Ultrasound-Guided Regional Anesthesia and Patient Safety: An Evidence-Based Analysis

State-of-the-art anesthesia practices: a comprehensive review on optimizing patient safety and recovery

OBJECTIVE

This review explores recent advancements in anesthesia care, focusing on the integration of innovative practices to enhance patient outcomes across the perioperative period.

METHODS

Following the framework of Whitmore and Knafl, we systematically searched six databases (PubMed, Google Scholar, EMBASE, CINAHL, OVID, and Cochrane Library) for studies published from January 2020 to January 2024, relating to advancements in anesthesia care, best practice implementation, and patient outcomes. After independent screening and data extraction by two reviewers, the review focuses on innovations in anesthetic drugs, monitoring technologies, anesthesia techniques, and evidence-based practices in anesthesia and clinical guidelines.

RESULTS

Of the 25,984 studies retrieved, 26 met inclusion criteria. Recent developments in anesthetic drugs have improved safety and efficacy, reducing complications. Advanced monitoring devices, such as multiparameter and brain function monitors, have enhanced patient safety through real-time assessments. Innovations in regional anesthesia and ultrasound-guided nerve blocks have led to better pain management, reduced recovery time, and minimized morbidity. Additionally, evidence-based practices like comprehensive preoperative assessment, patient education, and multidisciplinary teamwork significantly improved patient outcomes.

CONCLUSION

Integrating the latest innovations and best practices in anesthesia care is essential for optimizing patient outcomes. Ongoing research and adoption of advanced technologies are crucial to addressing current challenges and enhancing anesthesia quality. This review emphasizes the importance of a holistic approach from preoperative preparation to postoperative recovery to achieve optimal patient outcomes.

The Safety of Peripheral Nerve Blocks: The Role of Triple Monitoring in Regional Anaesthesia, a Comprehensive Review

Regional anaesthesia, referred to as regional blocks, is one of the most frequently used methods of anaesthesia for surgery and for pain management. Local anaesthetic drug should be administered as close to the nerve as possible. If administered too far away, this may result in insufficient block. If it is administrated too close, severe nerve damage can occur. Neurostimulation techniques and ultrasound imaging have improved the effectiveness and safety of blockade, but the risk of nerve injury with permanent nerve disfunction has not been eliminated. Intraneural administration of a local anaesthetic damages the nerve mechanically by the needle and the high pressure generated by the drug inside the nerve. In many studies, injection pressure is described as significantly higher for unintended intraneural injections than for perineural ones. In recent years, the concept of combining techniques (neurostimulation + USG imaging + injection pressure monitoring) has emerged as a method increasing safety and efficiency in regional anaesthesia. This study focuses on the contribution of nerve identification methods to improve the safety of peripheral nerve blocks by reducing the risk of neural damage.

"Knowing It Before Blocking It," the ABCD of the Peripheral Nerves: Part C (Prevention of Nerve Injuries)

"A clever person solves the problem. A wise person avoids it" (Albert Einstein). There is no convincing evidence that any modality 100% effectively prevents nerve injury. The risk of nerve injury remains the same even with the ultrasound due to limitations in the resolution of images and inter-operator and inter-patient differences. In a nutshell, caution is required when dealing with precious nerves in the perioperative period, either during peripheral nerve blocks (PNBs), patient positioning, or surgery. Identifying pre-existing nerve injury, either due to trauma or an existing neuropathy, and preventing further nerve injury should be an important goal in providing safe regional anesthesia (RA). Multimodal monitoring is key to avoiding multifactorial nerve injuries. The use of triple guidance (ultrasound + peripheral nerve stimulator + injection pressure monitor) during PNBs further improves the safety of RA. The ultrasound helps in real-time visualization of the nerve, needle, and drug spread; the peripheral nerve stimulator helps confirm the target nerves; and the injection pressure monitor helps avoid nerve injury. Such multimodalities can also give the confidence to administer PNB without risk of nerve injury. This article is part of the comprehensive overview of the essential understanding of peripheral nerves before blocking them. It describes various preventive measures to avoid peripheral nerve injuries while administering PNBs. It will help readers understand the importance of prevention in each step to avoid perioperative PNIs.

Multimodal Approach in Minimizing Transient Neurological Complications Following Single Shot Brachial Plexus Block: A Prospective Observational Study

PURPOSE

The aim of the study was to assess the benefit of a using multimodal approach, including injection pressure monitoring (IPM) and different techniques of nerve localization, with respect to complications following single-shot brachial plexus block (SSBPB).

