Ultrasound visibility of needles used for regional nerve block: An in vitro study

Ultrasound-guided stellate ganglion blockade - patient positioning is everything: a case report demonstrating the efficacy of a modified out-of-plane approach

Background

Insomnia has become increasingly prevalent in modern society and is notoriously difficult to treat. Many patients exhibit a poor response to pharmacological interventions. Stellate ganglion block (SGB) has emerged as an effective method for managing insomnia; however, its efficacy may be compromised in some patients, primarily due to a variant vertebral artery anatomy.

Case presentation

This case report describes a patient with severe insomnia accompanied by anxiety. Through cervical ultrasound scanning, we identified richly branched cervical arteries at the C6-C7 segment of the vertebral artery, along with anatomical variations, which could pose a heightened risk for the traditional SGB procedure. Therefore, after carefully adjusting the patient's positioning, we proceeded with ultrasound-guided SGB using a lateral paravein out-of-plane approach. Clinical signs of successful insomnia symptoms alleviation were consistently observed after each block utilizing this alternative technique multiple times in a single patient.

Conclusion

Our report reveals a new lateral paravein out-of-plane approach for ultrasound-guided SGB to treat insomnia, which might be considered an alternative method. More studies should be carried out to confirm the efficacy of this new approach.

Nominal logistic regression analysis of variables determining needle visibility in ultrasound images - a full factorial cadaver study

BACKGROUND

Needle visualization is essential to avoid vascular puncture and nerve injury in ultrasound-guided regional anesthesia. Several factors that statistically influence needle visibility have been described but the dimensions of their individual impact remain unclear. This study aimed to quantify the impact of various independent factors on ultrasound needle visibility.

METHODS

A total of 1500 ultrasound videos of in-plane needle insertions were obtained in embalmed cadavers with ten different commercially available echogenic and non-echogenic needles at different insertion angles and bevel orientations in a full factorial study design. The visibility of needle tip and shaft were rated as "good" or "poor" visibility. Nominal logistic regression analyses were calculated for the visibility of the needle tip and shaft.

RESULTS

SonoPlex Stim Sprotte, SonoTAP Facet (needle tip and shaft) and Spinostar PencilPoint (needle tip)), insertion angle and bevel orientation were associated with good ultrasound visibility, reaching statistical significance (p < 0.05). The range of the effect on the log-odds scale for needle tip visibility was largest for the insertion angle with 6.33, followed by the tissue condition (3.76), bevel orientation (1.45) and the needle types (1.25). Regarding the needle shaft visibility, the largest effect range was observed with the insertion angle (7.36), followed by the tissue conditions with 3.96, needle type (1.86) and bevel orientation (0.95).

CONCLUSION

In-plane needle visibility in ultrasound images depends mainly on the insertion angle, as expected. This is closely followed by the tissue condition, which is a factor related to the patient, thus cannot be altered to improve needle visibility. In the dimensions of the log-odds scale, the choice of a specific needle is far less important towards achieving a good visualization, whereas optimizing the bevel orientation can have a larger impact than the needle choice. Concluding from the relative dimensions of factors that determine needle visibility in this model, the importance of needles with echogenic features may be overrated.

Needle visualization during ultrasound-guided puncture: image optimization

Background

Obtaining an adequate image of the needle by ultrasound reduces complications resulting from punctures, increasing patient safety and reducing hospitalization costs.

Objectives

To verify human perception in relation to number of pixels, while also identifying the best puncture angle and which needle should be used, and to evaluate whether there is a difference if needle visualization software is used.

Methods

20 images were analyzed by 103 students who classified them as being sufficient or insufficient and were compared with the quality observed using photoshop. We evaluated whether there were differences between puncture angles of less than 45º and more than 45º, between IV catheter and introducer needles, and between images obtained with and without visualization software.

Results

There was a higher percentage of sufficient ratings for images those that had more than 60 pixels and when the puncture angle was less than 45º, with significant associations between students' evaluations and each of these groups (p < 0.001). The percentages of images classified as sufficient were higher for images in which a IV catheter was used and also higher for those using the needle visualization software, with significant associations between the results for students' classifications and each of these groups (p < 0.001).

Conclusions

The human eye classifies an image as sufficient according to higher numbers of pixels. Images of punctures at angles smaller than 45º in relation to the surface, of punctures performed with a IV catheter, and when using specific visualization software are also better detected by the human eye.

Short communication: ultrasound-guided percutaneous cryoanalgesia of intercostal nerves for uniportal video-assisted thoracic surgery

Background

Pain after thoracic surgery impairs lung function and increases the rate of postoperative pulmonary complications. Ultrasound-guided percutaneous cryoanalgesia of intercostal nerves constitutes a valid option for adequate postoperative analgesia. A key issue for a successful cryoanalgesia is placing the cryoprobe tip close to the intercostal nerve. This report describes an ultrasound technique using a high-resolution ultrasound probe to accomplish this goal.

Findings

Images of five anesthetized patients undergoing uniportal video-thoracoscopic surgeries are used as clinical examples. In the lateral position, a high-frequency 12 MHz probe is placed longitudinally at 5–7 cm parallel to the spine at the 4th, 5th, and 6th ipsilateral intercostal spaces. Ultrasound images detect the intercostal neurovascular bundle and a 14G angiocath is placed beside the nerve. The cryoprobe is inserted throughout the 14G catheter and the cryoanalgesia cycle is performed for 3 min. Two ultrasound signs confirm the right cryoprobe position close to the nerve: one is a color Doppler twinkling artifact that is seen as the quick shift of colors that delineates the cryoprobe contour. The other is a spherical hypoechoic image caused by the ice ball formed at the cryoprobe tip.

