Abstrict A generally flat, elongated edge-sealed polymeric blood bag having
a length to width ratio of at least 2 to 1 and one end portion in
tapering communication with a connected single tubing which in turn
is in closed communication via a Y-connector with both a bag access
port and at least one other Y-connector. The second Y-connector
is in closed communication with at least one auxiliary bag, preferably
two auxiliary bags. Once the upper neocyte portion is expressed
from the elongated blood bag the lower, more dense gerocytes can
be saved in the original elongated bag or expressed into another
connected bag via the Y-connector assembly for subsequent use or
storage. The bag system is especially useful for separating and
isolating both components of a neocyte/gerocyte red blood cell mixture
in an open system and for providing a means for saving the otherwise
discarded gerocytes for subsequent use. A physiological solution
can be introduced via the Y-connector assemblies into the elongated
bag to reconstitute the dense gerocytes.
Claims I claim:
1. A method of preparing both neocytes and gerocytes from a blood
cell mixture containing some from the group consisting essentially
of neocytes, gerocytes, and supernatant including plasma and preservative
solution, the method comprising the steps of:
a) obtaining the blood cell mixture in an elongated bag having
a length to width ratio of at least about 2 to about 1
b) centrifuging the elongated bag containing the blood cell mixture
to form a supernatant portion, a neocyte portion, and a gerocyte
portion,
c) expressing at least part of the supernatant portion from the
elongated bag into a first auxiliary blood bag in closed communication
with the elongated bag,
d) expressing a predetermined fraction of the neocyte portion,
from the elongated bag into a second auxiliary blood bag in closed
communication with the elongated bag,
e) transferring the expressed supernatant from the first auxiliary
blood bag into the elongated blood bag to provide a suspension of
the gerocytes; and
f) transferring the gerocyte suspension from the elongated bag
into the first auxiliary bag.
2. A method of preparing, from an initial mixture of red blood
cells and white blood cells including leukocytes, both neocytes
and gerocytes from a blood cell mixture containing some from the
group consisting essentially of neocytes, gerocytes, and supernatant
including plasma and preservative solution, the method comprising
the sequential steps of:
a) obtaining the blood cell mixture in an elongated bag having
a length to width ratio of at least about 2 to about 1
b) filtering the initial mixture of red blood cells and white blood
cells to remove the leukocytes,
c) centrifuging the elongated bag containing the blood cell mixture
to form a supernatant portion, a neocyte portion, and a gerocyte
portion,
d) expressing at least part of the supernatant portion from the
elongated bag into a first auxiliary blood bag in closed communication
with the elongated bag,
e) expressing a predetermined fraction of the neocyte portion,
from the elongated bag into a second auxiliary blood bag in closed
communication with the elongated bag,
f) transferring the expressed supernatant from the first auxiliary
blood bag into the elongated blood bag to provide a suspension of
the gerocytes; and
g) transferring the gerocyte suspension from the elongated bag
into the first auxiliary bag.
3. A method of preparing, from an initial mixture of red blood
cells and white blood cells including leukocytes, both neocytes
and gerocytes from a blood cell mixture containing some from the
group consisting essentially of neocytes, gerocytes, and supernatant
including plasma and preservative solution, the method comprising
the sequential steps of:
a) obtaining the blood cell mixture in an elongated bag having
a length to width ratio of at least about 2 to about 1
b) centrifuging the elongated bag containing the blood cell mixture
to form a supernatant portion, a neocyte portion, and a gerocyte
portion,
c) expressing at least part of the supernatant portion from the
elongated bag into a first auxiliary blood bag in closed communication
with the elongated bag,
d) filtering a predetermined fraction of the neocyte portion, which
may include residual supernatant, by expressing that portion from
the elongated bag into a second auxiliary blood bag in closed communication
with the elongated bag through a filter element,
e) transferring the expressed supernatant from the first auxiliary
blood bag into the elongated blood bag to provide a suspension of
the gerocytes; and
f) transferring the gerocyte suspension from the elongated bag
into the first auxiliary bag.