METHODS

In this study, 238 adults (132 males and 106 females) undergoing upper-limb surgeries under peripheral nerve block (PNB) were evaluated. Of these, 198 patients were given supraclavicular block, and 40 patients received interscalene block using either ultrasound (USG) and peripheral nerve stimulation (PNS) or PNS alone. Injection pressure monitoring was used in 216 patients.

RESULTS

Transient neurological deficit (TND) was observed in six out of 198 patients where USG and NS were used along with IPM as opposed to 12 out of 18 patients without IPM (p<0.0001). In patients where only PNS was used, transient neurological deficit (TND) was seen in six out of 18 patients with IPM as opposed to all the patients (n=4) without IPM (p<0.02). Among the patients where injection pressure was monitored, six out of 198 patients developed TND when both USG and NS were used, compared to six out of 18 patients where only PNS was used (p<0.007).

CONCLUSION

Use of injection pressure monitoring along with different nerve localization techniques results in fewer transient neurological deficits.

Local anesthetic systemic toxicity: A narrative review for emergency clinicians

INTRODUCTION

Emergency clinicians utilize local anesthetics for a variety of procedures in the emergency department (ED) setting. Local anesthetic systemic toxicity (LAST) is a potentially deadly complication.

OBJECTIVE

This narrative review provides emergency clinicians with the most current evidence regarding the pathophysiology, evaluation, and management of patients with LAST.

DISCUSSION

LAST is an uncommon but potentially life-threatening complication of local anesthetic use that may be encountered in the ED. Patients at extremes of age or with organ dysfunction are at higher risk. Inadvertent intra-arterial or intravenous injection, as well as repeated doses and higher doses of local anesthetics are associated with greater risk of developing LAST. Neurologic and cardiovascular manifestations can occur. Early recognition and intervention, including supportive care and intravenous lipid emulsion 20%, are the mainstays of treatment. Using ultrasound guidance, aspirating prior to injection, and utilizing the minimal local anesthetic dose needed are techniques that can reduce the risk of LAST.

CONCLUSIONS

This focused review provides an update for the emergency clinician to manage patients with LAST.

Awake Regional Anesthesia for Upper Limb Orthopedic Surgery During the COVID-19 Pandemic

Background:

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19 illness, is mainly transmitted because of close contact with respiratory droplets and airborne particles. Aerosol-generating procedures during general anesthesia can increase the risk of COVID-19 transmission. An effective alternative to general anesthesia for upper limb orthopedic surgery is regional anesthesia (RA) using brachial plexus block.

Materials and Methods:

Seventy-eight patients who received a brachial plexus block for upper limb trauma and elective operations before and during the COVID-19 pandemic, from 2017 to 2020, were included in this study. A protocol was devised for patient positioning, draping and equipment positioning for each location group—shoulder and upper arm; elbow and forearm; and distal extremities.

Results:

RA was effective for upper limb surgery in 77 of 78 (98.7%) patients. Sixty-five patients (83.3%) were discharged the same day, with the average time from leaving the operating theater to discharge from hospital of 2.8 hours. No postoperative complications were recorded, and no patient nor staff member contracted COVID-19 infection 2 weeks after the operation.

Conclusion:

We demonstrate the efficacy of awake RA for upper limb orthopedic procedures. We share our tips and tricks for implementing this into clinical practice and discuss the specific advantages of RA in the context of the COVID-19 global pandemic.

Combination Lower Extremity Nerve Blocks and Their Effect on Postoperative Pain and Opioid Consumption: A Systematic Review

