Pumps – Processes
Reexamination Certificate
1999-09-03
2001-07-17
Thorpe, Timothy S. (Department: 3746)
Pumps
Processes
Reexamination Certificate
active
06261065
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to systems and methods for processing and collecting blood, blood constituents, or other suspensions of cellular material.
BACKGROUND OF THE INVENTION
Today people routinely separate whole blood, usually by centrifugation, into its various therapeutic components, such as red blood cells, platelets, and plasma.
Conventional blood processing methods use durable centrifuge equipment in association with single use, sterile processing systems, typically made of plastic. The operator loads the disposable systems upon the centrifuge before processing and removes them afterwards.
Conventional blood centrifuges are of a size that does not permit easy transport between collection sites. Furthermore, loading and unloading operations can sometimes be time consuming and tedious.
In addition, a need exists for further improved systems and methods for collecting blood components in a way that lends itself to use in high volume, on line blood collection environments, where higher yields of critically needed cellular blood components, like plasma, red blood cells, and platelets, can be realized in reasonable short processing times.
The operational and performance demands upon such fluid processing systems become more complex and sophisticated, even as the demand for smaller and more portable systems intensifies. The need therefore exists for automated blood processing controllers that can gather and generate more detailed information and control signals to aid the operator in maximizing processing and separation efficiencies.
SUMMARY OF THE INVENTION
The invention provides systems and methods for processing blood and blood constituents that lend themselves to portable, flexible processing platforms equipped with straightforward and accurate control functions.
More particularly, the invention provides various systems and related methods for pumping fluid through a pump. The pump comprises a pump chamber, which is responsive to applied fluid pressures to convey fluid. The systems and methods place an electrode in the pump chamber in electrical conductive contact with the fluid in the pump chamber and coupled to an electrical source. The electrode generates an electrical field in the pump chamber that varies according volume of fluid in the pump chamber. The systems and methods register variations in the electrical field as fluid is conveyed through the pump chamber.
In one embodiment, the systems and methods generating an output based upon variations in the electrical field over time. Based upon the output, the systems and methods derive, for example, a value indicating volume of fluid conveyed by the pump chamber or a value indicating a flow rate of fluid conveyed by the pump chamber.
In one embodiment, based upon the output, the systems and methods detect abnormal operating conditions and generate an alarm condition. The abnormal operating conditions can, for example, indicate the presence of air in the pump chamber, or an occlusion of flow through the pump chamber.
In one embodiment, the systems and methods calibrate the output according to stroke volume of the pump chamber.
In one embodiment, the systems and methods vary pressures applied to a flexible diaphragm on the pump chamber based, at least in part, upon the output.
In one embodiment, the systems and methods register variations in capacitance due to variations in the electrical field.
In one embodiment, the stroke volume of the pump chamber is essentially constant. The systems and methods place the pump chamber into association with an actuator that interacts with a flexible diaphragm during a stroke interval to convey fluid through the pump. The systems and methods register variations in the electrical field as fluid is conveyed through the pump chamber and command a desired flow rate by deriving an actual flow rate based upon the variations in the electric field over a sample time period and adjusting the stroke interval so that the desired flow rate is achieved. In one embodiment, the stroke interval comprises a time interval component to draw fluid into the pump chamber, a time interval component to expel the fluid from the pump chamber, and an idle time interval component. The systems and methods adjust one or more of the time interval components to achieve the desired flow rate.
In one embodiment, the systems and methods couple the pump chamber in-line between a source of blood and a blood separation device, as part of a blood processing system or method.
Another aspect of the invention provides a blood processing system coupled to a blood separation device. The system comprises a cassette containing at least one pneumatically actuated pump station comprising a pump chamber having a known stroke volume, which is essentially constant. The system also includes a pneumatic actuator to hold the cassette and selectively apply pneumatic force to the pump station during a stroke interval to pump fluid through the pump chamber. The system places an electrode in the pump chamber in electrical conductive contact with the fluid in the pump chamber. The electrode is coupled to an electrical source, to generate an electrical field in the pump chamber that varies according volume of fluid in the pump chamber. The system includes a sensing circuit coupled to the electrode to register variations in the electrical field as fluid is conveyed through the pump chamber.
Other features and advantages of the inventions are set forth in the following specification and attached drawings.
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Brach William E
Brown Richard I
Jacobson James D.
Nayak Abinash
Westberg Tom
Baxter International Inc.
Price Bradford R. L.
Rockwell Amy L. H.
Rodriguez William
Ryan Daniel D.
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