthesia in the British Journal of Anaesthesia

To coincide with the annual scientific meeting of Regional Anaesthesia UK in London 2024, where there is a joint scientific session with the British Journal of Anaesthesia, a special regional anaesthesia edition of the journal has been produced. This editorial offers some highlights from the manuscripts contained within the special edition.

Beyond the Echo: The Evolution and Revolution of Ultrasound in Anesthesia

This article explores the evolving role of ultrasound technology in anesthesia. Ultrasound emerged decades ago, offering clinicians noninvasive, economical, radiation-free, and real-time imaging capabilities. It might seem that such an old technology with apparent limitations might have had its day, but this review discusses both the current applications of ultrasound (in nerve blocks, vascular access, and airway management) and then, more speculatively, shows how integration of advanced ultrasound modalities such as contrast-enhanced imaging with virtual reality (VR), or nanotechnology can alter perioperative patient care. This article will also explore the potential of robotics and artificial intelligence (AI) in augmenting ultrasound-guided anesthetic procedures and their implications for medical practice and education.

Transversus abdominis plane (TAP) block for pain management of rectus sheath hematoma in the emergency department (ED)

Peripheral nerve blocks for pain management have historically been discussed in anesthesiology literature but, until recently, have not been considered in emergency medicine contexts. Transversus abdominis plane (TAP) blocks, in particular, have recently been explored in the emergency department for pain control in acute appendicitis but are potentially helpful for managing abdominal pain of other etiologies. One such pathology is rectus sheath hematomas, where conservative management is often necessary as curative treatments often pose more significant risks than are necessary. We report the case of a 57-year-old female presenting to the emergency department with severe abdominal pain following vigorous exercise. She was found to have a large rectus sheath hematoma on computed tomography. An ultrasound-guided transversus abdominis plane block was performed in the emergency department, and the patient had complete resolution of her pain.

A Practical Guide to Lower Extremity Nerve Blocks for the Sports Medicine Surgeon

BACKGROUND

Peripheral nerve blocks (PNBs) are vital in the administration of surgical analgesia and have grown in popularity for use in lower extremity arthroscopic procedures because of their capacity to safely and effectively control pain. The number and specificity of PNBs, however, have made choosing the best option for a procedure nebulous for orthopaedic surgeons.

PURPOSE

To present a narrative literature review of the PNBs available for arthroscopic hip and knee procedures that is adapted to an audience of orthopaedic surgeons.

STUDY DESIGN

Narrative literature review.

METHODS

A combination of the names of various lower extremity PNBs AND "hip arthroscopy" OR "knee arthroscopy" was used to search the English medical literature including PubMed, Cochrane Library, ScienceDirect, Embase, and Scopus. Placement technique, specificity of blockade, efficacy, and complications were assessed. Searches were performed through May 2, 2021.

RESULTS

A total of 157 studies were included in this review of lower extremity PNBs. Femoral nerve, lumbar plexus, sciatic nerve, and fascia iliaca compartment blocks were most commonly used in arthroscopic hip surgery, while femoral nerve, 3-in-1, and adductor canal blocks were preferred for arthroscopic knee surgery. Each block demonstrated a significant benefit (P > .05) in ≥1 of the following outcomes: intraoperative morphine, pain scores, nausea, and/or opioid consumption. Combination blocks including the lateral femoral cutaneous nerve block, obturator nerve block, quadratus lumborum block, and L1 and L2 paravertebral block have also been described. Complication rates ranged from 0% to 4.8% in those administered with ultrasound guidance. The most commonly reported complications included muscular weakness, postoperative falls, neuropathy, intravascular and intraneural injections, and hematomas.

CONCLUSION

When administered properly, PNBs were a safe and effective adjuvant method of pain control with a significant potential to limit postoperative narcotic use. While blockade choice varies by surgeon preference and procedure, all PNBs should be administered with ultrasound guidance, and vigilant protocols for the risk of postoperative falls should be exercised in patients who receive them.

Retrospective Single-Center Comparative Analysis of Ultrasound-Guided Versus Non-ultrasound-Guided Nerve Blocks in Extremity Surgeries

OBJECTIVES

Although ultrasound-guided peripheral nerve blocks have become increasingly popular, it is arguable at present whether ultrasound guidance is a necessary tool for peripheral nerve blocks. The purpose of this study was to assess the significance of ultrasound-guided peripheral nerve blocks in reducing complications.

METHODS

From January 2013 to January 2019, 17,823 patients who underwent peripheral nerve blocks with/without ultrasound guidance were reviewed, recording data on their age, sex, height, weight, American Society of Anesthesiologists, block type, operation type, operation duration, and complications. The patients were divided into 2 groups: 9372 cases with ultrasound guidance (US Group) and 8451 cases without ultrasound guidance (No-US Group). To control selection bias, a total of 16,236 patients were finally included in this study after 1:1 propensity score matching, including 8118 cases in the US Group and 8118 cases in the No-US Group. Outcome measures included local anesthetic systemic toxicity (LAST), nerve injury, incomplete block anesthesia (IBA), local hematoma, and infection at the block site.

RESULTS

Baseline characteristics of patients were similar between the two groups (P >.05, respectively). Our study revealed that the incidence of infection was similar between the two groups (P >.05). However, the incidences of LAST, nerve injury, IBA, and local hematoma in the US Group were significantly lower than those in the No-US Group (P <.05, respectively).

