Ultrasound-Guided Regional Anaesthesia: Visualising the Nerve and Needle.

Regional anaesthesia involves targeting specific peripheral nerves with local anaesthetic. It facilitates the delivery of anaesthesia and analgesia to an increasingly complex, elderly and co-morbid patient population. Regional anaesthesia practice has been transformed by the use of ultrasound, which confers advantages such as accuracy of needle placement, visualisation of local anaesthetic spread, avoidance of intraneural injection and the ability to accommodate for anatomical variation.An US beam is generated by the application of electrical current to an array of piezoelectric crystals, causing vibration and consequential production of high-frequency sound waves. The sound energy is reflected at tissue interfaces, detected by the piezoelectric crystals in the ultrasound probe, and most frequently displayed as a 2D image.Optimising image acquisition involves selection of the appropriate US frequency: this represents a trade-off between image resolution (better with high frequency) and tissue penetration/beam attenuation (better with low frequency). Altering alignment, rotation and tilt of the probe is often required to optimise the view as nerves are best visualised when the ultrasound beam is directly perpendicular to their fibres. Adjusting the focus, depth, and gain (brightness) of the image display can also help in this matter.Three key challenges exist in regional anaesthesia; image optimisation, image interpretation (nerve visualisation) and needle visualisation. There are characteristic sonographic appearances of the nerve structures for peripheral nerve blocks, as discussed in this chapter, and the above techniques can be used to enhance their appearance. Much research has been done, and is ongoing, with the aim of improving needle visualisation; this is also reviewed. Image interpretation requires the application of anatomical knowledge and understanding of the typical sonographic appearance of different tissues (as well as the needle). Years of practice are required to attain expertise, although it is hoped that continuing advances in nerve and needle visualisation, as described in this chapter, will expedite that process.

Anesthesia management for low-grade glioma awake surgery: a European Low-Grade Glioma Network survey.

BACKGROUND: Awake surgery has become a key treatment of diffuse low-grade gliomas (DLGG) and is divided in three main phases: opening, tumor resection - during which the patient needs to be fully awake - and closure. The anesthetic management of awake neurosurgery is a challenge, and there are currently no guidelines. OBJECTIVE: The objective of the survey was to explore differences and commonalities regarding the anesthetic management of awake DLGG surgery within the European Low-Grade Glioma Network (ELGGN) centers. METHODS: A form that contained 14 questions about the anesthetic management was sent to 28 centers in May 2015. RESULTS: Twenty centers responded. During the opening and closing non-awake periods, 56% of teams chose general anesthesia with mechanical ventilation for at least one period (asleep-awake-asleep, SAS protocol), and 44% monitored anesthesia care including sedation without mechanical ventilation (MAC protocol). In case of SAS, all the teams chose intravenous anesthesia, 82% used laryngeal mask instead of endotracheal intubation during the opening sequence, and 71% during closure. Local and regional anesthesia was practiced by all the teams. The most frequently reported cause of pain was dural and cerebral vessels manipulation (77%). Pain management was mostly based on paracetamol (70%) and remifentanil (55%). CONCLUSION: Our survey showed that there was an equivalent proportion of centers using SAS or MAC protocols in the anesthetic management of awake surgery in ELGGN centers. The advantages and disadvantages of each anesthesia protocol were reviewed.

Vulnerability of different nerves to intrafascicular injection by different needle types and at different approach angles: a mathematical model.

