Antibiofilm and Immune-Modulatory Activity of Cannabidiol and Cannabigerol in Oral Environments-In Vitro Study.

OBJECTIVE: To evaluate the in vitro antimicrobial and antibiofilm properties and the immune modulatory activity of cannabidiol (CBD) and cannabigerol (CBG) on oral bacteria and periodontal ligament fibroblasts (PLF). METHODS: Cytotoxicity was assessed by propidium iodide flow cytometry on fibroblasts derived from the periodontal ligament. The minimum inhibitory concentration (MIC) of CBD and CBG for S. mutans and C. albicans and the metabolic activity of a subgingival 33-species biofilm under CBD and CBG treatments were determined. The Quantification of cytokines was performed using the LEGENDplex kit (BioLegend, Ref 740930, San Diego, CA, USA). RESULTS: CBD-treated cell viability was greater than 95%, and for CBG, it was higher than 88%. MIC for S. mutans with CBD was 20 µM, and 10 µM for CBG. For C. albicans, no inhibitory effect was observed. Multispecies biofilm metabolic activity was reduced by 50.38% with CBD at 125 µg/mL (p = 0.03) and 39.9% with CBG at 62 µg/mL (p = 0.023). CBD exposure at 500 µg/mL reduced the metabolic activity of the formed biofilm by 15.41%, but CBG did not have an effect. CBG at 10 µM caused considerable production of anti-inflammatory mediators such as TGF-ß and IL-4 at 12 h. CBD at 10 µM to 20 µM produced the highest amount of IFN-γ. CONCLUSION: Both CBG and CBD inhibit S. mutans; they also moderately lower the metabolic activity of multispecies biofilms that form; however, CBD had an effect on biofilms that had already developed. This, together with the production of anti-inflammatory mediators and the maintenance of the viability of mammalian cells from the oral cavity, make these substances promising for clinical use and should be taken into account for future studies.

Image features for quality analysis of thick blood smears employed in malaria diagnosis.

BACKGROUND: The World Health Organization (WHO) provides protocols for the diagnosis of malaria. One of them is related to the staining process of blood samples to guarantee the correct parasite visualization. Ensuring the quality of the staining procedure on thick blood smears (TBS) is a difficult task, especially in rural centres, where there are factors that can affect the smear quality (e.g. types of reagents employed, place of sample preparation, among others). This work presents an analysis of an image-based approach to evaluate the coloration quality of the staining process of TBS used for malaria diagnosis. METHODS: According to the WHO, there are different coloration quality descriptors of smears. Among those, the background colour is one of the best indicators of how well the staining process was conducted. An image database with 420 images (corresponding to 42 TBS samples) was created for analysing and testing image-based algorithms to detect the quality of the coloration of TBS. Background segmentation techniques were explored (based on RGB and HSV colour spaces) to separate the background and foreground (leukocytes, platelets, parasites) information. Then, different features (PCA, correlation, Histograms, variance) were explored as image criteria of coloration quality on the extracted background information; and evaluated according to their capability to classify images as with Good or Bad coloration quality from TBS. RESULTS: For background segmentation, a thresholding-based approach in the SV components of the HSV colour space was selected. It provided robustness separating the background information independently of its coloration quality. On the other hand, as image criteria of coloration quality, among the 19 feature vectors explored, the best one corresponds to the 15-bins histogram of the Hue component with classification rates of > 97%. CONCLUSIONS: An analysis of an image-based approach to describe the coloration quality of TBS was presented. It was demonstrated that if a robust background segmentation is conducted, the histogram of the H component from the HSV colour space is the best feature vector to discriminate the coloration quality of the smears. These results are the baseline for automating the estimation of the coloration quality, which has not been studied before, but that can be crucial for automating TBS's analysis for assisting malaria diagnosis process.

Machine learning for surgical time prediction.

BACKGROUND AND OBJECTIVE: Operating Rooms (ORs) are among the most expensive services in hospitals. A challenge to optimize the OR efficiency is to improve the surgery scheduling task, which requires the estimation of surgical time duration. Surgeons or programming units (based on people's experience) typically do the duration estimation using an experience-based strategy, which may include some bias, such as overestimating the surgery time, increasing ORs' operational cost. METHODS: This paper analyzes a machine learning-based solution for surgical time predictions. We apply and compare four machine-learning algorithms (Linear Regression, Support Vector Machines, Regression Trees, and Bagged Trees) to predict the surgical time duration at a tertiary referral university hospital in Bogotá, Colombia. Historical data from 2004 until 2019 was used to train the algorithms. Comparison among algorithms was given in terms of the Root Mean Square Error (RMSE) of the predicted surgery duration and the algorithms' computing time. The algorithm with the best performance was compared to the currently used experience-based method. RESULTS: All the ML algorithms predict the surgery duration with an error between 26 and 37 min. The best overall performance was obtained using Bagged Trees (26 min RMSE, 3.16 min training time, 0.49 min testing time) when using a subset of the DB with the nine specialties containing 80% of the surgeries. Bagged Trees also outperformed the experience-based method with a lower RMSE; however, it also shifted from a predominant overestimation to underestimating surgeries' duration. CONCLUSIONS: Different ML algorithms for predicting the surgical time duration, showing and comparing their performance. Bagged Trees showed the best performance in terms of RMSE and computing time. Depending on the initial data, Bagged Trees outperformed the experience-based method, but future work is necessary to suit it, like any other ML algorithm, to the hospitals' needs.

