ABSTRACT
BACKGROUND AND PURPOSE: Several training models have been developed to improve surgeons' operative skills as well as patient outcomes. Before implementing these models in training programs, their usefulness and accuracy need to be assessed. In this study, we examined the ability of a laparoscopic nephrectomy (LN) virtual reality (VR) simulator to distinguish between different levels of expertise (construct validity). METHODS: Twenty-two novices (no LN experience), 32 intermediates (<10 LN procedures performed) and 10 experienced urologists (> or =10 LN procedures performed) performed the same retroperitoneal task on the LN VR simulator (Mentice, Sweden) three times, performing a practice task before and after the second time. Outcome parameters were time, blood loss, path length, and total score (combination of 62 different parameters). RESULTS: No significant differences were found between intermediate and experienced participants. Task 3 performance showed no significant difference between any of the groups. Both intermediates and experienced participants were significantly faster than novices on the first two tasks and had a better total score. Learning curves of intermediate and experienced participants were flat after task two. CONCLUSIONS: The LN-VR simulator did not distinguish between intermediate and experienced participants. The analysis of the learning curves suggests that the tasks measured dexterity in using the simulator rather than an actual improvement of operative skills. We conclude that the LN-VR simulator does not have sufficient construct validity and is therefore, in its present form, not suitable for implementation in a urologic training program.
Subject(s)
Computer Simulation , Laparoscopy , Nephrectomy/education , User-Computer Interface , Validation Studies as Topic , Adult , Clinical Competence , Demography , Education, Medical, Graduate , Female , Humans , Learning , Male , Task Performance and Analysis , Young AdultABSTRACT
The preparation of pure cardiac myocyte cultures from neonatal rats is hampered by the presence of non-myocytes, which can proliferate during culturing, thereby causing a progressive decrease in the proportion of myocytes. In order to obtain myocyte cell suspensions of high purity, a method based on centrifugal elutriation was developed. Cardiac cells, isolated from neonatal rat heart ventricles, were subjected to elutriation using flow rates that increased step-wise from 20 to 80 ml/min. The cell fraction obtained at 80 ml/min consisted of 68-90% myocytes. Still, upon culturing, the remaining non-myocytes proliferate, causing the proportion of myocytes to decrease to 60 +/- 2% at day 5. A second elutriation protocol was developed in which myocytes and non-myocytes were separated after a period of co-culturing for 4-5 days. By this approach a fibroblast-rich cell fraction (87 +/- 5%) and a myocyte-rich cell fraction (82 +/- 6%) were obtained. In conclusion, centrifugal elutriation creates the opportunity to separate neonatal rat myocytes from non-myocytes, either freshly isolated or after a period of culturing. Particularly, cell separation after a period of culturing ventricular cells offers an advantage to analyse the experimental effects on myocytes and non-myocytes separately.
