Blood bag having affixed thereto a label, portions of which are
adapted to permit enhanced gas transmissibility between the interior
and exterior of the bag. In preferred embodiments the affixed label
has an outwardly facing surface adapted to provide useful information
about the bag or bag contents and an inwardly facing surface having
raised portions and depressed portions with the label generally
adhering to the bag surface via only the raised or selected raised
1. A blood or blood component container, the container demonstating
gas transmissibility, and having affixed directly thereto a label,
the label having an outwardly facing surface adapted to provide
useful printed information and an inwardly facing surface, the inwardly
facing surface having both raised and depressed portions, the raised
portions comprising less than about 50% of the total inner surface
area of the label and the depressed portions being interconnected
and in communication with the periphery of the label to facilitate
gas transmission between the interior of the container and the atmosphere
surrounding the bag.
2. The blood bag system of claim 1 wherein the raised portions
of the label comprise less than about 25% of the inner surface area
of the label with the raised portions of the inner surface of the
label being bonded to the bag by means of a thermoplastic adhesive.
3. The blood bag system of claim 1 wherein the loss in O.sub.2
transmission attributable to the presence of the label on the bag
surface is less than about 10% of the total O.sub.2 transmission
possible through the total surface area of the bag in the absence
of a label.
4. The blood bag system of claim 1 wherein the gas transmissible
polymeric material is a plasticized polyvinylchloride.
5. The blood bag system of claim 4 wherein the polyvinylchloride
material is plasticized with at least about 30% by weight of plasticizer.
6. The blood bag system of claim 5 wherein the plasticizer is TOTM.
7. The blood or blood component container of claim 1 wherein the
container comprises a polymeric material selected from the group
consisting of polyolefins and plasticized polyvinylchloride.
BACKGROUND OF THE INVENTION
This disclosure is concerned generally with the field of blood
bags made from flexible polymeric materials and specifically with
a blood bag and blood bag label combination which provides increased
gas transmissibility for the blood bag.
2. Prior Art
Blood and blood components are commonly collected, processed, stored
and administered in containers simply referred to as blood bags
or blood bag systems. These are made from a flexible polymeric film
which should be of a medically acceptable quality. The bags may
exist as single bags having various access ports or multiple bags
comprising two or more otherwise single bags in closed communication
with one another via appropriate tubings which may include various
valves or temporary seals. In the case of multiple blood bags, there
are typically a so-called donor bag (or primary bag) into which
whole blood is collected via attached tubing and attached donor
needle and various satellite bags (or secondary bags). Into these
various components or sub-components of whole blood may be expressed
via connecting tubing after they have been separated (usually via
centrifugation) in an attached bag, typically the donor bag or an
additional satellite bag.
The above bags are commonly made from films of polyolefins, polyolefin
mixtures, or polyvinyl chloride plasticized with plasticizers known
in the art as di-2-ethylhexyl phthalate (DEHP or DOP) or, in some
cases certain triesters of trimellitic acid such as tri-2-ethylhexyl
trimellitate (TOTM or TEHTM). These films and the above PVC plasticizers
are described more fully, for example, in U.S. Pat. No. 4280497
to W. Warner et al and U.S. Pat. No. 4222379 to D. Smith, the
teachings of both being incorporated herein by reference.
It is known that certain blood components (particularly platelets)
require an exchange of CO.sub.2 and O.sub.2 through the plastic
collection bag during storage to remain viable. See, for example,
U.S. Pat. No. 4280497 to Warner et al, cited above, and the publications
cited therein. It has been found, for example, that when platelets
are stored in a TOTM-plasticized PVC blood bag or certain polyolefin
bags, a greater degree of gas transmissibility is possible. This
greater gas transmissibility in turn permits better platelet storage
properties (e.g. 5 days storage vs. 3 days), a desirable property.
Conventional blood banking practices require a relatively large
(3".times.4" or 4".times.4") paper label be
securely attached to the bag throughout the preparation, storage,
and administration of a unit of blood or a blood component. This
label may cover up to one fourth of the bag surface and, unfortunately,
it has been found that the label may significantly reduce the amount
of gas diffusion through the bag/label structure, thus, in some
cases, impairing component viability.
Currently, paper labels are attached to a blood bag in either of
1. The more common heat seal method employs a heated platen which,
with heat and pressure, melts the adhesive backing of the label
and presses it into the bag film. About 100% of the inner label
surface is then firmly attached to the bag.
