U.S. patent application number 10/774127 was filed with the patent office on 2005-01-06 for hemodilution cap and methods of use in blood-processing procedures.
Invention is credited to Brugger, James M., Burbank, Jeffrey H., Stillig, Martin.
Application Number | 20050000882 10/774127 |
Document ID | / |
Family ID | 25419613 |
Filed Date | 2005-01-06 |
United States Patent
Application |
20050000882 |
Kind Code |
A1 |
Brugger, James M. ; et
al. |
January 6, 2005 |
Hemodilution cap and methods of use in blood-processing
procedures
Abstract
Devices and methods that prevent clotting of blood during
blood-processing procedures such as hemofiltration, hemodialysis,
hemodiafiltration, and peritoneal dialysis are described. The
device comprises a cap and a housing that is shaped to receive a
blood filter. The housing has an inlet for blood and may have an
outlet for waste and ultrafiltrate. The cap is attached to the
housing. The cap has an outlet for blood and a port adjacent the
outlet for receiving dilution fluid. Methods of use during
blood-processing procedures to provide immediate hemodilution to
blood exiting a filter are also described.
Inventors: |
Brugger, James M.;
(Newburyport, MA) ; Burbank, Jeffrey H.; (Boxford,
MA) ; Stillig, Martin; (Dransfeld, DE) |
Correspondence
Address: |
PROSKAUER ROSE LLP
PATENT DEPARTMENT
1585 BROADWAY
NEW YORK
NY
10036-8299
US
|
Family ID: |
25419613 |
Appl. No.: |
10/774127 |
Filed: |
February 6, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10774127 |
Feb 6, 2004 |
|
|
|
09904709 |
Jul 12, 2001 |
|
|
|
Current U.S.
Class: |
210/321.79 ;
210/321.8 |
Current CPC
Class: |
B01D 61/30 20130101;
B01D 2313/21 20130101; A61M 1/3434 20140204; A61M 1/3437 20140204;
B01D 63/02 20130101; A61M 1/342 20130101; B01D 61/20 20130101; A61M
1/3672 20130101 |
Class at
Publication: |
210/321.79 ;
210/321.8 |
International
Class: |
B01D 063/00 |
Claims
1. An extracorporeal filter, comprising: a housing having an inlet
for blood; said housing having an interior volume divided into
filtrate portions and blood portions; an outlet for waste and
ultrafiltrate in flow communication with said filtrate portion of
said interior volume of said housing; a cap attached to the housing
opposite the inlet, the cap having an outlet port for blood and an
infusion port, both the outlet port for blood and the infusion port
being connected to the housing such that they open directly to said
blood portion of said interior volume of said housing, whereby
blood may be diluted by fluid infused in said infusion port; and a
filter media received within the housing configured to separate
said blood portion of said housing from said filtrate portion of
said housing such that communication therebetween within said
interior of said housing is provided only through said filter
media.
2. The filter of claim 1, wherein the infusion port is adjacent the
outlet port for blood such that fluid injected into said infusion
port is mixed with blood therein.
3. The filter of claim 1, wherein said infusion port conveys an
aqueous replacement fluid.
4. The filter of claim 1, wherein the cap is removably attached to
the housing.
5. The filter of claim 1, wherein the port is adapted to receive
replacement fluid.
6. The filter of claim 1, wherein the housing has a second cap that
carries the inlet.
7. The filter of claim 1, further comprising a second port adapted
to receive dilution fluid radially adjacent the inlet.
8. The filter of claim 1, wherein a gap between the filter and the
cap defines a headspace.
9. The filter of claim 1, wherein the housing is generally
cylindrical.
10. An extracorporeal filter, comprising: a housing having a bundle
of parallel tubular filter membranes separating first and second
interior volume portions within the housing, said housing having
first and second ends with said filter membrane running along a
length of said housing between said first and second ends; said
housing having a first port with a tubing connector located at said
first end in flow communication with said first interior volume
portion; said housing having a second port with a tubing connector
located at said second end in flow communication with said second
interior volume portion; said housing first end having a chamber,
said first port opening into said chamber; said housing having a
third port proximate said first port and opening into said chamber
such that a fluid injected therethrough would mix within said
chamber without passing through said filter membrane; said housing
having at least one fourth port in communication with said second
interior volume portion; said first, second ports and said bundle
being configured to permit a flow of blood during an extracorporeal
blood treatment of at least 50 mL/min and said third port being
configured to permit a flow of aqueous dilution fluid of at least
25 mL/min.