CONCLUSIONS

Our findings suggest that ultrasound-guided peripheral nerve blocks are associated with fewer complications and higher success rates, compared with the paresthesia approach.

High-Impact Clinical Studies That Fomented New Developments in Anesthesia: History of Achievements, 1966-2015

The aim of this work is to identify the most influential initial clinical studies that fomented important developments in anesthesiology over the past 50 years. Studies fomenting new development can be selected using vastly different approaches and, therefore, might provide diverse outcomes. In the present work, two basic aspects of study assessments – the stage of development (eg, generation of idea, preclinical studies, clinical trials) and the method of selection (eg, committee vote, various types of citation analysis, method of finding the invention disclosure) – were chosen according to the following model. The stage of development: the initial clinical studies demonstrating the basic advantage of an innovation for providing anesthesia. The method: a combination of two factors – the study priority in terms of the time of its publication and the degree of its acknowledgement in the form of citation impact; the time of study publication was regarded as a primary factor, but only if the study’s citation count was =/>20. The initial high-impact studies were selected for 16 drug-related topics (ketamine, isoflurane, etomidate, propofol, midazolam in anesthesia, vecuronium, alfentanil, atracurium, sevoflurane, sufentanil, rocuronium, desflurane, ropivacaine, remifentanil, dexmedetomidine in anesthesia, and sugammadex), and 9 technique-related topics (ultrasound-guided peripheral nerve block, capnography in anesthesia, target-controlled intravenous anesthesia, pulse oximetry in anesthesia, total intravenous anesthesia, transesophageal echocardiography in anesthesia, combined spinal-epidural anesthesia, and bispectral index). Twenty-five studies were designated the first high-impact studies (one for each topic); 16 are drug-related and 9 are technique-related. Half of the first high-impact studies had a citation count of =/>100, (range: 100 to 555). The citation count of the other half of high-impact studies did not reach the 100-citation threshold (range: 41 to 97). If a selected first high-impact study had a citation count <100, a next-on-timeline, additional study with citation count =/>100 was also selected; (range: 100 to 344). The present results show that an initial high-impact clinical study on a new development in anesthesiology can be determined and that related citations usually vary from one hundred to five hundred.

Ultrasound-guided regional anaesthesia in foot and ankle surgery

The use of regional anaesthesia in foot and ankle surgery is becoming well recognised, particularly in patients who prefer to stay awake during the procedure and for better post-operative analgesia. Its use is ideal for patients with multiple co-morbidities, in whom general anaesthesia (GA) otherwise would could be challenging. The procedures performed with landmark/anatomical guidance alone carry a relatively higher risk of complications, risk of inadvertant injection into the intarvascualr space leadinf to local anaesthetic toxicity, the majority of which complications are caused by incorrect placement of the needle. Hence, ultrasound guidance is frequently used to minimise those risks. Although various regional anaesthetic techniques for foot and ankle surgery have been described, their comprehensive review is lacking. This manuscript aims to fulfil this void. The focus will be on the peripheral methods of regional anaesthesia including the plexus and single nerve blocks. Various techniques with their benefits and potential complications will be discussed. In addition, the evidence on the efficacy of an ultrasound-guided approach as well as its cost implications will be explored. There are significant considerations in deciding whether to implement this technique in routine clinical practice and this review aims to summarise the available literature to establish the evidence base behind it.

Mini-invasive methods of treatment of diabetic foot pain

Neuropathic pain occurs with diabetic polyneuropathy more often than with all polyneuropathies of another etiology. Because the cause of pain can rarely be cured, treatment is usually symptomatic. Neuropathic pain is usually poorly controlled by analgesics. Management of neuropathic pain is started with conservative pharmacotherapy before invasive pain management is applied. Although there are many drugs that can be used in patients with diabetic pain syndrome, pain syndrome can not be surely stoped with monotherapy. In addition, the patient may not tolerate the full therapeutic dose of the drug. All this dictates the need for combination therapy. It is believed that regional anesthesia as an independent type of analgesia or a component of combined anesthesia is the method of choice for the elderly and senile patients. The main reasons for this choice, when comparing regional anesthesia with narcosis, are less stressful response of the organism, absence of depression of the central nervous system, stable reliable analgesia with complete blockade of nociceptive reflexes with the provision of adequate muscle relaxation, prevention of neurovegetative reactions, which ultimately helps to reduce the incidence of postoperative complications and mortality. Clinicians have accumulated considerable experience demonstrating the need for regional analgesia in the management of diabetic foot pain.

Analysis of previous training with simulated models on the success rate of ultrasound-guided supraclavicular block. Prospective cohort study

INTRODUCTION

The teaching based on simulation and acquisition of skills is changing the paradigm of education and restructuring the clinical residences, with the aim of acquiring better skills, increasing procedural success, reducing complications, as well as providing safe, effective, and efficient and focused care of the patient. Peripheral nerve blocks have advanced as techniques for anatomical repairs, use of neurostimulator, and ultrasound. The posgraduate anaesthesiology program implemented a teaching program that included phases of theoretical teaching, training with simulated models, and application in real scenarios.