4. A method of preparing both neocytes and gerocytes from a blood
cell mixture containing some from the group consisting essentially
of neocytes, gerocytes, and supernatant including plasma and preservative
solution, the method comprising the steps of:
a) obtaining the blood cell mixture in an elongated bag having
a length to width ratio of at least about 2 to about 1
b) centrifuging the elongated bag containing the blood cell mixture
to form a supernatant portion, a neocyte portion, and a gerocyte
portion,
c) expressing at least part of the supernatant portion from the
elongated bag,
d) expressing a predetermined fraction of the neocyte portion from
the elongated bag into a first auxiliary blood bag in closed communication
with the elongated bag,
e) introducing a sufficient amount of the supernatant portion from
a second auxiliary blood bag into the elongated blood bag to provide
a suspension of the gerocytes; and
f) expressing the gerocyte suspension from the elongated bag into
the second auxiliary bag.
Description BACKGROUND OF THE INVENTION
This disclosure is concerned generally with flexible plastic bags
used for collecting, processing and storing blood and blood components.
The disclosure is especially concerned with a blood bag system found
useful for separating, isolating and storing both old and young
red cells on the basis of their relative densities.
The manufacture and use of flexible, plastic containers, or bags,
for the collection, processing and storage of blood and blood components
is well known. Whole blood from a donor is typically obtained via
venipuncture and collected via tubing in a donor bag. The donor
bag may or may not be connected via tubing to one or more satellite
or transfer bags.
When connected to at least one transfer bag, the donor/transfer
bag combination is commonly referred to as a "multiple"
blood bag system. Such a system may include one, two, or three transfer
bags, all in sealed communication with the donor bag so that, once
blood or blood components are introduced into the system, the whole
blood or its components may be moved from one bag to another by
external manipulation of valves, and the like, thereby avoiding
or minimizing contamination. Such multiple bag systems are thus
commonly referred to as "closed" blood bag systems. Multiple
blood bag systems not in sealed communication with the donor bag,
or designed for attachment to the donor bag following initial collection
are generally referred to as "open" blood bag systems.
In a typical multiple blood bag application, whole blood is collected
into a donor bag and all connected transfer bags, which are typically
empty, are placed in a centrifuge cup designed to hold the filled
donor bag in a generally upright position. The bag contents are
then centrifuged to separate whole blood into its lighter plasma
component and its heavier red blood cell component.
By manipulating a valve, which typically is a frangible valve within
the system, the upper plasma may then be expressed into one of the
transfer bags, possibly for further processing (e.g., into platelet-rich
and platelet-poor components which may be expressed further into
other connected transfer bags). The separated platelet-poor plasma
component subsequently may be fractionated into a variety of other
products useful in so-called component therapy, including clotting
factors, immune serum globulins, albumin, and the like.
During the first separation of plasma from red blood cells in a
centrifuged donor bag, the upper plasma portion is often removed
from the donor bag using a relatively simple device known as a plasma
expresser. The expresser simply squeezes the donor bag until the
upper, less dense plasma is fully expressed out of the bag, typically
into a connected transfer bag.
In U.S. Pat. No. 4857190 (Wada et al.), a blood bag for separating
white blood cells from platelets is shown. In that disclosure, a
conventional blood bag is modified at the bottom to provide a small
receptacle for collection and isolation of white blood cells (WBCs)
from a platelet/WBC mixture. That disclosure focuses on minimizing
the interface between the separated platelets and WBCs by carefully
controlling the volume and dimensions of the continuous receptacle
and by providing a centrifuge insert adapted to accommodate the
bag and receptacle.
In U.S. Pat. No. 3911918 (Turner), there is disclosed an hour-glass
shaped plastic blood bag comprising several compartments for the
separation and isolation of blood components. That bag is capable
of being separated to form a number of individual storage compartments
for the separated components following component separation. As
pointed out in that patent, prior art blood storage containers previously
had not been detailed in size and shape to contain a predetermined
quantity of blood or a blood component, such as plasma, in separate
compartments.
More recently in U.S. Pat. No. 4416778 (Rogers), there is disclosed
a dual compartment plastic blood bag in which the two compartments
are connected via a tubing. The tubing includes a valve adapted
to open only after a given centrifugation force is obtained. The
bag is said to be especially useful for separating less dense and
relatively younger red blood cells (i.e., neocytes) from more dense
and relatively older red blood cells (i.e., gerocytes). As pointed
out in that patent, the teachings of which are incorporated herein
by reference, the use of neocytes is thought to be useful in minimizing
iron overload possibilities in patients who depend on repeated blood
transfusions.
To date, the primary method used for separating various blood components
is simple centrifugation using either conventional bags or specially
designed blood bags or using a specialized mechanical apparatus.
