Ultrasound Guidance In Regional Anesthesia Research Articles

Ultrasound-guided brachial plexus blocks in pediatric anesthesia: non-systematic review

Background: The ultrasound guidance for regional anesthesia has gate a widespread as a recent technique to identify, visualize, and monitoring targeted nerves, needle insertion local anesthetic injection and distribution, catheters and adjacent anatomical structures, and helps to avoid complications such as inadvertent intravascular or intrafascicular injection in comparison to other traditional techniques. Purpose of review: To show and explain if any superiority has added to brachial plexus approaches with this sonography guidance for the pediatric population over other traditional techniques in terms of increasing the success rate or reducing the complications. Methods: Three authors1 independently searched the literature using MEDLINE and EMBASE bibliographic databases, Cochrane Central Register of Controlled Trials (CENTRAL), and manually in either the title or abstract, we also searched Google Scholar, Web of Science and reviewed the references of included trials for potentially relevant trials. Results: Reviewed literature suggests that ultrasound-guided peripheral blocks reduce block performance time in comparison with nerve stimulation, increase the success rate, reduced intended LA agent, and increase the quality of the block (as measured by analgesic consumption, block duration, and pain scores). Conclusion: The introduction of ultrasound imaging improved the safety profile, reduced performance time, and advanced the upper limbs block approach.

The Effect of Adding Ketamine or Midazolam to Bupivacaine for Ultrasound-Guided Supraclavicular Brachial Plexus Block for Upper Extremity Surgeries

AbstractBackground: The use of supraclavicular brachial plexus block is one of the most effective anesthetic techniques in operations for the upper extremity. The use of ultrasound guidance for regional anesthesia became popular owing to detection of anatomical variants, painless performance and correct needle placement. Aim of the study is to evaluate the value of adding ketamine or midazolam to bupivacaine when used for ultrasound guided supraclavicular brachial plexus block in upper extremity surgical procedures as regard the quality of surgical anesthesia and post-operative analgesia.Patients and Methods: Seventy adult patients of both sexes aged (18-60) years with ASA physical status I/II sched-uled for elective surgical procedure of the elbow, forearm, wrist and hand. Patients divided into two groups thirty-five patients were given 30ml total volume of 0.5% bupivacaine with midazolam 50μg/kg injected around brachial plexus cluster (Group A) and thirty-five patients were given 30ml general volume contained 0.5% bupivacaine with ketamine 2mg/kg injected around brachial plexus cluster (Group B).Results: There was no significant difference among both groups according to demographic data, hemodynamic changes, onset of motor and sensory block, sedation score, total doses of rescue analgesia and incidence of complications. There was significant prolongation in duration of sensory and motor block, significant decrease in VAS and significant delay in first request of rescue analgesia in Group A.Conclusion: The addition of midazolam (50μg/kg) when used as adjuvants to bupivacaine in ultrasound guided brachial plexus block produced prolongation of sensory and motor block, providing desirable sedation, improved quality of postoperative analgesia and decreased necessities of rescue analgesics in post-operative period.

Easier and Safer Regional Anesthesia and Peripheral Nerve Block under Ultrasound Guidance.

Regional anesthesia for the peripheral nerve or plexus has been widely used in the management of acute or chronic pain. To deliver a smaller volume to the targeted nerve without injury to it or its surrounding structures can be critical in the practice of regional anesthesia [1]. Therefore, the identification of the target nerve is important to provide better efficacy and safety in regional anesthesia. To increase the success rate of target nerve blocks, an electrical nerve stimulation device is popularly used. However, in spite of the use of a nerve stimulator, it is sometimes difficult to identify the exact position of the tip of the needle [2]. Since 1978, ultrasound has been widely used in several kinds of regional anesthetic practices. Recently, the improvements in ultrasound technology allow you to place the tip of the needle near the targeted nerve and monitor the spread of the local anesthetics precisely. In addition, ultrasound guidance enables the physician to replace the needle in the case of mal-distribution of the local anesthetic in real time. Therefore, ultrasound-guided technique has been considered the gold standard for performing regional anesthesia or peripheral nerve blocks [3]. The interscalene brachial plexus (IBP) block is very useful for upper extremity surgery. But IBP at the C6 level often fails to affect the ulnar nerve in up to 50% of blocks [4]. Kim et al. [2] injected 55 ml of local anesthetic via low approach IBP below the C6 level using a nerve stimulator for upper extremity surgery. A low approach IBP provided more caudad spread of local anesthesia in the brachial plexus, resulting in a better efficacy in blocking the ulnar nerve than the conventional IBP approach at the C 6 level (46% vs 81%; P < 0.0001). However, it may be associated with several concerns. The vertebral artery enters deep into the transverse process at the level of C6 or C7. Therefore, a nerve stimulant guided low approach IBP below the C6 level increases the risk of vertebral artery puncture, which may result in catastrophic outcomes. The nerves from C5 and C6 innervate the upper arm or forearm. When muscular twitching in the forearm is observed, it is difficult to identify whether the motor response originates from the C5 or C6 nerve. And thus, it is difficult to identify the exact position of the tip of the needle from the nerve stimulation. In this issue, Park et al. [5] reported the effect of ultrasound guided low approach IBP for upper limb surgery. They used 40 ml of local anesthetics for IBP, which provided adequate anesthesia without any significant complications in all 20 patients. Ultrasound provides direct visualization of the best site for the injection and helps avoid incidental puncture of blood vessels and damage to nerves. In addition, the volume of local anesthetic needed can be reduced by monitoring the spread of local anesthetics. Thus, continuously observing the distribution of local anesthetic and replacing the needle when mal-distribution of the injectate occurs improves the efficacy and safety of regional anesthesia or peripheral nerve block under ultrasound guidance. Substantially, the use of ultrasound can decrease the performance time of regional anesthesia, which may promote the routine use of ultrasound guidance in regional anesthesia. Therefore, it is justified to enable physicians to acquire the knowledge and techniques to use ultrasound guidance in regional anesthesia and in performing peripheral nerve blocks.

