Proposition d'une procédure d'étalonnage pour la numérisation du corps humain

Dans cet article, nous développons une procédure d'étalonnage d'un système optique, basée sur la lumière structurée, adaptée à la numérisation de grands objets. Le but de ces travaux est une application de technique de mesure optique au corps humain afin d'en fournir des mesure anthropométriques personnalisée. L'analyse se base sur une étude systématique de cas de polynômes dont le degré varie de 1 à 4. Les premiers résultats montrent qu'il est nécessaire d'utiliser un degré de polynôme au moins égale à trois pour avoir une bonne estimation du relief recherché

Adaptation de la méthode de projection de franges pour la mesure du relief de grands objets et pour la modélisation anthropométrique (application à l'étude de flotteurs sous pression et au suivi de pathologie de l'abdomen)

L'étude proposée porte sur l'adaptation d'une méthode de mesure optique à lamesure de la topologie d'objet de grandes dimensions et à une distance de travail proche. Laméthode optique utilisée est la projection de franges car elle permet l'étude de grands objets.Dans un premier temps, des essais expérimentaux ont été réalisés pour évaluer l'exactitudedu développement actuel ; ce dernier utilisant une analyse de franges s'appuyant sur lacombinaison d'une méthode quasi-hétérodyne utilisant une transformation de Fourier etd'une méthode de code gray.Après avoir quantifié les erreurs et déterminé leurs sources, le choix dudéveloppement d'une procédure d'étalonnage et de nouvelles équations associées à cetteprocédure se sont imposés. Le nouvel étalonnage est quant à lui basé sur une interpolationpolynomiale de points définissant un volume de grandes dimensions. Un objet étalon a étéspécialement conçu pour cette procédure de calibration. Pour évaluer l'erreur du à lacalibration, une étude systématique de cas de polynômes dont le plus haut degré varie de 1à 4 a été effectué. Cette approche a permis de déterminer le degré optimal du polynôme àutiliser. Dans le meilleur cas, l'estimation de l'erreur a permis d'évaluer la précision del'étalonnage à 1 mm sur un objet de 2 m évalué à une distance de 2 m.La méthode a été par la suite appliquée, dans un cadre industriel à l'étude deflotteurs et dans un cadre médical à l'étude du relief de la paroi abdominale. D'un point devue médical, cette méthode permet d'obtenir rapidement et facilement la morphologie ducorps humain. Elle permet aussi d'effectuer un meilleur suivi des pathologiesmorphologiques des patients.The proposed study deals with the adaptation of an optical method to themeasurement of large objects at a low working distance. The optical method used is thefringe projection technique allowing the study of large objects. At first, experimental trials hasbeen used to evaluate the accuracy of the actual development combining the phase shiftingmethod using a Fourier transform and the gray code technique.When the errors have been quantified and their origins determined, the developmentof a calibration procedure and new associated equations have been chosen. The newcalibration is based on polynomial interpolation of points defining a volume of largedimensions. A tested object was designed specifically for this calibration procedure. Toestimate the calibration error, a systematic study of polynomials cases is performed. Thehighest degree of those cases varies from 1 to 4. This approach allows the determination theoptimal polynomial degree to be used. In the best case, the estimation of the error allows theevaluation of the calibration accuracy of about 1 mm for an object of 2 m large, measured ata distance of 2 m.The method has been subsequently applied, in an industrial setting, to the study offloats and in a medical setting to the study of the relief of the abdominal wall. From a medicalpoint of view, this method gives a rapid and easy access to the topology of human body. Itallows a better follow-up of the patient pathology.POITIERS-SCD-Bib. électronique (861949901) / SudocSudocFranceF

Development and validation of a performance assessment checklist for insertion of an intra-uterine device (IUD)

Objectives: The World Health Organization (WHO) supports increasing the availability and acceptability of long-acting reversible contraception including intra-uterine device (IUD), but its insertion includes certain risks (uterine perforation). The objective was to develop and validate an IUD insertion performance assessment checklist. Material and methods: This prospective study took place in hospitals and simulation center of the Poitou-Charentes region, France. The checklist content reached consensus among 10 experts solicited by a Delphi method. A modified gynecologic mannequin Zoe (Gaumard®) was used for simulations. Psychometric testing included 30 multi-professional participants for internal consistency and reliability between two independent observers, and 27 residents for assessment of score evolution over time and reliability. Cronbach alpha (CA) and intraclass coefficient (ICC) were used. Progression of performance was carried out using ANOVA for repeated measures. The data collected were used to plot receiver operating characteristic (ROC) curves for the score values and the area under the curve (AUC) was determined. Results: The checklist included 27 items (2 sections, total score = 27). Psychometric testing showed CA = 0.79, ICC = 0.99, and good clinical relevance. The checklist is discriminative, showing a significant increase in performance scores when the simulations were repeated (F = 77.6, p < 0.0001). ROC curve [AUC: 0.792 (95% CI: 0.71–0.89); p < 0.0001] revealed the best score cutoff predictive of 100% sensitivity, i.e., true positive rate or success rate. Performance score was highly correlated to success rate. The cut-off score guaranteeing successful IUD insertion was 22/27. Conclusions: This coherent and reproducible checklist for IUD insertion provide an objective assessment of the procedure during SBT, with the aim of obtaining a score ≥ 22/27

Développement et mise en oeuvre de méthodes optiques pour la mesure de relief et de champ de déformations en vue de la modélisation d'organes biologiques

