[The mathematical modelling of water-osmotic equilibrium during the performance of hemodialysis].

The model has been designed by the authors to prevent complications as a result of redistribution of liquid between cellular and extracellular spaces arising in the patient's body in the course of hemodialysis. Because movements of the liquid between the spaces depends on the osmolality gradient, two principal systems were identified: body water system and system of osmotically active substances. The latter incorporates sodium and potassium salts and urea. The model is based on 6 differential equations. The least squares method derived individual parameters of the model. Using the model, the physician can regulate to optimal the regimen of hemodialysis: blood flow rate, speed of ultrafiltration, concentration of sodium and potassium in dialysate.