OBJECTIVE

To analyse the success, the management of the ultrasound equipment and the incidence of complications of ultrasound-guided supraclavicular blocks (BSE) in the clinical scenario, performed by residents of anaesthesiology previously trained with a theoretical and simulated model.

METHODS

Prospective cohort study among residents of anaesthesiology (R1, R2, R3, R4), who received previous theoretical-practical training on simulated models. The evaluation was performed by expert anaesthesiologists, with video analysis of the ultrasound screen performed at the time of BSE initiation.

RESULTS

The evaluation included 16 residents, who performed 156 BSE. None had previous experience in ultrasound-guided blocks. The success of the block was 96.15%. The team management was excellent (from 86% to 95%), with no significant differences among the residents. (P=.61) The incidence of complications was 0.64%, corresponding to arterial puncture.

CONCLUSIONS

In BSE, previous training with a theoretical and simulated model could increase the probability of success and reduce complications. With adequate training, first year residents managed to successfully carry out the procedure.

The use of ultrasound guidance for perioperative neuraxial and peripheral nerve blocks in children

BACKGROUND

The use of ultrasound guidance for regional anaesthesia has become popular over the past two decades. However, it is not recognized by all experts as an essential tool, perhaps because it is unclear whether ultrasound reduces the risk of severe neurological complications, and the cost of an ultrasound machine (USD 22,000) is substantially higher than the cost of other tools. This review was published in 2016 and updated in 2019.

OBJECTIVES

To determine whether ultrasound guidance offers any clinical advantage when neuraxial and peripheral nerve blocks are performed in children in terms of decreasing failure rate or the rate of complications.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and two trial registers up to March 2018 together with reference checking to identify additional studies and contacted study authors to obtain additional trial information.

SELECTION CRITERIA

We included all parallel randomized controlled trials that evaluated the effects of ultrasound guidance used when a regional blockade technique was performed in children. We included studies performed in children (≤ 18 years of age) undergoing any type of surgical procedure (open or laparoscopic), for which a neuraxial (spinal, epidural, caudal, or combined spinal and epidural) or peripheral nerve block (any peripheral nerve block including fascial (fascia iliaca, transversus abdominis plane, rectus sheath blocks) or perivascular blocks), for surgical anaesthesia (alone or in combination with general anaesthesia) or for postoperative analgesia, was performed with ultrasound guidance. We excluded studies in which regional blockade was used to treat chronic pain.We included studies in which ultrasound guidance was used to perform the technique in real time (in-plane or out-of-plane), as pre-scanning before the procedure or to evaluate the spread of the local anaesthetic so the position of the needle could be adjusted or the block complemented. For control groups, any other technique used to perform the block including landmarks, loss of resistance (air or fluid), click, paraesthesia, nerve stimulator, transarterial, or infiltration was accepted.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. Our primary outcomes were failed blocks, pain scores at one hour after surgery, and block duration. Secondary outcomes included time to perform the block, number of needle passes, and minor and major complications. We used GRADE to assess the quality of evidence for each outcome.

MAIN RESULTS

We included 33 trials with a total of 2293 participants from 0.9 to 12 (mean or median) years of age. Most trials were at low risk of selection, detection, attrition, and reporting bias, however the lack of blinding of participants and personnel caring for participants resulted in 25 trials being judged as at high or unclear risk of bias. We identified five ongoing trials.Ultrasound guidance probably reduces the risk of failed block (risk difference (RD) -0.16, 95% confidence interval (CI) -0.25 to -0.07; 22 trials; 1789 participants; moderate-quality evidence). When ultrasound guidance was used, there was a small to moderate reduction in pain one hour after surgery, equivalent to a reduction of 1.3 points on the revised Bieri FACES pain scale (scale; 0 = no pain, 10 = maximal pain) (standardized mean difference (SMD) -0.41, 95% CI -0.74 to -0.07 (medium effect size); 15 trials; 982 participants; moderate-quality evidence). Ultrasound guidance increases block duration by the equivalent of 42 minutes (SMD 1.24, 95% CI 0.72 to 1.75; 10 trials; 460 participants; high-quality evidence).There is probably little or no difference in the time taken to perform the block (SMD -0.46, 95% CI -1.06 to 0.13; 9 trials; 680 participants; moderate-quality evidence). It is uncertain whether the number of needle passes required is reduced with the use of ultrasound guidance (SMD -0.63, 95% CI -1.08 to -0.18; 3 trials; 256 participants; very low-quality evidence).There were no occurrences of major complications in either the intervention or control arms of the trials (cardiac arrest from local anaesthetic toxicity (22 trials; 1576 participants; moderate-quality evidence); lasting neurological injury (19 trials; 1250 participants; low-quality evidence)).There may be little of no difference in the risk of bloody puncture (RD -0.02, 95% CI -0.05 to 0.00; 13 trials; 896 participants; low-quality evidence) or transient neurological injury (RD -0.00, 95% CI -0.01 to 0.01; 18 trials; 1230 participants; low-quality evidence). There were no occurrences of seizure from local anaesthetic toxicity (22 trials; 1576 participants; moderate-quality evidence) or block infections without neurological injury (18 trials; 1238 participants; low-quality evidence).

