RESUMEN
This paper proposes a fuzzy logic based procedure able to control the behavior of a patient's blood pressure during a dialysis session, allowing him to reach the planned dry weight. A proportional integrative discrete-time fuzzy control is used to subject the controlled variables (blood pressure and blood volume) to the reference values. Two different tables that refer to pressure and volume errors and rates are consulted and the proposed control actions are taken to obtain the final value (net ultrafiltration rate). A saturation-threshold function of volemia acts on the second control variable, Na concentration in the dialysate. The adaptive control system was simulated on an IBM PC, and rules and terms were expressed by linguistic judgments such as: IF "situation," THEN "action." A pre processor converts the rules into the numerical values in the tables. The obtained simulation results are satisfactory, and the introduction of Na control allows achievement of the target dry weight of the patient with a stable blood pressure.