RESUMO
El comportamiento de la orina durante su transporte, desde la pelvis renal hasta la vejiga, tiene un gran interés para los urólogos. El conocimiento de las diferentes variables físicas y su interrelación, en movimientos fisiológicos y patologías, ayudará a un mejor diagnóstico y tratamiento. El objetivo de este capítulo es exponer y acercar al mundo clínico los conceptos físicos y sus relaciones básicas más relevantes en el transporte de orina. Para ello, se explica el movimiento de la orina durante una peristalsis, una obstrucción ureteral y un uréter tutorizado con un catéter ureteral. Esta explicación se basa en dos herramientas muy utilizadas en bioingeniería: el análisis teórico a través de la Teoría de los Medios Continuos y la Mecánica de Fluidos y la simulación computacional que ofrece una solución práctica de cada uno de los escenarios. Además, se repasan otras aportaciones de la bioingeniería al campo de la Urología, como la simulación física o las técnicas de fabricación aditiva y sustractiva. Finalmente, se enumeran las limitaciones actuales de estas herramientas y las líneas de desarrollo tecnológico con más proyección. CONCLUSIÓN: Se pretende que este capítulo ayude a los urólogos a comprender algunos conceptos importantes de bioingeniería, fomentando la colaboración multidisciplinar para ofrecer herramientas complementarias que les ayuden en el diagnóstico y el tratamiento de enfermedades
The mechanics of urine during its transport from the renal pelvis to the bladder is of great interest for urologists. The knowledge of the different physical variables and their interrelationship, both in physiologic movements and pathologies, will help a better diagnosis and treatment. The objective of this chapter is to show the physics principles and their most relevant basic relations in urine transport, and to bring them over the clinical world. For that, we explain the movement of urine during peristalsis, ureteral obstruction and in a ureter with a stent. This explanation is based in two tools used in bioengineering: the theoretical analysis through the Theory of concontinuous media and Ffluid mechanics and computational simulation that offers a practical solution for each scenario. Moreover, we review other contributions of bioengineering to the field of Urology, such as physical simulation or additive and subtractive manufacturing techniques. Finally, we list the current limitations for these tools and the technological development lines with more future projection. CONCLUSIONS: In this chapter we aim to help urologists to understand some important concepts of bioengineering, promoting multidisciplinary cooperation to offer complementary tools that help in diagnosis and treatment of diseases
Assuntos
Humanos , Masculino , Feminino , Mecânica dos Fluidos/análise , Mecânica dos Fluidos/métodos , Ablação por Cateter/métodos , Peristaltismo/fisiologia , Obstrução Ureteral/diagnóstico , Obstrução Ureteral/cirurgia , Obstrução Uretral/diagnóstico , Obstrução Uretral/terapia , Bioengenharia/métodos , Bioengenharia/normas , Bioengenharia/tendênciasRESUMO
Many urologists are currently studying new designs of ureteral stents to improve the quality of their operations and the subsequent recovery of the patient. In order to help during this design process, many computational models have been developed to simulate the behaviour of different biological tissues and provide a realistic computational environment to evaluate the stents. However, due to the high complexity of the involved tissues, they usually introduce simplifications to make these models less computationally demanding. In this study, the interaction between urine flow and a double-J stented ureter with a simplified geometry has been analysed. The Fluid-Structure Interaction (FSI) of urine and the ureteral wall was studied using three models for the solid domain: Mooney-Rivlin, Yeoh, and Ogden. The ureter was assumed to be quasi-incompressible and isotropic. Data obtained in previous studies from ex vivo and in vivo mechanical characterization of different ureters were used to fit the mentioned models. The results show that the interaction between the stented ureter and urine is negligible. Therefore, we can conclude that this type of models does not need to include the FSI and could be solved quite accurately assuming that the ureter is a rigid body and, thus, using the more simple Computational Fluid Dynamics (CFD) approach.
