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Steps on how a phantom can be 3D printed and embedded within a medium suitable for training of ultrasound-guided procedures
Abstract
Practice is required for acquiring procedural proficiency and this can be obtained from clinical practice, or more sensibly, having novices first practice the skill on an inanimate phantom or trainer. Commercially produced phantoms are expensive and 3D printing is becoming more cost effective. In our example, we have used a 3D-printed thoracic spine. This allows practitioners to improve their ultrasound-guided regional anesthesia needle imaging skills through deliberate practice. In this report, we describe in detail the requirements for producing a 3D-printed phantom comprising a 3D segment of thoracic spine set within a semi-solid medium.
The theoretical framework presented in this article explains expert performance as the end result of individuals' prolonged efforts to improve performance while negotiating motivational and external constraints. In most domains of expertise, individuals begin in their childhood a regimen of effortful activities (deliberate practice) designed to optimize improvement. Individual differences, even among elite performers, are closely related to assessed amounts of deliberate practice. Many characteristics once believed to reflect innate talent are actually the result of intense practice extended for a minimum of 10 years. Analysis of expert performance provides unique evidence on the potential and limits of extreme environmental adaptation and learning.
A scoping review was performed to assess published evidence regarding how best to teach ultrasound-guided regional anesthesia (UGRA). The literature search yielded 205 articles, of which 35 met the inclusion criteria. Current literature on the topic can be divided into 3 main themes: the development of motor skills, learning and teaching sonoanatomy, and understanding of the requirements for establishing a UGRA education program and evaluation. We discuss the current status and future direction of research on UGRA training.
The four major categories of skill sets associated with proficiency in ultrasound guided regional anaesthesia are 1) understanding device operations, 2) image optimization, 3) image interpretation and 4) visualization of needle insertion and injection of the local anesthetic solution. Of these, visualization of needle insertion and injection of local anaesthetic solution can be practiced using simulators and phantoms. This survey of existing simulators summarizes advantages and disadvantages of each. Current deficits pertain to the validation process.
Quantitative analysis has tremendous but mostly unrealized potential in healthcare to support objective and accurate interpretation of the clinical imaging. In 2008, the National Cancer Institute began building the Quantitative Imaging Network (QIN) initiative with the goal of advancing quantitative imaging in the context of personalized therapy and evaluation of treatment response. Computerized analysis is an important component contributing to reproducibility and efficiency of the quantitative imaging techniques. The success of quantitative imaging is contingent on robust analysis methods and software tools to bring these methods from bench to bedside.
Ultrasound needle visualization is a fundamental skill required for competency in ultrasound-guided regional anesthesia. The primary objective of this study using a cadaver model was to quantify the number of procedures that novices need to perform before competency, using a predefined dynamic scoring system was achieved in ultrasound needle visualization skills.
Fifteen trainees, novices to ultrasound-guided regional anesthesia, performed 30 simulated sciatic nerve blocks in cadavers. After each procedure, a supervisor provided feedback regarding quality-compromising behaviors. Learning curves were constructed for each individual trainee by calculating cusum statistics. Trainees were categorized into those who were proficient, not proficient, and undetermined. A mathematical model predicted the number of procedures required before an acceptable success rate would be attained. Logistic regression was used to identify factors associated with success.
There was wide variability in individual cusum curves. The mean number of trials required to achieve competency in this cohort was 28. Trainees were categorized as proficient (n = 6), not proficient (n = 5), and undetermined (n = 4). With each subsequent procedure, there was a significant increase in the likelihood of success for trainees categorized as not proficient (P = 0.023) or undetermined (P = 0.024) but not for trainees categorized as proficient (P = 0.076). Participants recruited later in the study had an increased likelihood of success (P < 0.001).
Trainees became competent in ultrasound needle visualization at a variable rate. This study estimates that novices would require approximately 28 supervised trials with feedback before competency in ultrasound needle visualization is achieved.
Simulation-based training is becoming an accepted tool for educating physicians before direct patient care. As ultrasound-guided regional anesthesia (UGRA) becomes a popular method for performing regional blocks, there is a need for learning the technical skills associated with the technique. Although simulator models do exist for learning UGRA, they either contain food and are therefore perishable or are not anatomically based. We developed 3 sonoanatomically based partial-task simulators for learning UGRA: an upper body torso for learning UGRA interscalene and infraclavicular nerve blocks, a femoral manikin for learning UGRA femoral nerve blocks, and a leg model for learning UGRA sciatic nerve blocks in the subgluteal and popliteal areas.
Success in performing ultrasound-guided peripheral nerve blockade (PNB) demands sound knowledge of sonoanatomy, good scanning techniques, and proper hand-eye coordination. The objectives of our study were to evaluate whether simulator training aids success of novice operators in ultrasound-guided PNB and to determine what number of procedures is required to attain proficiency.
Twenty Postgraduate Year 2 anesthesiology residents with no previous experience in ultrasound-guided PNB were randomly assigned into 2 groups. Both groups received conventional teaching comprising of 4 didactic lectures on PNBs with ultrasound guidance. Using a low-fidelity simulation model, 1 group further received an hourlong training session on needling and proper hand-eye coordination. Once the training was over, the residents started their rotation through our block room. Using a logbook, each resident recorded the number of successful and failed ultrasound-guided regional anesthesia blocks performed over a 3-week period. A successful block was defined as one that was effective for surgical anesthesia and performed within 15 mins, with only verbal guidance from a staff anesthesiologist. Cumulative summation charts were created to track progress using a predetermined acceptable failure rate of 30%.
The conventional training group had 98 successful blocks, and the simulation group had 144 (51.3% vs 64%; P = 0.016). In the conventional training group, 4 of 10 residents achieved proficiency, and in the simulation training group, 8 of 10 residents achieved proficiency (80% vs 40%; P = 0.0849).
Simulation training improves success rate in ultrasound-guided performance of 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.