Conclusions

Ultrasound images obtained with a high-frequency probe allow precise location of the cryoprobe tip close to the intercostal nerve for cold axonotmesis.

The Use of a New Device-Assisted Needle Guidance versus Conventional Approach to Perform Ultrasound Guided Brachial Plexus Blockade: A Randomized Controlled Study

Purpose

Ultrasound guidance during nerve blockade poses the challenge of maintaining in-plane alignment of the needle tip. The needle guidance device maintains needle alignment and assists with in-plane needle visualization. The purpose of this study is to evaluate the utility of this device by comparing procedure performance during brachial plexus blockade with the conventional approach.

Methods

After the Institutional Review Board approval and obtaining informed consent, 70 patients receiving either interscalene or supraclavicular nerve blocks were randomly assigned into 2 groups, a conventional approach versus utilizing the needle guidance device. An independent observer recorded: total procedure time; needle insertion time; number of unplanned redirections; and number of reinsertions. Additionally, physician satisfaction and ease of needle visualization were assessed.

Results

Data from seventy patients were analyzed. The median [25th percentile-75th percentile] time to complete the block by the device assisted needle guidance group was 3 (2–3.75) minutes and 4 (3–6) minutes in the conventional approach group (p < 0.001). Additionally, subgroup analyses were performed in the supraclavicular block and interscalene block. Supraclavicular blockade, needle insertion time (median [25th percentile-75th percentile] in seconds) (106 [92–162] vs 197 [140–278]), total procedure time (3 [2–3] vs 4.5 [4–6] in minutes) and unplanned needle redirections (2 [1–5] vs 5.5 [3–9]) were significantly lower in needle guidance group (p < 0.001). With interscalene blockade, needle insertion time (86 [76–146] vs 126 [94–295]) and unplanned needle redirections (2 [1–3] vs 4 [2–8.5]) were significantly lower with needle guidance (p < 0.001), but total procedure time was similar. All the physicians reported that they would use the needle guidance again, and 90% would prefer it for in-plane blocks.

Conclusion

Performing regional blocks using the needle guidance device reduces needle insertion time and unplanned needle redirections in brachial plexus blockade. Moreover, physician satisfaction also improved compared to the use of the conventional technique.

Effect of ultrasound angle for radial artery cannulation in adults: a randomized controlled trial

BACKGROUND

Although the first attempt success rate of radial artery cannulation has been significantly improved by using dynamic needle tip positioning (DNTP) method, there are still problems with long cannulation time. We hereby observe the effect of ultrasound angle for radial artery cannulation in adult patients.

METHODS

Adult patients scheduled to undergo elective surgeries with continuous invasive blood pressure monitoring were included and randomly allocated into either a U-P-artery (ultrasound probe perpendicular to the artery) or U-P-needle (ultrasound probe perpendicular to the needle) group. The primary outcome measure was cannulation time at the first attempt, the secondary outcome measures included the first attempt success rate, number of attempts and the total puncture procedure duration. In addition, the incidence of complications was included as secondary outcomes.

RESULTS

Fifty-nine patients were evaluated finally. The cannulation time at the first attempt in U-P-needle group (N.=28) was significantly lower than that in U-P-artery group (N.=31; median [IQR]: 16 [13.5-20] seconds vs. 41 [25.5-54.5] seconds, P<0.001). The total puncture procedure duration in group U-P-needle was also shorter than that in the group U-P-artery (median [IQR]: 17.4 [13.5-20] seconds vs. 52.2 [25.5-54.5] seconds, P<0.001). No significant difference was observed with respect to first-attempt success rate (96.4% vs. 93.5%, relative risk: 0.97, 95% CI: 0.863-1.0907, P=0.615). The number of attempts showed no statistical difference as well.

CONCLUSIONS

The usage of the U-P-needle approach could remarkably reduce radial arterial cannulation time at the first attempt as well as total puncture procedure duration, comparing with the U-P-artery approach.

Photoacoustic-guided endovenous laser ablation: Characterization and in vivo canine study

Endovenous laser ablation (EVLA) is a minimally invasive surgical procedure, often guided by ultrasound (US) imaging, for treating venous insufficiencies. US imaging limitations in accurately visualizing the catheter and the lack of a temperature monitoring system can lead to sub-optimal outcomes. An integrated photoacoustic (PA)-guided EVLA system has been previously developed and reported to overcome the shortcomings of US-guided procedure. In this study, we further characterized the system and tested the in vivo utility. In addition, PA thermometry was further explored by compensating the variation of PA signal with temperature with respect to the temperature-dependent absorption of blood and water. In vivo imaging results indicated that the PA-guided EVLA system can provide high contrast and accurate images of the ablation catheter tip overlaid on US images of the background tissue. Additionally, absorption-compensated PA signal amplitudes over a relevant range of temperature were measured and demonstrated.

Block-matching-based registration to evaluate ultrasound visibility of percutaneous needles in liver-mimicking phantoms

Purpose

To present a novel methodical approach to compare visibility of percutaneous needles in ultrasound images.

Methods

A motor‐driven rotation platform was used to gradually change the needle angle while capturing image data. Data analysis was automated using block‐matching‐based registration, with a tracking and refinement step. Every 25 frames, a Hough transform was used to improve needle alignments after large rotations. The method was demonstrated by comparing three commercial needles (14G radiofrequency ablation, RFA; 18G Trocar; 22G Chiba) and six prototype needles with different sizes, materials, and surface conditions (polished, sand‐blasted, and kerfed), within polyvinyl alcohol phantom tissue and ex vivo bovine liver models. For each needle and angle, a contrast‐to‐noise ratio (CNR) was determined to quantify visibility. CNR values are presented as a function of needle type and insertion angle. In addition, the normalized area under the (CNR‐angle) curve was used as a summary metric to compare needles.

