Optical monitoring of dialysis dose

Abstract

Utilizing optics in hemodialysis estimating quality parameters for dialysis dose has been developed during the last ten years. In principle, two optical techniques have made progress toward clinical use, namely the ultraviolet (UV) absorbance- and the near infrared (NIR) techniques. Both methods have shown reliable results of estimating urea in the spent dialysate resulting in the possibility to calculate urea-based quality parameters of dialysis dose in terms of Kt/V and URR. Even nutrition parameters derived from optical urea estimations has been provided to be possible using the UV absorbance method. The UV absorbance method cannot measure urea as a single solute; instead the high correlation between urea concentration and UV absorbance in spent dialysate is utilized when estimating urea parameters. The NIR-method can measure urea directly using signal processing of the raw NIR spectra. Predicted urea concentrations from the NIR measurement show an excellent agreement to urea concentrations measured by the standard chemical assays. The UV-method has recently been commercialized as a monitoring tool for dialysis dose in terms of the urea-based parameters, Kt/V and URR. On-going research is now focusing to monitor even other waste solutes than urea in spent dialysate. This aims to move towards a more comprehensive picture of the dialysis clearance process that is strongly linked to morbidity and survival of the dialysis patients compared with current dialysis dose calculations. © 2013 Springer-Verlag Berlin Heidelberg.