BACKGROUND AND OBJECTIVES: We assume that intrafascicular spread of a solution can only occur if a large enough portion of the distal needle orifice is placed inside the fascicle. Our aim is to present and evaluate a mathematical model that can calculate the theoretical vulnerability of fascicles, analyzing the degree of occupancy of the needle orifice in fascicular tissue by performing simulations of multiple positions that a needle orifice can take inside a cross-sectional nerve area. METHODS: We superimposed microscopic images of two routinely used nerve block needles (22-gauge, 15° needle and 22-gauge, 30° needle) over the microscopic images of cross-sections of four nerve types photographed at the same magnification. Fascicular tissue that was overlapped between 80% and 100% by a needle orifice was considered at risk to possible intrafascicular injection. The effect of three angular approaches was evaluated. RESULTS: There were statistical differences between the vulnerability of fascicular tissue depending on nerve type, the bevel angle of the needle and the angle approach. Fascicular vulnerability was greater in nerve roots of the brachial plexus after using a 22-gauge 30° needle, as was choosing a 45° angle approach to the longitudinal axis of the nerve. CONCLUSIONS: Our results suggest that clinicians may want to consider needle insertion angle and bevel type as they perform peripheral nerve blocks. Furthermore, researchers may want to consider this mathematical model when estimating vulnerabilities of various nerves, needle types and angles of approach of needles to nerves.

An initial evaluation of the effect of a novel regional block needle with tip-tracking technology on the novice performance of cadaveric ultrasound-guided sciatic nerve block.

Visibility of the needle tip is difficult to maintain during ultrasound-guided nerve block. A new needle has been developed that incorporates a piezo element 2-2.3 mm from the tip, activated by ultrasound. The electrical signal manifests as a coloured circle surrounding the needle tip, and allows real-time tracking. We hypothesised that novice regional anaesthetists would perform nerve block better with the tracker turned on rather than off. Our primary objective was to evaluate the new needle by measuring the performance of novice anaesthetists conducting simulated sciatic block on the soft embalmed Thiel cadaver. Training consisted of a lecture, scanning in volunteers and practice on cadavers. Testing entailed scanning the sciatic nerve of a cadaver and conducting 20 in-plane sciatic blocks in the mid-to-upper thigh region. Subjects were randomised equally, in groups of five, according to the sequence: tracker on/off/on/off; or tracker off/on/off/on. Video recordings were assessed by six raters for steps performed correctly and errors committed. Eight subjects were recruited and 160 videos were analysed. Using the tracking needle, five correct steps improved and one error reduced. The benefits included: better identification of the needle tip before advancing the needle, OR (95%CI) 3.4 (1.6-7.7; p < 0.001); better alignment of the needle to the transducer, 3.1 (1.3-8.7; p = 0.009); and better visibility of the needle tip 3.0 (1.4-7.3; p = 0.005). In conclusion, use of the tracker needle improved the sciatic block performance of novices on the soft embalmed cadaver.

Regional Anesthesia for Pediatric Ophthalmic Surgery: A Review of the Literature.

Ophthalmic pediatric regional anesthesia has been widely described, but infrequently used. This review summarizes the available evidence supporting the use of conduction anesthesia in pediatric ophthalmic surgery. Key anatomic differences in axial length, intraocular pressure, and available orbital space between young children and adults impact conduct of ophthalmic regional anesthesia. The eye is near adult size at birth and completes its growth rapidly while the orbit does not. This results in significantly diminished extraocular orbital volumes for local anesthetic deposition. Needle-based blocks are categorized by relation of the needle to the extraocular muscle cone (ie, intraconal or extraconal) and in the cannula-based block, by description of the potential space deep to the Tenon capsule. In children, blocks are placed after induction of anesthesia by a pediatric anesthesiologist or ophthalmologist, via anatomic landmarks or under ultrasonography. Ocular conduction anesthesia confers several advantages for eye surgery including analgesia, akinesia, ablation of the oculocardiac reflex, and reduction of postoperative nausea and vomiting. Short (16 mm), blunt-tip needles are preferred because of altered globe-to-orbit ratios in children. Soft-tip cannulae of varying length have been demonstrated as safe in sub-Tenon blockade. Ultrasound technology facilitates direct, real-time visualization of needle position and local anesthetic spread and reduces inadvertent intraconal needle placement. The developing eye is vulnerable to thermal and mechanical insults, so ocular-rated transducers are mandated. The adjuvant hyaluronidase improves ocular akinesia, decreases local anesthetic dosage requirements, and improves initial block success; meanwhile, dexmedetomidine increases local anesthetic potency and prolongs duration of analgesia without an increase in adverse events. Intraconal blockade is a relative contraindication in neonates and infants, retinoblastoma surgery, and in the presence of posterior staphylomas and buphthalmos. Specific considerations include pertinent pediatric ophthalmologic topics, block placement in the syndromic child, and potential adverse effects associated with each technique. Recommendations based on our experience at a busy academic ophthalmologic tertiary referral center are provided.