AUTHORS' CONCLUSIONS

Ultrasound guidance for regional blockade in children probably decreases the risk of failed block. It increases the duration of the block and probably decreases pain scores at one hour after surgery. There may be little or no difference in the risks of some minor complications. The five ongoing studies may alter the conclusions of the review once published and assessed.

The Principles and Procedures of Ultrasound-guided Anesthesia Techniques

For inexperienced users, training with phantoms is an important part of training. Inexperienced users can teach themselves to gain significant procedural skills. Participating in training courses or practising with experts can enhance the outcomes. Inexperienced users need to understand the indications, clinical pearls, and pitfalls of each procedure to avoid potential complications. Inexperienced users can also train and teach themselves to become proficient in ultrasound techniques.

Comparison of Ultrasound with Peripheral Nerve Stimulator-guided Technique for Supraclavicular Block in Upper Limb Surgeries: A Randomized Controlled Trial

Background:

The supraclavicular approach is considered to be the easiest and most effective approach to block the brachial plexus for upper limb surgeries. The classical approach using the anatomical landmark technique was associated with higher failure rates and complications. Ultrasonography (USG) guidance and peripheral nerve stimulator (PNS) have improved the success rates and safety margin.

Aims:

The aim of the present study is to compare USG with PNS in supraclavicular brachial plexus block for upper limb surgeries with respect to the onset of motor and sensory blockade, total duration of blockade, procedure time, and complications.

Settings and Design:

Prospective, randomized controlled study.

Subject and Methods:

Sixty patients aged above 18 years scheduled for elective upper limb surgery were randomly allocated into two groups. Group A patients received supraclavicular brachial plexus block under ultrasound guidance and in Group B patients, PNS was used. In both groups, local anesthetic mixture consisting of 15 ml of 0.5% bupivacaine and 10 ml of 2% lignocaine with 1:200,000 adrenaline were used.

Statistical Analysis:

Independent t-test used to compare mean between groups; Chi-square test for categorical variables.

Results:

The procedure time was shorter with USG (11.57 ± 2.75 min) compared to PNS (21.73 ± 4.84). The onset time of sensory block (12.83 ± 3.64 min vs. 16 ± 3.57 min) and onset of motor block (23 ± 4.27 min vs. 27 ± 3.85 min) were significantly shorter in Group A compared to Group B (P < 0.05). The duration of sensory block was significantly prolonged in Group A (8.00 ± 0.891 h) compared to Group B (7.25 ± 1.418 h). None of the patients in either groups developed any complications.

Conclusion:

The ultrasound-guided supraclavicular brachial plexus block can be done quicker, with a faster onset of sensory and motor block compared to nerve stimulator technique.

Cervical vertebroplasty under sedoanalgesia using combined ultrasonography and fluoroscopy guidance: a novel technique

PURPOSE

The aim of this report was to describe a case using combined USG and fluoroscopy for cervical VP via a percutaneous route under sedoanalgesia.

METHODS

A 70-year-old male patient had severe neck pain for 6 weeks because of metastatic mass lesions in C6. After the decision to VP, the patient was placed on the operating table and 2 mg midazolam and 75 µg fentanyl were administered for conscious sedation. Localisation of the carotid artery, internal jugular vein, and trachea had been determined with USG. 3 mL of 2% lidocaine was infiltrated after proceeding a needle from the axis of the trochar to the C6 vertebra corpus. The trochar entered into the vertebra corpus between the carotid artery and trachea right-antero-laterally under C-arm and USG guidance. 6 mL of PMMA was injected into this field. Then C6 VP procedure had been completed without complications.

RESULTS

This case has three differences from studies in the literature. First, cervical VP was conducted under sedoanalgesia. The second important feature of this case is that cervical VP was performed via a percutaneous route. A third important feature of this case is that it was performed under USG guidance for the first time in the literature.

CONCLUSION

We consider that the combined use of C-arm fluoroscopy and USG should improve success rates and prevent vascular and neural injuries and dura perforation.

Assessing advances in regional anesthesia by their portrayals in meta-analyses: an alternative view on recent progress

BACKGROUND

The aim of this study was to delineate research reflecting advances in regional/local anesthesia where recent clinical progress was clearly defined by meta-analysis.

METHODS

We conducted a search to identify all articles with meta-analyses of randomized clinical trials related to the field of regional/local anesthesia. From 279 titles, after multiple exclusions, 16 meta-analyses on important clinical practice developments with high potential for a positive conclusion on the effectiveness of the treatment were left for the assessment. The assessment was performed in two steps. The first step was related to verification of proof-of-concept: the effect is statistically reliable (p-value, effect size, heterogeneity across different RCTs) and the risk of bias not too high. The second step was devoted to attempts to form an opinion on the real clinical benefits of a new development.

RESULTS

The assessment revealed that seven recent developments passed the proof-of-concept step. At the same time, positive conclusion on real clinical benefits was reached only by one of these seven developments: ultrasound guidance for peripheral nerve blocks (at least with some of the blocks). Meaningful clinical improvements with other developments remains uncertain. The assessment of the relationships between analyzed advancements over the past 30 years and earlier similar developments indicated that their evolution was usually incremental. The most original advancement was found to be the introduction of the transversus abdominis plane block.

CONCLUSION

The assessment of recent advances in regional/local anesthesia, based on the evaluation of related meta-analyses, revealed only incremental progress with mostly marginal benefits. The progress was the most notable with ultrasound guidance for some of peripheral nerve blocks.