Cette étude porte sur l'application des techniques de mesure optiques pour la caractérisation mécanique des biomatériaux. Deux voies ont été explorées : la réalisation de maillages en éléments finis et la mesure de déformations planes. Les maillages en éléments finis peuvent être réalisés à partir du relief des organes. Nous avons alors développé une technique de projection de réseaux de traits. Afin d'améliorer la précision, l'analyse des réseaux s'effectue par des techniques de décalages de phases. Une procédure de calibrage du montage a été spécialement développée. La mesure des déformations sur de la peau a été effectuée par une extension de la technique de suivi de marqueurs. Afin de voir l'ensemble des phénomènes mécaniques qui régissent ce biomatériau, nous avons réalisé des essais de traction simple, de relaxation, de traction à accélération constante et de traction biaxiale. Le caractère viscoplastique de la peau et l'orthotropie de sa structure ont été ainsi mis en évidence.This study concentrates on the characterisation of biological materials by means of optical methods of measurement. Two research fields were considered: meshes in finite elements and the measurement of plane strains. Meshes in finite elements can be obtained from the relief of the organs studied. We then developed a technique projecting sinusoidal gratings of vertical lines which were analysed using phase-shifting techniques to get a better accuracy. A special calibration procedure of the experimental set-up was developed for this purpose. An extension of the tracking method allowed measuring plane strains on skin. In order to study all the mechanical behaviours of this biological material we carried out simple tensile tests, relaxation tests, tensile tests with constant acceleration and biaxial tensile tests. The viscoplasticity of skin and the orthotropy of its structure were thus demonstrated.POITIERS-BU Sciences (861942102) / SudocSudocFranceF

Analyse 3D du comportement mécanique de l’os spongieux pour l’étude de fixations occipito-cervicales

Cette étude porte sur l’analyse du comportement mécanique de l’os spongieux humain lors d’un essai de compression. La microtomographie RX couplée à la corrélation d’images volumiques permet d’observer les déformations de la microstructure osseuse durant un chargement mécanique. Ces mesures apportent alors de nouvelles connaissances sur le comportement mécanique de l’os humain notamment pour aborder les problèmes liés à la mise en place de matériel d’ostéosynthèse

Toward Optimal Learning of the Gesture in Laparoscopic Surgery: Methodology and Performance

International audienceClassical surgical education has to face both a forensic reality and a technical issue: to train a learner in more complex techniques in an increasingly short time. Moreover, surgical training is still based on an empirical hierarchical relationship in which learners must reproduce a sequence of actions in a situation of strong emotional pressure. However, the effectiveness of learning and its quality are linked to the emotional states in which learners find themselves. Among these emotions, epistemic confusion can be found that arises in complex learning situations where there is a cognitive imbalance related to the comprehension of the task, and which results from a rupture between the pre-established patterns of the learner and the new learning task. Although one knows that confusion can have a beneficial or a negative impact on learning, depending on whether it is well regulated or not, the factors that can influence it positively are still poorly understood. Thus, the objective of this experiment is to assess the impact of confusion on the learning of a surgical procedure in an augmented reality context and to determine if this impact varies according to the feedback given to the learners and according to the occurrence of disruptive events. Medical externs were recruited (N = 15) who were required to perform a suturing task on a simulator and whose performance was measured using a Motion Capture (MoCap) system. Even though the statistical analyzes did not allow a conclusion to be reached, the protocol already established makes it possible to consider a longer-term study that will allow (by increasing the number of sessions and the number of participants) more significant results to be obtained in order to develop new surgical learning protocols. This preliminary study opens a new field of research on the influence of epistemic emotions, and more particularly of confusion, which is likely to upset traditional surgical teaching, and is based on negative conditioning and strong emotions with negative valence as well as stress and coercio

Stress response in the daily lives of simulation repeaters. A randomized controlled trial assessing stress evolution over one year of repetitive immersive simulations

International audienceBACKGROUND:Simulations in healthcare reproduce clinical situations in stressful conditions. Repeated stress exposure might influence the learning process in simulation as well as real-life.OBJECTIVES:1) To record heart rate and heart rate variability evolution during one-day simulation over one year; 2) To analyze the effect of repetitive high-fidelity simulations on the risk of post-traumatic stress disorder.STUDY DESIGN:Single-center, investigator-initiated RCT. 48 participants were randomized in 12 multidisciplinary teams of French Emergency Medical Services to manage infant shock in high-fidelity simulations. In the experimental group, 6 multidisciplinary teams were exposed to 9 different simulation sessions over 1 year. In the control group, 6 multidisciplinary teams participated in only 3 simulation sessions, in common with those of the experimental group (initial, intermediate after 6 months, and finally after 1 year). Heart rate (HR) and heart rate variability (HRV) were analyzed on a 24-hour Holter from the day prior to simulation until the end of simulation. Questionnaires of Impact of Event Scale-Revised at 7 days and Post-traumatic Check-List Scale at 1 month were used to detect possible post-traumatic stress disorder in participants. p<0.05 was considered significant.RESULTS:Stress increased during each simulation in the two groups. After analysis on the 24-hour period, there was no significant difference between the two groups during the initial simulation session in terms of heart rate and heart rate variability. In the 24-hour period of the intermediate and final simulation sessions, the level of stress was higher in the control group during the diurnal (p = 0.04) and nocturnal periods (p = 0.01). No participant developed post-traumatic stress disorder after the 72 simulation sessions.CONCLUSIONS:Despite the stress generated by simulation, the more the sessions were repeated, the less were their repercussions on the daily lives of participants, reflected by a lower sympathetic activity. Moreover, repetition of simulations did not lead to post-traumatic stress disorder.TRIAL REGISTRATION:ClinicalTrials.gov NCT02424890