Influence of wind speed and road grade on the estimation of drag area in cycling.

The estimation of aerodynamic drag in cycling through road tests has the advantage of considering actual cycling conditions. The main drawback is that its accuracy depends on factors of the testing scenario as the wind speed vw and the road grade θ. For that reason, the effect of vw and θ on the estimation of drag area (CDA) was studied. Numerical and experimental approaches were combined. The numerical approach investigated the sensitivity of CDA to vw and θ perturbations. The experimental approach analysed the effect of including or not vw and θ on the identification of CDA by comparing the changes in the prediction of power delivered. It was found that disregarding small values of vw (e.g. 0.5 m/s) and θ (e.g. gradient of 0.05%) leads to errors in the estimation of CDA of around 10%, referred to the actual value. It was also obtained that the average error of the power prediction when considering vw and θ for the identification of the parameters is about 4.4% and about 25.5% when vw and θ are neglected. It is concluded that including vw and θ data reduces the error on the identification of CDA through outdoor road experiments.

Selección de hospital destino para el traslado de urgencia de pacientes / Selecting the Destination Hospital to Carry Emergency Patients / Escolha de hospital alvo para traslado de urgência de pacientes

Resumen El tiempo total de atención prehospitalaria (APH) es el tiempo que transcurre desde que ingresa la llamada al operador hasta que la ambulancia queda disponible para atender otra emergencia. Esta investigación pretende demostrar que la selección del hospital destino afecta de manera significativa el tiempo total de APH, lo que influye en la supervivencia del paciente que es trasladado y en el tiempo de liberación del recurso (ambulancias). En consecuencia, se propone una técnica de selección de hospital destino que incluye dimensiones relacionadas con el paciente (diagnóstico, especialidad y asegurador) y el hospital (ocupación y cercanía). Se evalúa su desempeño por medio de una simulación de eventos discretos y se concluye que la técnica propuesta obtiene un mejor tiempo de APH en el 73% de los casos estudiados, con una reducción media entre 40 y 80 minutos, en comparación con la técnica más comúnmente usada (selección hospital más cercano).

Abstract Total time of prehospital care (PHC) is the time elapsing from the inbound call up to the moment when the ambulance is available for serve in another emergency event. This research aims to show that selecting the destination hospital impacts significantly the total PHC time, which influences the survival of the patient being transported as well as the time to make the resource available again (the ambulance). Consequently, a technique for selecting the destination hospital is proposed herein including some dimensions related both to the patient (diagnosis, specialty and insurance company) and to the hospital (occupancy and closeness). The performance was evaluated based on a simulation of discrete events. It is concluded that the proposed technique provides a better PHC time in 73% of the studied cases, with a mean decrease between 40 and 80 minutes as compared to the most commonly used technique (selecting the closest hospital).

Resumo O tempo total de atendimento pré-hospitalar (APH) é o tempo decorrente desde que a ligação for feita para o telefonista até a ambulância se disponibilizar para atender outra emergência. Esta pesquisa visa demostrar que a escolha do hospital alvo afeta significativamente o tempo total de APH, o que influi na sobrevida do paciente trasladado e no tempo de liberação do recurso (ambulâncias). Consequentemente, propõe-se uma técnica de escolha de hospital alvo que inclui dimensões relacionadas com paciente (diagnóstico, especialidade e assegurador) e hospital (ocupação e proximidade). Avalia-se o desempenho por meio de simulação de eventos discretos e conclui-se que a técnica proposta obtém melhor tempo de APH em 73% dos casos estudados com redução media entre 40 e 80 minutos, em comparação com a técnica mais comumente usada (escolha hospital mais próximo).