Results

In phantom tissue, the first kerfed needle design had the largest normalized area of visibility and the polished 1 mm diameter stainless steel needle the smallest (0.704 ± 0.199 vs. 0.154 ± 0.027, p < 0.01). In the ex vivo model, the second kerfed needle design had the largest normalized area of visibility, and the sand‐blasted stainless steel needle the smallest (0.470 ± 0.190 vs. 0.127 ± 0.047, p < 0.001). As expected, the analysis showed needle visibility peaks at orthogonal insertion angles. For acute or obtuse angles, needle visibility was similar or reduced. Overall, the variability in needle visibility was considerably higher in livers.

Conclusion

The best overall visibility was found with kerfed needles and the commercial RFA needle. The presented methodical approach to quantify ultrasound visibility allows comparisons of (echogenic) needles, as well as other technological innovations aiming to improve ultrasound visibility of percutaneous needles, such as coatings, material treatments, and beam steering approaches.

Filling of Fine and Core Biopsy Needles With the Contrast Agent Sulfur Hexafluoride: Ex Vivo and in vitro Evaluation of Ultrasound Needle Visibility

OBJECTIVES

To investigate whether the ex vivo and in vitro ultrasound visibility of fine needles (FNs) and core biopsy needles (CNBs) can be improved by filling them with an ultrasound contrast agent.

METHODS

After needle filling with the contrast agent sulfur hexafluoride, punctures with FNs and CBNs were recorded in the B-mode and contrast-specific imaging mode (10 observations in each of the 4 groups). Recordings were made in both butchered bovine liver (experiment I) and a water bath (experiment II). Air and normal saline were used as controls (total n = 120 for each experiment). In experiment I, 4 ultrasound specialists subjectively assessed the relative needle visibility in the recordings by using an arbitrary scale (integers 0-10). In experiment II, the contrast-to-noise ratio was calculated for both the entire needle course and the needle tip area.

RESULTS

In experiment I, subjective visibility was increased compared with both controls only for CBNs in the contrast-specific imaging mode (P < .01). In experiment II, the contrast-to-noise ratio for both the entire needle course and the needle tip area increased compared with both controls for both FNs and CBNs in the contrast-specific imaging mode (P < .05).

CONCLUSIONS

Ultrasound contrast agent needle filling is a promising new method to increase the visibility of CBNs in the contrast-specific imaging mode. This finding needs to be confirmed in vivo before its clinical value can be assessed.

Establishing a Technique for Pectoral II-Block Catheter Insertion with Ultrasound Guidance: A Randomized Controlled Trial

Purpose

To assess the efficacy and safety of a modified technique for ultrasound-guided pectoral II block for postoperative pain control after mastectomy.

Methods

In this randomized controlled trial, patients were randomly allocated into two groups (40 patients each). Group I patients were subjected to ultrasound-guided pectoral II block with injection of 10 mL lidocaine 1% as a dissecting solution before attempting catheter insertion, while group II patients underwent the standard procedure without a dissecting solution. Measured outcomes included catheter visibility, pain, patient satisfaction, performance time, and complications.

Results

Compared with group II, group I had significantly lower median catheter-visibility scores, shorter block performance time, and fewer insertion attempts. Group I had a nonsignificantly higher rate of complications than group II.

Conclusion

The modified technique facilitated the procedure, shortened the catheter-insertion time, and showed higher patient satisfaction. However, it was associated with lower catheter visibility on ultrasonography. Further studies are required to confirm the present findings and assess the safety of the modified technique.

Novel ultrasound-guided lateral approach for femoral nerve block in cats: a pilot study

OBJECTIVES

The aim of this study was to describe the technique for a novel lateral approach to femoral nerve block in cat cadavers.

METHODS

Five feline cadavers were used in our prospective cadaveric experimental study. Ultrasonography was used to identify the anatomy injection site. Both pelvic limbs were injected with a volume (0.1 ml/kg) of methylene blue in each cat. The cadavers were placed in lateral recumbency, with the limb to be blocked positioned uppermost. The transducer was held perpendicular to the most proximal area of the pelvic limb, ventral to the greater trochanter and slightly cranial to the femur. Methylene blue was injected after the localisation of the femoral nerve. Immediately after the injection, the cat was turned and the technique was repeated on the contralateral side. After performing the 'block' in both limbs, the area was dissected bilaterally and the success was evaluated. A positive femoral nerve staining was considered for a coverage of ⩾1 cm.

RESULTS

A total of 10 ultrasound-guided femoral nerve injections were performed. Ninety percent (n = 9/10) of the nerves were successfully dyed.

CONCLUSIONS AND RELEVANCE

The novel ultrasound-guided lateral approach may be suitable and reproducible for a successful femoral nerve blockade in cats. Further investigations about the clinical usefulness and safety of this femoral nerve block in live cats are required.

Diagnostic and therapeutic musculoskeletal ultrasound applications of the shoulder

High frequency ultrasound is a valuable tool for assessing soft tissue injuries about the shoulder. It has advantages over other imaging modalities including relatively low cost, portability, and dynamic real-time visualization. It has a high sensitivity for identifying tendon degeneration, bursitis, and rotator cuff tears. Ultrasound is also an excellent modality for diagnostic and therapeutic needle-guided procedures. A detailed knowledge of shoulder anatomy and transducer positioning is required for obtaining adequate diagnostic value from ultrasound. This Monograph is designed to help develop scanning protocols for optimizing image acquisition for musculoskeletal assessment of the shoulder. Muscle Nerve, 2019.

