Liquid purification or separation – Processes – Including controlling process in response to a sensed condition
Reexamination Certificate
1997-11-26
2001-06-26
Kim, John (Department: 1723)
Liquid purification or separation
Processes
Including controlling process in response to a sensed condition
C210S085000, C210S097000, C210S109000, C210S143000, C210S782000, C210S787000, C210S789000, C494S037000, C494S043000, C494S045000, C604S004010, C604S006010, C604S006020, C604S006030, C604S006040, C604S065000, C604S067000
Reexamination Certificate
active
06251284
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to blood collection and processing systems and methods. In a more particular sense, the invention relates to systems and methods for collecting concentrated red blood cells for transfusion or long term storage.
BACKGROUND OF THE INVENTION
Today, most whole blood collected from donors is not itself stored and used for transfusion. Instead, the whole blood is separated into its clinically proven components (typically red blood cells, platelets, and plasma), which are themselves individually stored and used to treat a multiplicity of specific conditions and diseased states. For example, the red blood cell component is used to treat anemia; the concentrated platelet component is used to control thrombocytopenic bleeding; and the platelet-poor plasma component is used as a volume expander or as a source of Clotting Factor VIII for the treatment of hemophilia.
Systems composed of multiple, interconnected plastic bags have met widespread use and acceptance in manually collecting these blood components for storage. A typical manual collection procedure collects 450 ml of whole blood from a donor in a primary bag. The donor departs, and the primary bag is centrifuged to separate the whole blood into plasma and red blood cells. For a typical donor, the manual collection procedure yields about 250 ml of concentrated red blood cells and about 200 ml of plasma, which are each expressed from the primary bag into individual storage bags. A majority of the platelets reside either with the plasma or with the red blood cells, depending upon the amount of centrifugal force exerted. Leukocytes typically reside primarily with the red blood cells. These leukocytes can be removed by filtration either before or after storage and prior to transfusion.
Manual collection procedures typically produce relatively high concentrations of red blood cells, which typically have hematocrits after centrifugal separation of about 70% to 80%. Hematocrit expresses the percentage volume of red blood cells to whole, or total, blood volume. In comparison, the hematocrit of whole blood for a typical healthy donor before centrifugation is about 40% to 45%, although whole blood hematocrits do vary significantly among donors from the 30 percentile range into the 50 percentile range. In the United States, federal regulations prohibit individuals with whole blood hematocrits of 38% and below from donating blood.
In the United States, federal regulations also prohibit collecting more than 250 ml of red blood cells from an individual donor during a given collection procedure. These federal regulations further require a six week interval between red blood cell collections.
Manual and automated blood collection procedures, called plasmapheresis, have been developed for collecting increased volumes of plasma from an individual donor at more frequent intervals. During plasmapheresis, red blood cells are returned to the donor, so that greater total volumes of whole blood can be processed. The result is greater total volumes of plasma collected, which typically range between 400-450 ml (for manual plasmapheresis) up to 880 ml (for automated plasmapheresis procedures).
Fischel U.S. Pat. No. 5,034,135, entitled “Blood Fractionation System and Method,” discloses a membrane separation device widely used today for performing automated plasmapheresis. The device employs a rotating microporous membrane to separate whole blood into platelet poor plasma, which is retained, and concentrated red blood cells, which are returned to the donor. Prince et al. U.S. Pat. Nos. 4,879,040 and 5,069,792 describe control systems for optimizing plasma flow using the rotating membrane device, based in part upon monitoring transmembrane pressure.
While very effective in optimizing the collection of plasma, these control systems, as implemented in the Prince et al. '040 and '792 Patents, are not practically adapted for the collection of red blood cells for storage. This is because, as implemented in the Prince et al. '040 and '792 Patents, the hematocrit of the concentrated red blood cell collected is highly dependent upon the whole blood hematocrit of the donor. That is, the hematocrit of the concentrated red blood cell output for a low hematocrit donor will be lower than the hematocrit of the concentrated red blood cell output for a high hematocrit donor.
The need still exists for systems and methods that marry the collection of red blood cells in uniformly high concentrations, comparable to those of centrifugal whole blood separation procedures, with the collection of plasma in increased volume amounts comparable to those of at least manual plasmapheresis procedures. The need particularly exists for such systems and methods that can achieve these objectives uniformly for all donors, including those having relatively low whole blood hematocrits. The need is further intensified for systems that can accomplish low cost, efficient red blood cell collection on a par with manual systems, but in an automated fashion.
SUMMARY OF THE INVENTION
The invention provides blood separation systems and methods which obtain a targeted volume of concentrated red blood cells, which is substantially constant for a diverse population of healthy blood donors, despite variances in known hematocrit values among the donors.
The systems and methods draw whole blood from a blood donor through an inlet line. The blood donor is selected from the population of blood donors. The whole blood of the selected blood donor has a known hematocrit value, which varies within the population of blood donors according to morphology of the selected blood donor. The systems and methods operate a pump in the inlet line to convey a volume of whole blood from the donor at a commanded flow rate for processing into plasma constituent and concentrated red blood cells. The systems and methods set the commanded flow rate to vary the volume of whole blood conveyed over time, at least in part, as a function of the known hematocrit value of the selected donor. In this way, the systems and methods can obtain a targeted volume of concentrated red blood cells, which is substantially constant for the population of blood donors despite variances in known hematocrit values among the donors.
In one embodiment, the systems and methods also select a targeted collection time. In this embodiment, the systems and methods set the commanded flow rate of the pump to vary the volume of whole blood conveyed over time, at least in part, as a function of both the known hematocrit value of the selected donor and the targeted collection time.
In one embodiment, the systems and methods record the known hematocrit value of the selected blood donor, a targeted collection time, and a targeted volume of concentrated red blood cells. In this embodiment, the systems and methods set the commanded flow rate of the pump to vary the volume of whole blood conveyed over time as a function of the known hematocrit value of the selected donor, the targeted collection time, and the targeted volume of concentrated red blood cells. In this way, the systems and methods can obtain the targeted volume of concentrated red blood cells for any donor in the population of blood donors, despite variances in known hematocrit values among the donors.
In one embodiment, the pump conveys the volume of whole blood into a collection container. The volume of whole blood can be centrifugally processed in the collection container to yield the plasma constituent and the targeted volume of concentrated red blood cells.
In one embodiment, the pump conveys the volume of whole blood to a multiple blood bag system. The volume of whole blood can be processed in the multiple blood bag system to yield the plasma constituent and the targeted volume of concentrated red blood cells.
In one embodiment, the pump conveys the volume of whole blood through an in line separation device to separate the volume of whole blood into plasma constituent and the targeted volume of concentrated red blood cells.
In one e
Bischof Daniel F
Deniega Jose C
Duff Daniel H
Goldhaber Richard P
Likens Matthew E
Baxter International Inc.
Kim John
Price Bradford R. L.
Ryan Daniel D.
Serewicz Denise
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