Sistema de evaluación de habilidades psicomotrices en cirujanos de laparoscopia / An Assessment of Psychomotor Skills in Laparoscopy / Sistema de avaliação de habilidades psicomotoras em cirurgiões de laparoscopia

Objetivo: este estudio tiene como propósito diseñar y validar un sistema de evaluación objetivo y práctico de habilidades psicomotrices en laparoscopia que permita discriminar la competencia de los cirujanos. Materiales y métodos: fue llevado a cabo en el Centro de Simulación Clínica de la Universidad Javeriana. Voluntariamente participaron seis cirujanos expertos, seis residentes de cirugía y seis estudiantes de Medicina. Cada participante hizo una evaluación compuesta por ocho actividades en simuladores de caja con instrumental regular de laparoscopia. Los resultados obtenidos en los tres grupos fueron analizados por medio de un Anova y un test de Tukey. Además, se hizo un análisis de validez por fuentes de evidencia y la fiabilidad del sistema de evaluación se valoró con alfa de Cronbach. Resultados: tres actividades evaluativas discriminaron los tres grupos de estudio o grados de competencia (novato, intermedio y experto) y otras dos actividades revisaron dos de los grupos. La validez del sistema de evaluación fue comprobada al considerar el contenido, la respuesta del proceso, la estructura interna y las consecuencias de la evaluación. La fiabilidad del sistema de evaluación fue sobresaliente (alfa de Cronbach=0,90). Conclusión: el sistema de evaluación propuesto es una herramienta viable en procesos de formación de cirujanos que permite complementar el método tradicional de evaluación.

Objective: this study aims at designing and validating an objective and practical assessment of psychomotor skills in laparoscopy. This assessment would allow a classification of the surgeons and residents by their psychomotor competence. Materials and methods: this study evaluated the psychomotor competence of three groups of voluntaries: experts (6 senior surgeons), residents (6 surgery residents), and novices (6 students of medical school). The assessment was performed at the Clinical Simulation Center in the Pontificia Universidad Javeriana. The assessment was designed as a composition of eight different activities to be performed by each of the participants in a box trainer and using minimally invasive surgical instruments. The results were analyzed using an Anova and a Tukey's test. Additionally, a validity test by evidence source and the assessment reliability was evaluated using a Cronbach's alpha analysis. Results: three of the eight assessment's activities correctly discriminated three study groups, and other two activities only discriminate two of the three groups. The validity of the assessment was positively evaluated using a content analysis, the response to the assessment, the internal structure and the possible future consequences of the assessment. The reliability of the assessment was considered excellent (Cronbach's alpha=0,90). Conclusion: the propose assessment is a good alternative in formative processes of surgeons and allows to complement the traditional assessment method in surgery education.

Objetivo: este estudo tem como objetivo desenhar e validar um sistema de avaliação objetiva e prática de habilidade psicomotoras em laparoscopia que permita discriminar o nível de competência dos cirurgiões. Metodologia: O estudo foi levado a cabo no Centro de Simulação Clínica da Universidad Javeriana onde voluntariamente participaram 6 cirurgiões expertos, 6 residentes de cirurgia e 6 estudantes de medicina. Cada participante realizou uma avaliação composta por oito atividades em simuladores de caixa com instrumental regular de laparoscopia. Os resultados obtidos pelos três grupos de participantes foram analisados através de um ANOVA e um teste de Tukey. Adicionalmente, realizou-se uma análise de validez por fontes de evidência e a fiabilidade do sistema de avaliação valorou-se empregando uma análise de Alpha de Cronbach. Resultados: três atividades avaliativas discriminaram os três grupos de estudo ou níveis de competência (novato, intermédio e experto), e outras duas atividades discriminaram dois dos grupos. A validez do sistema de avaliação foi comprovada ao considerar o conteúdo, a resposta do processo, a estrutura interna e as consequências da avaliação. A fiabilidade do sistema de avaliação foi sobressalente (Alpha de Cronbach=0,90). Conclusão: O sistema de avaliação proposto é uma ferramenta viável em processos de formação de cirurgiões que permite complementar o método tradicional de avaliação de médicos cirurgiões.

Drawing sounds: representing tones and chords spatially.

Research on the crossmodal correspondences has revealed that seemingly unrelated perceptual information can be matched across the senses in a manner that is consistent across individuals. An interesting extension of this line of research is to study how sensory information biases action. In the present study, we investigated whether different sounds (i.e. tones and piano chords) would bias participants' hand movements in a free movement task. Right-handed participants were instructed to move a computer mouse in order to represent three tones and two chords. They also had to rate each sound in terms of three visual analogue scales (slow-fast, unpleasant-pleasant, and weak-strong). The results demonstrate that tones and chords influence hand movements, with higher-(lower-)pitched sounds giving rise to a significant bias towards upper (lower) locations in space. These results are discussed in terms of the literature on forward models, embodied cognition, crossmodal correspondences, and mental imagery. Potential applications sports and rehabilitation are discussed briefly.