Minimum anesthetic volume in regional anesthesia by using ultrasound-guidance

The ultrasound guidance in regional anesthesia ensures the visualization of needle placement and the spread of Local Anesthetics.Over the past few years there was a substantial interest in determining the Minimum Effective Anesthetic Volume necessary to accomplish surgical anesthesia. The precise and real-time visualization of Local Anesthetics spread under ultrasound guidance block may represent the best requisite for reducing Local Anesthetics dose and Local Anesthetics-related effects.We will report a series of studies that have demonstrated the efficacy of ultrasound guidance blocks to reduce Local Anesthetics and obtain surgical anesthesia as compared to block performed under blind or electrical nerve stimulation technique.Unfortunately, the results of studies are widely divergent and not seem to indicate a dose considered effective, for each block, in a definitive way; but it is true that, through the use of ultrasound guidance, it is possible to reduce the dose of anesthetic in the performance of anesthetic blocks.

Management of mediastinal syndromes in pediatrics: a new challenge of ultrasound guidance to avoid high‐risk general anesthesia

Adverse events associated with anesthetic management of anterior mediastinal masses in pediatrics are common. To avoid an extremely hazardous general anesthesia, the use of real-time ultrasonography offers an effective alternative in high-risk cases. We report the anesthetic management including a light sedation and ultrasound guidance for regional anesthesia, surgical node biopsy, and placement of a central venous line in two children with an anterior symptomatic mediastinal mass. For pediatric patients with clinical and/or radiologic signs of airway compression, ultrasound guidance provides safety technical assistance to avoid general anesthesia and should be performed for the initial diagnostic and therapeutic procedures.

Reporting Functional Outcome After Knee Arthroplasty and Regional Anesthesia

The introduction of ultrasound guidance for regional anesthesia has resulted in an explosion of interest in its use for postoperative analgesia, particularly for orthopedic surgery. Regional anesthesia demonstrates unequivocal superiority compared with systemic opioids with respect to analgesia, reduced opioid consumption, increased patient satisfaction, and earlier achievement of discharge criteria. Improved acute postoperative analgesia can facilitate effective rehabilitation. Investigators are in the early stages of reporting the effects of regional anesthesia on functional outcome. Recent studies reporting functional outcomes have been plagued with sample sizes of inadequate power to generate meaningful results. Furthermore, the functional outcome measures are used inappropriately in terms of clinically meaningful difference, assessment intervals, and/or duration of follow-up. This report aims to address these issues by discussing functional outcomes used in the physiotherapy or orthopedic literature and their appropriate utilization, so that future research into the effects of regional anesthesia can be methodologically sound. Outcomes discussed include those that are physical-performance-based (ie, range of motion, quadriceps strength, Timed Up and Go test, 6-Minute Walk Test, Stair Time, and Self-paced Walk Test) and those that are self-reported (ie,Western Ontario and McMaster Universities Osteoarthritis Index, Knee Osteoarthritis Severity Score, Lower Extremity Function Scale).

Atlas of Ultrasound-Guided Regional Anesthesia.