Intraoperative lung ultrasound: A clinicodynamic perspective

In the era of evidence-based medicine, ultrasonography has emerged as an important and indispensable tool in clinical practice in various specialties including critical care. Lung ultrasound (LUS) has a wide potential in various surgical and clinical situations for timely and easy detection of an impending crisis such as pulmonary edema, endobronchial tube migration, pneumothorax, atelectasis, pleural effusion, and various other causes of desaturation before it clinically ensues to critical level. Although ultrasonography is frequently used in nerve blocks, airway handling, and vascular access, LUS for routine intraoperative monitoring and in crisis management still necessitates recognition. After reviewing the various articles regarding the use of LUS in critical care, we found, that LUS can be used in various intraoperative circumstances similar to Intensive Care Unit with some limitations. Except for few attempts in the intraoperative detection of pneumothorax, LUS is hardly used but has wider perspective for routine and crisis management in real-time. If anesthesiologists add LUS in their routine monitoring armamentarium, it can assist to move a step ahead in the dynamic management of critically ill and high-risk patients.

The use of ultrasound guidance for perioperative neuraxial and peripheral nerve blocks in children

BACKGROUND

The use of ultrasound guidance for regional anaesthesia has become popular over the past two decades. However, it is not recognized by all experts as an essential tool. The cost of an ultrasound machine is substantially higher than the cost of other tools such as a nerve stimulator.

OBJECTIVES

To determine whether ultrasound guidance offers any clinical advantage when neuraxial and peripheral nerve blocks are performed in children in terms of increasing the success rate or decreasing the rate of complications.

SEARCH METHODS

We searched the following databases to March 2015: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (OvidSP), EMBASE (OvidSP) and Scopus (from inception to 27 January 2015).

SELECTION CRITERIA

We included all parallel randomized controlled trials (RCTs) that evaluated the effects of ultrasound guidance used when a regional blockade technique was performed in children, and that included any of our selected outcomes.

DATA COLLECTION AND ANALYSIS

We assessed selected studies for risk of bias by using the assessment tool of The Cochrane Collaboration. Two review authors independently extracted data. We graded the level of evidence for each outcome according to the GRADE (Grades of Recommendation, Assessment, Development and Evaluation) Working Group scale.

MAIN RESULTS

We included 20 studies (1241 participants) for which the source of funding was a government organization (two studies), a charitable organization (one study), an institutional department (four studies) or an unspecified source (11 studies); two studies declared that they received help from the industry (equipment loan). In 14 studies (939 participants), ultrasound guidance increased the success rate by decreasing the occurrence of a failed block: risk difference (RD) -0.11 (95% confidence interval (CI) -0.17 to -0.05); I(2) = 64%; number needed for additional beneficial outcome for a peripheral nerve block (NNTB) 6 (95% CI 5 to 8). Blocks were performed under general anaesthesia (usual clinical practice in this population); therefore, haemodynamic changes to the surgical stimulus (rather than classic sensory/motor blockade evaluation) were used to define success. For peripheral nerve blocks, the younger the child, the greater was the benefit. In eight studies (414 participants), pain scores at one hour in the post-anaesthesia care unit were reduced when ultrasound guidance was used; however, the clinical relevance of the difference was unclear (equivalent to -0.2 on a scale from 0 to 10). In eight studies (358 participants), block duration was longer when ultrasound guidance was used: standardized mean difference (SMD) 1.21 (95% CI 0.76 to 1.65; I(2) = 73%; equivalent to 62 minutes). Here again, younger children benefited most from ultrasound guidance. Time to perform the procedure was reduced when ultrasound guidance was used for pre-scanning before a neuraxial block (SMD -1.97, 95% CI -2.41 to -1.54; I(2) = 0%; equivalent to 2.4 minutes; two studies with 122 participants) or as an out-of-plane technique (SMD -0.68, 95% CI -0.96 to -0.40; I(2) = 0%; equivalent to 94 seconds; two studies with 204 participants). In two studies (122 participants), ultrasound guidance reduced the number of needle passes required to perform the block (SMD -0.90, 95% CI -1.27 to -0.52; I(2) = 0%; equivalent to 0.6 needle pass per participant). For two studies (204 participants), we could not demonstrate a difference in the incidence of bloody puncture when ultrasound guidance was used for neuraxial blockade, but we found that the number of participants was well below the optimal information size (RD -0.07, 95% CI -0.19 to 0.04). No major complications were reported for any of the 1241 participants. We rated the quality of evidence as high for success, pain scores at one hour, block duration, time to perform the block and number of needle passes. We rated the quality of evidence as low for bloody punctures.

AUTHORS' CONCLUSIONS

Ultrasound guidance seems advantageous, particularly in young children, for whom it improves the success rate and increases the block duration. Additional data are required before conclusions can be drawn on the effect of ultrasound guidance in reducing the rate of bloody puncture.

