Patent ID: 8496807

Claim:
A hemodialysis apparatus comprising: a dialysis device connecting with a dialyzer and an extracorporeal blood circuit, the dialysis device comprising an ultrafiltration apparatus and a dialysate supply; a detecting device connected with a sensor, wherein the detecting device receives, from the sensor, periodic measurements of a parameter related to the concentration of the blood circulating extracorporeally, and calculates, using the periodic measurements, time series data representing a rate of change of circulating blood volume; an evaluation device, connected with the detecting device, calculating time series data representing changes in plasma water index (PWI) during hemodialysis, based on a relation between a variation rate of circulating blood volume and a variation rate of a patient's body weight, using data including time series data received from the detecting device, and evaluating whether an estimated dry weight of a hemodialysis patient approximates to a calculated dry weight of the hemodialysis patient; and a memory device connected with the evaluation device and comprising a database, residing on a storage media, wherein the database contains a plurality of any of said time series data, wherein the evaluation device calculates the plasma water index (PWI) according to equation 1: PWI = Δ ⁢ ⁢ CPV ⁢ % Δ ⁢ ⁢ BW ⁢ % wherein ΔCPV % is the change in circulating blood plasma volume and ΔBW % is a variation rate of the body weight.