University of Utah, Salt Lake City. jennifer.davis@hsc.utah.eduBy Andrew T. Gray, M.D., Ph.D. Philadelphia, Saunders Elsevier, 2010. Pages: 365. Price: $165.00.For those of us who perform regional anesthesia, ultrasound technology has revolutionized our practice in many ways. As the literature supporting the use of ultrasound guidance in regional anesthesia continues to mount, it has been a daunting task for practitioners who trained before this technology was in use to incorporate it into their practice. Atlas of Ultrasound-Guided Regional Anesthesia is a unique and extremely informative resource for practitioners who are attempting to learn ultrasound-guided regional anesthesia as well as experienced regionalists who want to expand their block armamentarium.The Atlas consists of 62 concise chapters and two appendices of self-assessment questions and answers. Each chapter, which is up to 11 pages long, begins with a detailed description of the topic, followed by suggested techniques where applicable, clinical pearls, and extensive pictures.The first 15 chapters of the book discuss the fundamental principles of ultrasound and its terminology. The author discusses various imaging techniques, transducer manipulation, and needle approaches. During many of the workshops I teach, participants express their frustration at not being able to “get a good image” when no one with experience is around to guide them. These pages clearly and concisely explain the ultrasound concepts that are essential to becoming a skilled ultrasonographer and safely performing ultrasound-guided blocks.The book's second section describes the ultrasound appearance of comingled structures, such as tendons, blood vessels, lymph nodes, pleura, and bone. The remainder of the book addresses ultrasound-guided techniques for upper extremity blocks, lower extremity blocks, trunk blocks, and head and neck blocks in a great deal of breadth but without too much depth on any given procedure. The final section is devoted to adverse events in regional anesthesia and using ultrasound for both prevention and recognition thereof. It is noteworthy that this book has the benefit of being available online so practitioners have ready access to the text and numerous pictures.The Atlas is a valuable addition to our literature on ultrasound-guided regional anesthesia. Before the publication of this book, there were very few texts of this nature available to practitioners who are attempting to introduce ultrasound to their practice. The descriptions of ultrasound fundamentals are well written and well illustrated. The pictures in the book are plentiful, of outstanding quality, and clearly labeled—an essential feature for learning ultrasound-guided regional anesthesia.The author gives helpful suggestions for block techniques. However, I would caution the reader to remember that many of the techniques described in this book represent regional preferences. With an adequate understanding of anatomy, there are a number of acceptable techniques for each block. A nice addition to this book would have been online video clips for each block, with transducer position as a correlate. Such a feature would allow demonstration of ultrasound principles and transducer manipulation, with corresponding changes in image appearance. Although still images are important, video clips add a great deal to a reader's understanding of block performance.Overall, this book is extremely useful and well done. The Atlas is a much-needed addition to our literature and will be a valuable resource for practitioners who are learning ultrasound-guided regional anesthesia.University of Utah, Salt Lake City. jennifer.davis@hsc.utah.edu

Current concepts and future trends in ultrasound-guided regional anesthesia

Ultrasound guidance for regional anesthesia has gained enormous popularity during the past several years. This review article highlights the importance of acquiring an understanding and knowledge of human anatomy for well tolerated and effective performance of regional anesthesia; includes description of some of the major principles of ultrasound-guided regional anesthesia techniques (adequate identification of neuronal and adjacent anatomical structures along with the procedure needle); use of adequate volumes of local anesthetic and the proper administration of local anesthetic; and discusses economical along with educational aspects of ultrasound-guided regional blocks. Recent studies by various authors have indicated that ultrasound-guided regional blocks can be performed by using smaller volumes of local anesthetics. Such findings will further contribute to the safety of regional anesthesia in daily clinical practice. Additional positive economical aspects associated with regional anesthesia have also been described in the recent literature. With little reservation, it is anticipated that ultrasound-guided regional anesthesia will become the 'GOLD' standard for performance of regional anesthesia. Excellent science and educational concepts will continue to be required with the continued increase in popularity of this exciting specialty of anesthesia.