A Methodical Quantification of Needle Visibility and Echogenicity in Ultrasound Images

During ultrasound-guided percutaneous interventions, needle localization can be a challenge. To increase needle visibility, enhancements of both the imaging methods and the needle surface properties have been investigated. However, a methodical approach to compare potential solutions is currently unavailable. The work described here involves automated image acquisition, analysis and reporting techniques to collect large amounts of data efficiently, delineate relevant factors and communicate effects. Data processing included filtering, line fitting and image intensity analysis steps. Foreground and background image samples were used to compute a contrast-to-noise ratio or a signal ratio. The approach was evaluated in a comparative study of commercially available and custom-made needles. Varied parameters included needle material, diameter and surface roughness. The shafts with kerfed patterns and the trocar and chiba tips performed best. The approach enabled an intuitive polar depiction of needle visibility in ultrasound images for a large range of insertion angles.

Investigation of a New Echogenic Needle for use with Ultrasound Peripheral Nerve Blocks

A new ‘texturing method’ has been developed for nerve block needles in an attempt to improve the ultrasonic image of the needles. Using a synthetic phantom, these textured needles were compared to currently available needles. The textured needle had improved visibility under ultrasound. This type of needle may assist the anaesthetist perform ultrasound-guided regional anaesthesia.

Accurate Needle Localization Using Two-Dimensional Power Doppler and B-Mode Ultrasound Image Analyses: A Feasibility Study

Curvilinear ultrasound transducers are commonly used in various needle insertion interventions, but localizing the needle in curvilinear ultrasound images is usually challenging. In this paper, a new method is proposed to localize the needle in curvilinear ultrasound images by exciting the needle using a piezoelectric buzzer and imaging the excited needle using a curvilinear ultrasound transducer to acquire a power Doppler image and a B-mode image. The needle-induced Doppler responses that appear in the power Doppler image are analyzed to estimate the needle axis initially and identify the candidate regions that are expected to include the needle. The candidate needle regions in the B-mode image are analyzed to improve the localization of the needle axis. The needle tip is determined by analyzing the intensity variations of the power Doppler and B-mode images around the needle axis. The proposed method is employed to localize different needles that are inserted in three ex vivo animal tissue types at various insertion angles, and the results demonstrate the capability of the method to achieve automatic, reliable and accurate needle localization. Furthermore, the proposed method outperformed two existing needle localization methods.

Breast Ultrasound Technology and Performance Evaluation of Ultrasound Equipment: B-Mode

Ultrasound (US) has become increasingly important in imaging and image-guided interventional procedures. In order to ensure that the imaging equipment performs to the highest level achievable and thus provides reliable clinical results, a number of quality control (QC) methods have been developed. Such QC is increasingly required by accrediting agencies and professional organizations; however, these requirements typically do not include detailed procedures for how the tests should be performed. In this paper, a detailed overview of QC methods for general and breast US imaging using computer-based objective methods is described. The application of QC is then discussed within the context of a common clinical application (US-guided needle biopsy) as well as for research applications, where QC may not be mandated, and thus is rarely discussed. The implementation of these methods will help in finding early stage equipment faults and in optimizing image quality, which could lead to better detection and classification of suspicious findings in clinical applications, as well as improving the robustness of research studies.

EUS Needle Identification Comparison and Evaluation study (with videos)

BACKGROUND AND AIMS

EUS-guided FNA or biopsy sampling is widely practiced. Optimal sonographic visualization of the needle is critical for image-guided interventions. Of the several commercially available needles, bench-top testing and direct comparison of these needles have not been done to reveal their inherent echogenicity. The aims are to provide bench-top data that can be used to guide clinical applications and to promote future device research and development.

METHODS

Descriptive bench-top testing and comparison of 8 commonly used EUS-FNA needles (all size 22 gauge): SonoTip Pro Control (Medi-Globe); Expect Slimline (Boston Scientific); EchoTip, EchoTip Ultra, EchoTip ProCore High Definition (Cook Medical); ClearView (Conmed); EZ Shot 2 (Olympus); and BNX (Beacon Endoscopic), and 2 new prototype needles, SonoCoat (Medi-Globe), coated by echogenic polymers made by Encapson. Blinded evaluation of standardized and unedited videos by 43 EUS endoscopists and 17 radiologists specialized in GI US examination who were unfamiliar with EUS needle devices.

RESULTS

There was no significant difference in the ratings and rankings of these needles between endosonographers and radiologists. Overall, 1 prototype needle was rated as the best, ranking 10% to 40% higher than all other needles (P < .01). Among the commercially available needles, the EchoTip Ultra needle and the ClearView needle were top choices. The EZ Shot 2 needle was ranked statistically lower than other needles (30%-75% worse, P < .001).

CONCLUSIONS

All FNA needles have their inherent and different echogenicities, and these differences are similarly recognized by EUS endoscopists and radiologists. Needles with polymeric coating from the entire shaft to the needle tip may offer better echogenicity.

Phantom Study of a New Laser-Etched Needle for Improving Visibility During Ultrasonography-Guided Lumbar Medial Branch Access With Novices

OBJECTIVE

To compare the visibility and procedural parameters between a standard spinal needle and a new laser-etched needle (LEN) in real-time ultrasonography guided lumbar medial branch access in a phantom of the lumbosacral spine.