Feature extraction and classification for ultrasound images of lumbar spine with support vector machine

In this paper, we proposed a feature extraction and machine learning method for the classification of ultrasound images obtained from lumbar spine of pregnant patients in the transverse plane. A group of features, including matching values and positions, appearance of black pixels within predefined windows along the midline, are extracted from the ultrasound images using template matching and midline detection. Support vector machine (SVM) with Gaussian kernel is utilized to classify the bone images and interspinous images with optimal separation hyperplane. The SVM is trained with 800 images from 20 pregnant subjects and tested with 640 images from a separate set of 16 pregnant patients. A high success rate (97.25% on training set and 95.00% on test set) is achieved with the proposed method. The trained SVM model is further tested on 36 videos collected from 36 pregnant subjects and successfully identified the proper needle insertion site (interspinous region) on all of the cases. Therefore, the proposed method is able to identify the ultrasound images of lumbar spine in an automatic manner, so as to facilitate the anesthetists' work to identify the needle insertion point precisely and effectively.

Preoperative transcutaneous electrical nerve stimulation for localizing superficial nerve paths

During surgery, peripheral nerves are often seen to follow unpredictable paths because of previous surgeries and/or compression caused by a tumor. Iatrogenic nerve injury is a serious complication that must be avoided, and preoperative evaluation of nerve paths is important for preventing it. In this study, transcutaneous electrical nerve stimulation (TENS) was used for an in-depth analysis of peripheral nerve paths. This study included 27 patients who underwent the TENS procedure to evaluate the peripheral nerve path (17 males and 10 females; mean age: 59.9 years, range: 18-83 years) of each patient preoperatively. An electrode pen coupled to an electrical nerve stimulator was used for superficial nerve mapping. The TENS procedure was performed on patients' major peripheral nerves that passed close to the surgical field of tumor resection or trauma surgery, and intraoperative damage to those nerves was apprehensive. The paths of the target nerve were detected in most patients preoperatively. The nerve paths of 26 patients were precisely under the markings drawn preoperatively. The nerve path of one patient substantially differed from the preoperative markings with numbness at the surgical region. During surgery, the nerve paths could be accurately mapped preoperatively using the TENS procedure as confirmed by direct visualization of the nerve. This stimulation device is easy to use and offers highly accurate mapping of nerves for surgical planning without major complications. The authors conclude that TENS is a useful tool for noninvasive nerve localization and makes tumor resection a safe and smooth procedure.

Lumbar Ultrasound Image Feature Extraction and Classification with Support Vector Machine

Needle entry site localization remains a challenge for procedures that involve lumbar puncture, for example, epidural anesthesia. To solve the problem, we have developed an image classification algorithm that can automatically identify the bone/interspinous region for ultrasound images obtained from lumbar spine of pregnant patients in the transverse plane. The proposed algorithm consists of feature extraction, feature selection and machine learning procedures. A set of features, including matching values, positions and the appearance of black pixels within pre-defined windows along the midline, were extracted from the ultrasound images using template matching and midline detection methods. A support vector machine was then used to classify the bone images and interspinous images. The support vector machine model was trained with 1,040 images from 26 pregnant subjects and tested on 800 images from a separate set of 20 pregnant patients. A success rate of 95.0% on training set and 93.2% on test set was achieved with the proposed method. The trained support vector machine model was further tested on 46 off-line collected videos, and successfully identified the proper needle insertion site (interspinous region) in 45 of the cases. Therefore, the proposed method is able to process the ultrasound images of lumbar spine in an automatic manner, so as to facilitate the anesthetists' work of identifying the needle entry site.

An evaluation of brachial plexus block using a nerve stimulator versus ultrasound guidance: A randomized controlled trial

Background and Aims:

This study was carried out to evaluate the difference in efficacy, safety, and complications of performing brachial plexus nerve blocks by using a nerve locator when compared to ultrasound (US) guidance.

Material and Methods:

A total of 102 patients undergoing upper limb surgery under supraclavicular brachial plexus blocks were randomly divided into two groups, one with US and the other with nerve stimulator (NS). In Group US, “Titan” Portable US Machine, Sonosite, Inc. Kensington, UK with a 9.0 MHz probe was used to visualize the brachial plexus and 40 ml of 0.25% bupivacaine solution was deposited around the brachial plexus in a graded manner. In Group (NS), the needle was inserted 1-1.5 cm above mid-point of clavicle. Once hand or wrist motion was detected at a current intensity of less than 0.4 mA 40 ml of 0.25% bupivacaine was administered. Onset of sensory and motor block of radial, ulnar and median nerves was recorded at 5-min intervals for 30-min. Block execution time, duration of block (time to first analgesic), inadvertent vascular puncture, and neurological complications were taken as the secondary outcome variables.

Results:

About 90% patients in US group and 73.1% in NS group, had successful blocks P = 0.028. The onset of block was faster in the Group US as compared to Group NS and this difference was significant (P 0.007) only in the radial nerve territory. The mean duration of the block was longer in Group US, 286.22 ± 42.339 compared to 204.37 ± 28.54-min in Group NS (P < 0.05). Accidental vascular punctures occurred in 7 patients in the NS group and only 1 patient in the US group.

Conclusion:

Ultrasound guidance for supraclavicular brachial plexus blockade provides a block that is faster in onset, has a better quality and lasts longer when compared with an equal dose delivered by conventional means.

