Imperforate bowl: centrifugal separators – Including plurality of miniature bowls distrubuted about... – Comprising flexible bowls embraced by pockets provided...
Reexamination Certificate
2001-05-21
2003-10-07
Cooley, Charles E. (Department: 1723)
Imperforate bowl: centrifugal separators
Including plurality of miniature bowls distrubuted about...
Comprising flexible bowls embraced by pockets provided...
C422S105000
Reexamination Certificate
active
06629918
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to centrifuges and, in particular, to the balancing of centrifuges during thawing of frozen materials.
BACKGROUND OF THE INVENTION
A typical bloodbanking refrigerated centrifuge
2
is shown in FIG.
1
and includes a rotatable rotor
4
. Buckets or carriers
6
are pivotally connected to the rotor. This particular centrifuge employs a lid
8
which permits high speed rotation. The carriers swing on axis A—A and assume a horizontal position during centrifuge operation as a result of centrifugal forces caused by spinning of the rotor.
In early centrifuge usage, blood was collected in glass bottles which were placed in cylindrical centrifuge carriers. The bottles were prone to breakage and made decanting liquid a difficult task. This lead to the use of flexible containers or bags in centrifugation. Bags are more convenient in handling and withstand mishaps such as falls much better than glass bottles.
The contents of a centrifuge are to be placed in radial symmetry to the axis of rotation to achieve an approximate balance of masses. The material to be centrifuged is first statically balanced, such as through the use of a two-plate balance, to achieve the same weight in each container. Typically, water is added to increase the weight of a container. Then, the balanced containers are placed in diametrically opposed relationship on the rotor. Therefore, the number of carriers is, for example, four or six rather than an odd number.
Centrifuges evolved into high speed machines. The bags did not always perfectly fit the carriers and ruptured at high pressures. Also, doctors differed in the volume of contents placed in each bag.
Centrifuge adapters were placed in the carriers to simplify operation and avoid bag breakage. Also, adapters were used to place all sorts of small containers, such as “Radio Immuno Assay” test tubes in the carriers, to enhance the usefulness of the centrifuge around the laboratory.
Adapters have a rigid construction which is intended to keep the contents safe during the centrifuge run. Some adapters help the centrifuge operator with a difficult part of the separation: taking the centrifuged goods out of the carriers and decanting the supernatant liquid without mixing it with the separated cell packets or pellets. Other adapters prevent whole blood from remaining in the pleats at the top part of the bags, caused when tubing of the bag is placed into the carrier.
Adapters such as those described in U.S. Pat. Nos. 5,549,540 and 4,582,606, employ elliptical cavities defined by rigid walls for separation of liquid/cell combinations. However, such elliptical adapters, as well as cylindrical (circular) adapters, exhibit problems when used on frozen material. Ice clumps that separate from the frozen mass tend to “float” to sections of the container at lower pressure. The liquid resulting from the melting of the frozen masses flows to high pressure areas replacing their volume. All this happens in an aleatory or haphazard manner in circular and elliptical adapters, whether bags or bottles. Also, the adapters, by virtue of their rigid construction, may rupture bags when ice clumps push against the inner walls of the flexible container supported by the rigid walls. This is a major cause for growing imbalance problems and risk to operator and machine during the run.
The medical community could benefit greatly from safe operation of a centrifuge which prevents flexible bag rupture, especially in the case of thawing frozen contents by centrifuging. Such safe operation should enable centrifuges to be used to thaw biomaterial while avoiding splashing (such as in the case of blood). Other areas that could benefit are blood banks in that they could quickly prepare their own fresh Cryoprecipitated AHF in advance during normal blood bank operation. Summer shortage cases would be solved by the safe use of centrifuges for thawing as would emergency cases by on-the-spot donation by volunteers. Independent operation from commercial blood clotting concentrates for any special reason would be possible. More flexible care of hemophilia, von Willebrand's disease and other low blood clotting diseases would be possible. Also, new possibilities of investigation may occur as new mixtures of biomedical compounds can be made and studied.
SUMMARY OF THE INVENTION
In general, the invention pertains to an adapter for supporting a flexible container or bag in a centrifuge carrier. The adapter is of a size that can be received in a cylindrical cavity of the carrier and comprises a wall formed of a flexible material. The wall comprises a first concave wall portion or section having a first curvature and a second wall portion or section which has a second curvature that is lower than the first curvature. The first wall portion and second wall portion are diametrically opposed to each other so as to receive the flexible container in an interior region substantially bounded by an inner surface of the wall.
In all embodiments of the present invention, it will be appreciated by those skilled in the art that reference to the wall “substantially bounding” the crescent shaped interior region (or interior region between the first concave wall portion having a first curvature and diametrically opposed second wall portion having a lower curvature than the first curvature) includes within its scope walls which do not completely surround the flexible bag that they shape. In a preferred embodiment the interior of the adapter wall completely surrounds the interior region.
More specifically, the invention is directed to an adapter formed of a flexible material. The first and second sections are fastened by a hinge. A latch interconnects the first and second sections together. This two-part adapter may include a plurality of latch openings to adjust the size of the interior region. Flexible containers thus may be contacted with even pressure by the adapter and placed in the resulting shape without room for substantial movement within the interior region of the adapter, regardless of the volume of the flexible container and its contents. In this disclosure, the term “flexible” in regards to the adapter wall, means material which is suitable to withstand freezing of the liquid components of the flexible container and allows flexure of the flexible container during thawing effective to avoid rupture of the flexible container. For example, the adapter should allow a maximum linear dimension distortion of the wall ranging from 0.3 to 1.0 mm when freezing or thawing the bag contents.
In particular, the adapter includes the first concave wall portion and a second convex wall portion having a larger curvature radius (i.e., lower curvature) than the first wall portion, the first and second wall portions being diametrically opposed to each other. The radius of curvature of the first higher curvature, concave wall portion approximates the radius of curvature of the centrifuge carrier, for example, to within a tolerance on the order of 5-10 mm to allow easy setting of the loaded adapter. In this way, the curvature provides a sufficient hold for practical purposes and allows for easy handling of the adapter. Centrifugal force will suffice to retain the adapter in position during centrifugation. The radius of curvature of the low curvature wall portion is, for example, 3 to 4 times the radius of curvature of the high curvature wall portion. As a practical matter it is expected that the adapter will seldom be used alone in a carrier as a second bag can usually be placed in the carrier along with the bag carried by the adapter.
Until now, accelerated thawing of biological material such as plasma or other liquid placed in a flexible container by means of centrifugation, resulted in severe mechanical overload in the centrifuge because of the imbalance created during the run. This put the machine and its operator at risk.
Placing of frozen material in the centrifuge poses no risk as the solid filled soft containers (such as bags) are placed in the carriers and the usual static
Cooley Charles E.
Mesa Carlos G.
Watts Hoffmann Co. L.P.A.
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