Mathematical analysis of the hemodynamic response during hemodialysis

A computer model was developed to cardiovascular response to hypovolemia hemodialysis. The main aspects included are: the systemic arterial and venous circulations, the Starling´s law of the heart and the arterial and cardiopulmonary baroreceptor regulation of arteriolar resistance, venous unstressed volume and heart rate. The model was used to study the different hemodynamic responses of hypotension-prone and hypotension-resistant patients to the hemodialysis-induced hypovolemia. Arterial pressure, heart rate and blood volume were measured during the dialysis in six patients. Blood volume changes were used as input to the model and the time patterns of mean arterial pressure and heart rate were reproduced, by adjusting a few parameters which characterize the autonomic regulatory system. The analysis performed with the model suggests that the behavior of hypotension-prone and hypotension resistant patients can be explained by a different strength of regulatory mechanisms and by a different vascular refilling rate