Valorização do índice de resistência renal em felinos com doença renal

Dissertação de Mestrado Integrado em Medicina VeterináriaA Doença Renal Crónica (DRC) é frequentemente diagnosticada em felinos geriátricos. Um diagnóstico precoce é importante porque permite a introdução da terapêutica que diminui significativamente a sua progressão. A presente dissertação pretende compreender se as alterações hemodinâmicas renais avaliadas pela técnica de Duplex Doppler, através da medição do Índice de Resistência (IR), poderão ser utilizadas para melhorar o diagnóstico de felinos com DRC. A população em estudo consistiu em 6 gatos Persa com DRC e 5 gatos Persa saudáveis, que constituiram o grupo-controlo. A DRC foi diagnosticada com base em parâmetros clínicos e laboratoriais. O IR foi avaliado ao nível das artérias interlobares e arqueadas do rim esquerdo nos 11 animais incluídos no estudo. No grupo-controlo obteve-se um IR (0,59±0,06) semelhante à restante bibliografia consultada. No grupo de animais com doença renal obteve-se um IR superior (0,75±0,07). Comprovou-se haver uma diferença estatisticamente significativa entre o IR das duas populações (P<0,05) através do teste estatístico Mann-Whitney U do programa SPSS19. Obteve-se um IR acima do limiar estabelecido para a espécie em 100% dos animais com aumento da concentração de ureia plasmática (n=5) e da concentração de creatinina plasmática (n=4) e em 80% dos animais proteinúricos (n=5) avaliados pelo rácio entre a proteína e a creatinina urinárias. Observou-se uma nítida tendência para que os valores de IR fossem mais elevados em animais com parâmetros de função renal mais alterados. Dado o reduzido número de animais em estudo, não foi possível estabelecer a correlação estatística entre o IR e os restantes parâmetros de função avaliados. Acreditamos que a avaliação do IR possa ser útil no maneio clínico das nefropatias felinas mas são necessários mais estudos para avaliar a utilidade do IR como factor de prognóstico. Para tal, deve ser efectuada a sua avaliação numa fase inicial de doença e ao longo da sua progressão.ABSTRACT - Chronic Kidney Disease (CKD) is often diagnosed in geriatric cats. An early diagnosis is important as it allows the therapeutic introduction that significantly slows down its progression. The present dissertation intends to understand whether the renal hemodynamic changes assessed by Duplex Doppler technique, through the measurement of the Resistive Index (RI), can be used to improve the diagnosis of feline CKD. The study population consisted in 6 Persian cats with CKD and 5 healthy Persian cats that constituted the control group. CKD was diagnosed based on clinical and laboratory parameters. The RI was evaluated at the level of the interlobar and arcuate arteries of the left kidney in the 11 animals included in the study. In the control group was obtained an RI (0,59±0,06) similar to the rest of the consulted bibliography. In the group of animals with kidney disease it was obtained a higher RI (0,75±0,07). It was shown that there is a statistically significant difference between the two populations RI (P<0,05) by the Mann-Whitney U statistic test of SPSS19 program. An RI above the limit for the specie was obtained in 100% of the animals with increase concentration of plasma urea (n=5) and concentration of plasma creatinine (n=4) and in 80% of the proteinuric animals (n=5) evaluated through the urinary protein creatinine ratio. It was observed a marked tendency for the RI values to be higher in those animals where the renal function parameters were more increased. Due to the small number of studied animals, it was not possible to establish a statistic correlation between the RI and the rest of the function parameters evaluated. We believe that the RI evaluation can be usefull in the feline nephropathies clinical management, but more studies are needed to evaluate the utility of the RI as a factor of prognosis. For that, its evaluation in an early phase of the disease and along its progression should be assessed

A novel flexible field-aligned coordinate system for tokamak edge plasma simulation

Tokamak plasmas are confined by a magnetic field that limits the particle and heat transport perpendicular to the field. Parallel to the field the ionised particles can move freely, so to obtain confinement the field lines are “closed” (ie.form closed surfaces of constant poloidal flux) in the core of a tokamak. Towards, the edge, however, the field lines intersect physical surfaces, leading to interaction between neutral and ionised particles, and the potential melting of the material surface. Simulation of this interaction is important for predicting the performance and lifetime of future tokamak devices such as ITER. Field-aligned coordinates are commonly used in the simulation of tokamak plasmas due to the geometry and magnetic topology of the system. However, these coordinates are limited in the geometry they allow in the poloidal plane due to orthogonality requirements. A novel 3D coordinate system is proposed herein that relaxes this constraint so that any arbitrary, smoothly varying geometry can be matched in the poloidal plane while maintaining a field-aligned coordinate. This system is implemented in BOUT++ and tested for accuracy using the method of manufactured solutions. A MAST edge cross-section is simulated using a fluid plasma model and the results show expected behaviour for density, temperature, and velocity. Finally, simulations of an isolated divertor leg are conducted with and without neutrals to demonstrate the ion-neutral interaction near the divertor plate and the corresponding beneficial decrease in plasma temperature