Ultrasound Guidance: Concerns and Safety Issues May Have Some Answers

Clement Zablocki Veterans Affairs Medical Center, Medical College of Wisconsin, Milwaukee, Wisconsin.hshankar@mcw.eduThe letter by Cory1brings to attention the importance of being aware of the bioeffects of ultrasound. It is a topic close to my heart and hence was exciting to read. Some of his queries may already have an answer. I would like to highlight some of the changes in the past few decades that he may have missed by oversight.The safety concerns based on more than four decades of animal research prompted many organizations including American Institute of Ultrasound in Medicine and other international organizations to perform an in-depth analysis of this issue to arrive at conclusions and recommendations.2–5These have been mostly comforting in that no human studies have yet identified a potential risk. But they all do warn about the need for continued vigilance, especially with the use of currently available ultrasound machines with capabilities for higher outputs.The other change that has happened is the display of indices for potential harm. The Food and Drug Administration mandated that machines with higher acoustic outputs display the thermal and mechanical indices to qualify for track 3, which shifted the responsibility of monitoring to the end user.6These calculated indices based on the data derived from animal studies are worst-case scenario estimates for potential harm. Most modern machines are programmed to limit the indices by changing the pulse repetition frequency, the pulse duration, and so forth.Various animal models of crush injury to nerves followed by insonation have shown faster recovery of function besides histologic signs of earlier myelination when compared with sham.7–9Ultrasound bioeffects on the nervous tissue seems to span from neurolysis with high-intensity focused ultrasound to changes in ion channels besides changes in amplitudes and latency with therapeutic ultrasound.10–12All these changes were demonstrated at higher intensities or at least the upper limits of the diagnostic ultrasound intensities. Citing the capabilities of ultrasound to cause neurolysis may be an extreme as one should not be denied the use of the excellent image guidance that ultrasound provides.Although animal studies have shown myriad effects with insonation, many well-conducted epidemiologic studies have failed to demonstrate causality.13,14The claims about autism, dyslexia, and handedness with ultrasound exposure have been disproved by studies including a longitudinal follow-up of children whose mothers had more than one exposure to ultrasound during pregnancy.14Many animal studies have shown the potential for nonthermal effects with ultrasound including inertial and noninertial cavitation especially in gas-containing bodies.15Ultrasound has been shown to produce high temperatures and also generate free radicals during cavitation.6But the threshold for both inertial and noninertial cavitation is lowered only with microbubble contrast agents and not with the larger bubbles as may be encountered during injections.16Cavitation, a frequency-dependent phenomenon, may be unlikely with the bubbles that he refers to.17It is further reduced as the radius of the bubble required for cavitation at the higher frequencies used in regional anesthesia and pain medicine becomes restricted to a very narrow range.6A small study looking at lung hemorrhage during transechocardiography found no intraoperative evidence of lung hemorrhage as seen in animals.18Human lung seems to be protected from nonthermal effects because of factors yet unknown.As he mentions, the attenuation coefficient changes with fluid or injectate. Using the National Council for Radiation Protection deration may provide safety with low attenuation. But most importantly, keeping the indices and the duration of insonation within limits especially during use of power Doppler, a stationary mode, may be all that is necessary.6During the use of ultrasound guidance for regional anesthesia and pain medicine, mostly the B mode is used with constant movement of the transducer until the target is identified.I do agree with him that the low-intensity values that ultrasound machines claim is derived and sometimes differ between machines, as all the manufactured machines do not undergo standardization and only some machines undergo the laborious acoustic parameter assessment in the laboratory. This is mainly for cost and time savings, but the difference is likely to be small. But practicing vigilance may help to detect the unknown or an extremely rare event.Clement Zablocki Veterans Affairs Medical Center, Medical College of Wisconsin, Milwaukee, Wisconsin.hshankar@mcw.edu

