Surgery – Container for blood or body treating material – or means used... – Bag type
Reexamination Certificate
1997-07-18
2002-10-22
Sykes, Angela D. (Department: 3762)
Surgery
Container for blood or body treating material, or means used...
Bag type
C604S006150, C128SDIG008, C428S035700, C428S474400
Reexamination Certificate
active
06468258
ABSTRACT:
The present invention relates, in general, to plastic compositions and, in particular, to plastic compositions that may be used for medical containers, such as containers for the storage of blood and/or blood cells. The present invention also relates to methods for storing blood and/or blood cells in containers made from such compositions.
BACKGROUND
Whole blood is typically described as being made up of various cellular components such as red blood cells (RBCs), white blood cells (WBCs) and platelets, suspended in a liquid component, plasma. Each component plays a specific and important role in the human body. For example, platelets (together with clotting factors and other substances in the blood) are responsible for blood clotting. WBCs are primarily responsible for fighting disease. RBCs transport oxygen (O
2
) and carbon dioxide (CO
2
) to and from body tissues. The O
2
and CO
2
are carried by a protein called hemoglobin, which is found inside the RBC.
Blood and blood components are collected in a variety of ways. One of the most common blood collection techniques, and perhaps the most well known, is the manual collection of whole blood from healthy donors. This is usually performed at a local hospital, blood collection center or even a community center such as a local school or church as part of a blood collection drive. In the manual technique, a needle is inserted into the donor's arm and blood is withdrawn from the donor through the needle and associated tubing. The withdrawn whole blood is collected in a sterile plastic collection container or pouch attached to the other end of the tubing. The collected “unit” of whole blood may then be transfused into a patient.
Alternatively, rather than transfusing an entire unit of whole blood, the collected whole blood may be separated into its various components, and the desired component may be transfused to a patient in need of that particular component. For example, separated RBCs may be administered to patients who have experienced rapid blood loss, or to improve the oxygen carrying capability of blood in patients suffering from anemia and the like. Platelets may be administered, for example, to cancer patients whose ability to produce platelets has been destroyed by chemotherapy and/or radiation treatment. Thus, separation of whole blood into individual components to be used as needed in different patients, results in more efficient usage of the available blood supply.
Briefly, manually collected whole blood may be separated into its components by first centrifuging the bag of collected whole blood to separate RBCs from the remaining components. Rotation of the centrifuge imparts a centrifugal force on the whole blood and causes the components of whole blood to sediment into layers or bands based on the densities of the components. Thus, the more dense (or “heavier”) components, such RBCs, are separated from the lighter components such as platelets and plasma. For example, centrifugation forces the RBCs to the bottom of the collection container, leaving most of the less dense platelets and plasma in a layer above the RBCs. The layers of blood components may be segregated from each other by either allowing the RBCs to drain out of the collection container and into a separate container, or by squeezing the collection container to express the remaining components (e.g. platelets and plasma) to a separate container. If additional separation of the platelets from plasma is desired, the remaining platelets and plasma may be centrifuged in similar fashion to provide “platelet-poor plasma” and platelet concentrate.
As an alternative to manual collection, whole blood may be separated and its components collected in an “automated” procedure or system. Automated blood collection systems or instruments typically include a separation device, such as a centrifuge, pumps and an associated disposable tubing set for moving blood, blood components and other fluids from the donor, to the centrifuge device and back to the donor. The disposable tubing set may also include containers which are placed inside the centrifuge device and where the blood is separated into its components. Examples of automated blood separation and collection instruments are the CS3000® Plus Blood Cell Separator and the Amicus™ Separator, both made by Baxter Healthcare Corporation of Deerfield, Ill.
In an automated system, a needle (which is attached to tubing of the disposable tubing set) is inserted into the arm of the donor. Whole blood is then continuously or intermittently withdrawn from the donor and introduced into the separation container inside the rotating centrifuge where, under the influence of the centrifugal force (as described above), the desired components are separated from the undesired components. The desired component is collected in a collection container, while the undesired components may be returned (for example, by pumping) to the donor. The collected component may be transferred to a separate container for storage or, alternatively, may be stored in the collection container.
The containers for collection and/or storage of blood and blood components should be flexible, sterilizable and suitable for storage (and often extended storage) of blood and blood components. They are typically made of a plastic composition, two sheets of which are sealed together (in a facing arrangement) along their peripheries. Prior to introduction of the blood component, the container is sterilized by steam, gas or radiation sterilization. Like the disposable tubing sets described above, the containers are typically intended for one-time use and are disposed of after such use.
The plastic composition used in such containers typically includes a plastic resin that is suitable for contact with blood, such as polyvinyl chloride, polyolefin or polyester. The plastic composition may also include additives, for example, to stabilize the plastic composition during processing or during sterilization of the container, which may, at times, be carried out at high temperatures.
Unfortunately, exposure of certain plastic compositions to high temperatures, such as during extrusion of the plastic composition and/or during steam sterilization, may occasionally cause degradation of the plastic composition. Degradation, which is believed to be associated with a molecular breakdown of the polymer resins and other materials, may result in a weakening of the overall mechanical strength of the container. More particularly, degradation may result in a weakening of the peripheral seals and a reduction in the impact strength (i.e. ability of the container to withstand impact). Moreover, exposure to heat and/or even extended exposure to less severe environments may also cause undesirable and aesthetically unacceptable discoloration (e.g. yellowing) of the plastic material.
To prevent or reduce degradation and/or discoloration, inclusion of a small amount of certain additives can help stabilize the plastic material during high temperature heating and during exposure to certain other environments. As reported in U.S. Pat. No. 4,280,497, which is incorporated by reference herein, epoxodized oils, such as epodoxidized soy been oil and epoxodized linseed oil may be used as heat stabilizers. Also, as reported in Laermer et al. “Use of Biological Antioxidants as Propylene stabilizers”,
Plastics and Rubber Processing and Applicants
14 (1990) 235-239 and Laermer et al. “Alpha-Tocopherol (Vitamin E)—The Natural Antioxidant for Polyolefins “
Journal of Plastic Film and Sheeting
, Vol. 8, July 1992 (both of which are also incorporated by reference), Vitamin E (which is a mixture of tocopherols and tocotrienols) is an antioxidant that can serve as a stabilizer during extrusion of polyolefins. Vitamin E as an antioxidant is preferred because, as reported in the 1992 article by Laermer, it is non-toxic and is “generally regarded as safe” (GRAS) by the FDA.
Additives may also be combined with the plastic resin to enhance the storage of the blood and/or blood components. For example, a concern durin
Baxter International Inc.
Bianco P M
Kolomayets Andrew G.
Rockwell Amy L. H.
Sykes Angela D.
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