Automatic identification of needle insertion site in epidural anesthesia with a cascading classifier

Ultrasound imaging was used to detect the anatomic structure of lumbar spine from the transverse view, to facilitate needle insertion in epidural anesthesia. The interspinous images that represent proper needle insertion sites were identified automatically with image processing and pattern recognition techniques. On the basis of ultrasound video streams obtained in pregnant patients, the image processing and identification procedure in a previous work was tested and improved. The test results indicate that the pre-processing algorithm performs well on lumbar spine ultrasound images, whereas the classifier is not flexible enough for pregnant patients. To improve the accuracy of identification, we propose a cascading classifier that successfully located the proper needle insertion site on all of the 36 video streams collected from pregnant patients. The results indicate that the proposed image identification procedure is able to identify the ultrasound images of lumbar spine in an automatic manner, so as to facilitate the anesthetists' work to identify the needle insertion point precisely and effectively.

A low cost, high fidelity nerve block model

Background

We have constructed a simple, inexpensive simulation model for ultrasound guided nerve blocks. To date there are no low cost, high fidelity models for nerve block simulations. The models that do exist are expensive and vaguely resemble actual anatomy. As ultrasound guided nerve blocks become more common in medical education it is essential to develop better training models to help increase the comfort level of the individual provider and increase the chances for success during live-patient procedures [Anaesth Intensive Care 37: 824-829, 2009].

Methods

The nerve block model was produced with a single pork loin with pressure-injected ultrasound gel through both CAT 5 cable and IV tubing inserted length-wise into the pork loin.

Results

Our nerve block model had a realistic, life-like feel simulating human tissue.

Conclusion

This ultrasound nerve block model was inexpensive with life-like feel allowing resident trainees to develop more confidence and tactile skill to increase the chance for success.

Review of essential understanding of ultrasound physics and equipment operation

Ultrasound (US) is being extensively used an imaging tool in regional anesthesia (RA) and pain practice. Although it was first used in a regional block in 1978, it was only in 1994 that the first direct use of US in RA was reported. Like any other medical tool, its utility is only realized when the performing physician is able to understand the principles behind its application. Efficient use of US also requires an understanding of physical variables which can be suitable modified to produce a clear image of the structure of importance. This brief narrative review summarises the advantages of US in RA and pain practice over the conventionally used localising or imaging tools. The second section deals with the physics behind US. It highlights the necessary physical concepts such as wavelength, frequency and generation of US waves. It also informs the reader about the possible US and tissue interactions, use of US transducers and their differences. The third section deals with understanding the control variables in a typical US machine and how they could be modified to improve the image quality. The final section highlights the various artifacts that could be associated.

Efficacy of popliteal block in postoperative pain control after ankle fracture fixation: a prospective randomized study

OBJECTIVES

To compare postoperative pain control in patients treated surgically for ankle fractures who receive popliteal blocks with those who received general anesthesia alone.

DESIGN

Institutional Review Board approved prospective randomized study.

SETTING

Metropolitan tertiary-care referral center.

PATIENTS

All patients being treated with open reduction internal fixation for ankle fractures who met inclusion criteria and consented to participate were enrolled.

INTERVENTIONS

Patients were randomized to receive either general anesthesia (GETA) or intravenous sedation and popliteal block.

MAIN OUTCOME MEASURES

Patients were assessed for duration of procedure, total time in the operating room, and postoperative pain at 2, 4, 8, 12, 24, and 48 hours after surgery using a visual analog scale.

RESULTS

Fifty-one patients agreed to participate in the study. Twenty-five patients received popliteal block, while 26 patients received GETA. There were no anesthesia-related complications. At 2, 4, and 8 hours postoperatively, patients who underwent GETA demonstrated significantly higher pain. At 12 hours, there was no significant difference between the 2 groups with regard to pain control. However, by 24 hours, those who had received popliteal blocks had significantly higher pain with no difference by 48 hours.

CONCLUSIONS

Popliteal block provides equivalent postoperative pain control to general anesthesia alone in patients undergoing operative fixation of ankle fractures. However, patients who receive popliteal blocks do experience a significant increase in pain between 12 and 24 hours. Recognition of this "rebound pain" with early narcotic administration may allow patients to have more effective postoperative pain control.

Feasibility and safety of ultrasound-guided nerve block for management of limb injuries by emergency care physicians

Background:

Patients require procedural sedation and analgesia (PSA) for the treatment of acute traumatic injuries. PSA has complications. Ultrasound (US) guided peripheral nerve block is a safe alternative.

Aim:

Ultrasound guided nerve blocks for management of traumatic limb emergencies in Emergency Department (ED).

Setting and Design:

Prospective observational study conducted in ED.

Materials and Methods:

Patients above five years requiring analgesia for management of limb emergencies were recruited. Emergency Physicians trained in US guided nerve blocks performed the procedure.

Statistical analysis:

Effectiveness of pain control, using visual analogue scale was assessed at baseline and at 15 and 60 minutes after the procedure. Paired t test was used for comparison.

Results:

Fifty US guided nerve blocks were sciatic- 4 (8%), femoral-7 (14%), brachial- 29 (58%), median -6 (12%), and radial 2 (4%) nerves. No patients required rescue PSA. Initial median VAS score was 9 (Inter Quartile Range [IQR] 7-10) and at 1 hour was 2(IQR 0-4). Median reduction in VAS score was 7.44 (IQR 8-10(75%), 1-2(25%) (P=0.0001). Median procedure time was 9 minutes (IQR 3, 12 minutes) and median time to reduction of pain was 5 minutes (IQR 1,15 minutes). No immediate or late complications noticed at 3 months.