One apparatus useful for separating blood components, including
neocytes and gerocytes, is an instrument known as an IBM Model 2991
blood cell separator.
Unfortunately, the bags and apparatus available for fine separation
of blood components tend to be fairly complex and expensive, thus
limiting their use. Various ways of providing simpler, less costly
methods and devices for the separation and isolation of blood components,
especially the separation of neocytes and gerocytes, have been investigated
recently.
An elongated bag specifically designed for neocyte preparation
is described in U.S. Pat. No. 4892537 (Carmen et al.). See also
continuation U.S. Pat. No. 4969882 to the same inventors. That
system does not provide a way for saving gerocytes for later use.
Furthermore, in that system the supernatant is expressed along with
the neocytes into the satellite bag, which results in a generally
undesirable increase in total neocyte transfusion volume.
In practicing that patented system, the tubing leading from the
donor bag to the elongated bag is often severed after both transfer
of the RBC mixture into the elongated bag and centrifugation. The
supernatant is then expressed out of the severed tube, and the remaining
packed neocytes are transferred into the satellite bag. The remaining
gerocytes are viscous and generally are not used. Thus, it is desirable
to provide a self-contained system for introducing a diluting solution
into the main bag to enable storage and subsequent use of gerocytes
from a neocyte/gerocyte mixture.
SUMMARY OF THE INVENTION
The inventive blood bag system for the separation and isolation
of both neocytes and gerocytes comprises a generally flat, elongated
plastic bag which has a length to width ratio of at least about
2 to about 1 and a top end in tapering communication with a connected
tubing. The tubing is in closed communication with at least one
access port and at least one other bag. In a preferred embodiment,
the tubing leading from the elongated bag is connected to a paired
series of Y-connectors enabling communication with at least two
other bags, one of which may contain a RBC preservative solution,
as well as the tubing enabling introduction of the neocyte/gerocyte
mixture into the elongated bag.
In practicing the inventive system, an RBC blood component mixture
of neocytes and gerocytes is introduced into the first elongated
bag. It should be noted that at this point, the mixture transfer
is considered "open" unless done using a so-called "sterile
connection" or "docking device". The tubing leading
from the blood source to the elongated bag may include a filter
for selectively filtering leukocytes from the neocyte/gerocyte mixture
as it is introduced from the donor bag into the elongated bag. Alternatively,
the tubing leading from the elongated bag to an auxiliary bag may
include a similar filter for removing leukocytes as the neocytes
are expressed into an auxiliary bag.
The mixture is then separated into neocyte and gerocyte components
using conventional means, such as centrifugation. The weight of
the neocytes to be separated is determined based on the weight and
the hematocrit (HCT) of the original mixture. This neocyte weight
typically is about 50% of total RBC mixture sample size by weight,
and can range from between about 40% to 60%, depending on considerations
such as blood availability, need for younger cells, and the like.
The upper component, consisting of the separated neocytes and supernatant,
is then expressed out of the tapered top of the bag which, when
expanded by its contents, forms a funnel- like guide for directing
the separated upper component from the bag and through the tubing
in a substantially unobstructed manner.
In a preferred embodiment, the elongated bag has a volume of about
275 ml and a length to width ratio of at least about 2.5 to about
1. The bag has a pair of substantially parallel major sides, or
edges, continuous with converging minor sides, or edges, defining
an interior obtuse angle of at least about 110.degree., preferably
about 145.degree.. In a closed system, the elongated main bag is
pre-connected or sterilely connected to the donor bag via a Y-connector
assembly. In an open system the elongated main bag is connected
to the donor bag via a spike located at the end of tubing extending
from a Y-connector in communication with the elongated main bag.
In a preferred embodiment, the elongated bag is in closed communication
with a first Y-connector assembly, including a Y-connector and appropriate
tubing. One arm of the first Y-connector is in closed communication
with a port access, while the other arm is in closed communication
with a second Y-connector assembly. The second Y-connector of that
assembly is in closed communication with at least one, preferably
two, auxiliary blood bags. These bags may be used for receiving
supernatant and/or neocytes expressed from the elongated bag. One
auxiliary bag may contain a physiological solution or RBC preservative
to be delivered into the elongated bag following neocyte expression
to dilute the gerocytes and facilitate gerocyte expression from
the bag. In another embodiment, one arm of the Y-connector of the
second Y-connector assembly may provide access to additional Y-connector
assemblies for a plurality of connections to additional satellite
bags.
