Evaluation of a Novel Out-of-Plane Needle Guide

On the physics of ultrasound transmission for in-plane needle tracking in guided interventions

Objective.In ultrasound (US) guided interventions, the accurate visualization and tracking of needles is a critical challenge, particularly during in-plane insertions. An inaccurate identification and localization of needles lead to severe inadvertent complications and increased procedure times. This is due to the inherent specular reflections from the needle with directivity depending on the angle of incidence of the US beam, and the needle inclination.Approach.Though several methods have been proposed for improved needle visualization, a detailed study emphasizing the physics of specular reflections resulting from the interaction of transmitted US beam with the needle remains to be explored. In this work, we discuss the properties of specular reflections from planar and spherical wave US transmissions respectively through multi-angle plane wave (PW) and synthetic transmit aperture (STA) techniques for in-plane needle insertion angles between 15°-50°.Main Results.The qualitative and quantitative results from simulations and experiments reveal that the spherical waves enable better visualization and characterization of needles than planar wavefronts. The needle visibility in PW transmissions is severely degraded by the receive aperture weighting during image reconstruction than STA due to greater deviation in reflection directivity. It is also observed that the spherical wave characteristics starts to alter to planar characteristics due to wave divergence at large needle insertion depths.Significance.The study highlights that synergistic transmit-receive imaging schemes addressing the physical properties of reflections from the transmit wavefronts are imperative for the precise imaging of needle interfaces and hence have strong potential in elevating the quality of outcomes from US guided interventional practices.

Percutaneous nephrolithotomy - the puncture

OBJECTIVE

To determine what importance is given to the puncture and assistive technologies in percutaneous nephrolithotomy (PNL) in the current urological literature.

METHODS

PubMed was searched for English publications and reviews for the keywords: 'percutaneous nephrolithotomy', 'percutaneous nephrostomy', 'puncture'. The search was limited to the last 5 years, January 2016 until February 2021. Based on 183 abstracts, 121 publications were selected, read, and reviewed. References, older or seminal papers were read and cited if they contributed to a better understanding. A total of 198 references form the basis of this narrative review.

RESULTS

The puncture is frequently referred to as the most crucial part of PNL. In contrast, the influence of the puncture on the failure rate of PNL and the specific puncture-related complications seems to be low in the single-digit percentage range. However, there are no universally accepted definitions and standards measuring the quality of puncture. Consequently, the impact of the puncture on general PNL complications, on stone scores predicting success rates and on learning curves evaluating surgeons' performance have not been systematically studied. Assistive technologies rely on fluoroscopy and ultrasonography, the latter of which is becoming the preferred imaging modality for monitoring the entire procedure. Needle bending, a problem relevant to all puncture techniques, is not addressed in the urological literature.

CONCLUSIONS

The importance attached to puncture in PNL in the current urological literature is subjectively high but objectively low. Some basics of puncture are not well understood in urology. Disciplines other than urology are more actively involved in the development of puncture techniques.

Prevention of posterior wall puncture with a self-made needle block

Vascular access is one of the most commonly performed invasive procedures in medicine. Ultrasound-guided vascular access has been shown to improve patient safety, decrease associated complications and increase first attempt success rates, however, the risk for a posterior venous wall puncture (PVWP) still exists. To reduce this complication, needle guides have been used, though, current methods have limited accessibility and generalizability. Thus, the aim of this article is to describe how a self-made needle block constructed with materials present in a central line kit can reduce the incidence of PVWP and its associated complications in novice POCUS users.

Training novice in ultrasound-guided venipuncture: A randomized controlled trial comparing out-of-plane needle-guided versus free-hand ultrasound techniques on a simulator

BACKGROUND

Peripheral intravenous access is a common medical procedure, however, it can be difficult to perform in some patients. Success rates have proved greater with ultrasound guidance. Peripheral intravenous access using ultrasound requires specific training, especially for new ultrasound users. To overcome these difficulties, guidance devices on ultrasound probes are able to control the angle of penetration into tissues. We hypothesized that, and particularly for new ultrasound users, the use of a needle guide (NG) paired with the out-of-plane approach would facilitate puncture of a simulation model of vessel more effectively than similar free hand (FH) techniques.

METHODS

A prospective controlled randomized study was conducted of new ultrasound users using a guide wire introducer needle on gelatine phantom. After a 30-min lecture, one group performed the FH technique and the other group performed the NG technique both in an out-of-plane approach. The main criterion was the number of attempts before success of catheterization of this model of vessel.

RESULTS

Thirty-four nurse anesthetist students participated in the study. The number of attempts before success using the NG technique was significantly lower: 3.7 (±0.9) in the NG group versus 6.7 (±3.3) in the FH group (p = 0.01). In the NG group, 100% of the participants achieved success after the sixth attempt. In the FH group, only 81.25% (n = 13/16) reached success.

CONCLUSION

NG technique has been proved to have a steeper learning curve compared with the FH technique. A study on a learning curve in clinical practice is needed to confirm these results.

Education and training in ultrasound-guided regional anaesthesia and pain medicine

PURPOSE OF REVIEW

Effective and safe regional anaesthesia and pain medicine procedures require clinicians to learn and master complex theoretical knowledge and motor skills. This review aims to summarize articles relevant to education and training in these skill sets in the previous 2 years.

