Device to control the transmembrane pressure in a plasmapheresis system

摘要

A fluid flow control device comprises first second, and third fluid pathways. The first and second pathways are adapted for communication with separate sources of pressurized fluid. The third pathway is coupled in flow communication with the first pathway and includes a flexible wall which forms an interface with a portion of the second pathway. The flexible wall meters the flow communication between the first and third pathways in response to fluid pressure fluctuations in the second pathway. The fluid pressure in the first pathway is thereby elevated until substantial equilibrium with the fluid pressure in the second pathway occurs, and is thereafter continuously adjusted in response to subsequent fluctuations of fluid pressure in the second pathway to maintain this condition of substantial equilibrium.