A preferred method of preparing gerocytes using the system of this
disclosure involves obtaining a mixture of neocytes and gerocytes,
together called packed RBCs, having a hematocrit of about 75% and
being less than 4 days old. The packed RBCs are preferably filtered
to remove at least 90%, preferably at least 99%, of any WBCs. The
combination of neocyte and gerocyte cells are then weighed and centrifuged
in the main bag to form an upper portion of neocytes and supernatant
which are then expressed out of the bag, leaving concentrated gerocytes.
An RBC preservative or other appropriate solution may be added to
the gerocytes for storage, or a physiological solution may be added
to dilute and enable expression of the gerocytes.
Details of our system and preferred variations are described in
more detail below.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1A shows a plan view of a very preferred embodiment of this
disclosure, a key feature of which is enclosed within the dotted-line
box 43.
FIG. 1 is a plan view illustrating an exemplary neocyte/gerocyte
blood bag system of this disclosure.
FIG. 2 is a plan view of one preferred embodiment of the inventive
blood bag system where three bags are used.
FIG. 3 is a plan view of an alternative blood bag system having
a plurality of Y-connector assemblies that allows a port access
for adding a RBC preservative or saline solution to the packed gerocytes
of the first bag, and access for transfusion of the gerocytes.
Like elements in each Figure have the same reference number.
DETAILED DESCRIPTION OF INVENTION
As can be seen in FIG. 1A, one embodiment of the inventive system
comprises a total of six bags of various types in closed communication
with an intermediately located filter means.
The inventive system can be described in terms of its use and the
various processing and storage steps which permit the preparation
and long term storage of neocytes and, preferably, gerocytes.
Whole blood is drawn from a donor using a conventional phlebotomy
needle 3. The blood is collected via conventional PVC tubing 5 into
a conventional donor bag 7 which contains an anticoagulant such
as citrate-phosphate-double dextrose. Bag 7 may be made of conventional
blood bag film such as DEHP or TOTM plasticized PVC (e.g., see U.S.
Pat. No. 4222379 Smith) and has a volume large enough to accommodate
both the anticoagulant and a unit of donated whole blood (e.g. total
volume for bag 7 is about 600 ml). Bag 7 typically includes one
or more conventional blood bag port structures 9 and an internal
frangible valve 11 such as that described in U.S. Pat. No. 4586928
(Barnes et al.). Such a frangible valve 11 is preferred and can
also be seen in bags 39 and 41 described below.
In practicing the illustrated embodiment of FIG. 1A, after the
plasma and RBC's are separated by centrifugation of bag 7 valve
11 is opened by external manipulation and the upper plasma is expressed
via tubing 13 through the right side of Y device 15 through tubing
17 into bag 19. The plasma may include blood platelets. Tubing 17
may now be sealed and cut using conventional techniques leaving
bag 19 containing the plasma and platelets still in closed communication
with bag 21. The contents of bag 19 are centrifuged and the lighter
platelet poor plasma is expressed into bag 21. Bags 19 and 21 are
preferably made from a plastic film having a high gas transmissivity,
such as TOTM (see, for example, U.S. Pat. No. 4280497 to Carmen
et al., incorporated herein).
In the illustrated embodiment, after the plasma has been expressed
from donor bag 7 to bag 19 a RBC concentrate remains in donor bag
7. After reconstitution, with a RBC preservative solution, already
in the closed system such as the solution in bag 41 (which is also
used to prime the filter 27), the RBC mixture (unseparated neocytes,
gerocytes and leukocytes) is passed via tubing 13 through the left
side of Y device 15 and tubing 23 into the first port 25 of filter
27 which is adapted to remove at least about 98% of WBCs from the
mixture and can be like that of U.S. Pat. No. 4767541 (Wisdom)
or U.S. Pat. No. 4810378 (Carmen et al.).