11. A filter as in claim 10, wherein said third port has a tubing
connector by which replacement fluid may be continuously injected
therethrough.
12. A filter as in claim 10, wherein said filter membrane comprises
filter fibers.
13. A filter as in claim 12, wherein said housing includes end
caps, each enclosing said first and second interior volume portions
at a respective one of said first and second housing ends.
14. A filter as in claim 13, wherein said first, second, and third
ports are in said end caps.
15. A filter as in claim 13, wherein one of said end caps has said
first and third ports and encloses said chamber, said chamber being
cylindrical and said third port being arranged such that a flow
through said third port flows tangentially to said cylindrical
chamber.
16. An extracorporeal filter, comprising: a housing supporting
multiple filter fibers connected to head spaces at ends of said
multiple filter fibers, said head spaces being in flow
communication through interiors of said filter fibers, said head
spaces otherwise being isolated from each other; a blood inlet in a
first of said head spaces with blood flowing from said first of
said head spaces to a second of said head spaces through said
multiple filter fibers; a blood outlet in said second of said head
spaces, said blood outlet having a dilution fluid inlet with
dilution fluid injected into said blood in said second of said head
spaces, whereby a potential for clotting in said second of said
head spaces is reduced.
17. A filter as in claim 16, wherein said dilution fluid inlet is
arranged to generate turbulent mixing of said blood and said
dilution fluid in said second of said head spaces.
18. A filter as in claim 16, wherein a direction of flow of said
dilution fluid inlet is substantially opposite and parallel a
direction of flow of said blood outlet.
19. An extracorporeal filter, comprising: a housing supporting
multiple filter fibers connected to inlet and outlet head spaces
joined for flow communication by said multiple filter fibers, said
head spaces otherwise being isolated from each other; a blood inlet
in inlet head space arranged to allow blood to flow from said inlet
head space; a blood outlet in said outlet head space; and a
dilution fluid inlet in said outlet head space connected to receive
replacement fluid from a source thereof; said blood inlet and
outlets being connected to external blood lines.
20. A filter as in claim 19, wherein a direction of flow of said
dilution fluid inlet is substantially opposite and parallel a
direction of flow of said blood outlet.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to devices and
methods useful in preventing coagulation in filtered blood during
hemofiltration. More specifically, the devices and methods provide
a cap having a port, the cap adapted for attachment to a blood
filter housing to provide hemodilution of blood as it enters and/or
exits the filter.
BACKGROUND OF THE INVENTION
[0002] Undesired coagulation of blood often complicates
blood-processing procedures such as hemofiltration, hemodialysis,
and hemodiafiltration, particularly where a filter is used. Blood
generally coagulates by transforming soluble fibrinogen into
insoluble fibrin by activation of numerous circulating proteins
that interact in a cascading series of limited proteolytic
reactions. At each step of reaction, a clotting factor undergoes
limited proteolysis and becomes an active protease that in turn
activates the next clotting factor until finally a solid fibrin
clot is formed. Fibrinogen (factor I) is activated by thrombin
(factor IIa), which is converted from prothrombin by activated
factor X. There are two separate coagulation pathways that activate
factor X--the intrinsic system and the extrinsic system. Activation
of the extrinsic system requires tissue thromboplastin (factor
III), which is released from damaged tissue into the circulating
blood to activate clotting. The intrinsic system, on the other
hand, has all the factors necessary for coagulation contained in
the circulating blood. The intrinsic system is, for example,
partially responsible for clotting of blood in a test tube.
Aggregation of platelets caused by stagnation of blood also
facilitates blood coagulation.
[0003] During hemofiltration, for example, blood is removed from
the patient, filtered through a filtering column to remove waste
products, and returned to the patient's circulation. However,
during removal of waste products, fluid is also removed, causing
concentration of blood leaving the outflow tubing. As a result of
hemoconcentration, hematocrit rises, and the intrinsic coagulation
pathway and platelets are activated causing clotting of blood
around the outlet of the filtering column, thereby compromising the
hemofiltrating process.