Intravenous Regional Anesthesia: A Historical Overview and Clinical Review.

Intravenous regional anesthesia (IVRA) is an established, safe and simple technique, being applicable for various surgeries on the upper and lower limbs. In 1908, IVRA was first described by the Berlin surgeon August Bier, hence the name "Bier's Block". Although his technique was effective, it was cumbersome and fell into disuse when neuroaxial and percutaneous plexus blockades gained widespread popularity in the early 20th century. In the 1960s, it became widespread, when the New Zealand anesthesiologist Charles McKinnon Holmes praised its use by means of new available local anesthetics. Today, IVRA is still popular in many countries being used in the emergency room, for outpatients and for high-risk patients with contraindications for general anesthesia. IVRA offers a favorable risk-benefit ratio, cost-effectiveness, sufficient muscle relaxation and a fast on- and offset. New upcoming methods for monitoring, specialized personnel and improved emergency equipment made IVRA even safer. Moreover, IVRA may be applied to treat complex regional pain syndromes. Prilocaine and lidocaine are considered as first-choice local anesthetics for IVRA. Also, various adjuvant drugs have been tested to augment the effect of IVRA, and to reduce post-deflation tourniquet pain. Since major adverse events are rare in IVRA, it is regarded as a very safe technique. Nevertheless, systemic neuro- and cardiotoxic side effects may be linked to an uncontrolled systemic flush-in of local anesthetics and must be avoided. This review gives a historical overview of more than 100 years of experience with IVRA and provides a current view of IVRA with relevant key facts for the daily clinical routine.

Catheter use in regional anesthesia: pros and cons.

Continuous peripheral nerve blocks refer to a local anesthetic solution administered via perineurally placed catheters in an effort to extend the benefits of a single-shot peripheral nerve block. They offer several advantages in the postoperative period including excellent analgesia, reduced opioid consumption and associated side effects, enhanced rehabilitation and improved patient satisfaction. The current trend towards less invasive, one-day surgery and enhanced recovery programs may decrease the requirement of catheter use. Prolonged motor block in particular is associated with undesirable outcomes. Should we routinely use continuous peripheral nerve blocks in our daily practice? This PRO-CON debate aims at answering the question from the experts' perspectives. Fascial compartment and wound catheters are outside the scope of this debate.

Barriers and facilitators to implementing a regional anesthesia service in a low-income country: a qualitative study.

INTRODUCTION: Regional anesthesia is a safe alternative to general anesthesia. Despite benefits for perioperative morbidity and mortality, this technique is underutilized in low-resource settings. In response to an identified need, a regional anesthesia service was established at the University Teaching Hospital of Kigali (CHUK), Rwanda. This qualitative study investigates the factors influencing implementation of this service in a low-resource tertiary-level teaching hospital. METHODS: Following service establishment, we recruited 18 local staff at CHUK for in-depth interviews informed by the "Consolidated Framework for Implementation Research" (CFIR). Data were coded using an inductive approach to discover emergent themes. RESULTS: Four themes emerged during data analysis. Patient experience and outcomes: where equipment failure is frequent and medications unavailable, regional anesthesia offered clear advantages including avoidance of airway intervention, improved analgesia and recovery and cost-effective care. Professional satisfaction: morale among healthcare providers suffers when outcomes are poor. Participants were motivated to learn techniques that they believe improve patient care. Human and material shortages: clinical services are challenged by high workload and human resource shortages. Advocacy is required to solve procurement issues for regional anesthesia equipment. Local engagement for sustainability: participants emphasized the need for a locally run, sustainable service. This requires broad engagement through education of staff and long-term strategic planning to expand regional anesthesia in Rwanda. CONCLUSION: While the establishment of regional anesthesia in Rwanda is challenged by human and resource shortages, collaboration with local stakeholders in an academic institution is pivotal to sustainability.

