ABSTRACT
En México, la mortalidad debido a enfermedades bronco-respiratorias se ubica en el sexto lugar según datos estadísticos dados por el Instituto Nacional de Enfermedades Respiratorias (INER). Esto genera la necesidad de incrementar la eficiencia en la aplicación de los tratamientos usados para este tipo de patología. Algunos de los métodos utilizados con mayor frecuencia para el tratamiento de estas dolencias hacen uso de micro dispositivos, también conocidos como válvulas endobronquiales. Este es un sistema alternativo que evita cirugías invasivas y logra prolongar e incrementar la calidad de vida de los pacientes. En este trabajo se presenta el análisis del desempeño de la válvula IBV®. Para el desarrollo del estudio numérico se determinaron las dimensiones y propiedades mecánicas del modelo a partir de catálogos del fabricante. Se desarrolló un modelo para el cual se consideraron las propiedades del Nitinol® y Silastic®. Asimismo, se propusieron dos condiciones de operación para la válvula, una anclada en el bronquio y la otra en la condición en la que se encuentra plegada dentro del broncoscopio. Se utilizó el Método del elemento finito (MEF) para simular las condiciones de trabajo de la válvula. Los resultados encontrados muestran el funcionamiento estructural y el nivel de los esfuerzos generados en el implante durante el ciclo de respiración forzada del individuo. Además, se proporcionan las bases para generar un nuevo dispositivo que pueda emular el funcionamiento de este tipo de implantes y aumente la eficiencia del tratamiento de dicha patología.
In Mexico, the mortality rate due to bronchial respiratory sickness is placed in the sixth position, according to statistics from the National Institute of Breathing Sickness (INER), so it is convenient to increment the efficiency of treatments for those pathologies. The intrabronchial valve is a recommended alternative method; being it main objective to avoid invasive surgery and increase the time and quality of patient´s life. Within this work a biomechanical analysis of an IBV® valve is carried out. Regarding the numerical analysis, the dimensions and mechanical properties of the valve were proposed based on catalogues published by the manufacturer as more reliable information was not available in the open literature. As a result, a new model was developed in which both materials Nitinol® and Silastic® are considered as the main valve materials. The proposed working conditions assume that the valve is implanted in folded form at the bronchus and then anchored when it is unfolded. Finite Element Method (FEM) was used to simulate the proposed working conditions. Results obtained show the structural performance and the level of stress generated in the implant during the breathing cycle. In addition, it provides the knowledge to generate a new device that could emulate the performance of these implants and develop a more efficient treatment this disease.
Subject(s)
Lung Neoplasms/surgery , Lung Neoplasms/diagnosis , Lung Neoplasms/nursing , Lung Neoplasms/epidemiology , Lung Neoplasms/physiopathology , Lung Neoplasms/chemically induced , Lung Neoplasms/pathology , Lung Neoplasms/chemistry , Lung Neoplasms/drug therapy , Heart Valves/abnormalities , Heart Valves/physiology , Heart Valves/immunology , Heart Valves/pathology , Heart Valves/chemistryABSTRACT
This study included 48 patients with chronic rheumatic heart disease, 60 control subjects for plasma zinc comparison and 20 control specimens of heart valves from postmortem cases of accident deaths. Plasma and cardiac tissue levels of zinc in patients with rheumatic heart disease were significantly lowered compared to controls. Since zinc is important in the synthesis of nucleic acids and proteins it may influence tissue growth, reparative process and structure and function of biomembrane. Low zinc levels may also influence cell mediated immunity and may increase susceptibility of patients to infection and increased rheumatic activity which needs further study.