[0004] What is needed are devices and methods that can be used with
a filtering column during blood-processing procedures, such as
hemofiltration, hemodialysis, hemodiafiltration, and peritoneal
dialysis, to prevent clotting. Existing devices are inadequate for
this purpose.
SUMMARY OF THE INVENTION
[0005] The present invention provides devices and methods that
prevent clotting of blood during blood-processing procedures, such
as hemofiltration, hemodialysis, and hemodiafiltration. More
particularly, blood is diluted by replacement fluid, such as
saline, Ringer's lactate, or other physiological solutions, as it
enters and/or exits the filter. In a first embodiment, the device,
also known as a filter, is comprised of a bundle of hollow fiber
membrane made of resins such as polysulfone that is fixed in a
cylindrical housing with a potting material. The interior of the
fibers is the blood flow path. The exterior of the fibers is the
dialysate and/or waste space. The potting material is typically a
polyurethane material. The cylindrical housing may have one or two
access ports. One port is for the hemofiltration filter, and two
ports allow dialysate to flow through the housing contacting the
exterior surface of the membrane for hemodialysis or
hemodiafiltration. In one embodiment, the open fibers at the end of
the cylindrical housing are covered at both ends with a cap. One
cap is the blood entry cap, the other is the blood exit cap. In
other embodiments, the housing includes end plates at one or both
ends, the end plates integral with the housing.
[0006] The exit cap is attached to the housing, in some cases
removably attached, and generally at a position opposite the inlet
cap. The exit cap has an outlet for blood and a port adjacent the
outlet for receiving replacement fluid. In certain embodiments, the
blood outlet, the replacement fluid port, the blood inlet, and/or
the waste outlet of the filter assembly communicate with bond
sockets adapted to receive flexible tubing.
[0007] In another embodiment, the filter has an outlet or exit cap
for blood at one end and an inlet or inlet cap at the other end,
the cap having an inlet for blood and a port adjacent to the inlet
for receiving dilution fluid, such as saline, Ringer's lactate, or
other physiological solutions. The housing also includes access
ports for waste and ultrafiltrate.
[0008] In still another embodiment, the housing includes first and
second caps at opposite ends and an outlet for waste and
ultrafiltrate. The first cap has an inlet for blood and a port
adjacent to the inlet for receiving dilution fluid. The second cap
has an outlet for blood and a port adjacent to the outlet for
receiving dilution fluid.
[0009] In use, blood is passed through the blood inlet of the entry
cap, through the filter membrane fibers, and through the blood
outlet of the exit cap. Replacement fluid or dilution fluid, such
as saline, Ringer's lactate, or other physiological solutions, is
infused into the port adjacent the blood outlet to produce
hemodilution at the blood outlet. Alternatively, the fluid is
infused into the port adjacent the blood inlet of the entry cap to
produce hemodilution at the inlet. In still another alternative
method, fluid is infused into the port adjacent the blood inlet of
the entry cap and into the port adjacent the blood outlet of the
exit cap to produce hemodilution as blood enters and exits the
filter housing. In certain constrictions the replacement fluid
swirls in a circular pattern in a headspace that is defined by the
gap between the filter and the cap. Swirling of the replacement
fluid facilitates mixing of the fluid and the blood, thereby
preventing hemoconcentration and stasis of blood, and sweeping any
particles of thrombus away from the filter.
[0010] The advantages associated with the hemodilution cap
described herein include (1) preventing coagulation during blood
processing procedures, (2) manufacturing efficiency, i.e., reducing
plastic used in disposable components, (3) eliminating up to two
bonds and up to two components, (4) less expense in materials costs
and manufacturing costs, (5) more robust system, not subject to
tolerances like bonding two rigid parts, and (6) integration of
parts saves labor, materials, and precious resources.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1A depicts a filter within a housing for
hemofiltration.
[0012] FIG. 1B depicts a filter within a housing having a
replacement fluid port adjacent the blood outlet port for
hemofiltration.
[0013] FIG. 1C depicts a filter within a housing having a
replacement fluid port adjacent the blood inlet port for
hemofiltration.