A Prototype Patient-Maintained Propofol Sedation System Using Target Controlled Infusion for Primary Lower-Limb Arthroplasty.

Each year, many operations in the UK are performed with the patient awake, without the use of general anaesthesia. These include joint replacement procedures, and in order to reduce patient anxiety, the supervising anaesthetist delivers the sedative propofol intravenously using a target-controlled infusion (TCI) device. However, it is clinically challenging to judge the required effect-site concentration of sedative for an individual patient, resulting in patient care issues related to over or under-sedation. To improve the process, patient-maintained propofol sedation (PMPS), where the patient can request an increase in concentration through a hand-held button, has been considered as an alternative. However, due to the proprietary nature of modern TCI pumps, the majority of PMPS research has been conducted using prototypes in research studies. In this work, a PMPS system is presented that effectively converts a standard infusion pump into a TCI device using a laptop with TCI software. Functionally, the system delivers sedation analogous to a modern TCI pump, with the differences in propofol consumption and dosage within the tolerance of clinically approved devices. Therefore, the Medicines and Healthcare products Regulatory Agency (MHRA) has approved the system as a safe alternative to anaesthetist-controlled TCI procedures. It represents a step forward in the consideration of PMPS as a sedation method as viable alternative, allowing further assessment in clinical trials.

Evaluation of the B-Smart manometer and the CompuFlo computerized injection pump technology for accurate needle-tip injection pressure measurement during peripheral nerve blockade.

BACKGROUND AND OBJECTIVES: The exact mechanism of peripheral nerve blocks causing/leading to nerve injury remains controversial. Evidence from animal experiments suggests that intrafascicular injection resulting in high injection pressure has the potential to rupture nerve fascicles and may consequently cause permanent nerve injury and neurological deficits. The B-Smart (BS) in-line manometer and the CompuFlo (CF) computerized injection pump technology are two modalities used for monitoring pressure during regional anesthesia. This study sought to explore the accuracy of these two technologies in measuring needle-tip pressures in a simulated environment. METHODS: In seven simulated needle-syringe combinations, the BS and the CF devices were connected in series through a closed system and attached to a digital manometer at the tip of various needles. The pressures were evaluated in three trials per needle-syringe combination. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy (F1 Score) were determined for each needle type and overall. RESULTS: For pressures ≥15 psi and ≥20 psi, respectively, the CF device demonstrated a sensitivity of 100%, 100%; specificity of 96%, 98%; positive predictive value 93%, 93%; and negative predictive value of 100%, 100%. The BS device demonstrated a sensitivity of 60%, 100%; specificity of 99%, 95%; positive predictive value of 96%, 85%; and negative predictive value of 85%, 100%. Accuracy, as measured by the F1 Score, for detecting a pressure of ≥15 psi was 0.96 for the CF and 0.74 for the BS. CONCLUSIONS: Future research is needed to explore in-vivo performance and evaluate whether either of these devices can impact on clinical outcomes.

Effect of ultrasound image enhancement software on the quality of vision of regional anesthesia needles.

BACKGROUND: Our objective was to evaluate and compare the visualization of different types of needles with or without ultrasound image enhancement software, both in biological tissues and artificial models. METHODS: This is an observational study on fresh porcine tissue and gelatin models. Six types of plexus needles were studied. The same anesthesiologist performed in-plane punctures with each needle at 30°, 40° and 50° in both 2D mode and using software-based enhanced mode without changing position, generating 72 images. The images were evaluated blind by 38 anesthesiologists with at least two years of experience in ultrasound and rated from 0 to 10. A univariate and multivariate analysis was performed to identify differences between the images according to needle, mode, angle and experimental model. We described the results as mean (standard deviation). RESULTS: The Echoplex needle, 8.31 (1.94), was significantly better than the Sonoplex needle, 7.53 (2.16), P=0.0003, and both were significantly better than the other needles (P<0.0001). Significant differences were also found in favor of the gelatin model, 7.26 (2.48) vs. 6.24 (3.67), P<0.0001, and with ultrasound image enhancement software, 8.59 (1.55) vs. 4.91 (3.31), P<0.0001. These differences were confirmed by multivariate analysis. CONCLUSIONS: Although there are differences between the different types of needles used with ultrasound visualization strategies, ultrasound image enhancement software provides good visualization, regardless of the model chosen.