2. A second method uses a label with a pressure sensitive adhesive
backing which requires only pressure to attach it to the bag. A
disadvantage of this method is that the label is not as firmly attached
to the bag as with the heat seal method noted above. Accordingly,
it is a preferred practice to use the above heat seal method for
label attachment even though, because of its size and attachment,
it interferes with gas diffusion through the bag.
Quite surprisingly, we have devised a blood bag-label combination
which enhances or maximizes gas transmissibility while still permitting
the label to be firmly affixed or attached via thermoplastic adhesive
to the bag throughout common blood banking procedures. Details of
our invention are disclosed below.
SUMMARY OF THE INVENTION
Our new blood bag system includes at least one blood bag having
affixed thereto a label, portions of which are adapted to permit
enhanced gas transmissibility between the bag interior and the bag
exterior (e.g. the environment or atmosphere surrounding the label
and bag). In preferred embodiments, the blood bag is made from a
gas transmitting polymeric film (such as a plasticized PVC or certain
polyolefins) and at least a portion of the bag's external surface
has the blood bag label affixed to it. The label has an outwardly
facing surface adapted to provide useful printed information about
the bag or its contents and an inwardly facing surface. The inwardly
facing surface is preferably coated with a thermoplastic adhesive
and comprises raised and depressed portions with the label generally
adhering to the bag surface via the adhesive only at the raised
portions, or selected raised portions. In very preferred embodiments
a heated "patterned platen" is used in applying the label
to the bag and the platen is used to form the raised and depressed
portions by pressing the label at elevated temperatures and pressures
sufficient to activate the thermoplastic adhesive and bond the label.
In yet another preferred embodiment, the blood bag is a platelet
storage bag and the raised (adhering) portions of the inner surface
of the label comprise less than about 50% (preferably less than
25%) of the inner surface area of the label. The depressed portions
about the raised portions communicate with one another and the edge
of the label via connecting channels to further facilitate gas transmission
between the interior and exterior of the bag.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 illustrates a front view of the blood bag-label combination.
FIG. 2 illustrates the combination as seen from the opposite side
through the essentially transparent, non-labeled rear portion of
the bag of FIG. 1.
FIG. 3 illustrates the pressing surface of a "patterned platen"
which may be used to create the blood bag-label combination.
FIG. 4 illustrates a side cross section of the label just after
it has been applied to the bag using the platen of FIG. 3.
It should be understood that the invention disclosed herein is
particularly useful for labeled blood and blood component containers,
especially labeled blood bags intended for use in any application
where gas transmissibility through the container or bag is important.
In the illustrative examples below we prepared a blood bag-label
combination in which the bag was made from a TOTM-plasticized film
of about 15 mils thickness. This type of bag has been found especially
useful for platelet storage as pointed out in U.S. Pat. No. 4280497
cited above. Such platelet bags are commonly the secondary or satellite
bags of a multiple blood bag system in which two or more bags are
connected via appropriate tubing. Although the blood bag may be
made from any film having gas transmissibility properties that may
be enhanced with the labeling technique disclosed herein (e.g. various
gas transmitting PVC materials, polyolefins and mixtures of polyolefins),
a preferred film is made from a PVC film having a relatively large
amount of plasticizer (e.g. more than 30% by weight plasticizer)
and is similar to that described in the '497 patent. In the film
of the examples, we used a PVC formulation comprising about 71 parts
TOTM by weight per 100 parts per weight PVC resin, as well as conventional
PVC additives known in the art.
The labels themselves were made from bleached kraft paper (conforming
to surgical grade) having a basis weight of about 40-45 lbs. per
ream. The labels were about 3".times.4". On one side useful
information about the bag, its manufacturer and the bag contents
are printed. On the opposite side, a thin coat of adhesive is applied.
For a thermoplastic bond, the adhesive may be any heat seal or hot
melt formulation such as wax, polymers or wax/polymer combinations
such as polyethylene wax known to those skilled in the art as useful
for bonding kraft paper to flexible PVC films.
The bags to which the labels were applied were satellite bags of
generally conventional size and volume and similar to those available
commercially as CLX.RTM. blood bags from the Cutter Biological Division
of Miles Laboratories, Inc., Berkeley, Calif.
