Liquid purification or separation – Processes – Including controlling process in response to a sensed condition
Reexamination Certificate
2001-10-22
2003-08-12
Reifsnyder, David A. (Department: 1723)
Liquid purification or separation
Processes
Including controlling process in response to a sensed condition
C210S782000, C210S806000, C210S094000, C210S143000, C210S232000, C210S295000, C210S304000, C210S324000, C210S360100, C210S380100, C494S002000, C494S021000, C494S025000, C494S026000, C494S036000, C494S037000, C494S045000, C494S084000, C604S406000, C604S410000
Reexamination Certificate
active
06605223
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to methods and apparatus for the separation of one or more cell fractions from their suspending fluid and/or the resuspension of cells in fresh suspending fluid media. More particularly, the invention relates to automated methods and apparatus that allow for the separation of multiple units of blood simultaneously where the red blood cells and platelet cells are separated from the plasma, the red blood cells are subsequently resuspended in a storage solution, and the platelets are suspended in a concentrating volume of plasma. The method and apparatus dramatically decrease the labor and time required to separate blood into its components and simplifies the data retention required to validate the processing parameters for each unit of blood as required by the evolving FDA regulations governing the safety of the nation's blood supply. Other embodiments of the invention include in-line filter elements that remove contaminating cells, called leukocytes, which are believed to be responsible for a variety of adverse reactions by the recipient of the blood components. Similarly, other types of filters and packed columns positioned in-line with the flow of these blood components can remove viruses, bacteria or other contaminants, which further enhances the purity and safety of the blood components.
BACKGROUND OF THE INVENTION
Approximately 12 million units of blood are collected annually in the United States. Another 8 million are collected in the rest of the world. Each donated unit of blood is referred to as “whole blood.” Whole blood contains red blood cells, white blood cells and platelets suspended in a proteinaceous fluid called plasma. Because patients often do not require all of the components of whole blood, most units of whole blood are separated into their multiple components. Individual components are then transfused to different individuals with different needs, a practice referred to as “blood component therapy”.
Red blood cells carry oxygen and usually are used to treat patients with anemia. For example, patients with chronic anemia resulting from disorders such as kidney failure, malignancies, or gastrointestinal bleeding and those with acute blood loss resulting from trauma or surgery. White blood cells are responsible for protecting the body from invasion by foreign substances such as bacteria, fungi and viruses.
Plasma contains albumin, fibrinogen, globulins and other clotting proteins. Albumin is a chief protein constituent, fibrinogen plays an important role in the clotting of blood and globulins include antibodies. Thus, plasma serves many functions, including maintenance of satisfactory blood pressures and volume, the control of bleeding by blood clotting, immunity and maintenance of a proper balance of vital minerals in the body. Plasma typically is transfused to control bleeding due to low levels of some clotting factors or it may be transfused to expand the volume of circulating blood. Plasma also may be further fractionated to derive its component proteins.
Platelets help the clotting process by sticking to the lining of blood vessels. Platelets are generally used to improve wound healing and stop bleeding, for example, in patients with leukemia and other forms of cancer.
Cryoprecipitated Antihemophilic Factor (AHF) is rich in certain clotting factors, including Factor VIII, fibrinogen, von Willebrand factor and Factor XIII. It is used to prevent or control bleeding in individuals with hemophilia and von Willebrand's disease, which are common, inherited major coagulation abnormalities.
Whole blood will separate into its components if treated to prevent clotting and permitted to stand in a container. The red blood cells, weighing the most, will settle to the bottom, the plasma will stay on top, and the white blood cells and platelets will remain suspended between the plasma and the red blood cells. Typically, a centrifuge process is used to speed up this separation.
A common centrifuge process is described in the AABB Technical Manual, methods 9.4 and 9.11 as follows: Typically, the bag of whole blood is carefully loaded into one of the buckets of a large swinging bucket centrifuge. The opposing buckets are weighed and balanced so that their weight is within a few grams. Then, the buckets are loaded into a rotor and the rotor spun at conditions called “light spin” by the blood banking community (2000 g for 3 min).
After a considerable wait for the centrifuge to slowly decelerate to zero speed, each bucket is very carefully removed from the rotor so that the bags can be removed from the buckets. This delicate operation must be done in a way that does not disturb or in any way re-suspend the cells. The bag is placed between the two expressing plates of a plasma extractor which force the platelet-rich plasma (PRP) from the whole blood bag to the platelet storage bag. A bag of nutrient solution then is emptied into the packaged red cell bag which is, in turn, placed in storage. The platelet-rich plasma (PRP) can be used to prepare platelets and plasma or Cryoprecipitated AHF.
To make platelets, the platelet-rich plasma (PRP) bags again are balanced and then placed back in the centrifuge for a “heavy spin” (5000 g for 5 minutes) causing the platelets to settle at the bottom of the bag. Plasma and platelets then are separated and made available for transfusion. A plasma extractor generally is used to remove all but 50 to 70 ml of plasma, which is required to maintain viability of the platelets. The plasma also may be pooled with plasma from other donors and further processed, or fractionated to provide purified plasma proteins such as albumin, immunoglobulin and clotting factors. Cryoprecipitated AHF may be made from fresh frozen plasma by freezing and then slowly thawing the plasma.
In each case, the components must each be identified in inventory by a method that allows for the traceablilty of that component back to the test results for the original donor, the donated unit, the disposable set in which it was collected, the centrifuge in which it was processed, and, if applicable, the leuko-filter that was used. This traceability is required by law.
Although the centrifuge process speeds up separation of the whole blood into its components, the process is labor intensive and prone to errors and even the most sophisticated inventory control system is subject to the possibility of error as hundreds of data entries are input manually for each unit.
A method and apparatus for the separation of whole blood that is quick, easy and less prone to errors still is needed.
SUMMARY OF THE PRESENT INVENTION
The present invention provides an improved method and apparatus for the separation of whole blood into its components. The method and apparatus automates the separation process, thereby dramatically reducing the labor involved in conventional separation of whole blood. Further, the method and apparatus allows for the separation of multiple units simultaneously, thereby dramatically reducing separation time.
In a preferred embodiment of the present invention, the apparatus includes a centrifuge designed for holding, on a hollow central drive shaft, a plurality of circular cassettes stacked in a co-axial configuration. Each circular cassette has a plurality of cavities for holding a plurality of bags, e.g. a whole blood bag and blood component bags including, for example, a red blood cell bag, a platelet concentrate bag and a platelet poor plasma bag. The cassettes may include further cavities for holding additional components such as filters, other storage bags and an expressor chamber or expressor bag. The various bags are in fluid communication with each other by, for example, tubing or the like to allow transfer of components from one bag to the other. The co-axial configuration is advantageous in that it is self-balancing as the components move from one compartment to another.
Preferably, the whole blood bag and blood component bags are fabricated of materials that allows them to expand and contract repeated
Barry Donald E.
Jorgensen Glen
Edwards & Angell LLP
Hazzard Lisa Swiszcz
MEDIcept, Inc.
Neuner George W.
Reifsnyder David A.
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