Apparatus for the filtration of plasma from blood

Claim 1

A plasma filtration apparatus which comprises: a blood circulating circuit means including a plasma filter for separating whole blood, extracted from a subject of interest through a blood inlet, into a blood plasma component and a blood corpuscle component and for supplying the blood corpuscle component to a blood outlet for the return thereof to the subject of interest; a plasma circulating circuit means for draining at least a portion of the blood plasma component, which has been separated from the whole blood, and for supplying a physiologically compatible fluid substitute in a quantity substantially equal to the amount of said portion of the blood plasma component, which has been drained, to a portion of the blood circulating circuit means downstream of the plasma filter and then to the blood outlet; a first pumping means disposed on the blood circulating circuit means; a second pumping means disposed on the plasma circulating circuit means; a source of priming fluid adapted to be fluid-connected with the blood outlet and a fluid intake for receiving the fluid substitute into the plasma circulating circuit means; a first detector for detecting the flow through the blood circulating circuit means; a second detector for detecting the flow through the plasma circulating circuit means; a first valve means for selectively establishing and interrupting a first fluid circuit between a downstream portion of the plasma circulating circuit means adjacent the blood outlet and said portion of the blood circulating circuit means downstream of the plasma filter; a second valving means for selectively establishing and interrupting a second fluid circuit between said portion of the plasma circulating circuit means adjacent the blood outlet and the outside of the apparatus; a first drive means operable to cause the first and second valving means to interrupt the respective first and second fluid circuits and for driving the first pumping means to cause the priming fluid to flow through the blood circulating circuit means; a second drive means operable in response to an output signal from the first detector for causing the second valving means to establish the second fluid circuit and, at the same time, driving the second pumping means to cause the priming fluid to flow through the plasma circulating circuit means when the flow through the blood circulating circuit means attains a first predetermined value; and means operable in response to respective output signals from the first and second detectors for bringing the first and second pumping means to a halt when both of the flows through the blood circulating circuit means and the plasma circulating circuit means attain a second predetermined value.