Chemistry: molecular biology and microbiology – Maintaining blood or sperm in a physiologically active state...
Patent
1997-09-22
1999-02-23
Smith, Lynette F.
Chemistry: molecular biology and microbiology
Maintaining blood or sperm in a physiologically active state...
210 86, 210109, 210 94, 210143, 222513, 222 23, 222 52, 222 95, 222 96, 222103, 222214, A01N 102, B01D 3514, B01D 2124, B01D 2438
Patent
active
058742085
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to blood component preparation. More specifically, the invention relates to a method and an extractor for pressing out plasma and buffy coat from a collapsible blood container, e.g. a blood bag, in which blood has been divided, by centrifugation, into a plasma layer, a buffy coat layer and a layer of red blood cells, the plasma and then the buffy coat being pressed out each through a separate outlet tube or through a common outlet tube, which is connected to the top of the blood container.
2. Description of the Related Art
In blood component preparation, blood is donated to a blood bag via a blood drawoff tube permanently connected to the bag. In addition, a number of side bags are connected to the blood bag by means of tubes. These connections are normally collected in the upper edge of the blood bag. Subsequently, the blood bag is centrifuged upright in a centrifuge cup, such that the blood forms layers, viz. an uppermost plasma layer, a subjacent buffy coat layer whose volume is relatively small, and a lowermost layer of red blood cells. At least the plasma and buffy coat fractions are then transferred to side bags by the blood bag being suspended at its upper edge in an extractor and subjected to mechanical pressure between a support surface and a pressure plate. The plasma then flows through an outlet tube over to a plasma container, while the buffy coat slowly flows upwards in the blood container. The outlet tube is normally branched into a plasma tube extending to a plasma container and a buffy coat tube extending to a buffy coat container but, alternatively, separate outlet tubes can be provided for each container. When the buffy coat has reached the top of the blood container, the plasma tube is closed and the buffy coat tube is opened. The major part of the buffy coat now flows over to the buffy coat container. However, a certain amount of buffy coat penetrates into the indentations formed by the various connections in the upper edge of the blood container, and there is a great risk that this amount remains in the blood bag after pressing-out. The remaining amount of buffy coat will mix with the red blood cell fraction and constitute a contamination therein. In manually operated extractors, one may manually press out these residues and feed them to the outlet tube, such that they can be pressed over to the buffy coat container. However, an efficient method of reaching these buffy coat residues in automatic extractors has not been available.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and an extractor which yield a more complete discharge of the buffy coat fraction and, thus, a purer fraction of red blood cells.
The method according to the invention is characterised in that a pulsating pressure is applied to a top section or top portion or top portion of the blood container during the end phase of the pressing-out of the buffy coat. At this stage of the pressing-out operation, the buffy coat constitutes a narrow layer right at the very top at the edge of the blood container. The pulsating pressure gives the layer a pulsating motion and causes the buffy coat to be sucked out from said indentations in the edge of the blood container and flow freely towards the outlet tube for the buffy coat. This flow is additionally facilitated if the pulsating motion is not uniform along the entire width of the blood container but is designed so as to produce a pumping effect towards the outlet tube. Such a pumping effect can be achieved, for instance, by the pulsating pressure being applied on both sides of the connection of the buffy coat outlet tube to the top of the blood container.
The pulsating pressure can be produced in various ways. According to a preferred embodiment, use is made of one or more inflatable cushions abutting against the top section of the blood bag, and the pressure in said cushions is caused to pulsate at a certain selected frequency.
The inventive extractor, which compri
REFERENCES:
patent: 4359005 (1982-11-01), Greenblatt
patent: 4663032 (1987-05-01), Loos et al.
patent: 4976851 (1990-12-01), Tanokura et al.
patent: 5045185 (1991-09-01), Ohnaka et al.
patent: 5135646 (1992-08-01), Tanokura et al.
patent: 5207645 (1993-05-01), Ross et al.
Nelson Brett
Omega Medicinteknik AB
Smith Lynette F.
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