Filtration is preferably by gravity. The RBC's then pass from filter
27 through second port 29 past Y device 35 via tubing 31 into neocyte/gerocyte
separation bag 33 very preferably of the elongated conventional
funnel-ended type described in EPO Application No. 0191360. A
conventional seal is made on the tubing between filter exit port
29 and Y device 35 and bags 33 39 and 41 are detached. The bags
are centrifuged as described in EPO Application 0191360 to form
a cell-free upper layer (preservative solution plus residual plasma)
and a lower layer of density-separated red cells (both neocytes
and denser gerocytes). Approximately 1/2 volume of upper layer (preservative
solution plus residual plasma) is expressed into bag 41. The remaining
upper layer (preservative solution plus residual plasma) and about
the upper 1/2 of the red cells (the less dense neocytes) are expressed
into final neocyte storage bag 39 (about 200 mL volume). Preservative
solution plus residual plasma in bag 41 is added back to bag 33
to reconstitute, or dilute, the remaining red cells (gerocytes).
The reconstituted gerocytes are transferred bag to bag 41 for long
term storage. The neocytes in bag 39 are capable of storage for
up to 42 days, depending upon the storage solution used. An example
of such a 42 day RBC storage or preservative solution is AS-3 described
by Simon et al. (Transfusion 1987 27:178-182).
An added bonus of this illustrated system is that the gerocytes
(presently often simply discarded) are maintained in the closed
system and also in a preservative solution. Uniquely, this is all
accomplished within a closed blood bag system. Thus, the gerocytes
are not wasted and can be used in cases where RBC age is not a concern
(e.g. where RBC's of a given type are given in relatively small,
non-recurring amounts and where iron overload is not a concern).
A unique aspect of our closed system described above is shown within
the dotted box 43 of FIG. 1A, and is shown in its various exemplary
embodiments in FIGS. 1-3.
In an actual closed neocyte separation and storage method using
our preferred system described in FIG. 1A, we were able to prepare
neocytes from packed RBC's from which at least 98% of all WBC's
were filtered out. In combination with the RBC storage solution
(e.g. AS-3), these neocytes could be stored successfully for up
to 42 days and still be used in a patient. These results are obtained
because of the novel closed system of this disclosure.
Although a key feature of this disclosure is the sub-system within
the dotted line box of FIG. 1A, a preferred system includes all
components of that Figure, including pre-attached donor bag 7 and
satellite bags 19 and 21. It can be appreciated, however, that a
bag containing RBC's can be sterile docked into the sub-system within
dotted line box 43 at, for example, a point on tubing 23 while still
maintaining a closed system.
Unless otherwise indicated above, conventional blood handling techniques
and materials can be used in making and using our novel system.
All terms used (e.g. sterile, sterile connection, etc.) have their
conventional meaning known to those skilled in the art. As used
herein, RBC storage solution, RBC preservative solution and RBC
additive solution are used interchangeably and should be considered
equivalent.
Referring now to FIG. 1 main bag 33 is considerably elongated
having a ratio of length (L) to width (W) dimensions of at least
2 to 1 preferably a ratio of about 2.5 to about 1. The bag 33 is
substantially the same overall dimensions as that illustrated in
U.S. Pat. No. 4892537 (Carmen et al.), the teachings of which
are incorporated herein. The bag 33 includes substantially parallel
major edges 20 comprising at least 50% of the bag length. These
edges 20 are continuous with converging minor sides 22 which meet
to form an interior obtuse angle A.degree. that is at least about
110.degree., preferably about 145.degree.. Converging edges 22 are
designed to expand when the bag is filled and to guide the filled
bag contents in a substantially unobstructed, funnel-like manner
to exit port 12. Exit port 12 is continuous with a tubing 35a that
is in closed communication with Y-connector 35.
In the embodiment of FIG. 1 exit port 12 communicates with the
base of a conventional plastic 2-for-1 Y-connector 35 via tubing
31. The Y-connector 35 communicates at one arm with tubing 40 connected
to satellite bag 39 which bag typically includes a sealed exit
port 9. The Y-connector 35 communicates at the other arm with tubing
46. Tubing 46 communicates with a second conventional Y-connector
47 and spike tubing 23 and spike 3 through which the initial mixture
of RBCs is introduced into main bag 33. In one embodiment, to maintain
a totally "closed" system as described above, the RBC
mixture (both neocytes and gerocytes) is introduced into main bag
33 via a pre-connected or sterilely connected Y-connector assembly
10. Otherwise, under current practice and when not processed under
"closed" conditions, the useful cell component must be
administered within 24 hours of introduction of the RBC mixture
into the main bag 33.
One arm of the second Y-connector 47 of FIG. 1 may lead to a remote
sealed port assembly 50. This assembly 50 includes a port element
52 and tubing 51. The port element 52 may be any commercially available
port having a membrane enabling access to bag 39. Typically, such
ports are adapted to receive conventional spike element 3 and are
used to introduce preselected physiological solutions and/or expressing
components, such as supernatant, gerocytes, or neocytes from the
main bag 33.
