| abstract |
A cassette for use in controlling the flow of IV fluid from a patient to a source. The cassette may include along the fluid passage through the cassette, first and second membrane-based valves ( 6, 7 ) on either side of a pressure-conduction chamber ( 50 ), and a stopcock-type valve ( 20 ). The stopcock valve is preferably located downstream of the second membrane-based valve ( 7 ), which is preferably located downstream of the pressure-conduction chamber ( 50 ). The membrane defining the valving chamber of the second membrane-based valve ( 7 ) is preferably large and resilient, so that the valving chamber ( 75 ) may provide a supply of pressurized intravenous fluid to the patient, when the valve ( 6 ) is closed and the stopcock valve ( 20 ) provides a restriction downstream of the valve ( 7 ). The pressure-conduction chamber ( 50 ) preferably has a membrane ( 41 ) that is stable in the empty-chamber position but relatively unstable in the filled-chamber position. |