Reglas de despacho en la programación de procedimientos quirúrgicos electivos: impacto en los indicadores de ocupación y oportunidad / Dispatching Rules in Elective Surgery Scheduling: Impact on Service Occupation and Opportunity / Regras de despacho na programação de procedimentos cirúrgicos eletivos: impacto nos indicadores de ocupação e oportunidade

Introducción: la programación de los quirófanos es el factor de mayor incidencia en el desempeño de los servicios de cirugías. Este estudio cuantificó el impacto de la variabilidad artificial creada por una programación manual de las cirugías en el Hospital Universitario Mayor - Méderi (HUM), Colombia. La hipótesis planteada es que una programación semiautomática podría: (i) reducir la variabilidad diaria del servicio de cirugías, (ii) aumentar la disponibilidad de los quirófanos y (iii) mejorar el tiempo de oportunidad por cirugía. Materiales y métodos: este estudio empleó los registros del servicio de cirugía de un mes regular. El servicio estudiado ejecuta alrededor de 35 000 cirugías al año y el proceso de programación es manual. La programación real fue comparada con las generadas a partir del empleo del algoritmo Bin Packing y las reglas de despacho Longest Processing Time (LPT) y Shortest Processing Time (SPT). Resultados: la aplicación del algoritmo con la regla LPT logró una mejora en la programación del mes estudiado: los coeficientes de variación del flujo de pacientes y ocupación diaria se redujeron (25,09% y 36,71%, respectivamente). Adicionalmente, el tiempo de oportunidad se redujo en 6,2 días y la ocupación del servicio subió un 26,22%. La programación con la regla SPT aumentó la variabilidad en el flujo de paciente en 22,7% y disminuyó la ocupación en 2,28%. Conclusiones: una programación semiautomática de las salas de cirugía en el HUM empleando la regla LPT lograría mejorar sustancialmente indicadores de variabilidad del servicio, tiempo de oportunidad y ocupación.

Introduction: The performance of a surgery service is highly impacted by its schedule. This study measured the impact of the artificial variability caused by a manual scheduling of surgeries at "Hospital Universitario Mayor - Méderi (HUM)" (Colombia). The hypotheses were that the proposed algorithm is able to (i) reduce daily service variation, (ii) increase the availability of service resources, and (iii) improve the opportunity time for each surgery. Materials and methods: The studied surgical service performs around 35 000 annual surgeries and its scheduling process is presently manually made. Actual scheduling records of a regular month were compared to schedules generated by a Bin Packing (BP) algorithm hybridized with the Longest Processing Time (LPT) and Shortest Processing Time (SPT) dispatching rules. Results: It was found that the BP algorithm with LPT rule could improve service performance, reducing the variation coefficients of patients' flow and daily service occupation by 25.09% and 36.71%, respectively. The programmed surgeries were also moved ahead 6.2 days, and the overall occupation rate increased by 26.72%. Results were not better when a SPT rule was used, boosting the variability on patient flow by 22.7% and reducing the occupation by 2.28%. Conclusions: Semiautomatic scheduling of the surgical service at the HUM, a BP algorithm with LPT rule, may substantially increase service performance in terms of service occupation and opportunity.

Introdução: A programação das salas de cirurgia é o fator de maior incidência no desempenho dos serviços de cirurgias. Este estudo quantificou o impacto da variabilidade artificial criada por uma programação manual das cirurgias no Hospital Universitário Mayor - Méderi (HUM), Colômbia. A hipótese apresentada é que uma programação semiautomática poderia: (i) reduzir a variabilidade diária do serviço de cirurgias, (ii) aumentar a disponibilidade das salas de cirurgia, e (iii) melhorar o tempo de oportunidade por cirurgia. Materiais e métodos: Este estudo empregou os registros do serviço de cirurgia de um mês regular. O serviço estudado executa cerca de 35 000 cirurgias por ano e o processo de programação é manual. A programação real foi comparada com as geradas a partir do emprego do algoritmo Bin Packing e as regras de despacho Longest Processing Time (LPT) e Shortest Processing Time (SPT). Resultados: A aplicação do algoritmo com a regra LPT conseguiu uma melhora na programação do mês estudado: os coeficientes de variação do fluxo de pacientes e ocupação diária reduziram-se (25,09% y 36,71%, respectivamente). Adicionalmente, o tempo de oportunidade reduziu-se em 6,2 dias e a ocupação do serviço subiu um 26,22%. A programação com a regra SPT aumentou a variabilidade no fluxo de paciente em 22,7% e diminuiu a ocupação em 2,28%. Conclusões: Uma programação semiautomática das salas de cirurgia no HUM empregando a regra LPT conseguiria melhorar substancialmente indicadores de variabilidade do serviço, tempo de oportunidade e ocupação.

Objective evaluation of surgical competency for minimally invasive surgery with a collection of simple tests.