Conclusion:

Ultrasound-guided nerve blocks can be safely and effectively performed for upper and lower limb emergencies by emergency physicians with adequate training.

The validation of ultrasound-guided lumbar facet nerve blocks as confirmed by fluoroscopy

Study Design

This is a prospective study.

Purpose

To develop a methodological approach for conducting ultrasound-guided lumbar facet nerve block by defining essential ultrasound-guided landmarks in order to assess the feasibility of this method.

Overview of Literature

The current role of ultrasound guidance for musculoskeletal intervention treatments has been reported upon in previous literature.

Methods

Ultrasound-guided facet nerve block was done in 95 segments for 50 patients with chronic back pain by facet arthropathy. After the surface landmarks of the spinous process and iliac crest line were confirmed, longitudinal facet views were obtained by a curved array transducer to identify the different spinal segments. The spinous process and facet joint with transverse process were delineated by transverse sonograms at each level and the target point for the block was defined as lying on the upper edge of the transverse process. The needle was inserted toward the target point. After a contrast injection, the placement of the needle and contrast was checked by fluoroscopy.

Results

Eighty-seven segments (91.6%) could be guided successfully to the right facet nerve block by using ultrasound. After fluoroscopic control, 8 needles had to be corrected because of problems with other segments (3 cases) and lamina placements (5 cases). For the 42 patients who underwent successful block by ultrasound, however, the mean visual analogue score for back pain was improved from 6.2 ± 0.9 before the block to 4.0 ± 1.0 after the block (p = 0.001).

Conclusions

Ultrasound-guided longitudinal facet view and the surface landmarks of the spinous process and iliac crest line seems to be a promising guidance technique for the lumbar facet nerve block technique.

Ultrasound-guided nerve blocks in the emergency department

Peripheral nerve blocks preclude the need for procedural sedation and provide adequate anesthesia during painful procedures. This technique can be performed in the emergency department with the aid of ultrasound imaging to identify target nerves. We describe eight cases of upper and lower extremity nerve blocks performed under ultrasound guidance in the emergency department of the Jai Prakash Narayan Trauma Centre, All India Institute of Medical Sciences, New Delhi. Only two of the patients, both with extensive injuries, required any additional anesthesia during the subsequent procedures and all of them reported significant pain control and muscle relaxation.

Ultrasound in obstetric anaesthesia: a review of current applications

Ultrasound equipment is increasingly used by non-radiologists to perform interventional techniques and for diagnostic evaluation. Equipment is becoming more portable and durable, with easier user-interface and software enhancement to improve image quality. While obstetric utilisation of ultrasound for fetal assessment has developed over more than 40years, the same technology has not found a widespread role in obstetric anaesthesia. Within the broader specialty of anaesthesia; vascular access, cardiac imaging and regional anaesthesia are the areas in which ultrasound is becoming increasingly established. In addition to ultrasound for neuraxial blocks, these other clinical applications may be of value in obstetric anaesthesia practice.

Fifteen years of ultrasound guidance in regional anaesthesia: part 1

Ultrasound guidance for regional anaesthesia has gained enormous popularity in the past decade. The use of ultrasound guidance for many regional anaesthetic techniques is common in daily clinical practice, and the number of practitioners using it is increasing. However, alongside the enthusiasm, there should be a degree of informed scepticism. The widespread use of the various techniques of ultrasound-guided regional blocks without adequate training raises the danger of malpractice and subsequent impaired outcome. Adequate education in the use of regional block techniques under ultrasound guidance is essential. This review article addresses ultrasound guidance for regional anaesthesia, and is divided into two parts because of the size of the topic and the number of issues covered. This first part includes a review and preview of ultrasound guidance in regional anaesthesia and discusses all aspects of ultrasound for regional anaesthesia with a focus on recent technical developments, the positive implications in economics, further potential advantages (e.g. detection of anatomical variants, painless performance of blocks) and education. It also attempts to define a 'gold standard' in regional anaesthesia with the most recent findings in adequate volumes of local anaesthetics for peripheral nerve blocks. This standard should include an extraneural needle position, a high success rate, and wide application of ultrasound guidance in regional anaesthesia. The second part describes the impact of ultrasound on the development of nerve block techniques in the past 5 yr.

Ultrasound-guided nerve blocks: efficacy and safety

The introduction of affordable, portable and high-resolution ultrasound machines has rejuvenated interest in regional anaesthesia. The inherent benefits of direct visualisation of nerves and surrounding anatomy, continual observation of the needle tip and spread of local anaesthetic make ultrasound-guided regional anaesthesia highly appealing. However, in the cost-conscious health-care setting and to convince sceptics, there also needs to be evidence of increased benefits and reduced complications. Ultrasound is a rapidly developing area of technology and some of the newer modalities are discussed. This article focusses on the recent growing evidence to support the benefits of its use in nerve and plexus blocks. Common complications of nerve blocks can be avoided with ultrasound but have still been reported. Anatomical variants have been demonstrated by ultrasound and it has proved to be useful in performing regional anaesthesia in difficult situations or where peripheral nerve stimulation is unsuccessful or inappropriate.