Superior gluteal nerve: a new block on the block? / Nervo glúteo superior: um novo bloqueio a caminho?

Abstract Background and objectives The superior gluteal nerve is responsible for innervating the gluteus medius, gluteus minimus and tensor fascia latae muscles, all of which can be injured during surgical procedures. We describe an ultrasound-guided approach to block the superior gluteal nerve which allowed us to provide efficient analgesia and anesthesia for two orthopedic procedures, in a patient who had significant risk factors for neuraxial techniques and deep peripheral nerve blocks. Clinical report An 84-year-old female whose regular use of clopidogrel contraindicated neuraxial techniques or deep peripheral nerve blocks presented for urgent bipolar hemiarthroplasty in our hospital. Taking into consideration the surgical approach chosen by the orthopedic team, we set to use a combination of general anesthesia and superficial peripheral nerve blocks (femoral, lateral cutaneous of thigh and superior gluteal nerve) for the procedure. A month and a half post-discharge the patient was re-admitted for debriding and correction of suture dehiscence; we performed the same blocks and light sedation. She remained comfortable in both cases, and reported no pain in the post-operative period. Conclusions Deep understanding of anatomy and innervation empowers anesthesiologists to solve potentially complex cases with safer, albeit creative, approaches. The relevance of this block in this case arises from its innervation of the gluteus medius muscle and posterolateral portion of the hip joint. To the best of our knowledge, this is the first report of an ultrasound-guided superior gluteal nerve block with an analgesic and anesthetic goal, which was successfully achieved.

Resumo Justificativa e objetivos O nervo glúteo superior é responsável pela inervação dos músculos glúteo médio, glúteo mínimo e tensor da fáscia lata, todos podem ser lesados durante procedimentos cirúrgicos. Descrevemos uma abordagem guiada por ultrassom para bloqueio do nervo glúteo superior, o que nos permitiu fornecer analgesia e anestesia eficientes para dois procedimentos ortopédicos a uma paciente que apresentava fatores de risco significativos para técnicas neuraxiais e bloqueios profundos de nervos periféricos. Relato de caso Paciente do sexo feminino, 84 anos, cujo uso regular de clopidogrel contraindicava técnicas neuraxiais ou bloqueios profundos de nervos periféricos, apresentou-se para hemiartroplastia bipolar urgente em nosso hospital. Levando em consideração a abordagem cirúrgica escolhida pela equipe de ortopedia, estabelecemos o uso de uma combinação de anestesia geral e bloqueios superficiais de nervos periféricos (femoral, cutâneo lateral da coxa e nervo glúteo superior) para o procedimento. Um mês e meio após a alta, a paciente foi readmitida para desbridamento e correção da deiscência de sutura quando fizemos os mesmos bloqueios e sedação leve. A paciente permaneceu confortável em ambos os casos, sem queixa de dor no período pós-operatório. Conclusões A compreensão profunda da anatomia e da inervação capacita os anestesiologistas a resolver casos potencialmente complexos com abordagens mais seguras, até criativas. A relevância desse bloqueio neste caso resulta da sua inervação do músculo glúteo médio e da porção posterolateral da articulação do quadril. De acordo com nossa pesquisa, este é o primeiro relato de um bloqueio do nervo glúteo superior guiado por ultrassom com objetivo analgésico e anestésico que foi obtido com sucesso.