METHODS

We conducted a prospective single-blinded observational study at a rehabilitation medicine center. A new model of LEN was manufactured with a standard 22-gauge spinal needle and a laser etching machine. Thirty-two inexperienced polyclinic medical students performed ultrasonography-guided lumbar medial branch access using both a standard spinal needle and a LEN with scanning protocol. The outcomes included needle visibility score, needle elapsed time, first-pass success rate, and number of needle sticks.

RESULTS

The LEN received significantly better visibility scores and shorter needle elapsed time compared to the standard spinal needle. First-pass success rate and the number of needle sticks were not significantly different between needles.

CONCLUSION

A new LEN is expected to offer better visibility and enable inexperienced users to perform an ultrasonography-guided lumbar medial branch block more quickly. However, further study of variables may be necessary for clinical application.

Modeling, Production, and Testing of an Echogenic Needle for Ultrasound-Guided Nerve Blocks

We have designed, produced, and tested an echogenic needle based on a sawtooth pattern where the height of the tooth was 1.25 times the wavelength of the ultrasound transducer. A numeric solution to the time-independent wave equation (Helmholtz equation) was used to create a model of backscattering from a needle. A 21-gauge stainless steel prototype was manufactured and tested in a water bath. Backscattering from the needle was compared to theoretical predications from our model. Based on these results, an 18-gauge prototype needle was fabricated from stainless steel and tested in a pig cadaver. This needle was compared to a commercial 18-gauge echogenic needle (Pajunk Medical Systems, Tucker, GA) by measuring the brightness of the needle relative to the background of sonograms of a needle in a pig cadaver. The backscattering from the 21-gauge prototype needle reproduced the qualitative predictions of our model. At 30° and 45° of insonation, our prototype performed equivalently to the Pajunk needle. At 60°, our prototype was significantly brighter than the Pajunk needle (P = .017). In conclusion, we chose a model for the design of an echogenic needle and modeled it on the basis of a solution to the Helmholtz equation. A prototype needle was tested in a water bath and compared to the model prediction. After verification of our model, we designed an 18-gauge needle, which performed better than an existing echogenic needle (Pajunk) at 60° of insonation. Our needle will require further testing in human trials.

[Improvement of sonographic visualization of cannula needle tips by alignment of the needle lumen : In vitro investigation of established needle tip forms]

BACKGROUND

In the context of ultrasound-guided peripheral nerve blocks (regional anesthesia), clear visualization of the needle tip and the target structure are mandatory for the performance of a safe puncture and injection. The purpose of this in vitro study was to analyze the visualization of different forms of needle tips and calibers of cannulas in a phantom simulating human tissue, with the help of a standardized image analysis system. Different depths and angles of the puncture needle in relation to the ultrasound probe were tested.

MATERIAL AND METHODS

Cannula needles established for use in regional anesthesia with different surfaces, diameters and needle tip form in 23 different combinations were analyzed. A gelatine-based phantom was used to simulate human tissue. The standardized visualization of the needle tip with the ultrasound probe was performed in plane at different angles (30°, 45° and 60°), depths of penetration (1 cm, 2 cm and 3 cm) and two different alignments of the cannula needle lumen to the ultrasound probe (0° and 180°). The screenshots of the ultrasound pictures were analyzed by quantifying the pixel brightness around the needle tip (region of interest) with a standardized software (score 0-255).

RESULTS

In this study 1104 ultrasound images of cannula needles were analyzed. Diminished scores (reduced pixel brightness) of the needle tips were documented with increasing distance from the ultrasound probe. Comparison of punctures at angles of 30° and 45° showed no differences in needle tip visibility (same scores) but punctures at an angle of 60° were poorly visualized compared with 30° and 45° (mean scores 87.90 ± 11.60 vs. 78.40 ± 12.07, p < 0.001 and 81.85 ± 11.79 vs. 78.40 ± 12.07, p < 0.001, respectively). The direct alignment of the cannula lumen towards the ultrasound probe (0°) was significantly more easily visualized when compared with the reverse alignment of 180° (mean scores 86.90 ± 12.74 vs. 84.80 ± 11.66, p = 0.003, respectively). No differences in visibility were detected between the different cannula needle diameters examined. The Sprotte cannula showed the best visibility score with respect to the cut of the needle tip (mean score 89.40 ± 11.72).

CONCLUSION

The visibility of cannulas in ultrasound scans depends on the ultrasound frequency, angle of the puncture in relation to the ultrasound probe and the depth of penetration. The results of this study showed that direct alignment of the cannula needle lumen towards the ultrasound probe (0°) independently improved needle tip visualization. This simple measure allows a significant improvement in the safe performance of ultrasound-guided peripheral nerve blocks.

A Randomized Controlled Trial Evaluating the See, Tilt, Align, and Rotate (STAR) Maneuver on Skill Acquisition for Simulated Ultrasound-Guided Interventional Procedures

OBJECTIVES

Achieving the best view of the needle and target anatomy when performing ultrasound-guided interventional procedures requires technical skill, which novices may find difficult to learn. We hypothesized that teaching novice performers to use 4 sequential steps (see, tilt, align, and rotate [STAR] method) to identify the needle under ultrasound guidance is more efficient than training with the commonly described probe movements of align, rotate, and tilt (ART).

METHODS

This study compared 2 instructional methods for transducer manipulation including alignment of a probe and needle by novices during a simulated ultrasound-guided nerve block. Right-handed volunteers between the ages of 18 and 55 years who had no previous ultrasound experience were recruited and randomized to 1 of 2 groups; one group was trained to troubleshoot misalignment with the ART method, and the other was trained with the new STAR maneuver. Participants performed the task, consisting of directing a needle in plane to 3 targets in a standardized gelatin phantom 3 times. The performance assessor and data analyst were blinded to group assignment.

