Abstract: Method and apparatus for purging air from a tubing network finds particular utility as a component part of a blood constituent processing system. Collection and return needles of a disposable tubing network are initially contained within a common antiseptic enclosure. A purge fluid (e.g., saline solution) may then be introduced into the interior chamber of the enclosure via one of the needles and withdrawn from the interior chamber via the other of the needles. Air entrained in the tubing network may thus be trapped within the common enclosure itself and/or vented therefrom via a one-way valve and hydrophobic microbe filter and/or the entrained air pockets may be encouraged to flow to a separate suitable air trap location of the tubing network whereby the network is purged of air.

Abstract: A reliable flow rate plasmapheresis system includes a rotating enhanced vortex of membrane filter coupled to receive a flow of anticoagulated whole blood and separate concentrate and filtrate in response thereto. An anticoagulant pump is coupled to mix controlled amounts of anticoagulant with the input blood flow. Degradation of plasma flow rate during multiple extraction-reinfusion cycles is inhibited by selecting the starting anticoagulant pH value and controlling the anticoagulant flow rate relative to the whole blood to establish a final whole blood/plasma pH value in the range of 6.8 to 7.2, with an anticoagulant to blood ratio in the range of 1:6 to 1:25.

Abstract: In a disposable biomedical system for processing fluids in a closed environment such as a plasmapheresis system, comprising a plastic rotor mounted for rotation on a pivot pin bearing and a seal, particularly a silicone lubricated O-ring seal, between the rotor and pin, the improvement wherein said pivot pin is a molded pivot pin of a hard plastic material having a low coefficient of friction and lubriciousness, and which is capable of being irradiated by gamma radiation for sterilization and modification of the plastic material without degradation or loss of lubricious properties. The pivot pin bearing preferably comprises an injection molded polyamide based resin.

Abstract: A blood extraction and reinfusion flow control system includes a blood pump coupled to pump intravenous fluid to or from a subject, a pressure sensor coupled to sense extra veinous pressure at the subject, and a microprocessor based flow control subsystem. The flow control subsystem optimizes the flow rate by sensing pressure at at least two different fluid flow test points and extrapolating and translating the test point data to generate a flow control curve. The blood pump is then operated at a maximum speed that is limited by a desired maximum flow command and the flow control curve to maximize flow without vein collapse or damage during both blood extraction and reinfusion.