The purpose of this study was to perform a systematic review of the literature examining postoperative outcomes following single site and combined peripheral nerve blocks (PNBs), including (1) sciatic and femoral nerve, (2) popliteal and saphenous nerve, and (3) popliteal and ankle nerve, during elective foot and ankle surgery. We hypothesized that combination blocks would decrease postoperative narcotic consumption and afford more effective postoperative pain control as compared to general anesthesia, spinal anesthesia, or single site PNBs. A review of the literature was performed according to the PRISMA guidelines. Medline, EMBASE, and the Cochrane Library were searched from January 2009 to October 2019. We identified studies by using synonyms for "foot," "ankle" "pain management," "opioid," and "nerve block." Included articles explicitly focused on elective foot and ankle procedures performed under general anesthesia, spinal anesthesia, PNB, or with some combination of these techniques. PNB techniques included femoral, adductor canal, sciatic, popliteal, saphenous, and ankle blocks, as well as blocks that combined multiple anatomic sites. Outcomes measured included postoperative narcotic consumption as well as patient-reported efficacy of pain control. Twenty-eight studies encompassing 6703 patients were included. Of the included studies, 57% were randomized controlled trials, 18% were prospective comparison studies, and 25% were retrospective comparison studies. Postoperative opioid consumption and postoperative pain levels were reduced over the first 24 to 48 hours with the use of combined PNBs when compared with single site PNBs, both when used as primary anesthesia or when used in concert with general anesthesia either alone or combined with systemic/local anesthesia in the first 24 to 48 hours following surgery. Studies demonstrated higher reported patient satisfaction of postoperative pain control in patients who received combined PNB. Nine of 14 (64%) studies reported no neurologic related complications with an overall reported rate among all studies ranging from 0% to 41%. Our study identified substantial improvement in postoperative pain levels, postoperative opioid consumption, and patient satisfaction in patients receiving PNB when compared with patients who did not receive PNB. Published data also demonstrated that combination PNB are more effective than single-site PNB for all data points. Notably, the addition of a femoral nerve block to a popliteal nerve block during use of a thigh tourniquet, as well as addition of either saphenous or ankle blockade to popliteal nerve block during use of calf tourniquet, may increase overall block effectiveness. Serious complications including neurologic damage following PNB administration are rare but do exist.

Successful intralipid-emulsion treatment of local anesthetic systemic toxicity following ultrasound-guided brachial plexus block: case report

Background

Local anesthetic systemic toxicity (LAST) is a life-threatening complication that may follow application of LAs through various routes. Despite increasing usage of LA techniques in a large number of health-care settings, contemporary awareness of LAST and understanding of its management are inadequate.

Case presentation

We report two cases who suffered LAST following brachial plexus block for surgery on the upper extremity. The first patient received an ultrasound-guided supraclavicular block with 300 mg lidocaine (6 mg/kg) and 50 mg ropivacaine (1 mg/kg) in 25 mL without epinephrine, and the second patient received an ultrasound guided interscalene block with 200 mg lidocaine (4.5 mg/kg) and 45 mg ropivacaine (1 mg/kg) supplemented with epinephrine 1:200,000. Both patients presented with symptoms of central nervous and respiratory system depression, the first roughly 10 minutes after injection, and the second immediately after withdrawal of the needle. In both cases, thorough recovery was obtained using lipid-emulsion therapy.

Conclusion

The complication of LAST following ultrasound-guided brachial plexus block could be treated successfully applying the American Society of Regional Anesthesia and Pain Medicineprotocol of intravenous administration of lipid emulsion.

'SCALD-ED' Block: Superficial Cutaneous Anesthesia in a Lateral Leg Distribution within the Emergency Department - A Case Series

BACKGROUND

In the midst of a nationwide opioid epidemic, focus has been placed on identifying and utilizing safe, effective opioid-free analgesic alternatives. Lower-extremity peripheral nerve blockades are common and often involve both motor and sensory anesthesia, resulting in leg weakness and ambulatory difficulty. The aim of this case report is to describe an ultrasound-guided peripheral nerve block technique (superficial cutaneous anesthesia in a lateral (leg) distribution within the emergency department ['SCALD-ED' block]) that provides motor-sparing, purely sensory anesthesia after a superficial injury to the lateral leg in patients presenting to the emergency department.

DISCUSSION

Two separate patients presenting with lateral leg pain after superficial injury (burn, cellulitis) reported continued breakthrough pain despite a standard analgesic modality of combination acetaminophen and ibuprofen. With the patient placed in prone position for ultrasound-guided access to lower-extremity nerve branches, the lateral sural cutaneous nerve (LSCN) was identified by tracing its pathway from the proximal sciatic nerve to the common peroneal (fibular) nerve to the superficial peroneal (fibular) nerve. Five mL of lidocaine (1%, with epinephrine) was injected along the superficial LSCN route for anesthetic blockade. Temporal assessments of anesthetic effect and pain improvement, and monitoring of motor or ambulatory impairment were conducted at regular intervals to assess the efficacy and feasibility of the blockade. Regional anesthesia along the LSCN sensory distribution was experienced at 7-9 min post blockade. Peak analgesic effect was experienced at 25-29 min. The duration of anesthesia was 120-150 min. A negligible amount of delayed sensory anesthesia was noted along the distal sural nerve distribution. No motor deficit, ambulatory difficulty, or adverse effects were experienced in either patient post blockade.