Prolonged Catheter Use and Infection in Regional Anesthesia: A Retrospective Registry Analysis.

BACKGROUND: Prolonged catheter use is controversial because of the risk of catheter-related infection, but the extent to which the risk increases over time remains unknown. We thus assessed the time-dependence of catheter-related infection risk up to 15 days. METHODS: Our analysis was based on the German Network for Regional Anesthesia, which includes 25 centers. We considered 44,555 patients who had surgery between 2007 and 2014 and had continuous regional anesthesia as well as complete covariable details. Cox regression analysis was performed and adjusted for confounding covariables to examine the relationship between catheter duration and probability of infection-free catheter use. RESULTS: After adjustment for confounding factors, the probability of infection-free catheter use decreases with each day of peripheral and epidural catheter use. In peripheral catheters, it was 99% at day 4 of catheter duration, 96% at day 7, and 73% at day 15. In epidural catheters, it was 99% at day 4 of catheter duration, 95% at day 7, and 73% at day 15. Only 31 patients (0.07%) had severe infections that prompted surgical intervention. Among these were five catheters that initially had only mild or moderate signs of infection and were left in situ; all progressed to severe infections. CONCLUSIONS: Infection risk in catheter use increases over time, especially after four days. Infected catheters should be removed as soon as practical. VISUAL ABSTRACT: An online visual overview is available for this article at http://links.lww.com/ALN/B683.

Influence of skin disinfection prior removal of perineural catheter on bacterial colonization, contamination and local inflammation: a prospective randomized study.

BACKGROUND: There is a wide variation of perineural catheter (PNC) colonization rates in the literature. The impact of skin disinfection on PNC colonization and inflammation is not clear. The objective of this prospective, randomized clinical study was to investigate the influence of alcoholic skin disinfection before PNC removal on the detection of bacteria on PNC. METHODS: Two hundred patients receiving a PNC for orthopedic surgery were randomized to receive (with-group) or not (without-group) a skin disinfection with a sprayed alcoholic solution before removal of the PNC. Bacterial colonization and contamination of the PNC and clinical signs of inflammation and infection of the PNC insertion site were evaluated. Skin disinfection with a sprayed alcoholic solution and sterile removal of the distal and subcutaneous part of the PNC was performed after 72 hours or earlier if signs of infection occurred with semiquantitative culture and enrichment culture of both parts. RESULTS: Alcoholic skin disinfection before PNC removal significantly reduced bacterial colonization with a reduction from 28% to 14% and from 32% to 17% for the tip and the subcutaneous part of the PNC, respectively (P<0.05). Clinical signs of inflammation at the PNC insertion site were similar (73%) in the two groups. The detection of colonization in 54 (27%) out of 200 PNC did not correlate with clinical signs of inflammation independently of the number of bacteria isolated. Redness was noted in 71% and 68% of patients in the without- and with-alcoholic skin disinfection-group respectively. Local pain on pressure was present in 28% and 19% in the without- and with-group respectively. CONCLUSIONS: Alcoholic skin disinfection before PNC removal reduced the detection of PNC colonisation by 50%. There was no correlation between clinical signs of inflammation and PNC colonization.

The Effect of High-Frequency, Structured Expert Feedback on the Learning Curves of Basic Interventional Ultrasound Skills Applied to Regional Anesthesia.

