APPARATUS FOR SEPARATING FROM A BIOLOGICAL LIQUID, IN PARTICULAR BLOOD, A FRACTION HAVING MOLECULAR WEIGHT BETWEEN AN UPPER AND LOWER LIMITING VALUE

摘要

A device for separating from a biological liquid, in particular blood, a fraction having a molecular weight between an upper limit value and a lower limit value, comprises a liquid container (B1) for the separated fraction, including in a closed flow circuit (I2) between first and second filters molecules (F1, F2) which are each provided with a flow driving pump (P1, P2). A control system used to control the volume V of liquid in the container according to the equation dV / dt = Qa + Qb, in which V is the regulated volume of liquid, the desired value is stored as a function of predetermined time V ( t) in the memory (M) of the control system, and Qa and Qb are the total flows of liquid towards and from the closed circulation circuit, respectively. The blood from a patient under treatment is sent to the first filter molecules (F1) and the liquid filtrate discharged from the outlet side of the second filter molecules (F2) is returned to the blood circulatory system (M) of the patient. The predetermined time function V (t) is defined so that the volume of the separated liquid is automatically adjusted relative to previous experience and adapted to the patient's particulars under treatment. A third filter (F3) can be arranged in the return line to the patient in order to extract the liquid return filtrate so as to increase the protein concentration in the filtrate, the extracted liquid being returned to the container (B1) in the closed flow circuit. In combination with a protein detector (PD) the filter (F3) can serve as a controller of the protein content of the filtrate return.