Description: The paper substantiates and develops a non-invasive information technology for covariance analysis and control of transient regimes in the patient's biophysical state during the ultrafiltration procedure. The article substantiates the research problems and provides an analytical review of the literature sources of information. A model of biophysical processes in the patient's body is proposed in the procedure of ultrafiltration based on the Starling-Landis equation, which takes into account the distribution of fluids between the intestinal space and the vascular bed. The proposed model allowed us to conditionally divide the procedure of ultrafiltration into three sections and to isolate the functional phase of hemodialysis and the phase of the critical state of the patient. Using the mathematical apparatus of the classical covariance decomposition, the bioimpedance signals obtained during the procedure for 7 patients were analyzed. Global and local trends, obtained as a result of covariance analysis, allow identifying transitional areas of the procedure. Separate use as informative parameters of F-statistics of BIM signals at different frequencies does not allow to unequivocally judge the level of hydration of the p atient, since it does not take into account the mutual influence of various components of bioimpedance signals, and can be used only to identify control-w arning intervals for changing the trend of each of them. The use of separate F-statistics can give additional information on the influence of parameters of the ultrafiltration procedure on the state of the biophysical object ( patient) and allows the use of standard tests on the significance of such influence.
Keywords: Hemodialysis, ultrafiltration, procedure control, bioimpedance measurement, covariance analysis, significance level