S Munirama1, R Eisma2, M Columb3, G A Corner4, G A McLeod5. 1. Manchester Royal Infirmary, Manchester, UK. 2. Centre for Anatomy and Human Identification, University of Dundee, Dundee, UK. 3. Intensive care Unit, Wythenshawe Hospital, South Manchester University Hospitals, Manchester, UK. 4. Department of Medical Physics. 5. Institute of Academic Anaesthesia, Ninewells Hospital & Medical School, Dundee, UK g.a.mcleod@dundee.ac.uk.
Abstract
BACKGROUND: We evaluated the physical properties and functional alignment of the soft-embalmed Thiel cadaver as follows: by assessing tissue visibility; by measuring its acoustic, mechanical and elastic properties; by evaluating its durability in response to repeated injection; and by aligning images with humans. METHODS: In four soft-embalmed Thiel cadavers, we conducted three independent studies. We assessed the following factors: (i) soft tissue visibility in a single cadaver for 28 weeks after embalming; (ii) the displacement of tissues in response to 1 and 5 ml interscalene and femoral nerve blocks in a single cadaver; and (iii) the stiffness of nerves and perineural tissue in two cadavers. We aligned our findings with ultrasound images from three patients and one volunteer. Durability was qualified by assessing B-mode images from repetitive injections during supervised training. RESULTS: There was no difference in visibility of nerves between 2 and 28 weeks after embalming {geometric mean ratio 1.13 [95% confidence interval (CI): 0.75-1.68], P=1.0}. Mean tissue displacement was similar for cadaver femoral and interscalene blocks [geometric mean ratio 1.02 (95% CI: 0.59-1.78), P=0.86], and for 1 and 5 ml injection volumes [geometric mean ratio 0.84 (95% CI: 0.70-1.01), P=0.19]. Cadavers had higher intraneural than extraneural stiffness [Young's modulus; geometric mean ratio 3.05 (95% CI: 2.98-3.12), P<0.001] and minimal distortion of anatomy when conducting 934 left-sided interscalene blocks on the same cadaver throughout a 10 day period. CONCLUSIONS: The soft-embalmed Thiel cadaver is a highly durable simulator that has excellent physical and functional properties that allow repeated injection for intensive ultrasound-guided regional anaesthesia training.
BACKGROUND: We evaluated the physical properties and functional alignment of the soft-embalmed Thiel cadaver as follows: by assessing tissue visibility; by measuring its acoustic, mechanical and elastic properties; by evaluating its durability in response to repeated injection; and by aligning images with humans. METHODS: In four soft-embalmed Thiel cadavers, we conducted three independent studies. We assessed the following factors: (i) soft tissue visibility in a single cadaver for 28 weeks after embalming; (ii) the displacement of tissues in response to 1 and 5 ml interscalene and femoral nerve blocks in a single cadaver; and (iii) the stiffness of nerves and perineural tissue in two cadavers. We aligned our findings with ultrasound images from three patients and one volunteer. Durability was qualified by assessing B-mode images from repetitive injections during supervised training. RESULTS: There was no difference in visibility of nerves between 2 and 28 weeks after embalming {geometric mean ratio 1.13 [95% confidence interval (CI): 0.75-1.68], P=1.0}. Mean tissue displacement was similar for cadaver femoral and interscalene blocks [geometric mean ratio 1.02 (95% CI: 0.59-1.78), P=0.86], and for 1 and 5 ml injection volumes [geometric mean ratio 0.84 (95% CI: 0.70-1.01), P=0.19]. Cadavers had higher intraneural than extraneural stiffness [Young's modulus; geometric mean ratio 3.05 (95% CI: 2.98-3.12), P<0.001] and minimal distortion of anatomy when conducting 934 left-sided interscalene blocks on the same cadaver throughout a 10 day period. CONCLUSIONS: The soft-embalmed Thiel cadaver is a highly durable simulator that has excellent physical and functional properties that allow repeated injection for intensive ultrasound-guided regional anaesthesia training.