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BACKGROUND AND AIMS: Oxaliplatin (OX) has been described as a potential etiologic agent for porto-sinusoidal vascular disorder (PSVD). Our aim was to describe the natural history of PSVD due to OX in colon cancer (CRC) and identify risk factors for its development. METHODS: We made a multicenter retrospective case-control (ratio 1:3) study with patients diagnosed of PSVD-OX. Baseline data, end of treatment, years of follow-up and diagnosis of PSVD were collected and compared to controls (without PSVD). Besides, 16 different SNPs were selected from bibliography and analyzed by genotyping in the case group to identify potential genetic risk factors. RESULTS: 41 cases were identified, with a median time to PSVD diagnosis after the end of OX of 34 months. Spleen diameter was the strongest predictor of PSVD during treatment (OR 43.94 (14.48-133.336); p < 0.0001). Additionally, thrombocytopenia (<150 × 10^9) at one year was a significant disease risk marker (OR 9.35; 95% CI: 3.71-23.58; p = 0.001). We could not establish any significant association between the selected SNPs and PSVD diagnosis. CONCLUSION: The increase of spleen diameter is the strongest predictor of PSVD in patients treated with OX for CRC. These patients could be candidates for a specific follow-up of portal hypertension-related complications.
RESUMO
Resumen: En este estudio, se presenta una metodología para evaluar lentes fáquicos intraoculares, cuando el flujo del humor acuoso es asimétrico, debido a modificaciones en el área de salida del fluido. El objetivo es determinar el efecto que tienen las asimetrías del flujo del humor acuoso en el esfuerzo cortante sobre el iris y la córnea en presencia de un lente fáquico intraocular. Se considera la geometría del ojo propuesta por Repetto et al.,7 y se resuelve el flujo del humor acuso con y sin lente empleando simulaciones mediante el método de elemento finito. Para validar el método, se compara la solución numérica obtenida con los resultados de Tychsen et al.8 obteniendo valores del mismo orden. Los resultados obtenidos son perfiles de velocidad, líneas de corriente y esfuerzos cortantes en las superficies del iris y la córnea. El modelo no toma en cuenta las variaciones de la temperatura, por lo que no se consideran los efectos de flotación. Los resultados muestran que las asimetrías tienen un gran impacto en la dinámica del humor acuoso e incrementan los esfuerzos cortantes; sin embargo no son suficientes como para causar desprendimiento de las céluas del iris o de la córnea.
Abstract: The study presents a methodology to evaluate intraocular phakic lenses, considering asymmetric aqueous humor flow due to modified conditions of the fluid outlet area. The main objective is to determine the effect of asymmetries on shear stresses with and without phakik lenses. A finite element numerical simulation was developed using the eye geometry proposed by Repetto et al.6 The numerical method was tested with the results obtained by Tychsen et al.8, giving results of the same order of magnitude. Velocity profiles, pressure distribution and shear stress at the solid boundaries are shown. The model does not take into account temperature variations. Therefore no buoyancy effects were considered. The results show that the induced asymmetries have a significant impact on aqueous humor velocity and on shear forces; however the shear stresses are not sufficient to cause cell detachment so the lens can be considered as harmless.
RESUMO
RESUMEN: El objetivo del presente trabajo es determinar la influencia que tiene la posición de los canales colectores en la presión intraocular y su contribución en el desarrollo del glaucoma. Para realizar el análisis se llevaron acabo simulaciones numéricas utilizando el método de elemento finito para dos casos de estudio. El primer caso es un modelo simplificado de sección rectangular que simula el flujo entre dos canales colectores; el segundo modelo describe el flujo en todo el canal de Schlemm (CS), considerando que es un aro rígido de espesor constante, con cuatro distribuciones de los canales colectores. Se obtuvieron los perfiles de presión y velocidad en los dos casos. En el caso simplificado se tienen diferencias de 10 P a entre las presiones medias. El segundo modelo muestra que el arreglo simétrico tiene una distribución de presiones constante mientras que los casos asimétricos presentan variaciones de 2 P a. Los resultados confirman que la posición de los canales colectores tiene influencia en la presión intraocular. Este estudio da lugar a realizar un análisis en estado transitorio, considerando las propiedades elásticas del CS así como las variaciones de diámetro de los canales colectores.
ABSTRACT: The aim of the present study is to determine the influence of the position of the collecting channels on intraocular pressure and its contribution to the development of glaucoma. Numerical simulations were performed using the finite element method for two case studies. The first case is a simplified model of rectangular section that simulates the flow between two collecting channels. The second model describes flow throughout the Schlemm channel (CS), considering that it is a rigid ring of constant thickness, with four distributions of the collector channels. The pressure and velocity profiles are shown for both cases. In the simplified case, there are differences of 10 P a between the average pressures. The second model shows that the symmetric arrangement has a constant pressure distribution while the asymmetric cases have variations of 2 P a. The results confirm that the position of the collecting channels influences the intraocular pressure. This study shows that a transient analysis is needed to understand the whole process, considering the elastic properties of the CS as well as the variations of diameter of the collecting channels.