Roberto Alcázar

Comparación de la eficacia de dos modalidades de hemodiafiltración en línea: mixta frente a posdilucional

INTRODUCTION Haemodiafiltration (HDF) with high reinfusion volumes is the most effective technique for clearing uraemic toxins. There are various modalities depending on the location where the replacement volume is administered in the extracorporeal circuit: pre-dilution, mixed or mid-dilution and post-dilution, in which the infusion is carried out pre-dilution, pre- and post-dilution simultaneously and post-dilution, respectively. OBJECTIVE Compare the clearance of small, medium-sized and protein-bound molecules and the convective volume administered in online HDF (OL-HDF) in post-dilution and mixed (pre-post-dilution) infusion. MATERIAL AND METHOD A prospective, randomised, crossover study comparing post-dilution and mixed OL-HDF. Patients (n=8) were randomly assigned to receive 6 sessions in each technique. We conducted 89 sessions, of which 68 were at a scheduled time (ST) and 21 at an effective time (ET). We determined the reduction rate (RR) percentages for various substances and the infusion volumes. The RR study was performed using ET. RESULTS The KT value obtained was greater with post-dilution OL-HDF [68 (8.1) compared to 64.9 (8.8) litres] (P=.009) when patients were dialysed at ST. This difference disappeared when dialysis was performed at ET. The difference between ST and ET was greater in mixed HDF than in post-dilution HDF [10.3 (7.4) compared to 6.5 (3.1) minutes, P=.02]. We found no differences in the RR of the substances analysed. CONCLUSION Mixed OL-HDF is not inferior to post-dilution OL-HDF either in the clearance of small and medium-sized molecules or in the clearance of protein-bound molecules at the same ET.

Hemos olvidado lo más importante para prevenir las bacteriemias en pacientes portadores de catéteres para hemodiálisis

Bacteremia associated with tunneled central venous catheters (CVC) is a major complication in hemodialysis patients. Strategies that aim to prevent catheter-related bacteremia (CRB), ranging from the application of topical antibiotics to the use of different catheter-lock solutions, have been studied, but limited interest has been shown about following standardization of aseptic care and maintenance of CVC by experienced staff. This study reports CRB incidence obtained with a strict infection prophylaxis protocol based on universal precautions against infection adopted in our Unit by qualified nursing hemodialysis staff. During a period of 20 months, 32 patients received 42 CVC. There were 2 CRB, with an incidence of 0.24 CRB/1000 days-catheter. This study shows that an optimal catheter-use management reduces the incidence of CRB to excellent rates. The use of a protocol directed to vigorously protect the catheter at the time of usage by specialized teams is critically important and is highly recommended.

El dializador en el año 2017: mucho más que una membrana

El dializador es el elemento central de la hemodiálisis, donde se producen el intercambio de sustancias entre la sangre y el líquido de diálisis (LD); la ultrafiltración (UF) y la retrofiltración. Desde las primeras diálisis con dializadores tubulares de colodión, trinitrato de celulosa, conocido como dializador de Haas, en 19241, la hemodiálisis y los dializadores han evolucionado enormemente. En esta revisión nos vamos a centrar en los cambios de los dializadores que han aparecido en las dos últimas décadas, que puede que no sean tan evidentes. Un dializador es más que una membrana, pero está claro que esta es uno de sus componentes fundamentales. Los poros de la membrana de un dializador deben ser de un tamaño determinado, numerosos y uniformes. Esto se consigue con la nanotecnología2. La formación de una capa proteica en la membrana, al ponerse en contacto con la sangre, restringe la eliminación de moléculas, modificando funcionalmente los poros3. De la aplicación de la nanotecnología van a depender varias de las especificaciones que se mencionan a continuación. El coeficiente de ultrafiltración (CUF) de un dializador es una de las características que más se valoran. El CUF y el diseño del dializador van a condicionar la retrofiltración, que no debe generar ninguna preocupación con un LD ultrapuro4, requisito imprescindible hoy en día. De hecho, es una forma de eliminar moléculas medias y grandes sin tener que recurrir a la hemodiafiltración (HDF). Un CUF alto, mayor de 40 ml/mmHg/h, es un requisito de un dializador moderno. El coeficiente de cribado (CC) debe ser alto para moléculas medias, sin pérdidas significativas de albúmina. En la hemo-

Receta para prescribir fósforo durante hemodiálisis

The addition of phosphorus (P) to the dialysate (LD) in the form of enema Casen® is common practice in patients with hypophosphatemia. The estimation of the amount to be used and the identification of the problems that may can occur are not well defined. As a result of our work we propose a practical approach of how to proceed to increase phosphate concentration in the hemodialysate. We present a reasoned formula to calculate how much enema has to be added and the problems that may arise.