RESULTS

Thirty-five participants were recruited. The STAR group was able to complete the task more quickly (P < .001) and visualized the needle in a greater proportion of the procedure time (P = .004) compared to the ART group. All STAR participants were able to complete the task, whereas 41% of ART participants abandoned the task (P = .003).

CONCLUSIONS

Novices are able to complete a simulated ultrasound-guided nerve block more quickly and efficiently when trained with the 4-step STAR maneuver compared to the ART method.

Evaluation of the eZono 4000 with eZGuide for ultrasound-guided procedures

Ultrasound-guided procedures are increasingly common in a variety of acute care settings, such as the operating room, critical care unit and emergency room. However, accurate judgment of needle tip position using traditional ultrasound technology is frequently difficult, and serious injury can result from inadvertently advancing beyond or through the target. Needle navigation is a recent innovation that allows the clinician to visualize the needle position and trajectory in real time as it approaches the target. A novel ultrasound machine has recently been introduced that is portable and designed for procedural guidance. The eZono 4000™ features an innovative needle navigation technology that is simple to use and permits the use of a wide range of commercially available needles, avoiding the inconvenience and cost of proprietary equipment. This article discusses this new ultrasound machine in the context of other currently available ultrasound machines featuring needle navigation.

Application of echogenic technology for catheters used in ultrasound-guided continuous peripheral nerve blocks

Limited data exist regarding the echogenicity of perineural catheters, but visualization is crucial to ensure accurate placement and efficacy of the subsequent local anesthetic infusion. The objective of this study was to determine the comparative echogenicity of various regional anesthesia catheters. In an in vitro porcine-bovine model, we compared the echogenic qualities of 3 commercially available regional anesthesia catheters and 1 catheter under development to optimize echogenicity. Outcomes included visual echogenicity ranking, image quality, and scanning time, as assessed by 2 blinded investigators. The experimental catheter was found to be more echogenic than 2 of the 3 comparators.

A comparison of free-hand vs laser-guided long-axis ultrasound techniques in novice users

OBJECTIVE

The increasing use of point-of-care ultrasonography for targeted procedures justifies a device that helps both novices in training and experts perform the long-axis needle approach. The initial success of traditional needle guidance devices in reducing the time of target procedures is not universal and they can be cumbersome. We aim to investigate whether the less bulky and previously untested laser guide can succeed in reducing procedure time in novice ultrasonographers.

METHODS

82 medical students with no ultrasound experience volunteered. Random allocation determined whether, during a targeted procedure in a turkey breast and olive phantom, participants were assisted by the laser guide or not. The time taken to pierce the target was recorded at 1-cm depth.

RESULTS

The mean procedure time in the laser-assisted (LA) group was 25.1 s (14.0 s; 18.0-25.0 s). The mean procedure time in the free-hand group was 45.5 s (23.0 s; 7.0-55.0 s). The procedure time in the LA group was significantly reduced (p<0.01).

CONCLUSION

The laser guide significantly improved procedure times. It is felt that the cheaper, smaller, easy to integrate, sterile and more user-friendly laser guidance unit may be a better alternative to the needle guide in improving procedure times for the novice ultrasonographer or to assist the expert, during training for, or performance of, ultrasound-guided targeted procedures.

ADVANCES IN KNOWLEDGE

Following from the prototype paper, this is the first study to investigate the effectiveness of attaching a laser-guidance device to an ultrasound probe. The device succeeded in reducing the procedure times of targeted procedures.

Use of needle enhancing software to improve injection technique amongst inexperienced anaesthetists performing ultrasound-guided peripheral nerves blocks in dogs

OBJECTIVE

To determine if the use of needle enhancing software facilitate injection technique in ultrasound-guided peripheral nerve blocks.

STUDY DESIGN

Prospective, blinded, randomized controlled trial.

ANIMALS

Eight hind limbs from canine cadavers.

METHODS

The limbs were randomly allocated to two groups; software on (group I) and software off (group II). Eight anaesthetists with no previous experience of ultrasound-guided regional anaesthesia were recruited. Thirty-six procedures were carried out (18 per group). After sciatic nerve visualisation via ultrasonography, the anaesthetist introduced a needle guided by ultrasonography. When the tip of the needle was considered by the anaesthetist to be as close as possible to the nerve without touching it, 0.05 mL of methylene blue dye was injected. Parameters evaluated included: number of attempts to visualise the needle with ultrasonography, time spent to perform the technique, subjective evaluation of ease of needle visualisation, proximity of the tip of the needle to the nerve, and, at dissection of the leg, inoculation site of the dye in relation to the nerve.

RESULTS

Significant differences between groups were identified in relation to the number of attempts (group I: median 1, IQR: 1 - 1 attempts versus group II: median 1, IQR: 1 - 4 attempts, p = 0.019), and the relationship between the dye and the nerve during hind limb dissection (72.2% of the nerves were stained in group I versus 16.6% in group II, p = 0.003). No significant difference between groups was observed with respect to the time taken to perform the procedure (group I: median 25.5, IQR: 18.4 - 44.3 seconds versus group II: median 35.7, IQR: 18.6-78.72 seconds, p = 0.31), subjective evaluation of the needle visualization (p = 0.45) or distance between the tip of the needle and the nerve as measured from the ultrasound screen (p = 0.23).

CONCLUSIONS AND CLINICAL RELEVANCE

This study identified greater success rate in nerve staining when the needle enhancing software was used. The results suggest that the use of this technique could improve injection technique amongst inexperienced anaesthetists performing ultrasound-guided peripheral nerve blocks in dogs.

