SENSITIVITY ANALYSIS FOR ESTIMATING UREA KINETICS PARAMETERS DURING HEMODIALYSIS

In this paper a time-varying volume, double-Pool urea kinetics model i s considered and a sensitivity analysis is carried out to determine th ose patient parameters that have greater influence on the time course of blood urea nitrogen concentration (BUN) during and between dialysis treatment. The model parameters include the urea generation rate, the initial distribution volume of the urea, the ratio between intracellu lar and extracellular volumes, and the mass transfer coefficient betwe en the true pools. The analysis demonstrates that BUN is highly sensit ive to the urea generation rate and total distribution, volume whereas it is influenced by the remaining parameters to a much lesser extent. In addition, the location of the absolute maxima of BUN sensitivity f unctions suggests the rational placement of a reduced number of blood samples that may still allow sufficiently accurate estimates for the p arameters of clinical interest, such as the urea generation rate, tota l distribution volume, and the ratio between intracellular and extrace llular volumes. This conclusion has been confirmed by simulation studi es where parameter estimation has been performed with a varying number of observation points.