Comparison Of The Learning Curves Of Novice Anaesthetists Using Needle Tip Tracking During Simulated Ultrasound-Guided Sciatic Regional Nerve Block On The Soft Embalmed Thiel Cadaver

Increased demand exists for regional anaesthesia, but the incidence of nerve injury remains unchanged despite the use of ultrasound.1 The precise location of the needle tip is difficult to see using current technology.2 A new tip tracking needle has a piezo element embedded onto the needle shaft 3 mm from its tip. The system allows primary identification of the needle tip within a green circle rather than the needle shaft. In a recent pilot study of eight volunteers, we showed better performance using needle tracking technology while conducting sciatic block on Thiel cadavers.3 We wished to repeat the pilot study and recruit medical students without experience of ultrasound alongside a wider range of anaesthetists. Our primary objective was to determine whether volunteers were able to identify the needle tip better when the piezo was activated. Secondary objectives were to measure psychometrics and cognition and capture focused attention using eye tracking. Forty volunteers repetitively conducted mid-thigh sciatic block for 2 h on 6-month-old Thiel cadavers at the Centre for Anatomy and Human Identification, University of Dundee. All underwent cognitive skills testing and sciatic block training on pig phantom and Thiel cadaver followed by testing on a separate cadaver. Subjects used an Onvision tip tracking needle and Xperius ultrasound system (both from B.Braun, Melsungen, Germany and Philips, Eindhoven, The Netherlands) with a 2–6 MHz curvilinear transducer. Sciatic block was performed twice with the tip tracker on and twice with the tracker off, and the process repeated for 2 h. Subjects were randomised using a computer programme to two study starting points—tracker off or on. All subjects wore eye tracking glasses and all blocks were filmed using two cameras. Research software was used to remove the coloured circle from the ultrasound image to allow blinded analysis of tasks and errors. Within subject data was analysed using the Wilcoxon test. Correlated proportions were analysed using McNemar’s test. We present results from 36 subjects (Table 1). There was no difference in psychometric or cognitive scores between groups. Eight tasks improved and seven errors reduced using the tracker needle. With the activated needle, tasks took longer (P=0.01), and overall fixations were longer (P=0.03). In conclusion, needle tip technology improved the performance of volunteers conducting sciatic block on the Thiel cadaver.Table 1Steps, errors and eye tracking results with tracker on and off.Tracker onTracker offMed IQRMed IQRDuration of task (sec)22.2 (18.1–34.2)31.0 (20.8–36.8) 0.01Fixations (overall) (number)20.5 (15.5–29.0)25.2 (18.7–36.9) 0.005Duration (at monitor) (sec)20.0 (16.7–31.8)23.4 (19.7–34.8) 0.002Fixations to monitor (number)19.8 (13.9–26.0)23.7 (16.0–34.8) 0.002 Open table in a new tab 1Munirama S, McLeod G. Anaesthesia 2015; 70: 1084–912Munirama S, Zealley K, Schwab A, et al. Br J Anaesth 2016; 117: 792–8003McLeod GA, McKendrick M, Taylor A, et al. Anaesthesia 2019, https://doi.org/10.1111/ange.14851