[0014] FIG. 1D depicts a filter within a housing having replacement
fluid ports adjacent both the blood inlet port and the blood outlet
port for hemofiltration.
[0015] FIG. 1E depicts a filter within a housing for
hemodiafiltration having dialysate inlet and outlet ports.
[0016] FIG. 1F depicts a filter within a housing for
hemodiafiltration having a replacement fluid port adjacent the
blood outlet port.
[0017] FIG. 2 depicts a filter-housing cap having a replacement
fluid port adjacent the blood outlet port for hemofiltration.
[0018] FIG. 3A depicts a cross-sectional view of a filter housing
cap having a replacement fluid port adjacent the blood outlet port
for hemofiltration.
[0019] FIG. 3B depicts another cross-sectional view of a filter
housing cap having a replacement fluid port adjacent the blood
outlet port for hemofiltration.
[0020] FIG. 3C depicts another cross-sectional view of a filter
housing cap having a replacement fluid port adjacent the blood
outlet port and a headspace for hemofiltration.
[0021] FIG. 4A depicts a fluid bond socket communicating with the
blood outlet.
[0022] FIG. 4B depicts a fluid bond socket communicating with the
replacement fluid port.
[0023] FIG. 5 depicts a filter-housing cap removably mounted on a
filter housing for hemofiltration.
[0024] FIG. 6 depicts a filter-housing cap for hemofiltration, the
cap being made of flexible PVC and having ribs for stability.
DETAILED DESCRIPTION
[0025] During blood-processing procedures, such as hemofiltration,
hemodialysis, and hemodiafiltration, blood has a tendency to clot
as it passes through processing equipment, particularly where it
exits the outlet of a filter, due to hemoconcentration. In FIG. 1A,
the hemofiltration device includes cylindrical housing 10 which
contains filter fibers 20 that remove waste from blood passing
through the fibers. It will be understood that any other suitable
shape can be used for the housing. Housing 10 is equipped with
entry cap 13 having blood inlet 11. Waste and ultrafiltrate that
are removed from the blood exits the housing through waste outlet
12. Exit cap 30 is mounted on housing 10 opposite blood entry cap
13. Headspace 31 is formed in the gap between filter fibers 20 and
cap 30 and between filters 20 and cap 13. Headspace 31 communicates
with blood outlet 32. Each of the inlet 11 waste outlet 12 and
blood outlet 32 are adapted for attachment to flexible tubing
sections that connect with a blood processing system.
[0026] In FIG. 1B, cap 30 further includes replacement fluid inlet
port 33 that communicates with headspace 31. Replacement fluid is
infused through port 33 to effect hemodilution of blood exiting
filter 20. The system thereby reconstitutes blood as close as
possible to the exit from the filter fibers. In this way
hemodilution is accomplished with one part (cap 30) and two bonds
(one between tubing and port 32, and another between tubing and
port 33).
[0027] In FIG. 1C, housing 10 includes cap 13 having blood inlet 11
and dilution fluid inlet port 15 that communicates with headspace
31. Blood is diluted as it enters housing 10, thereby helping to
prevent coagulation.
[0028] In FIG. 1D, housing 10 includes cap 13 having blood inlet
and dilution fluid inlet port 15 that communicates with headspace
31. The housing also includes cap 30 having blood outlet 32 and
fluid inlet port 33 that communicates with headspace 31. Dilution
fluid is infused through port 33 and port 15 to effect hemodilution
of blood entering and exiting filter 20.
[0029] FIG. 1E shows a housing 10 designed for hemodiafiltration.
Housing 10 includes dialysate inlet 16 and dialysate outlet 12 to
establish countercurrent dialysate flow. Filter fiber membrane 20
is mounted within potting material 21 at both ends, where the
potting material typically is a polyurethane material. In FIG. 1F,
cap 30 further includes replacement fluid inlet port 33 that
communicates with headspace 31. Replacement fluid is infused
through port 33 to effect hemodilution of blood exiting filter 20
as described for other embodiments above. It will be understood
that for hemodiafiltration, a hemodilution cap may be included
alternatively on the inlet to effect pre-dilution of blood, and/or
on both the inlet and outlet.