The inventive bag system of FIG. 1 is suited for separating and
saving the components of a neocyte/gerocyte mixture (see below).
The spike 3 connected to tubing 5 is adapted to be inserted into
one of the exit ports of a conventional donor bag containing mixed
red blood cells after the plasma has been expressed.
Auxiliary bag 39 is preferably also flat and may either be a conventional
square bag or an elongated bag similar in size to main bag 33 so
that when bag 33 is filled with mixed cells, empty and flat bag
39 may be wrapped around filled bag 33 for insertion into a centrifuge
cup adapted to receive both in that manner. This assumes a somewhat
cylindrical shape of filled bag 33 due to expansion. In one embodiment,
a conventional valve may be associated with tubing 40 either externally,
for example by a clamp, or internally, for example by a pierceable
membrane, a frangible in-line pierceable, or a frangible valve.
One such frangible internal valve 11 is illustrated in all Figures.
Such valve 11 may close communication to bag 39 until the upper
separated contents of bag 33 are ready for transfer to bag 39.
The ability to add solutions into the main bag 33 is perhaps the
most distinguishing feature of this invention. As discussed above,
prior art systems do not include sterile access to the main bag
containing viscous gerocyte cells. As shown in the preferred embodiment
of FIG. 2 the inventive blood bag system enables not only the selective
removal of supernatant and neocytes, but also enables the reintroduction
of supernatant or any other appropriate solution into main bag 33.
In that illustrated embodiment, the main bag 33 is in closed communication
with a first Y-connector assembly 10 consisting of tubing 31 and
Y-connector 35. The main bag 33 is adapted to receive an RBC mixture
from tubing 23 via one arm of Y-connector 35. The second arm of
Y-connector is in closed communication with second Y-connector assembly
10', that includes tubing 37 and Y-connector 45. This second assembly
10', in turn, is in communication with auxiliary bags 39 and 41.
Either auxiliary bag may contain a predetermined amount of RBC storage
solution, saline solution, or the like.
In a preferred form of practicing the illustrated system, an RBC
mixture is introduced into main bag 33 then the entire system is
centrifuged. All or a portion of the resulting upper supernatant
layer may be expressed into bag 39 via connector assemblies 10 and
10' and tubing 40. Any remaining supernatant layer plus the neocyte
layer may then be expressed into bag 41 via connector assemblies
10 and 10' and tubing 42. A dense gerocyte layer remains in main
bag 33. The expressed supernatant may then be returned from bag
to main bag 33 again via tubing 40 to provide nutrition to the
gerocytes for storage, and dilute, or reconstitute, the gerocytes
for subsequent expression and use. The supernatant/gerocyte mixture
may then be re-introduced into bag 39 along tubing 40 for storage
and subsequent use.
FIG. 3 shows another embodiment of the inventive system having
a plurality of Y-connector assemblies. The elements in FIG. 3 correspond
to like elements of FIGS. 1 and 2. FIG. 3 has a third Y-connector
assembly 10", consisting of tubing 37 and Y-connector 45. That
assembly 10" may lead to one or more auxiliary bags, or may
have a remote sealed port assembly 11'. In a similar fashion, the
second assembly 10' may include a sealed remote port assembly 50.
Other embodiments may include a preselected number of Y-connector
assemblies, depending on the number of desired auxiliary bags and
remote port assemblies as required for the particular use.
In practicing the method of the present invention, the following
exemplary steps may be performed. First, about 275 ml of red blood
cells of mixed age and approximately 70-80% hematocrit (HCT) are
drawn into main bag 33 via tubing 23 using spike 3 or sterile connection
to tubing 23. In a closed system, a filter 27 may be incorporated
in the system between the blood source 24 (which source may be donor
bag 7) and main bag 33. Empty bag 39 is wrapped about the filled
bag 33 and both are inserted into a centrifuge cup insert about
63 mm in diameter and about 130 mm deep and generally conforming
to the volume of the filled bag. Centrifugation proceeds at about
4000 x g for 30 minutes or until optimal separation of the desired
cell components is achieved. The bag system is then removed and
the upper supernatant and neocyte component is expressed from bag
33 into bag 39. Preferably, the supernatant is first expressed via
port assembly 50 or 50' to an appropriate receptacle, e.g., a transfer
bag. The neocyte component (with any residual supernatant) is then
expressed into bag 39. To identify the amount of neocyte component
to express, a calculation is made based on the weight of the upper
component, as determined or calculated from the total weight of
pre-separated red cells (i.e., the original unseparated RBC mixture),
and the HCT. The amount of neocyte component expressed can readily
be determined by one skilled in the art, taking into consideration
such factors as whole blood availability, need to assure a relatively
lower average age of the neocytes to minimize risk of iron overload,
and the like. The neocyte component is then expressed using a conventional
plasma expresser from bag 33 into bag 39 until the desired weight,
as determined using the method described above, is transferred.
