A Model of the Patient-Artificial Kidney System

A mathematical analysis is made of the changes in body fluid volume and solute composition that occur during hemodialysis. The analysis considers the movement of water and solutes across the dialyzer membrane and between the intracellular and extracellular compartments. Dialyzer operating variables such as dialysate addition rate, solute dialysances, and ultrafiltration rate are included. The output of the mathematical model agrees well with data obtained during clinical dialysis. The results of the analysis indicate that the intracellular volume changes that would be expected during dialysis as a result of osmotic gradients are very small. The effects on solute removal of varying dialysate addition rate, ultrafiltration rate, and dialysance are analyzed.