BACKGROUND: Proficiency in needle-to-ultrasound beam alignment and accurate approach to structures are pivotal for ultrasound-guided regional anesthesia. This study evaluated the effects of high-frequency, structured expert feedback on simulation training of such abilities. METHODS: Forty-two subjects randomly allocated as controls or intervention participated in two 25-trial experiments. Experiment 1 consisted of inserting a needle into a bovine muscular phantom parallel to the ultrasound beam while maintaining full imaging of the needle. In experiment 2, the needle aimed to contact a target inside the phantom. Intervention subjects received structured feedback between trials. Controls received a global critique after completing the trials. The slopes of the learning curves derived from the sequences of successes and failures were compared. Change-point analyses identified the start and the end of learning in trial sequences. The number of trials associated with learning, the number of technical errors, and the duration of training sessions were compared between intervention and controls. RESULTS: In experiment 1, learning curves departed from 73% (controls) and 76% (intervention) success rates; slopes (standard error) were 0.79% (0.02%) and 0.71% (0.04), respectively, with mean absolute difference of 0.18% (95% confidence interval [CI], 0.17%-0.19%; P = 0). Intervention subjects' learning curves were shorter and steeper than those of controls. In experiment 2, the learning curves departed from 43% (controls) and 80% (intervention) success rates; slopes (standard error) were 1.06% (0.02%) and 0.42% (0.03%), respectively, with a mean difference of 0.65% (95% CI, 0.64%-0.66%; P = 0). Feedback was associated with a greater number of trials associated with learning in both experiment 1 (mean difference, 1.55 trials; 95% CI, 0.15-3 trials; P = 0) and experiment 2 (mean difference, 4.25 trials; 95% CI, 1.47-7.03 trials; P = 0) and a lower number of technical errors per trial in experiments 1 (mean difference, 0.19; 95% CI, 0.07-0.30; P = .02) and 2 (mean difference, 0.58; 95% CI, 0.45-0.70; P = 0), but longer training sessions in both experiments 1 (mean difference, 9.2 minutes; 95% CI, 4.15-14.24 minutes; P = .01) and 2 (mean difference, 7.4 minutes; 95% CI, 1.17-13.59 minutes; P = .02). CONCLUSIONS: High-frequency, structured expert feedback compared favorably to self-directed learning, being associated with shorter learning curves, smaller number of technical errors, and longer duration of in-training improvement, but increased duration of the training sessions.

Effect of Beam Steering on Echogenic and Nonechogenic Needle Visibility at 40°, 50°, and 60° Needle Insertion Angles.

Currently, there is little understanding of the role of echogenic needles and beam steering at moderate angles of needle insertion. The ultrasound images of the echogenic and nonechogenic needles inserted into pork at 40°, 50°, and 60° were scored by anesthesiologists on a scale of 0-10. The effect of different levels of beam steer was also explored. At 40°, steep beam steering improves visualization of both nonechogenic and echogenic needles to an equal, satisfactory level. At 50° and 60°, visualization of nonechogenic needles is poor, whereas visibility of an echogenic needle was adequate and may be improved with steep beam steering.

Analgesia multimodal y anestesia regional / Multimodal analgesia and regional anaesthesia

La analgesia multimodal permite conseguir una analgesia de calidad y con menos efectos secundarios gracias al uso de diferentes analgésicos o técnicas analgésicas. La anestesia regional juega un papel fundamental para conseguir este objetivo. Las diferentes técnicas de anestesia regional, que incluyen tanto los bloqueos periféricos como centrales, bien en dosis única, bien en perfusión continua, contribuyen a modular los estímulos nociceptivos que acceden a nivel central. La irrupción de los ultrasonidos como sistema efectivo para realizar las técnicas de anestesia regional ha permitido el desarrollo de nuevas técnicas de anestesia regional que antiguamente no podían realizarse al utilizar únicamente la neuroestimulación o las referencias cutáneas. Es fundamental tener en cuenta que aun teniendo un bloqueo efectivo es recomendable asociar otros fármacos por otras vías, de esta manera conseguiremos disminuir las dosis requeridas de forma individual e intentaremos incluso que el efecto sea sinérgico y no tan solo aditivo (AU)

Multimodal analgesia provides quality analgesia, with fewer side effects due to the use of combined analgesics or analgesic techniques. Regional anaesthesia plays a fundamental role in achieving this goal. The different techniques of regional anaesthesia that include both peripheral and central blocks in either a single dose or in continuous infusion help to modulate the nociceptive stimuli that access the central level. The emergence of the ultrasound as an effective system to perform regional anaesthesia techniques has allowed the development of new regional anaesthesia techniques that formerly could not be carried out since only neurostimulation or skin references were used (AU)