OBJECTIVE: This study aims at determining if a collection of 16 motor tests on a physical simulator can objectively discriminate and evaluate practitioners' competency level, i.e. novice, resident, and expert. METHODS: An experimental design with three study groups (novice, resident, and expert) was developed to test the evaluation power of each of the 16 simple tests. An ANOVA and a Student Newman-Keuls (SNK) test were used to analyze results of each test to determine which of them can discriminate participants' competency level. RESULTS: Four of the 16 tests used discriminated all of the three competency levels and 15 discriminated at least two of the three groups (α= 0.05). Moreover, other two tests differentiate beginners' level from intermediate, and other seven tests differentiate intermediate level from expert. CONCLUSION: The competency level of a practitioner of minimally invasive surgery can be evaluated by a specific collection of basic tests in a physical surgical simulator. Reduction of the number of tests needed to discriminate the competency level of surgeons can be the aim of future research.

OBJETIVO: Este estudio pretende determinar si una colección de 16 pruebas en un simulador físico puede discriminar y evaluar objetivamente el nivel de competencia de practicantes de cirugía laparoscópica (novato, resistente y experto). MÉTODOS: Se realizó un diseño de experimentos con tres grupos de estudio (novatos, residentes y expertos) para probar el poder de discriminación de 16 pruebas simples. Un ANOVA y un test de Student Newman-Keuls (SNK) fueron empleados para analizar los resultados de cada prueba con el fin de determinar cuáles de ellas podían discriminar los niveles de competencia de los participantes. RESULTADOS: Cuatro de las 16 pruebas evaluadas lograron discriminar los tres niveles de competencia, y 15 pruebas lograron discriminar al menos dos de los tres grupos (α= 0.05). Adicionalmente, otras dos pruebas diferenciaron los novatos de los residentes, y otras siete pruebas diferenciaron los residentes de los expertos. CONCLUSIÓN: El nivel de competencia de un practicante de cirugía mínimamente invasiva puede ser determinado mediante una colección de pruebas básicas en un simulador quirúrgico físico. El diseño de pruebas que discriminen los tres niveles de competencia y reduzcan el número de pruebas de la colección son posibles temas para nuevos trabajos.

Objective evaluation of surgical competency for minimally invasive surgery with a collection of simple tests / Evaluación objetiva de competencias quirúrgicas en cirugía mínimamente invasiva con una colección de pruebas simples

Objective: This study aims at determining if a collection of 16 motor tests on a physical simulator can objectively discriminate and evaluate practitioners' competency level, i.e. novice, resident, and expert. Methods: An experimental design with three study groups (novice, resident, and expert) was developed to test the evaluation power of each of the 16 simple tests. An ANOVA and a Student Newman-Keuls (SNK) test were used to analyze results of each test to determine which of them can discriminate participants' competency level. Results: Four of the 16 tests used discriminated all of the three competency levels and 15 discriminated at least two of the three groups (α= 0.05). Moreover, other two tests differentiate beginners' level from intermediate, and other seven tests differentiate intermediate level from expert. Conclusion: The competency level of a practitioner of minimally invasive surgery can be evaluated by a specific collection of basic tests in a physical surgical simulator. Reduction of the number of tests needed to discriminate the competency level of surgeons can be the aim of future research.

Objetivo: Este estudio pretende determinar si una colección de 16 pruebas en un simulador físico puede discriminar y evaluar objetivamente el nivel de competencia de practicantes de cirugía laparoscópica (novato, resistente y experto). Métodos: Se realizó un diseño de experimentos con tres grupos de estudio (novatos, residentes y expertos) para probar el poder de discriminación de 16 pruebas simples. Un ANOVA y un test de Student Newman-Keuls (SNK) fueron empleados para analizar los resultados de cada prueba con el fin de determinar cuáles de ellas podían discriminar los niveles de competencia de los participantes. Resultados: Cuatro de las 16 pruebas evaluadas lograron discriminar los tres niveles de competencia, y 15 pruebas lograron discriminar al menos dos de los tres grupos (α= 0.05). Adicionalmente, otras dos pruebas diferenciaron los novatos de los residentes, y otras siete pruebas diferenciaron los residentes de los expertos. Conclusión: El nivel de competencia de un practicante de cirugía mínimamente invasiva puede ser determinado mediante una colección de pruebas básicas en un simulador quirúrgico físico. El diseño de pruebas que discriminen los tres niveles de competencia y reduzcan el número de pruebas de la colección son posibles temas para nuevos trabajos.

Control de la variabilidad en la programación de pacientes electivos en salas de cirugía / Variability Control in the Scheduling of Elective Patients in Operating Rooms / Controle da variabilidade no agendamento de pacientes eletivos em salas de cirurgia

El Departamento de Cirugía genera una buena parte de los ingresos de un hospital. Este estudio evalúa la variabilidad en la programación de las cirugías y cómo esta atenta contra la eficiencia del servicio. Este estudio implemento un algoritmo para la generación de dos programaciones que luego fueron comparadas con la realizada manualmente en un hospital en Colombia. Las dos programaciones generadas se diferencian entre sí al incluir o no las máximas desviaciones en los tiempos de duración de las cirugías, asumiendo que estas son causadas por factores externas al proceso y pueden ser eliminadas. Los resultados muestran que al emplear un algoritmo automático para programar las cirugías, podrían mejorarse el tiempo de respuesta y la utilización de las salas. Aún más, se pudo concluir que la variabilidad asociada a la programación manual tiene un mayor impacto que la asociada a otros factores en los indicadores de desempeño del servicio.

