Imperforate bowl: centrifugal separators – Process
Reexamination Certificate
2001-07-30
2003-05-06
Kim, John (Department: 1723)
Imperforate bowl: centrifugal separators
Process
C494S007000, C494S010000, C494S045000
Reexamination Certificate
active
06558307
ABSTRACT:
TECHNICAL FIELD
This invention generally relates to systems and methods for processing blood and other biological fluids.
BACKGROUND ART
FIG. 1
shows a typical disposable bag set used in the prior art to collect platelets from whole blood. The set includes a needle
10
or cannula, which is inserted into a vein of a donor. The needle
10
is connected to the tube
11
, which in turn is connected to collection bag
12
, so as to allow whole blood to flow from the donor through the needle
10
and the tube
11
into collection bag
12
. The collection bag
12
contains anticoagulant. After the desired amount of blood has been collected into collection bag
12
, the needle
10
is removed from the donor, and tube
11
is cut and heat sealed. The remainder of the bag set is then brought to a centrifuge, which spins the bag set so that the blood in collection bag
12
separates into platelet-rich plasma and red blood cells. Typically, the centrifuge is not located at the point where the blood donation takes place.
After the blood has separated into platelet-rich plasma and red blood cells (RBCs), the bag set is removed from the centrifuge. The platelet-rich plasma is urged from collection bag
12
through tube
13
into platelet-storage bag
14
. The tube
13
leading to the platelet- and plasma-storage bags
14
,
15
is then cut and heat sealed. Storage-solution bag
16
holds RBC-storage solution. After the platelet-rich plasma has been urged into the platelet-storage bag
14
, the RBC-storage solution is urged from the storage-solution bag
16
into the collection bag
12
. The tube
41
connecting the collection and storage-solution bags
12
,
16
is then cut and heat sealed.
At this stage, the bag set has been divided into two portions: (i) the first portion consists of the collection bag
12
, which now holds primarily red blood cells (along with storage solution), filter
17
, RBC-storage bag
18
, and the tubing
19
that connects these components, and (ii) the second portion consists of the platelet-storage bag
14
, which now holds platelet-rich plasma, and the plasma-storage bag
15
and the tubing that connects these two components.
The first portion may be hung, so that gravity causes the RBC component to pass from the collection bag
12
through the filter
17
to RBC-storage bag
18
. The filter
17
removes white blood cells (WBCs) from the red blood cells. After the red blood cells (and storage solution) pass into the RBC-storage bag
18
, tube
19
is cut and heat sealed.
To collect platelets, the second portion is centrifuged at a high rotational speed in order to separate the platelets from the plasma. After the platelets have been separated from the plasma, some of the plasma is urged from the platelet-storage bag
14
into the plasma-storage bag
15
. Typically, 50 mls of plasma are left with the platelets in the platelet-storage bag
14
. After the desired amount of plasma has been removed from the platelet-storage bag
14
to the plasma-storage bag
15
, the tube connecting these two bags is cut and heat sealed. Thus, at the end of the procedure, the platelet-storage bag
14
holds platelets in about 50 ml of plasma, the plasma-storage bag
15
holds platelet-poor plasma, and the RBC-storage bag
18
, of course, holds red blood cells.
This prior-art process of collecting and separating blood components involves many steps and frequent human intervention. The arrangement of the prior-art bag set does not permit the process to be easily automated.
SUMMARY OF THE INVENTION
The present invention is directed to systems and methods for collecting, from whole blood, platelets suspended in plasma. By centrifuging the blood at a high enough rotational speed, the platelets are separated from the plasma and the red blood cells. In a preferred embodiment, some of the plasma is removed while the centrifuge is being spun to keep the platelets separated from the plasma. Then, the speed of rotation is altered so as to cause the platelets to mix with the remaining plasma. The platelets can then be collected with the remaining plasma.
A system that may be used for carrying out the invention includes a centrifuge rotor, a flow-control arrangement and a spinner. The flow-control arrangement introduces whole blood into the centrifuge rotor and removes blood components from the centrifuge rotor. A controller causes the spinner to rotate at two different speeds: The rotor is spun at a first speed so as to separate the blood into a first component, a second component and a third component. The first component is primarily plasma. The second component is located, while the rotor is being spun, outside of the first component and is primarily red blood cells. The third component is located, while the rotor is being spun, between the first and second components and includes platelets. The controller causes the rotor's speed of rotation to be altered so as to cause the third component to mix with the first component. The controller also causes the flow-control arrangement to remove from the rotor a portion of the plasma containing platelets.
As noted above, in a preferred embodiment, the controller causes the flow-control arrangement to remove some of the first component (the plasma) before the third component (comprising the platelets) is mixed with the first component. The system also preferably includes a plasma-volume determination sensor in communication with the controller; the plasma-volume determination sensor determines the volume of the first component in the rotor. The controller may thus remove a portion of the first component based on the determined volume of the first component.
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Bromberg & Sunstein LLP
Haemonetics Corporation
Kim John
LandOfFree
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