CONCLUSION

The LSCN is an identifiable target under ultrasound guidance, susceptible to localized, purely sensory blockade of pain from superficial cutaneous lateral leg injuries.

Updated Retrospective Single-Center Comparative Analysis of Peripheral Nerve Block Complications Using Landmark Peripheral Nerve Stimulation Versus Ultrasound Guidance as a Primary Means of Nerve Localization

OBJECTIVES

The purpose of this study was to perform an updated analysis of complications associated with upper and lower extremity peripheral nerve blocks (PNBs) performed with ultrasound (US) guidance versus the landmark approach.

METHODS

We conducted a single-center retrospective cohort analysis to compare the incidence of PNB complications between the techniques. The primary outcome was local anesthetic systemic toxicity (LAST), whereas the secondary outcomes included short- and long-term nerve injuries. The current query included cases performed between 2012 and 2015. A combined analysis included data extending to 2006. The Statistical examination relied on the χ² test.

RESULTS

During this 4-year period, we performed 7789 US-guided and 498 landmark-guided blocks with no statistically significant difference in the incidence of nerve injury or LAST between the groups. Our 10-year analysis, however, revealed a significant increase (P < .01) in the rate of LAST with the landmark technique: 7 of 5932 versus 0 of 16,858 cases. The combined data also revealed a significant increase (P < .01) in short-term injuries associated with the landmark approach (30 of 5932 versus 33 of 16,858) but no significant difference in the incidence of long-term injuries.

CONCLUSIONS

Our analysis supports a conclusion that the use of US guidance during PNBs leads to a significant reduction in the incidence of LAST, adding to growing evidence from similar investigations. The impact of US on the incidence of nerve injuries remains unclear, considering that the nature of transient deficits is thought to be multifactorial, and the frequency of lasting injuries did not differ significantly in this study.

What Can Regional Anesthesiology and Acute Pain Medicine Learn from "Big Data"?

Demonstrating value added to patients' experience through regional anesthesiology and acute pain medicine is critical. Evidence supporting improved outcomes can be derived from prospective studies or retrospective cohort studies. Population-based studies relying on existing clinical and administrative databases are helpful when an outcome is rare and detecting a change would require studying large numbers of patients. This article discusses the effect of regional anesthesiology and acute pain medicine interventions on mortality and morbidity, infection rate, cancer recurrence, inpatient falls, local anesthetic systemic toxicity, persistent postsurgical pain, and health care costs.

Optical signature of nerve tissue-Exploratory ex vivo study comparing optical, histological, and molecular characteristics of different adipose and nerve tissues

Background

During several anesthesiological procedures, needles are inserted through the skin of a patient to target nerves. In most cases, the needle traverses several tissues—skin, subcutaneous adipose tissue, muscles, nerves, and blood vessels—to reach the target nerve. A clear identification of the target nerve can improve the success of the nerve block and reduce the rate of complications. This may be accomplished with diffuse reflectance spectroscopy (DRS) which can provide a quantitative measure of the tissue composition. The goal of the current study was to further explore the morphological, biological, chemical, and optical characteristics of the tissues encountered during needle insertion to improve future DRS classification algorithms.

Methods

To compare characteristics of nerve tissue (sciatic nerve) and adipose tissues, the following techniques were used: histology, DRS, absorption spectrophotometry, high‐resolution magic‐angle spinning nuclear magnetic resonance (HR‐MAS NMR) spectroscopy, and solution 2D ¹³C‐¹H heteronuclear single‐quantum coherence spectroscopy. Tissues from five human freshly frozen cadavers were examined.

Results

Histology clearly highlights a higher density of cellular nuclei, collagen, and cytoplasm in fascicular nerve tissue (IFAS). IFAS showed lower absorption of light around 1200 nm and 1750 nm, higher absorption around 1500 nm and 2000 nm, and a shift in the peak observed around 1000 nm. DRS measurements showed a higher water percentage and collagen concentration in IFAS and a lower fat percentage compared to all other tissues. The scattering parameter (b) was highest in IFAS. The HR‐MAS NMR data showed three extra chemical peak shifts in IFAS tissue.