The Surgery Department generates a sizeable amount of the income of a hospital. This study evaluates the variability in the scheduling of surgeries and how this threatens the efficiency of the service. This study uses an algorithm for the generation of two schedules that were later compared with a manually-generated schedule in a hospital in Colombia. The difference between the generated schedules is the inclusion or lack thereof of the maximum time deviations in surgery times, under the assumption that these are caused by external factors and may be eliminated. Results show that by using an automatic algorithm to schedule the surgeries response time and operating room use can be improved. Moreover, it can be concluded that the variability associated with manual scheduling has a greater impact than the one associated to other factors in the service performance indicators.

O Departamento de Cirurgia gera uma boa parte das rendas de um hospital. Este estudo avalia a variabilidade no agendamento das cirurgias e como ele atenta contra a eficiencia do servico. Este estudo implementou um algoritmo para a geração de dois agendamentos após comparados com aqueles realizados manualmente em um hospital na Colombia. Os dois agendamentos gerados diferenciam-se entre se por incluir ou nao os máximos afastamentos nos tempos de duração da cirurgia, assumindo que estes sao causados por fatores externos ao processo e podem ser eliminados. Os resultados mostram que usando um algoritmo automático para programar cirurgias, poderia se melhorar o tempo de resposta e a utilização das salas. Além disso, pode-se concluir que a variabilidade associada ao agendamento manual tem maior impacto que a associada a outros fatores nos indicadores de desempenho do servico.

Evaluación del mejoramiento de habilidades básicas para cirugía laparoscópica por medio del entrenamiento con un videojuego / Evaluation of Basic Skills Improvement for Laparoscopy by Training with a Video Game / Avaliação do melhoramento de habilidades básicas para cirurgia laparoscópica por meio do treinamento com um videojogo

Introducción: debido a las crecientes limitaciones éticas y de recursos en el entrenamiento de aprendices en cirugía mínimamente invasiva (CMI, E. G. laparoscopia) en pacientes, se pretende evaluar el efecto de la práctica continua con un videojuego en particular en el desarrollo de las habilidades fundamentales a la hora de ejecutar una de estas cirugías. Materiales y métodos: se seleccionaron tres actividades esenciales (corte, sutura y coordinación mano-ojo) por realizar en simuladores laparoscópicos, con el fin de establecer si la práctica con el videojuego es efectiva en el desarrollo de las habilidades necesarias en CMI. Se evaluaron en total ocho variables de desempeño en las tres actividades seleccionadas. Con base en esto, se evaluaron catorce aprendices médicos sin experiencia en laparoscopia, divididos en dos grupos (control e intervención), antes y después de un programa de entrenamiento estandarizado con el videojuego Marblemanía® y una duración de un mes. Resultados: se evidenció que la práctica continua con el videojuego Marblemanía® mejoró todas las variables de desempeño. Estos resultados positivos fueron significativamente diferentes a favor del grupo que tuvo acceso al programa de entrenamiento con el videojuego en 3 de las 8 variables de desempeño medidas en las tres actividades seleccionadas: errores en la actividad de sutura (p = 0,003), y el tiempo de ejecución y errores en la actividad coordinación mano-ojo (p = 0,025 y 0,001, respectivamente).

Introduction: Due to the growing economical and ethical limitations in surgeons training for minimally invasive surgery (MIS, e.g. laparoscopy), this study aims at evaluating the effect of a continuous practice of a particular videogame on the development of the fundamental and specific skills needed to perform this type of procedure successfully. Materials and methods: To evaluate the effectiveness of video game practicing, three essential and common activities were chosen (cutting, suturing, and eye-hand coordination) to be performed in laparoscopic simulators. Eight different indexes or variables of performance were measured in the three activities. Fourteen voluntaries without previous experience in surgery were divided in two groups (intervention and control) and their performance was evaluated before and after a one-month standardized training program with the video game Marble Mania®. Results: A general improvement of all the performance variables was observed after one month training in the intervention group. This improvement was significant with respect to the control group in three of the eight variables: suturing errors (p = 0.003), and the execution and number of errors in the eye-hand coordination (p = 0.025 and 0.001, respectively).

