Background: Our goal is to develop metrics that quantify the translation of performance from cadavers to patients. Our primary objective was to develop steps and error checklists from a Delphi questionnaire. Our second objective was to show that our test scores were valid and reliable. Methods: Sixteen UK experts identified 15 steps conducive to good performance and 15 errors to be avoided during interscalene block on the soft-embalmed cadaver and patients. Thereafter, six experts and six novices were trained, and then tested. Training consisted of psychometric assessment, an anatomy tutorial, volunteer scanning, and ultrasoundguided needle insertion on a pork phantom and on a soft-embalmed cadaver. For testing, participants conducted a single interscalene block on a dedicated soft-embalmed cadaver whilst wearing eye tracking glasses. Results: We developed a 15-step checklist and a 15-error checklist. The internal consistency of our steps measures were 0.83 (95% confidence interval [CI]: 0.78e0.89) and 0.90 (95% CI: 0.87e0.93) for our error measures. The experts completed more steps (mean difference: 3.2 [95% CI: 1.5e4.8]; P<0.001), had less errors (mean difference: 4.9 [95% CI: 3.5e6.3]; P<0.001), had better global rating scores (mean difference: 6.8 [95% CI: 3.6e10.0]; P<0.001), and more eye-gaze fixations (median of differences: 128 [95% CI: 0e288]; P¼0.048). Fixation count correlated negatively with steps (r¼e0.60; P¼0.04) and with errors (r¼0.64; P¼0.03). Conclusions: Our tests to quantify ultrasound-guided interscalene nerve block training and performance were valid and reliable.

Summary Visibility of the needle tip is difficult to maintain during ultrasound‐guided nerve block. A new needle has been developed that incorporates a piezo element 2–2.3 mm from the tip, activated by ultrasound. The electrical signal manifests as a coloured circle surrounding the needle tip, and allows real‐time tracking. We hypothesised that novice regional anaesthetists would perform nerve block better with the tracker turned on rather than off. Our primary objective was to evaluate the new needle by measuring the performance of novice anaesthetists conducting simulated sciatic block on the soft embalmed Thiel cadaver. Training consisted of a lecture, scanning in volunteers and practice on cadavers. Testing entailed scanning the sciatic nerve of a cadaver and conducting 20 in‐plane sciatic blocks in the mid‐to‐upper thigh region. Subjects were randomised equally, in groups of five, according to the sequence: tracker on/off/on/off; or tracker off/on/off/on. Video recordings were assessed by six raters for steps performed correctly and errors committed. Eight subjects were recruited and 160 videos were analysed. Using the tracking needle, five correct steps improved and one error reduced. The benefits included: better identification of the needle tip before advancing the needle, OR (95%CI) 3.4 (1.6–7.7; p < 0.001); better alignment of the needle to the transducer, 3.1 (1.3–8.7; p = 0.009); and better visibility of the needle tip 3.0 (1.4–7.3; p = 0.005). In conclusion, use of the tracker needle improved the sciatic block performance of novices on the soft embalmed cadaver.

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Summary In this study, we measured the performance of medical students and anaesthetists using a new tracker needle during simulated sciatic nerve block on soft embalmed cadavers. The tracker needle incorporates a piezo element near its tip that generates an electrical signal in response to insonation. A circle, superimposed on the ultrasound image surrounding the needle tip, changes size and colour according to the position of the piezo element within the ultrasound beam. Our primary objective was to compare sciatic block performance with the tracker switched on and off. Our secondary objectives were to record psychometrics, procedure efficiency, participant self‐regulation and focused attention using eye‐tracking technology. Our primary outcome measures were the number of steps successfully performed and the number of errors committed during each block. Videos were scored by trained experts using validated checklists. Sequential tracker activation and deactivation was randomised equally within subjects. With needle activation, steps improved in 10 (25%) subjects and errors reduced in six (15%) subjects. The most important steps were: needle tip identification before injection, OR (95%CI) 2.12 (1.61–2.80; p < 0.001); and needle tip identification before advance of the needle, 1.80 (1.36–2.39; p < 0.001). The most important errors were: failure to identify the needle tip before injection, 2.40 (1.78–3.24; p < 0.001); and failure to quickly regain needle tip position when tip visibility was lost, 2.03 (1.5–2.75; p < 0.001). In conclusion, needle‐tracking technology improved performance in a quarter of subjects.

BackgroundErector spinae plane (ESP) and retrolaminar (RL) blocks show unreliable spread. We hypothesize that the combination of ESP and RL blocks provides more extensive and reliable spread of dye than single ESP blocks. Our primary objective was to compare the spread of dye to the paravertebral spaces after the combination block and ESP block in Thiel embalmed cadavers. Spread, the primary end point, was defined as the number of paravertebral spaces colored with dye per injection.Materials and methodsA single anesthetist performed ultrasound-guided ESP (20 mL) and combination of ESP and RL (10 mL each) blocks at the third thoracic vertebra of eight soft embalmed Thiel cadavers. Tissue displacement was visualized on an adjacent strain elastography image. Cadavers were dissected 24 hours later and anatomical structures were inspected for the presence of dye.FindingsDye was visualized in more paravertebral spaces with the combination block (median 3 (IQR 3–5 (range 0–8)) vs 1.5 (IQR 0.25–2.75 (range 0–3) and difference (1.5 (0–4), p=0.04). Six out of seven (86%) combined erector spinae and RL blocks spread to at least three paravertebral spaces compared with two out of eight (25%) ESP blocks (RR 3.4, 95% CI 1.0 to 11.8; p=0.04). Contralateral spread occurred in three combination blocks and in one ESP block (OR 9.0, 95% CI 4.0 to 21.1; p<0.001).ConclusionsIn conclusion, the combination of ESP and RL blocks was more extensive and reliable than ESP block alone.