Conclusion

Collagen, water, and cellular nuclei concentration are clearly different between nerve fascicular tissue and other adipose tissue and explain some of the differences observed in the optical absorption, DRS, and HR‐NMR spectra of these tissues. Some differences observed between fascicular nerve tissue and adipose tissues cannot yet be explained but may be helpful in improving the discriminatory capabilities of DRS in anesthesiology procedures. Lasers Surg. Med. 50:948–960, 2018. © 2018 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Supraclavicular Brachial Plexus Block for Arteriovenous Hemodialysis Access Procedures

Ultrasound-guided supraclavicular brachial plexus block using 1% and 2% lidocaine in 21 procedures is reported. Average procedure time was 5.1 minutes (± 1.2 min; range, 2-8 min). Average time of onset and duration were 4.8 minutes (± 3.7 min; range, 0-10 min) and 77.9 minutes (± 26.7 min; range, 44-133 min), respectively, for sensory block and 8.4 minutes (± 5.7 min; range, 3-23 min) and 99 minutes (± 40.5 min; range, 45-171 min), respectively, for motor block. The pain scale assessment averaged 0.4 (± 1.1; range, 0-4). There were no complications.

Spectral tissue sensing to identify intra- and extravascular needle placement - A randomized single-blind controlled trial

Safe vascular access is a prerequisite for intravenous drug admission. Discrimination between intra- and extravascular needle position is essential for procedure safety. Spectral tissue sensing (STS), based on optical spectroscopy, can provide tissue information directly from the needle tip. The primary objective of the trial was to investigate if STS can reliably discriminate intra-vascular (venous) from non-vascular punctures. In 20 healthy volunteers, a needle with an STS stylet was inserted, and measurements were performed for two intended locations: the first was subcutaneous, while the second location was randomly selected as either subcutaneous or intravenous. The needle position was assessed using ultrasound (US) and aspiration. The operators who collected the data from the spectral device were blinded to the insertion and ultrasonographic visualization procedure and the physician was blinded to the spectral data. Following offline spectral analysis, a prediction of intravascular or subcutaneous needle placement was made and compared with the “true” needle tip position as indicated by US and aspiration. Data for 19 volunteers were included in the analysis. Six out of 8 intended vascular needle placements were defined as intravascular according to US and aspiration. The remaining two intended vascular needle placements were negative for aspiration. For the other 11 final needle locations, the needle was clearly subcutaneous according to US examination and no blood was aspirated. The Mann-Whitney U test yielded a p-value of 0.012 for the between-group comparison. The differences between extra- and intravascular were in the within-group comparison computed with the Wilcoxon signed-rank test was a p-value of 0.022. In conclusion, STS is a promising method for discriminating between intravascular and extravascular needle placement. The information provided by this method may complement current methods for detecting an intravascular needle position.

The Requisites of Needle-to-Nerve Proximity for Ultrasound-Guided Regional Anesthesia: A Scoping Review of the Evidence

This scoping review examines the literature to determine whether the position of the needle tip relative to the target nerve is accurately and reliably detected during ultrasound (US)-guided regional anesthesia. The requisites for successful and safe needle tip positioning relative to the target nerve include accurate and reliable needle presentation by the machine, needle interpretation by the operator, nerve presentation by the machine, and nerve interpretation by the operator. Failure to visualize the needle tip is a common occurrence, frequently prompting operators to use needle and probe maneuvers, which are not necessarily based on evidence. Needle tip interpretation often relies on surrogate indicators that have not been validated. The acoustic resolution of modern portable US machines limits the extent to which nerve microanatomy can be reliably presented. Finally, our interpretation of the sonographic end points for local anesthetic injection that best balance success and safety for US-guided regional anesthesia continues to evolve.

WHAT'S NEW

In order to determine whether or not the position of the needle tip relative to the target nerve is accurately and reliably detected during US-guided regional anesthesia, the available literature is reviewed and interpreted to address the following 4 questions.

Histological confirmation of needle tip position during ultrasound-guided interscalene block: a randomized comparison between the intraplexus and the periplexus approach

PURPOSE

Ultrasound-guided interscalene block can be performed using either periplexus or intraplexus needle placement. In this novel study, we histologically examined the needle tip position in relation to the neural tissues with the two techniques. Our objective was to investigate the variable risk of subepineurial needle tip placement resulting from the two ultrasound-guided techniques.