Introdução: devido às crescentes limitações éticas e de recursos no treinamento de aprendizes em cirurgia minimamente invasiva (CMI, e.g. laparoscopia) em pacientes, pretende-se avaliar o efeito da prática contínua com um videojogo em particular no desenvolvimento das habilidades fundamentais na hora de executar uma destas cirurgias. Materiais e métodos: se selecionaram três atividades essenciais (corte, sutura e coordenação mão-olho), a realizar em simuladores laparoscópicos, com o fim de estabelecer se a prática com o videojogo é efetiva no desenvolvimento das habilidades necessárias em CMI. Em total, avaliaram-se oito variáveis de desempenho nas três atividades selecionadas. Com base nisso, avaliaram-se catorze aprendizes médicos sem experiência em laparoscopia, divididos em dois grupos (controles e intervenção), antes e depois de um programa de treinamento estandardizado com o videojogo Marblemanía® em uma duração de um mês. Resultados: se evidenciou que a pratica contínua com o videojogo Marblemanía® melhorou todas as variáveis de desempenho. Estes resultados positivos foram significativamente diferentes a favor do grupo que teve acesso ao programa de treinamento com o videojogo em três das oito variáveis de desempenho medidas nas três atividades selecionadas: erros na atividade de sutura (p = 0.003), o tempo de execução e erros na atividade coordenação mão-olho (p = 0.025 y 0.001, respectivamente).

Fracture risk and initial fixation of a cementless glenoid implant: the effect of numbers and types of screws.

The initial fixation of an anatomical cementless glenoid component, provided by different numbers and types of screws, and the risk of bone fracture were evaluated by estimating the bone-implant interface micromotions and the principal strains around the prosthesis. Four different fixation configurations using locking or compression screws were tested. Estimation of the micromotions at the bone-implant interface was performed both experimentally, using an in vitro model, and computationally, using a numerical model. Principal bone strains were estimated using the numerical model. Subject variability was included by modelling two different bone qualities (healthy and rheumatoid bone). For the fixation configurations that used two screws, experimental and modelling results found that the micromotions at the bone-implant interface did not change with screw type. However, screw type had a significant effect on fixation when only one screw was used; in this case, a locking screw resulted in less micromotion at the bone-implant interface compared with the compression screw. Bone strains were predicted by the numerical model, and strains were found to be independent of the screw type; however, the predicted strain levels calculated in rheumatoid bone were larger than the strain levels that may cause bone damage for most considered arm positions. Predicted bone strain in healthy bone did not reach this level. While proper initial component fixation that allows biological fixation can be achieved by using additional screws, the risk of bone failure around the screws must be considered, especially in cases of weak bone.

Bone remodelling around a cementless glenoid component.

Post-operative change in the mechanical loading of bone may trigger its (mechanically induced) adaptation and hamper the mechanical stability of prostheses. This is especially important in cementless components, where the final fixation is achieved by the bone itself. The aim of this study is, first, to gain insight into the bone remodelling process around a cementless glenoid component, and second, to compare the possible bone adaptation when the implant is assumed to be fully bonded (best case scenario) or completely loose (worst case scenario). 3D finite element models of a scapula with and without a cementless glenoid component were created. 3D geometry of the scapula, material properties, and several physiological loading conditions were acquired from or estimated for a specific cadaver. Update of the bone density after implantation was done according to a node-based bone remodelling scheme. Strain energy density for different loading conditions was evaluated, weighted according to their frequencies in activities of daily life and used as a mechanical stimulus for bone adaptation. The average bone density in the glenoid increased after implantation. However, local bone resorption was significant in some regions next to the bone-implant interface, regardless of the interface condition (bonded or loose). The amount of bone resorption was determined by the condition imposed to the interface, being slightly larger when the interface was loose. An ideal screw, e.g. in which material fatigue was not considered, was enough to keep the interface micromotions small and constant during the entire bone adaptation simulation.

Interface micromotions increase with less-conforming cementless glenoid components.

BACKGROUND: The optimal degree of conformity between the glenoid and humeral components in total shoulder arthroplasty for best performance and durability is still a matter of debate. The main aim of this study is to evaluate the influence of joint conformity on the bone-implant interface micromotions in a cementless glenoid implant. MATERIALS AND METHODS: Polyethylene inlays with different degrees of conformity (radial mismatch of 0, 2, 4, and 6 mm) were mounted on a cementless metal back and then implanted in a bone substitute. These glenoid components were loaded by a prosthetic humeral head during a force-controlled experiment. Normal-to-interface micromotions and bone substitute deformations were measured at different points of the interface. Rim displacement and humeral head translation were also measured. A finite element (FE) model of the experiments was implemented to estimate the normal- and tangent-to-interface micromotions in the entire bone-implant interface. RESULTS: All measured variables increased with less-conforming PE inlays. Normal-to-interface micromotions were significantly larger (P < .05) when the radial mismatch was 6 mm compared with the fully conforming inlay. The FE model was in agreement and complemented the experimental results. FE model-predicted interface micromotions were already significantly larger when the radial mismatch was equal to 4 mm. DISCUSSION: In a force-controlled experiment with a cementless glenoid component, a non-conforming PE inlay allows larger interface micromotions than a conforming inlay, reaching a magnitude that may hamper local bone ingrowth in this type of component. This is mainly because of the larger humeral head translation that boosts the effects of the so-called rocking-horse phenomenon.