Ultrasound and electrical nerve stimulation-guided S1 nerve root block

A selective lumbosacral nerve root block is generally is performed under X-ray fluoroscopy, which has the disadvantage of radiation exposure and the need for fluoroscopy equipment. In this study, we assessed the effectiveness of ultrasound and nerve stimulation-guided S1 nerve root block on 37 patients with S1 radicular syndrome. With the patient in a prone position, an ultrasound scan was performed by placing the probe parallel to the body axis. The needle was pointed slightly medial from the lateral side of the probe and advanced toward a hyperechoic area in the sacral foramina with ultrasound guidance. Contrast medium was then injected and its dispersion confirmed by fluoroscopy. The acquired contrast images were classified into intraneural, perineural, and paraneural patterns. The significance of differences in the effect of the block among the contrast image patterns was analyzed. After nerve block, decreased sensation at the S1 innervated region and pain relief was achieved in all patients. No significant difference was noted in the effect of the block between perineural and paraneural patterns. In conclusion, this technique provided reliable S1 nerve root block in patients with S1 radicular syndrome and minimized radiation exposure.

Optimizing the safety and practice of ultrasound-guided regional anesthesia: the role of echogenic technology

PURPOSE OF REVIEW

Significant improvements have been made in the quality of ultrasound imaging, and it is now much easier to see nerves. However, the key to safe ultrasound-guided regional anesthesia is to be able to direct the needle to the target. This relies on good needle visibility. We review the recent advances that have been made in this crucial area.

RECENT FINDINGS

Echogenic needles can improve shaft and tip visibility independent of experience level, compensate for suboptimal scanning technique, allow steeper insertion angles, reduce technical difficulty, and increase both confidence and satisfaction by anesthesiologists. An echogenic needle encourages holding the probe in one place on the patient, only advancing the needle when it can be seen, hence reducing the likelihood of quality-compromising behaviors. The poor visibility of nonechogenic needles when inserted at steeper angles commonly causes the observer to underestimate the insertion depth of the needle. Significant differences in echogenicity are found when comparing the currently available needles.

SUMMARY

Good echogenic needles should increase safety, efficacy, and simplicity, and hopefully further drive the adoption of ultrasound-guided techniques, to the benefit of our patients.

Needle echogenicity in sonographically guided regional anesthesia: blinded comparison of 4 enhanced needles and validation of visual criteria for evaluation

OBJECTIVES

Needle visualization is important for sonographically guided regional anesthesia procedures. Needle characteristics that improve needle visualization are therefore important to anesthesiologists. This study compared several echogenic needle designs by defining characteristics of needle echogenicity and assessing regional anesthesiologist preferences for these characteristics across various needle angles.

METHODS

Twelve blinded regional anesthesiologists graded 5 randomized block needles (1 nonechogenic control and 4 echogenic) on 4 predefined characteristics (overall brightness of the needle, overall clarity of the needle, brightness of the needle tip, and clarity of the needle tip). In-plane needle images in a gel phantom were obtained at 4 needle angles (15°, 30°, 45°, and 60°). Participants rated specific needle characteristics for each needle at each angle and then ranked their overall needle preferences.

RESULTS

Significant differences in all 4 needle characteristics were found across needle types (P< .01). Clarity of the needle tip was significantly associated with overall needle rank (P = .009). Other needle visualization characteristics were not significantly correlated with needle rank. The SonoPlex Stim needle (Pajunk Medical Systems, Tucker, GA) was rated highest in all 4 predefined needle characteristics as well as overall needle rank.

CONCLUSIONS

This study shows that anesthesiologists prefer certain visual characteristics of needles used in sonographically guided regional anesthesia procedures. Specifically, needle tip clarity most closely predicted clinician needle preferences. These results support the idea that all echogenic needle designs do not uniformly enhance needle visualization. Further studies are needed to determine whether needles with superior tip clarity predict not only clinician preferences but also improved sonographically guided regional anesthetic outcomes.

Assessment of the level of difficulty of four techniques of endovenous thermal ablation of the great saphenous vein and the echogenicity of the tip of the working device in vivo

BACKGROUND

To compare the level of difficulty of four techniques of endovenous thermal ablation (EVTA) of the great saphenous vein and the echogenicity of the tip of the working device in vivo.

METHODS

Sixty patients qualified to the EVTA of the great saphenous vein were randomly assigned to treatment with an 810-nm axial diode laser [endovenous laser ablation (EVLA) 810] with two different delivery systems: 4-F introducer, 0.018" guidewire, 22-G needle (EVLA810-1) and 4-F introducer, 0.035" guidewire, 19-G needle (EVLA810-2); a 1470-nm radial diode laser (EVLA1470); or radiofrequency ablation (RFA; ClosureFAST). The level of difficulty of four stages of the procedure-cannulation of a vein, advancement of the working part to the saphenofemoral junction (SFJ), visualization of a tip of the working part at SFJ, and difficulty of performing the ablation and delivering the planned linear energy density-was subjectively assessed. An objective comparison of visibility of working parts in ultrasonography was performed with analysis of grayscale median.

RESULTS

The cannulation of a distal segment of the obliterated vein was the most difficult in EVLA810-1, P = 0.015. The delivery of a working part to the SFJ was the least problematic in RFA and EVLA1470, P = 0.024. The visualization of the working tip at the SFJ was the most difficult in RFA, P = 0.028. The application of desired amount of energy was the easiest in RFA, P = 0.038. The EVLA1470 presented the best echogenicity.

CONCLUSIONS

Although all the examined techniques have advantages and disadvantages, EVTA with the 1470-nm diode laser with radial optic fiber seems to be the easiest.