METHODS

In an embalmed cadaveric model, periplexus or intraplexus interscalene injections were performed with the side, order, and technique assigned randomly. Under real-time ultrasound guidance, the block needle was placed next to the hyperechoic layer of the plexus (periplexus) or between the hypoechoic nerve roots (intraplexus). Once positioned, 0.1 mL of black acrylic ink was injected. The brachial plexus tissues were then removed and histology sections were prepared and then coded in order to blind two reviewers to group allocation. The area of ink staining was used to determine needle tip location, and the groups were compared for the presence of subepineurial ink.

RESULTS

Twenty-six cadavers had each of the blocks performed on either brachial plexus (i.e., 52 injections). No subepineurial ink deposits were observed in the periplexus group (0%), but subepineurial ink deposition was observed in 3/26 (11.5%) intraplexus injections (odds ratio, 0; 95% confidence interval, 0 to 2.362; P = 0.235). Furthermore, in the intraplexus group, two (of the three) subepineurial ink deposits were observed under the perineurium.

CONCLUSION

Although our study was somewhat underpowered due to a lower than previously reported rate of subepineurial needle tip positioning, our results suggest that there may be an increased likelihood of subepineurial needle tip position with the intraplexus approach. The periplexus technique resulted in no subepineurial spread of ink, suggesting that this approach may be less likely to result in mechanical trauma to nerves from direct needle injury.

Role of regional anesthesia in foot and ankle surgery

Regional anesthesia has increasingly expanded its role in the perioperative care of patients undergoing foot and ankle surgery. In addition to avoiding side effects associated with both general anesthesia and neuraxial anesthetic techniques, especially those related to cardiovascular and pulmonary systems, regional nerve blocks have been shown to improve postoperative pain and reduce hospital stay and associated expenses. The techniques utilized to achieve analgesia of the foot and ankle are diverse, multifaceted, and often incorporate ultrasound guidance. Given the aging of patient populations, and especially the growing incidence of cardiovascular-, pulmonary-, and obesity-related morbidity, the use of regional blocks is likely to expand in these surgical procedures. This review highlights some of the most current developments in the expanding role of regional anesthesia in foot and ankle surgery.

LEVELS OF EVIDENCE

Therapeutic, Level II.

Evidence-based medicine for ultrasound-guided regional anesthesia

Available evidence favoring the use of ultrasound for regional anesthesia is reviewed, updated, and critically assessed. Important outcome advantages include decreased time to block onset; decreased risk of local anesthetic systemic toxicity; and, depending on the outcome definition, increased block success rates. Ultrasound guidance, peripheral nerve blocks, and central neuraxial blocks are discussed.

The effect of needle dimensions and infusion rates on injection pressures in regional anaesthesia needles: a bench-top study

Animal studies have shown that injection pressures > 75 kPa indicate probable intrafascicular needle tip position. This study describes the flow/pressure characteristics of seven common needle systems. A syringe pump delivered flow rates of 5, 6.67, 10, 13.3, 15 and 20 ml.min(-1) through these needle systems, while keeping the needle tips open to atmosphere. A pressure transducer connected between the syringe and needle provided a real-time graphical display for analysis. Mean plateau pressures increased linearly with flow and with decreasing needle diameter (2.7-92 kPa). Flow rates > 17 ml.min(-1) and needle sizes 22 G and smaller produced mean plateau pressures > 75 kPa. Pressure monitors upstream from the needle may produce false-positive alarms at high flow rates due to needle resistance, and unreliable readings due to non-laminar flow. We recommend injection rates ≤ 15 ml.min(-1) (0.25 ml.s(-1) ) to reduce the effect of factors upstream from the needle tip as a cause of high pressure readings.

A randomized clinical trial comparing the effectiveness of ultrasound guidance versus nerve stimulation for lateral popliteal-sciatic nerve blocks in obese patients

OBJECTIVES

Ultrasound guidance may decrease the procedural time for many peripheral nerve blocks compared to nerve stimulation, but these studies have generally excluded obese patients. This single-blinded randomized clinical trial was designed to compare procedural times and related outcomes for ultrasound- versus nerve stimulation-guided lateral popliteal-sciatic nerve blockade specifically in obese patients.

