SYSTEM AND METHOD OF FILTERING AND COLLECTING BLOOD OR BLOOD PRODUCTS
PRIORITY INFORMATION
This application claims the priority of U.S. Serial No. 60/076,558, filed March
2, 1998, and which is incorporated fully herein by reference.
FIELD OF THE INVENTION
This invention relates generally to liquid filtration techniques. More
particularly, this invention relates to an in-line gravity driven liquid filtration method usable to filter and collect biological liquids such as blood or blood products.
BACKGROUND OF THE INVENTION
Typically, blood filtration devices allow liquid filtrate to remain within the
filtration device after filtration has occurred. This remaining liquid, referred to as a
hold up volume, is often greater than the desired maximum amount. Also, blood
filtration devices allow an undesirably high amount of air that is purged therefrom to
be left in the receiving blood bag.
Certain blood filtration devices are disclosed in U.S. Patent No. 5,472,605, and
entitled "A Filtration Device Usable for Removal of Leukocytes and Other Blood
Components" issued December 5, 1995, and in U.S. Serial No. 08/524,049, and
entitled "an In-Line Liquid Filtration Device Usable for Blood, Blood Products and
the Like" filed September 6, 1995, and in U.S. Serial No. 08/449,362, and entitled "A
Filtration Device Usable for Removal of Leukocytes and Other Blood Components"
filed May 24, 1995, and in U.S. Serial No. 08/661,804, and entitled "A Filtration
Device Usable for Removal of Leukocytes and Other Blood Components" filed June 11, 1996, which are hereby incorporated by reference and made a part of the
disclosure herein. Filtration methods using these types of devices may not readily
allow for the storage of filtered blood for use in cross matching and for the storage of
filtered blood which can be accurately tested for the quality of filtration of the entire
filtered blood sample.
It may be desirable to achieve a liquid filtration method that provides samples
of the filtered blood for cross matching and that provides a means to store a mixed
sample of filtered blood for quality control purposes.
SUMMARY OF THE INVENTION
The shortcomings of the prior art may be alleviated and the aforementioned
goals achieved by using a filtration method in accordance with the principles of the
present invention. The filtration method of the present invention is useable when
filtering blood or blood products to remove leukocytes, other blood components,
cells, and chemical agents which may be used to treat the blood.
In an aspect of the invention, a method of filtering and collecting blood or
blood products involves filtering the blood or blood product, collecting the blood or
blood product in a receiving bag (e.g., a conventional transfer or storage bag),
allowing the blood or blood product to remain in a first length of tubing, mixing the
blood or blood product within the receiving bag, sealing the first length of tubing into
one or more segments having blood or blood products remaining therein, expressing
blood or blood products from the receiving bag into a separate length of tubing, and
sealing the second length of tubing into one or more segments. The blood in the
sealed segments of the first length of tubing may then be used for cross-matching, and/or the blood sealed in the segments of the second length of tubing may be used for
quality control testing.
The air within the receiving bag may be expressed into an air bag which is
connected to the receiving bag through the second length of tubing. This may occur
prior to expressing blood or blood products from the receiving bag into the second
length of tubing. The blood or blood product may be filtered for removal of cells and
the blood or blood product within the segments of the second length of tubing may be
tested for the presence of such cells. For example, the filtered cells may be
leukocytes. Alternatively, or additionally, the blood or blood product may be filtered
for the removal of chemical or biological agents therein and the blood or blood
product in the second length of tubing tested for the presence of these agents. The
first and second lengths of tubing may be sealed using a heat sealing device.
BRIEF DESCRIPTION OF THE DRAWINGS The air within the receiving bag may be expressed into an air bag which is
connected to the receiving bag through the second length of tubing. This may occur
prior to expressing blood or blood products from the receiving bag into the second
length of tubing. The blood or blood product may be filtered for removal of cells and
the blood or blood product within the segments of the second length of tubing may be
tested for the presence of such cells. For example, the filtered cells may be
leukocytes. Alternatively, or additionally, the blood or blood product may be filtered
for the removal of chemical or biological agents therein and the blood or blood
product in the second length of tubing tested for the presence of these agents. The
first and second lengths of tubing may be sealed using a heat sealing device.
Figure 1 depicts a filtration device in an operational assembly with a blood
supply bag, a blood receiving bag, and an air bag useable with the blood filtration and
collection method in accordance with the principles of the present invention; and
Figure 2 depicts an isometric view of a receiving blood bag, air bag, air bag
tubing, and the segment markings on the air bag tubing as mounted downstream of a
filtration device, in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As referred to herein, the terms upstream, top or up refers to a location of the flow of liquid prior to filtration through filter elements within the filtration device of
the present invention. Conversely, the terms downstream, bottom or down as used
herein refers to a location of the flow of liquid after filtration through filter elements
within the filtration device of the present invention.
The present invention is intended to be used for in-line gravity filtration of
various liquids including biological liquids. However, the method described herein is
particularly suited for the filtration of blood and/or blood products and will be
described herein in reference to blood filtration.