Needle visibility in different tissue models for ultrasound-guided regional anaesthesia

BACKGROUND

Models for ultrasound-guided regional anaesthesia (USGRA) are important for research and training. However, the limited data available show great differences in quality of needle and tissue visualisation with regard to the applied model. This study aims to compare common USGRA models and human tissue with regard to their influence on needle visibility.

METHODS

We conducted this study using four models (embalmed human cadaver, turkey breast, pork, and synthetic gel models) and a volunteer (human control) as well as two different needles [Stimuplex A (StA), conventional needle; Stimuplex D Plus (StD+), needle with improved echogenicity]. We obtained ultrasound videos of needle advancement and withdrawal using the in-plane approach at a 45° angle in all four models and the volunteer. Fifteen test persons were prospectively enrolled. Ultrasound videos were presented in a randomised, blinded manner. The test persons were asked to rate the visibility of the needle shaft (VS) and tip (VT) on a four-point scale (0-3).

RESULTS

VS and VT were comparable between the human control and cadaver model for both needle types. The pork, turkey, and synthetic gel models had significantly higher visibility scores than the human control for both needle types. VS of StD+ was significantly higher than that of StA in the pork and turkey models, but not in the synthetic model, cadaver model, or human control.

CONCLUSION

In this pilot study, needle visibility in embalmed cadaver is comparable with that in human control. Needle visibility was significantly higher in other tissue models (turkey breast, pork, synthetic gel models) than in the human control, which may limit their value in training environments.

Ultrasound visibility of regional anesthesia catheters: an in vitro study

BACKGROUND

Ultrasound subjective visibility of in-plane needles is correlated with the intensity difference between the needle surface and the background. Regional anesthesia catheters are difficult to visualize by an ultrasound. In the present study, we investigated the ultrasound visibility of the catheters.

METHODS

Six catheters were placed at 0° and 30° relative to and at a depth of 1 cm below the pork phantom surface. Ultrasound images of in-plane catheters were evaluated, subjectively and objectively. Outer and inner objective visibilities were defined as the difference in the mean pixel intensity between the catheter surface and adjacent background, and between the surface and the center of the catheter, respectively. Evaluations were made based on the portion of the catheters. A P value < 0.05 was considered significant.

RESULTS

Subjective visibility was more strongly correlated with the inner objective visibility than with the outer objective visibility at both angles. Metallic 19-gauge catheters were more subjectively visible than the non-metallic 20-gauge catheters at 30° degrees (P < 0.01). Subjective, and outer and inner objective visibility were significantly lower at 30° than at 0° (P < 0.01, P < 0.01, P = 0.02). Perifix ONE at 0° and Perifix FX at 30° were the most visible catheters (P < 0.01 for both).

CONCLUSIONS

Subjective visibility of catheters can not be evaluated in the same manner as that of the needles. For the best possible visualization, we recommend selecting a catheter with a structure that enhances the dark at the center of catheter, rather than basing the catheter selection on the bore size.

Echogenic regional anaesthesia needles: a comparison study in Thiel cadavers

Ultrasound guidance is now the standard procedure for regional nerve block in anesthesiology. However, ultrasonic visualisation of needle manipulation and guidance within tissues remains a problem. Two new echogenic needles (Pajunk and Braun) have been introduced to anesthesiology clinical practice but evaluation has been restricted to preserved animal tissue. In this study, the visibility of both echogenic needles was compared with a standard nonechogenic needle in a Thiel cadaver model. A total of 144 intramuscular injections were made in the upper arm in-plane and out-of-plane to the ultrasound beam at four angles (30°, 45°, 60° and 75°). The visibility of the needle was assessed by two independent, blinded observers using a 5-point Likert ordinal scale. Weighted κ for interobserver agreement was 0.77 (95% confidence interval [CI]: 0.68-0.86). The Pajunk echogenic needle was more visible than the Braun standard needle in-plane (p = 0.04), and the Braun standard and Braun echogenic needles out-of-plane (p = 0.02). Independent predictors of visibility using logistic regression were needle (p < 0.001) and plane of insertion (p = 0.08), receiver operator characteristic (ROC) area under the curve 0.90. In conclusion, the Pajunk echogenic needle offers the best visibility for ultrasound-guided regional anesthesia.

A review of the benefits and pitfalls of phantoms in ultrasound-guided regional anesthesia

With the growth of ultrasound-guided regional anesthesia, so has the requirement for training tools to practice needle guidance skills and evaluate echogenic needles. Ethically, skills in ultrasound-guided needle placement should be gained in a phantom before performance of nerve blocks on patients in clinical practice. However, phantom technology is varied, and critical evaluation of the images is needed to understand their application to clinical use. Needle visibility depends on the echogenicity of the needle relative to the echogenicity of the tissue adjacent the needle. We demonstrate this point using images of echogenic and nonechogenic needles in 5 different phantoms at both shallow angles (20 degrees) and steep angles (45 degrees). The echogenicity of phantoms varies enormously, and this impacts on how needles are visualized. Water is anechoic, making all needles highly visible, but does not fix the needle to allow practice placement. Gelatin phantoms and Blue Phantoms provide tactile feedback but have very low background echogenicity, which greatly exaggerates needle visibility. This makes skill acquisition easier but can lead to false confidence in regard to clinical ability. Fresh-frozen cadavers retain much of the textural feel of live human tissue and are nearly as echogenic. Similar to clinical practice, this makes needles inserted at steep angles practically invisible, unless they are highly echogenic. This review describes the uses and pitfalls of phantoms that have been described or commercially produced.