The effect of injectable biocompatible elastomer (PDMS) on the strength of the proximal fixation of endovascular aneurysm repair grafts: an in vitro study.

PURPOSE: One of the major concerns in the long-term success of endovascular aneurysm repair (EVAR) is stent graft migration, which can cause type I endoleak and even aneurysm rupture. Fixation depends on the mechanical forces between the graft and both the aortic neck and the blood flow. Therefore, there are anatomical restrictions for EVAR, such as short and angulated necks. To improve the fixation of EVAR grafts, elastomer (PDMS) can be injected in the aneurysm sac. The support given by the elastomer might prevent dislocation and migration of the graft. The aim of this study was to measure the influence of an injectable biocompatible elastomer on the fixation strength of different EVAR grafts in an in vitro model. METHODS: The proximal part of three different stent grafts was inserted in a bovine artery with an attached latex aneurysm. The graft was connected to a tensile testing machine, applying force to the proximal fixation, while the artery with the aneurysm was fixated to the setup. The force to obtain graft dislodgement (DF) from the aorta was recorded in Newtons (N). Three different proximal seal lengths (5, 10, and 15 mm) were evaluated. The experiments were repeated after the space between the graft and the latex aneurysm was filled with the elastomer. Independent sample ttests were used for the comparison between the DF before and after elastomer treatment for each seal length. RESULTS: The mean DF (mean +/- SD) of all grafts without elastomer sac filling for a proximal seal length of 5, 10, and 15 mm were respectively, 4.4 +/- 3.1 N, 12.2 +/- 10.6 N, and 15.1 +/- 6.9 N. After elastomer sac filling, the dislodgement forces increased significantly (P < .001) to 20.9 +/- 3.8 N, 31.8 +/- 9.8 N, and 36.0 +/- 14.1 N, respectively. CONCLUSIONS: The present study shows that aneurysm sac filling may have a role as an adjuvant procedure to the present EVAR technique. The strength of the proximal fixation of three different stent grafts increases significantly in this in vitro setting. Further in vivo research must be done to see if this could facilitate the treatment of aneurysms with short infrarenal necks.

Minor influence of humeral component size on torsional stiffness of the Souter-Strathclyde total elbow prosthesis.

The use of Souter-Strathclyde total elbow prostheses is a well-studied replacement therapy for reconstruction of the elbow, but loosening of the humeral component is still of concern at long-term follow-up. In this study we looked at the effect of humeral component size and bone mineral density with respect to the bone size, torsional stiffness and torque to failure in cadaveric bones. Fourteen cadaveric humeri were available for testing purposes and four different humeral component size categories were used. First, we calculated the bone quality using dual-energy X-ray absorptiometry (DEXA). The torsional stiffness of the prosthetic humeri was measured during two mechanical tests: Firstly, the applied torque was recorded during a torsion fatigue test. The change of torsional stiffness between the tenth and last cycle was calculated. Secondly, a simple torsion test was performed and the torque to failure was recorded. No significant differences in outcome were seen between sizes of humeral components, even after correction for the bone size. Torsional stiffness and torque to failure were significantly correlated with bone mineral density and not with component size. In conclusion, bone quality seems to be a major eminent factor in the fixation of the humeral component in elbow replacement surgery.

Effect of rotator cuff dysfunction on the initial mechanical stability of cementless glenoid components.

The functional outcome of shoulder replacement is related to the condition of the rotator cuff. Rotator cuff disease is a common problem in candidates for total shoulder arthroplasty; this study relates the functional status of the rotator cuff to the initial stability of a cementless glenoid implant. A 3D finite element model of a complete scapula was used to quantify the effect of a dysfunctional rotator cuff in terms of bone-implant interface micromotions when the implant is physiologically loaded shortly after surgery. Four rotator cuff conditions (from fully intact to progressively ruptured rotator cuff tendons) as well as two bone qualities were simulated in a model. Micromotions were significantly larger in the worst modeled cuff dysfunction (i.e. the supraspinatus and infraspinatus tendons were fully dysfunctional). Micromotions were also significantly different between conditions with healthy and poor bone quality. The implant's initial stability was hardly influenced by a dysfunctional supraspinatus alone. However, when the infraspinatus was also affected, the glenohumeral joint force was displaced to the component's rim resulting in larger micromotions and instability of the implant.