Safety of Ultrasound-guided Regional Anesthesia

Four years ago, Anesthesiology published a clinical concepts and commentary article that reviewed the use of ultrasound guidance for regional anesthesia.1This article described the underlying principles and available literature of this nascent field. General efficacy and safety of these approaches have been borne out in a large number of subsequent clinical trials.2However, a recent letter to the editor has raised the theoretical concern that bioeffects may be harmful to patients undergoing regional anesthesia procedures guided by ultrasound.3Although it is clear that there are thermal and mechanical bioeffects of ultrasound, there are no confirmed adverse bioeffects when diagnostic levels of ultrasound are used.*Most bioeffects simply dissipate during the duty cycle of pulse sequence ultrasound and are significantly attenuated by the perfusion of living tissue.4Moreover, when using a handheld probe for imaging during peripheral nerve block, it would be very unlikely for a transducer to be maintained in a fixed position for an extended period. Interestingly, some of the postulated bioeffects of high-intensity ultrasound actually include the promotion of nerve regeneration and conduction block,5,6two effects potentially beneficial to those patients undergoing regional anesthesia procedures. Nonetheless, prudent use of ultrasound means using the lowest levels of exposure to achieve the desired goals (as low as reasonably achievable principle).When studied in vitro , the threshold for ultrasound producing reduction in peripheral nerve compound action potentials was approximately 100–200 W/cm2(continuous wave, 30-s burst, reported intensity as the spatial peak temporal average).7This reduction correlated with nerve temperature elevation from ultrasound exposure and was more pronounced at low frequencies. Irreversible effects only occurred at more than 400 W/cm2, well above the current Food and Drug Administration imposed limit of 720 mW/cm2(intensity as the spatial peak temporal average) for diagnostic imaging.8Admittedly, the interaction between local anesthetic toxicity and ultrasound has not been experimentally studied by such models, and the concerns that have been raised will hopefully encourage such investigations.The low incidence of significant adverse neurologic outcomes prevents definitive conclusions regarding these complications after regional anesthesia. The difficulties involved in investigating these low frequency, zero tolerance, events can be appreciated by the fact that the relative safety of using nerve stimulation versus a paresthetic technique has never been adequately resolved, despite decades of debate. Although the relatively high incidence of transient postoperative neurologic symptoms after regional block can be used to assess the relative risk,9the validity of these symptoms as a surrogate marker of significant injury is speculative. Although substantive data concerning significant injury are lacking, a large retrospective study recently reported five seizures and three nerve injuries in 3,290 patients undergoing peripheral nerve blocks guided by nerve stimulation, but no such events in 2,146 patients undergoing similar blocks guided by both nerve stimulation and ultrasound.10There are obviously substantial limitations to such retrospective reviews. Nonetheless, these data, and the published and unpublished experience with ultrasound in this setting, fail to raise alarm and instead imply greater safety by the addition of ultrasound imaging. Whether this is indeed true is obviously of great interest.Dr. Cory's letter raises important questions regarding the potential impact of beam intensity on neurologic outcomes after regional anesthesia. Beam intensity is only one of the numerous differences between ultrasound guidance and other approaches to regional blockade that could impact safety, all of which mandate rigorous investigation.†University of California, San Francisco, San Francisco General Hospital, San Francisco, California. graya@anesthesia.ucsf.edu

Modeling Cost of Ultrasound Versus Nerve Stimulator Guidance for Nerve Blocks With Sensitivity Analysis

Ultrasound guidance for regional anesthesia has increased in popularity. However, the cost of ultrasound versus nerve stimulator guidance is controversial, as multiple and varying cost inputs are involved. Sensitivity analysis allows modeling of different scenarios and determination of the relative importance of each cost input for a given scenario. We modeled cost per patient of ultrasound versus nerve stimulator using single-factor sensitivity analysis for 4 different clinical scenarios designed to span the expected financial impact of ultrasound guidance. The primary cost factors for ultrasound were revenue from billing for ultrasound (85% of variation in final cost), number of patients examined per ultrasound machine (10%), and block success rate (2.6%). In contrast, the most important input factors for nerve stimulator were the success rate of the nerve stimulator block (89%) and the amount of liability payout for failed airway due to rescue general anesthesia (9%). Depending on clinical scenario, ultrasound was either a profit or cost center. If revenue is generated, then ultrasound-guided blocks consistently become a profit center regardless of clinical scenario in our model. Without revenue, the clinical scenario dictates the cost of ultrasound. In an ambulatory setting, ultrasound is highly competitive with nerve stimulator and requires at least a 96% success rate with nerve stimulator before becoming more expensive. In a hospitalized scenario, ultrasound is consistently more expensive as the uniform use of general anesthesia and hospitalization negate any positive cost effects from greater efficiency with ultrasound.

Ultrasound guidance in regional anesthesia: state of the art review through challenging clinical scenarios.

Ultrasound guided regional anesthesia (UGRA) for peripheral nerve blockade is becoming increasingly popular. The advantage of ultrasound technology is that it affords the anesthesiologist the real time ability to visualize neural structures, needle advancement, and local anesthetic spread. Recent data suggest that UGRA generates improved success rates and reductions in performance times in comparison to traditional approaches. Further, the use of ultrasound technology in peripheral nerve blocks has provided insight into needle-nerve interactions, revealing distinct limitations of nerve stimulator techniques. Given that UGRA requires a unique set of skills, formal standards and guidelines are currently being developed by leadership societies in order to foster education and training. This review article, in a case vignette format, highlights important techniques, concepts, and limitations regarding the use of ultrasound to facilitate regional anesthesia. Clinically relevant aspects of ultrasound physics are also discussed.

Evidence-based review of ultrasound imaging for regional anesthesia

Use of ultrasound guidance for regional anesthesia has grown in popularity recently. Advocates claim many benefits, including higher success rates, a decrease in block performance time, a decrease in onset time, a higher quality block, the ability to use less local anesthetic, and a longer duration of block. Many also believe that the ability to visualize critical structures decreases the rate of complications. This article reviews the current evidence for these claimed benefits. In addition, discussion of how clinical practice patterns are affected and how ultrasound can add to the knowledge base of regional anesthesia practice is presented.