Gestación y anticoagulación en válvula mecánica: un reto terapéutico / Pregnancy and anticoagulation in mechanical valves: A therapeutic challenge

Resumen La gestación en presencia de una válvula mecánica es un reto terapéutico tanto para el ginecólogo como para el cardiólogo, en vista de las complicaciones materno-fetales y mayor el riesgo de trombosis valvular. Medio siglo después del primer reporte de una gestación a término en este contexto, mucho se ha aprendido, pero persisten controversias importantes, de ahí que conocerlas sea fundamental para encontrar el tratamiento más balanceado.

Abstract Pregnancy and mechanical valves are a therapeutic challenge both for the gynaecologist and the cardiologist in view of the maternal-foetal complications, and the higher risk of valvular thrombosis. Half a century after the first report of a full term pregnancy in this context, much has been learned, but there are still significant controversies, which are essential to know about, in order to find the most balanced treatment.

model to predict the behavior of UASB reactors

A model describing the main processes occurring in the UASB reactor was developed; in order to maintain simplicity and applicability of the model, only the fundamental aspects were considered. In the model, the reactor is divided in several well-stirred reactors coupled in series and it comprises substrate degradation, biomass growth and the reactions that take place within the granules. The important contribution of the paper is the development of a model taking into account the mass transfer through the film around the granules, the intra-particle diffusion, and the degradation reaction. The model enables the determination of the removal efficiency of the substrate and the increase of both the height of the sludge bed and the granule size with time. The simulated results of an experimental UASB reactor treating sugar-cane mill waste water were found to be in good agreement with the performance of the reactor. The sensitivity analysis shows that the performance of the reactor is determined by several parameters. The most important parameters are: the bioconversion rate, the mass transfer coefficient in the film, the intra-particle diffusivity, the volumetric fraction of biomass in the reactor, and the number of CSTR considered. These parameters should therefore be carefully determined. The model could be a useful tool in the optimization and development of UASB reactors