Patent ID: 6537240
Filing Date: 2003-03-25
Classification: A61M

Abstract:
Method for determining a mixture of treated blood and non-treated blood in an arterial line connecting a vascular system of a patient to an inlet of a first compartment of a blood treatment apparatus having first and second compartments separated by a semi-permeable membrane, the treated blood flowing in a venous line connecting an outlet of the first compartment to the patient's vascular system, the method comprising:circulating blood, at a determined blood flow rate (QB), in an extracorporeal blood circuit including the arterial line, the first compartment, and the venous line; determining, in the extracorporeal blood circuit, a first value (HGBAO) of a blood parameter indicative of a ratio of blood plasma volume to blood volume; inducing a first variation in the value of the blood parameter by varying an ultrafiltration rate of plasma water through the semi-permeable membrane by a determined amplitude (QUF); determining a second value (HGBA3) of the blood parameter in the arterial line; and calculating an extent (AR) of the mixture of the treated blood and the non-treated blood in the arterial line as a function of the blood flow rate (QB), the amplitude (QUF) of the variation of the ultrafiltration rate, and of the first and second values (HGBAO, HGBA3) of the blood parameter.