An Ex Situ Cadaver Liver Training Model Continuously Pressurized to Simulate Specific Skills Involved in Laparoscopic Liver Resection: the Lap-Liver Trainer.

BACKGROUND: Laparoscopic liver resection (LLR) requires delicate skills. The aim of the study was to develop a training model mimicking as much as possible intraoperative bleeding and bile leakage during LLR. We also assessed the educational value of the training model. METHODS: The Lap-liver trainer (LLT) combined a continuously pressurized ex situ cadaver liver and a customized mannequin. The customized mannequin was designed by computer-aided design and manufactured by 3D printing. The left lateral sectionectomy (LLS) was chosen to assess the feasibility of a LLR with the LLT. Eighteen volunteers were recruited to perform LLS and to assess the educational value of the LLT using a Likert scale. RESULTS: The customized mannequin consisted of a close laparoscopic training device based on a simplified reconstruction of the abdominal cavity in laparoscopic conditions. Ex situ cadaver livers were pressurized to simulate blood and bile supplies. Each expert surgeon (n = 3) performed two LLS. They were highly satisfied of simulation conditions (4.80 ± 0.45) and strongly recommended that the LLT should be incorporated into a teaching program (5.00 ± 0.0). Eight novice and 4 intermediate surgeons completed a teaching program and performed a LLS. Overall, the level of satisfaction was high (4.92 ± 0.29), and performing such a procedure under simulation conditions benefited their learning and clinical practice (4.92 ± 0.29). CONCLUSIONS: The LLT could provide better opportunities for trainees to acquire and practice LLR skills in a more realistic environment and to improve their ability to deal with specific events related to LLR.

The predictive capacity of the MADYMO ellipsoid pedestrian model for pedestrian ground contact kinematics and injury evaluation.

Pedestrian injuries occur in both the primary vehicle contact and the subsequent ground contact. Currently, no ground contact countermeasures have been implemented and no pedestrian model has been validated for ground contact, though this is needed for developing future ground contact injury countermeasures. In this paper, we assess the predictive capacity of the MADYMO ellipsoid pedestrian model in reconstructing six recent pedestrian cadaver ground contact experiments. Whole-body kinematics as well as vehicle and ground contact related aHIC (approximate HIC) and BrIC scores were evaluated. Reasonable results were generally achieved for the timings of the principal collision events, and for the overall ground contact mechanisms. However, the resulting head injury predictions based on the ground contact HIC and BrIC scores showed limited capacity of the model to replicate individual experiments. Sensitivity studies showed substantial influences of the vehicle-pedestrian contact characteristic and certain initial pedestrian joint angles on the subsequent ground contact kinematics and injury predictions. Further work is needed to improve the predictive capacity of the MADYMO pedestrian model for ground contact injury predictions.

A novel method to quantitate bioprosthetic valve leaflet mechanical stress: a numerical and in vitro study.

An original in vitro/in silico method was developed to estimate the local and global mechanical stress applied on the bioprosthetic valve leaflet, which can be important for better understanding of the valve durability. A non-contact system based on stereophotogammetry and digital image correlation enabled filming and studying the valve leaflet movement frame by frame and performing three-dimensional analysis. The deformation was applied in a finite element model in order to calculate the local mechanical stress applied. High stress regions were primarily observed in the upper leaflet edge and belly and to a lesser extent at the free leaflet edge.