Further descriptions of the preferred labeled bags and how to make
them are described better with reference to the Figures. FIG. 1
shows the front or label side of a typical generally flat, empty
plastic blood bag 1 having affixed thereto the label 3 which is
part of this invention. Bag 1 comprises two sheets (see sheets 2
of FIG. 4) of the PVC film edge sealed along line 21 and having
conventionally placed access ports 4 and 7 and removeable access
port protectors 5. In addition, the bag 1 has handling openings
9 and 11 for positioning the bag during bag handling operations,
conventional longitudinal slits 15 for holding blood sample tubes,
and hanger opening 13. Barely discernible on the face of label 3
is a honeycomb configuration consisting of slightly depressed portions
17 (which in FIG. 2 correspond to the similarly numbered raised
portions). Although the label 3 of FIG. 1 simply shows the words
"Blood Bag", in practice, other useful information would
be printed on that face of the label. Also showing on label 3 is
a tiny opening 22 about 1/16" diameter and conventionally
placed on the label to assist in optical identification of the bag.
It should be noted that this opening contributes essentially nothing
of significance to the operation of the invention (i.e. enhancement
of gas transmissibility through the bag).
FIG. 2 illustrates the reverse side of bag 1 of FIG. 1. Since the
PVC film of the preferred bags is essentially transparent, it is
possible to look through the back of the bag to see in more detail
how the label is affixed to the bag. As can be seen, the label adheres
to the bag only at raised portions 17 (via adhesive portions 37
in FIG. 4) on the inner surface of the label 3. Surrounding these
raised portions 17 are interconnected channels 19 which ultimately
connect with the periphery of the label at label edges 23 which,
in preferred embodiments, at least one of which is not bonded to
the bag surface. Edges 23 need only be about 1/16" wide and
by not adhering to the bag serve two purposes: (1) they permit channels
19 to communicate better with the atmosphere external to the bag,
thereby facilitating gas transmission through that portion of the
bag under the major part of the label, and (2) they assist in keeping
the heat sealing patterned platen (described below) from making
direct contact with the film per se during label application. In
preferred embodiments, at least 50%, preferably at least about 75%,
of the inner surface area of the label 3 does not adhere to the
blood bag. Since this inner surface communicates with the outside
atmosphere via interconnected channels 19 (and possibly via the
adhesive coated portions of the inner label surface which do not
adhere to the bag), gas transmissibility from the bag interior and
around the edge(s) and through the label is enhanced.
The actual application of the label may be appreciated by reference
to FIGS. 3 and 4. FIG. 3 illustrates the pressure face of an aluminum
platen having a pressing surface area slightly less than that of
the label surface area (to allow for non-adhering edges 23 in FIG.
2). The platen has a patterned working surface comprising selectively
spaced raised portions 17a and depressed portions of interconnected
channels 19a which communicate with the edges of the platen. Raised
portions 17a (about 1/16" high) are intended for pressing label
inner surfaces at selected points against the bag film to encourage
adhesion (at points 17 in FIG. 2). Also shown on the face of the
platen are six circular depressions 33 (about 1/2" in diameter
and about 1/16" deep) having centrally located smaller vacuum
openings 31 in sealed communication (not shown in FIG. 3 but seen
as channels 34 in FIG. 4) with external tubing 29 integral with
the platen edge as shown. In use, a partial vacuum generation means
is connected at 32 on tubing 29 and a partial vacuum is created
through channel 34 at the six larger circular depressions 33 via
smaller openings 31. This is then used to position and hold in place
a label to be applied to the bag. Item 35 of FIG. 3 is merely an
opening for connecting the platen to a heat/pressure producing means
and not an essential part of the invention.
The actual use of the patterned platen of FIG. 3 is illustrated
in FIG. 4. There, platen 25 is shown in cross-section above label
3 which is placed over the top layer of blood bag films 2. On the
inner surface of the label 3 facing film 2 is a thin layer of the
thermoplastic adhesive 37 previously applied to the inner surface
of the label.
When heat and pressure (for example about 300.degree. F. and 30
- 80 PSI for one half to two seconds) are briefly applied to platen
25 (as illustrated by the downward pointing arrows), the label is
then bonded to the top film 2. However, because of the pattern on
the platen (see FIG. 3) the label assumes a honeycomb-like structure
(especially on the bag film facing side) and the label adheres to
the bag only at pre-selected, adhesive-coated raised portions 37
(corresponding to raised portions 17 in FIG. 2). The label does
not adhere significantly to the film at depressed channel areas
19. Since these depressed areas 19 represent communicating channels
which ultimately communicate with the atmosphere outside of the
bag, the applied label enhances gas transmissibility between the
interior and exterior of the bag. This then minimizes the normally
deleterious effects on gas transmissibility caused by a label which
adheres to the bag over the majority or all of its inner surface.