Comparison of the Thorax Dynamic Responses of Small Female and Midsize Male Post Mortem Human Subjects in Side and Forward Oblique Impact Tests.

Despite the increasing knowledge of the thorax mechanics in impact loadings, the effects of inter-individual differences on the mechanical response are difficult to take into account. For example, the biofidelity corridors for the small female or large male are extrapolated from the midsize male corridors. The present study reports on the results of new tests performed on small female Post Mortem Human Subjects (PMHS), and compares them with test results on midsize male PMHS. Three tests in pure side impact and three tests in forward oblique impact were performed on the thorax of small female specimens. The average weight and stature were 43 kg and 1.58 m for the small female specimens. The initial speed of the impactor was 4.3 m/s. The mass and the diameter of the impactor face were respectively 23.4 kg and 130 mm. The instrumentation and methodology was the same as for the tests published in 2008 by Trosseille et al. on midsize male specimens. The rib cages were instrumented with accelerometers on the T1, T4 and T12 vertebrae, upper and lower sternum, and the ribs were instrumented with up to 110 strain gauges. A force transducer and an accelerometer were mounted on the impactor in order to record the force applied onto the thorax. Targets fixed on vertebrae were tracked using high speed cameras in order to estimate the thoracic deflection. For the six midsize males, the test conditions were exactly the same as for the small female specimens, except for the diameter of the impactor face which was 152 mm. The average weight and stature were 70.3 kg and 1.70 m for the midsize male specimens. The force and thoracic deflection time-histories and the injury assessments are given for each specimen. The thorax force magnitude varied from 1.05 to 1.45 kN and from 1.63 to 2.34 kN, respectively for the small female and midsize male groups. The maximum deflection varied from 51 to 117 mm and from 59 to 81 mm, respectively for the small female and midsize male groups. The maximum forces appeared to be a function of the total body mass for each loading angle.

In vitro training program to improve ambidextrous skill and reduce physical fatigue during laparoscopic surgery: preliminary experience.

PURPOSE: We illustrate the preliminary experience with our planned intensive in vitro training program focused on the nondominant hand and reducing physical fatigue. Apart from this, we tried to calculate how much training is required for a novice urologist to master laparoscopic freehand suturing with the dominant and nondominant hands. MATERIALS AND METHODS: Between December 2001 and May 2002, one trainee worked on a Pelvi-trainer, first with the dominant (right) hand and then with the left hand, practicing intracorporeal suturing and cutting and improving physical endurance by gradually increasing the duration of each training session. Along with the Pelvi-trainer, he worked on left-handed writing to improve wrist movements. Before starting this training, he did not have any laparoscopic experience as assistant or primary surgeon. The progress was stored in the computer prospectively to compare the results with those obtained at the end of the training. RESULTS: For the dominant hand, 30 hours over 2 months was required to master laparoscopic suturing skills. After training of the right hand, the nondominant hand required 40 hours of Pelvi-trainer work and 20 hours of handwriting during 2 months. Physical endurance for suturing in the Pelvi-trainer increased from 15 minutes to 150 minutes over 3 months. The main improvement was in the degree of pain over the right shoulder (because of the abducted position) and backache. CONCLUSION: Incorporation of sufficient in vitro training to improve nondominant hand functioning and reduce physical fatigue can make adaptation to laparoscopic surgery easier.