METHODS

With Institutional Review Board approval and informed consent, patients with a body mass index greater than 30 kg/m(2) who were scheduled for foot/ankle surgery and desiring a peripheral nerve block were offered enrollment. Study patients were randomly assigned to receive a lateral popliteal-sciatic nerve block under either ultrasound or nerve stimulation guidance. The patient and assessor were blinded to group assignment. The primary outcome was procedural time in seconds. Secondary outcomes included number of needle redirections, procedure-related pain, patient satisfaction with the block, success rate, sensory and motor onset times, block duration, and complication rates.

RESULTS

Twenty-four patients were enrolled and completed the study. All patients had successful nerve blocks. The mean procedural times (SD) were 577 (57) seconds under nerve stimulation and 206 (40) seconds with ultrasound guidance (P< .001; 95% confidence interval for difference, 329-412 seconds). Patients in the ultrasound group had fewer needle redirections and less procedure-related pain, required less opioids, and were more satisfied with their block procedures. There were no statistically significant differences in other outcomes.

CONCLUSIONS

The results of this study show that, for obese patients undergoing lateral popliteal-sciatic nerve blocks, ultrasound guidance reduces the procedural time and procedure-related pain and increases patient satisfaction compared to nerve stimulation while providing similar block characteristics.

Ultrasound guidance reduces the risk of local anesthetic systemic toxicity following peripheral nerve blockade

BACKGROUND AND OBJECTIVES

Local anesthetic systemic toxicity (LAST) is a potentially life-threatening complication of local anesthetic administration. In this article, the results of the Australian and New Zealand Registry of Regional Anaesthesia were analyzed to determine if ultrasound-guided peripheral nerve blockade (PNB) was associated with a reduced risk of LAST compared with techniques not utilizing ultrasound technology.

METHODS

The period of study for this multicenter study involving 20 hospitals was from January 2007 through May 2012. The primary outcome was LAST comprising minor, major, and cardiac arrest (due to toxicity) events determined using standardized definitions. Multivariable logistic regression models and propensity score analyses were used to determine significant event predictors.

RESULTS

The study population comprised 20,021 patients who received 25,336 PNBs. There were 22 episodes of LAST, resulting in an incidence of LAST of 0.87 per 1000 PNBs (95% confidence interval, 0.54-1.3 per 1000). Ultrasound guidance was associated with a reduced incidence of local anesthetic toxicity. Site of injection, local anesthetic type, dose per weight, dose, and patient weight were all predictors of LAST.

CONCLUSIONS

This study provides the strongest evidence, to date, that ultrasound guidance may improve safety because it is associated with a reduced risk of LAST following PNB.

Adverse outcomes associated with nerve stimulator-guided and ultrasound-guided peripheral nerve blocks by supervised trainees: update of a single-site database

BACKGROUND

We previously published a retrospective review of complications related to peripheral nerve blocks performed by supervised trainees, from our quality assurance and billing data, guided by either ultrasound, with nerve stimulator confirmation, or landmark-based nerve stimulator techniques. This report updates our results, for the period from May 2008 through December 2011, representing ongoing transition to near-complete combined ultrasound/nerve stimulator guidance in a block-oriented, outpatient orthopedic anesthesia practice.

METHODS

We queried our deidentified departmental quality improvement electronic database for adverse outcomes associated with peripheral nerve blocks. Billing records were also deidentified and used to provide the denominator of total number of blocks using each technique of neurolocation. The types of blocks considered in this analysis were interscalene, axillary, femoral, sciatic, and popliteal-sciatic blocks. Nerve block complications based on each type of guidance were then compared for the entire recent 30-month time period, as well as for the 6-year period of this report.

RESULTS

There were 9062 blocks performed by ultrasound/nerve stimulator, and 5436 by nerve stimulator alone over the entire 72-month period. Nerve injuries lasting longer than 1 year were rare, but similar in frequency with both nerve guidance techniques. The incidence of local anesthetic systemic toxicity was found to be higher with landmark-nerve stimulator technique than with use of ultrasound-guided nerve blocks (6/5436 vs 0/9069, P = 0.0061).

CONCLUSIONS

We report a large series of combined ultrasound/nerve stimulator nerve blocks by supervised trainees without major local anesthetic systemic toxicity. While lacking the compelling evidence of randomized controlled trials, this observational database nonetheless allows increased confidence in the safety of using combined ultrasound/nerve stimulator in the setting of anesthesiologists-in-training.