[0030] FIG. 2 shows a top view of cap 30 having blood outlet 32 and
replacement fluid infusion port 33. In use, replacement fluid, such
as saline, Ringer's lactate, sterile filtered dialysate, or other
physiological solutions, enters through port 33 and establishes a
swirling current within headspace 31. This current has the
beneficial effect of sweeping thrombus particles that may have
accumulated in the headspace and flushing the particle through
outlet 32. Inlet blood flow rate will typically be 50-1000 mL/min,
preferably 350-600 mL/min. Infusion of dilution fluid at the exit
cap will generally be 1-50% of inlet blood flow, preferably 20-30%
in order to establish swirling. The foregoing ranges are set forth
solely for the purpose of illustrating typical operating
parameters. The actual parameters for operation of a device
constructed according to the principles of the present invention
may obviously vary outside of the listed ranges without departing
from those basic principles.
[0031] Infusion port 33 includes bond socket 34, and outlet 32
includes bond socket 35. Each bond socket is adapted to receive
flexible tubing. Where the tubing is generally constructed of PVC
and the bond socket is constructed of any one of a number of
thermoplastic resins including PVC, polycarbonate, ABS, etc., PVC
being preferable as it is solvent bonded to the housing, the tubing
may be fused to the bond socket by brief immersion in cyclohexanone
or other suitable organic solvent before inserting the tubing in
the bond socket. Soft PVC is flexible, allowing the cap to have an
interference fit when solvent bonded. This makes it less
susceptible to tolerance problems.
[0032] FIG. 3A depicts a side view of an embodiment of cap 30 with
blood outlet 32 and bond socket 35. FIG. 3B depicts a side view of
another embodiment of cap 30 having blood outlet 32 and bond socket
35. FIG. 3C depicts a side view of still another embodiment of cap
30 having blood outlet 32 and bond socket 35. Filter housing 10 is
slideably received within the opening in cap 30 when fully
inserted, housing 10 rests against annular ridge 36. Headspace 31
is defined by the gap between filter 20 and cap 30.
[0033] FIG. 4A shows the details of bond socket 35 communicating
with the blood outlet designed for interference fit with
appropriately sized tubing. Passage 41 has a dimension of
approximately 0.185 inches in diameter. Surface 43 is approximately
0.248 inches in diameter. Annular member 42 has a height of
approximately 0.35 inches. Surface 45 is approximately 0.252 inches
in diameter. Thus, blood outlet 32 communicates with a quarter inch
bond socket. Replacement fluid infusion port 33 communicates with
bond socket 34 shown in details in FIG. 4B. Passage 41 has a
dimension of approximately 0.098 inches in diameter. Surface 43 is
approximately 0.142 inches in diameter. Annular member 42 has a
height of approximately 0.31 inches. Surface 45 is approximately
0.147 inches in diameter. The foregoing ranges are set forth solely
for the purpose of illustrating typical device dimensions. The
actual dimensions of a device constructed according to the
principles of the present invention may obviously vary outside of
the listed ranges without departing from those basic
principles.
[0034] FIG. 5 depicts housing 10 inserted within cap 30. Headspace
31 communicates with outlet 32, which in turn communicates with
bond socket 35. Headspace 31 ranges from approximately 1.5 mm at
the outer edge to approximately 3 mm in the center of the dome-like
region. In use, the pressure in headspace 31 can reach 40 PSI (2000
mmHg), resulting in 25 lbs force pushing the cap off. The cap 30
may therefore need to be bonded, threaded, or snapped on, or
attached by other suitable means, to withstand pressure. Solvent
bonding and use of a threaded cap are two suitable means to
accomplish attachment. It will again be understood that these
device dimension are merely illustrative as stated above. FIG. 6
depicts a top view of another embodiment of cap 30 having ribs
37.
[0035] Although the foregoing invention has, for the purposes of
clarity and understanding, been described in some detail by way of
illustration and example, it will be obvious that certain changes
and modifications may be practiced which will still fall within the
scope of the appended claims. For example, it will be understood
that any feature of any device or method disclosed herein can be
used with any of the other devices or methods, even though any
given figure might depict only a particular combination.
* * * * *