Tube 40 is sealed and cut and bag 39 containing the neocyte fraction
is then removed. At this point the expressed supernatant may then
be reintroduced into bag 33 to dilute the remaining gerocytes for
subsequent use.
Prior art systems require that the gerocytes are left in bag 33
without access to these gerocytes unless a sterile connection device
is used. The addition of connector assembly 10' permits access to
the gerocytes. A transfusion set can be attached to port assembly
50. In an alternative embodiment, the transfusion set can have a
Y-connector to allow attachment of an auxiliary bag of saline or
other similar solution.
Because the gerocytes are at a high hematocrit, they are viscous
and do not flow readily. Thus, a saline solution can be added through
port 52 to dilute the gerocytes to facilitate flow. The gerocytes
can then be transfused through a transfusion set connected to port
assembly 50. Alternatively, a second remote port assembly may be
added via a Y-connector to tubing 51 or tubing 51', as shown in
FIG. 3 such that saline may be added through one port. That port
is then sealed off and the diluted gerocytes may then be stored
and later transfused via the alternate port.
In one embodiment, a filter 27 may be included in tubing 38 or
42. In addition, illustrated embodiments shown in FIGS. 1-3 may
include a filter 27 along tubing 23.
SEPARATION STUDIES
The above separation of neocytes from a mixed neocyte/gerocyte
RBC population using a bag similar to bag 3 has already been described
in U.S. Pat. No. 4892537 the teaching of which is incorporated
herein by reference. Those data show that a satisfactory separation
of younger (less dense) and older (more dense) cells is achieved
with the blood bag system described in that patent. The separation
compared favorably with the two techniques of using a mechanical
cell separator and using a multi-chambered bag.
FIG. 2 shows a preferred embodiment of the system of this disclosure.
As illustrated, a secondary solution 32 such as a red cell preservative
solution or saline solution, may be contained in satellite bag 41.
Alternatively, the solution 32 may be added to bag 41 via port 9
after removal of bag 39 containing the neocytes. After separation
of the neocytes from the gerocytes, frangible valve 11 of bag 41
is opened to permit the secondary solution 32 to be added to the
gerocytes in bag 33 via tubing 42. The diluted gerocytes are then
transferred to bag 41 via tubing 42 for storage and ultimate transfusion
through port 9.
Alternative ways to add the secondary solution 32 include introduction
by either sterile connection to tubing 23 40 or 42 or by adding
a port to either tubing 23 40 or 42 via a Y-connector and tubing
as shown in FIG. 1. This would permit the addition of the secondary
solution 32 to the gerocytes, which cells could then be transferred
to bag 41 as mentioned above for storage and ultimate transfusion
to a patient through port 9.
FIG. 3 shows yet another embodiment wherein a second port may be
added to the system via a Y-connector attached either to tubing
23 51 or 51'. Having two ports on the system permits secondary
solution 32 to be added via one port and, after sealing off tubing
to that port, subsequent storage of the gerocytes for later transfusion
via the second port.
The embodiments of FIGS. 1-3 are particularly well-suited for use
in open systems as discussed above. The configuration of Y-connectors
permits such use, as contrasted with the closed system described
in conjunction with FIG. 1A. While a closed system generally requires
the inclusion of a filter to remove leukocytes from the neocyte/gerocyte
cell mixture, a filter is not generally required in an open system.
The omission of a filter element in the open system allows the expression
and reintroduction of the supernatant as described in detail above.
Given the above disclosures, it is thought that numerous variations
will occur to those skilled in the art. Accordingly, it is intended
that the above described preferred system should be considered as
illustrative and that the scope of the invention disclosed should
be limited only by the following claims. |