RECENT FINDINGS

Twenty-two articles were identified, investigating nine out of the 13 top-ranked research topics in education and training in regional anaesthesia. Research topics addressed by these articles included prerotation simulation, deliberate practice combined with formative assessment tools, validation of assessment tools, three-dimensional-printed models, and knowledge translation from simulation to clinical practice. Emerging concepts investigated for their applications in regional anaesthesia included eye-tracking as a surrogate metric when evaluating proficiency, and elastography aiding visual salience to distinguish appropriate perineural and inappropriate intraneural injections.

SUMMARY

Research into education and training in regional anaesthesia covered multiple and diverse topics. Methodological limitations were noted in several articles, reflecting the difficulties in designing and conducting medical education studies. Nonetheless, the evidence-base continues to mature and innovations provide exciting future possibilities.

Intraoperative Ultrasound Using Dorsal Root Entry Zone Lesioning: A Way to Guide Intraspinal Cord Therapeutic Lesions

Dorsal root entry zone (DREZ) lesioning is an effective method to treat refractory neuropathic pain in patients with radicular avulsion. In this procedure, we penetrate the spinal cord with a radiofrequency electrode using the posterior lateral sulcus as a guide. The intraspinal electrode trajectory has to be angled medially about 25°-45° to spare the corticospinal tract, which lies lateral to the DREZ, and also to spare the posterior column, which lies medial to it. Here we present a case of a patient with radicular avulsion lesion of rootlets of the cervical spinal cord successfully treated with DREZ lesioning using intraoperative ultrasound as a guide to perform the spinal cord lesions. The use of intraoperative ultrasound during DREZ lesioning in patients with radicular avulsion improves the neurosurgeon ability to precisely localize the posterior lateral sulcus and also to better define the correct angulation of the trajectory.

Ultrasound-guided sciatic nerve block at the midthigh level in a porcine model: A descriptive study

BACKGROUND AND OBJECTIVE

There are a growing number of porcine models being used for orthopaedic experiments for human beings. Therefore, pain management of those research pigs using ultrasound (US)-guided nerve block can be usefully performed. The aim of this study is to determine optimal US approaches for accessing and localizing the sciatic nerve at the midthigh level, a relevant block site for hindlimb surgery in female Yorkshire pigs.

METHODS

As a first step, we dissected the intubated, blood-washed out pigs (n = 3) and confirmed the anatomical position of the sciatic nerve at midthigh level. After dissection, we found the sciatic nerve, connected with nerve stimulator, and checked the dorsiflexion or plantar flexion of the hindlimb. We matched the sciatic nerve location with the US image. After the pigs were euthanized, the neural structures of the sciatic nerve were confirmed by histological examination with H&E staining. In second step, a main US-guided sciatic nerve block study was done in the intubated, live pigs (n = 8) based on the above study.

RESULTS

In lateral position, the effective US-guided nerve block site was about 6 cm from the patella crease level; immediately proximal to the bifurcation of the sciatic nerve into the tibial nerve and common peroneal nerve. The distal femur was selected as the landmark. There were no vessels or other nerves surrounding the sciatic nerve. The needle-tip was positioned less than 1 cm lateral from the distal femur and about 2 cm deep to skin. 'Donut sign' in US images was confirmed in all 16 nerves.

CONCLUSIONS

Midthigh level sciatic nerve is located superficially, which enables nerve block to be easily performed using US. This is the first study to describe midthigh sciatic nerve block in the lateral position under US guidance in a porcine model from a clinical perspective.

The Value of Needle-Guidance Technology in Ultrasound-Guided Percutaneous Procedures Performed by Radiology Residents: A Comparison of Freehand, In-Plane, Fixed-Angle, and Electromagnetic Needle Tracking Techniques

OBJECTIVES

Radiology residents typically learn ultrasound-guided procedures by performing supervised procedures on patients who may experience longer procedure times and higher complication rates. The purpose of this study was to determine if existing technologies, such as in-plane, fixed-angle guidance (IPFA) and electromagnetic needle tracking (ENT), can improve resident procedure time and accuracy.

METHODS

Radiology residents (18 total) were randomized to 1 of 3 ultrasound-guidance technique groups-freehand, IPFA, or ENT-and instructed to place a needle into 4 liver lesions in a humanoid phantom, each increasing in difficulty. For each lesion, residents were timed from skin puncture to needle placement, and the number of times the needle was pulled back and redirected (pullbacks) was recorded. Primary outcomes were total time and total number of pullbacks for all 4 lesions. Secondary outcomes were individual time and number of pullbacks for each lesion.

RESULTS

Compared to the freehand group, the IPFA and ENT groups demonstrated lower procedural time and number of pullbacks both in total and for each individual lesion. Differences in total time and total number of pullbacks were significant (P < .001), as were differences for lesion 3 (P = .002-.02) and lesion 4 (P < .001). Differences for lesions 1 and 2 were not statistically significant.

CONCLUSIONS

Radiology resident procedure time and procedure accuracy (as judged by number of pullbacks) are significantly improved by the use IPFA and ENT guidance technologies.