BLOOD-VOLUME MODELING AND REFILLING RATE ESTIMATION IN HEMODIALYSIS BY CONTINUOUS HEMOGLOBIN MONITORING

Eleven bicarbonate hemodialyses (HD) of 6 patients under constant ultr afiltration were continuously monitored with an optical Hb-meter, cons idered to be a marker of blood volume (BV) changes. A theoretical mode l was fed experimental data for prediction of blood volume and estimat ion of vascular parameters, and a time course of rate of refilling was extrapolated. The adequacy of the model was very good for the time co urse of BV prediction (r2=0.85-0.95, n=11) and for plasma protein conc entration (r2=0.83-0.86, n=2). Parameters estimated included (mean-DS) : filtration coefficient (Cf)=0.22(0.16) dl/min()mmHg, transcapillary hydrostatic pressure (DP)=17.80 (3.44) mmHg and protein concentration of the refilling fluid (Cref)=0.45 (0.30) g/dl. In conclusion our stu dy has shown that the model chosen fits the observed BV profile well i n all cases, thus the Hb data series can be used for BV dynamic modeli ng and for estimation of vascular parameters.