Although various filtration devices may be used in accordance with the present
invention, the filtration device used should automatically drain the upstream side
when filtration is complete. Preferably, draining occurs without the manipulation of
various components and the filtration device should not drain completely on the
downstream side.
One type of filtration device, useable in the present invention incorporates an
automatic vent filter, an inlet section, an outlet section, filter elements and means for
allowing gas to vent from the filtration device through an outlet port, and a means to
automatically drain the upstream side of the filtration device once filtration is
complete. Such a filtration device is disclosed in U.S. Patent Application Serial No.
08/812,717 filed on March 6, 1997, the specification of which is incorporated herein
by reference and made a part of this disclosure.
As shown in Figure 1 herein, a filtration device 223 is depicted in operational
assembly with inlet tubing 217, outlet tubing 218, feed blood bag 293, receiving blood
bag 294, air bag 295, inlet tube clamp 266, outlet tube clamp 267, and air tube clamp
268. Preferably, the user will purchase the entire assembly shown in Figure 1
sterilized without feed blood bag 293 (which will be used to contain, e.g., donated red
blood cells after processing to remove plasma) with the inlet end of inlet tubing 217
sealed to maintain system sterility. For performing filtration, inlet tube clamp 266,
preferably located close to the inlet end of inlet tubing 217, is closed. Next the outlet
tube clamp 267 is opened and air tube clamp 268, preferably located close to the air
tube port on receiving blood bag 294, is closed. Inlet tubing 217 attached to tube
socket 287 above the center of inlet section 201 may now be attached to a feed blood
bag 293 using a sterile docking device as is well known in the art, or connected to
another blood supply source including directly to a patient. Once the sterile docking
connection is made feed blood bag 293 may be hung from hook 297 on blood bag pole
296. Receiving blood bag 294 and air bag 295 could be placed on a surface such as a
table top, a bin or the like or could be hung. The complete assembly will now be
ready for filtration. The inlet tube hanging tab 211 and outlet tube hanging tab 212
position inlet tubing 217 and outlet tubing 218 respectively so that filtration device
223 hangs vertical and plumb.
Filtration is performed by opening inlet tube clamp 266 so that gravity now
forces blood to flow from feed blood bag 293, through inlet tubing 217, through and
into the filtration device 223. Blood filtration will occur until feed blood bag 293 is empty or until the flow of blood into the filtration device is otherwise stopped. When
feed blood bag 293 is empty it will be collapsed and therefore, close the inlet end of
inlet tubing 217. However, blood may remain in filter elements of the filtration
device and in outlet tubing 218.
Referring to Figure 1, tube clamp 267, located between the filtration device
223 and the receiving bag 294, on outlet tubing 218 may be closed. Then tubing 218,
above tube clamp 267, can be sealed, typically by heat using a conventional heat
safety device which closes portions of tubing by melting the same, by clamping the tubing closed or by any other means to temporarily or permanently seal or close the
tubing. Then, the tubing may be cut above the seal. Feed blood bag 293, inlet tubing
217, and filtration device 223 can now be discarded in a safe manner. Tube clamp
268 can then be opened so that air in receiving blood bag 294 can be expressed
through air bag tubing 298 into air bag 295. The blood in receiving blood bag 294
may now be mixed to ensure consistency, and preferably the blood is mixed after the
air is removed, though mixing could occur before removing the air if desired. Once
the air in receiving blood bag 294 has been expressed from receiving blood bag 294,
mixed blood from receiving blood bag 294 can be expressed into air bag tubing 298 to
fill the same. Tube clamp 268 can now be closed and air bag tubing 298 sealed near
the air bag 295, using any of the means similar to that for tubing 218. Air bag 295 can
now be cut away above the seal just made and discarded in a safe manner. Therefore,
receiving blood bag 294 with outlet tubing 218 and air bag tubing 298 now remain.
Both outlet tubing 218 and air bag tubing 298 may have segment marks
thereon. Figure 2 depicts the segment marks 292 on air bag tubing 298. The tubing
may, therefore, be sealed in premarked segments, if desired. The blood that is sealed in the segments in outlet tubing 218 may be tested for its compatibility with a patient
or other receiver, i.e., used for cross matching. Moreover, the mixed blood sealed in
segments of air bag tubing 298 may be tested for the concentration of filtered matter
or other quality control purposes. For example, if blood is filtered for leukocyte removal, the filtered blood sealed in tubing 298 may be tested for the presence and
concentration of leukocytes. Similarly, blood filtered for the removal of chemical
agents can be tested for the presence and concentration of such agents after filtration.
Since the blood in air bag tubing is used for quality control purposes, it is desirable to
mix or agitate the blood within the receiving bag prior to expressing the same into the
air bag tubing. Mixing or agitation will help minimize or prevent a concentration
gradient of constituting within the blood tested for quality control.
Although the invention has been described in conjunction with the
embodiments depicted herein, it will be apparent to one of ordinary skill in the art that
various modifications may be made to these embodiments without departing from the
scope of the invention as defined in the following claims.