U.S. patent application number 09/904709 was filed with the patent office on 2003-01-16 for hemodilution cap and methods of use in blood-processing procedures.
This patent application is currently assigned to NxStage Medical, Inc.. Invention is credited to Brugger, James M., Burbank, Jeffrey H., Stillig, Martin.
Application Number | 20030010718 09/904709 |
Document ID | / |
Family ID | 25419613 |
Filed Date | 2003-01-16 |
United States Patent
Application |
20030010718 |
Kind Code |
A1 |
Burbank, Jeffrey H. ; et
al. |
January 16, 2003 |
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: |
Burbank, Jeffrey H.;
(Boxford, MA) ; Stillig, Martin; (Dransfeld,
DE) ; Brugger, James M.; (Newburyport, MA) |
Correspondence
Address: |
PROSKAUER ROSE LLP
PATENT DEPARTMENT
1585 BROADWAY
NEW YORK
NY
10036
US
|
Assignee: |
NxStage Medical, Inc.
|
Family ID: |
25419613 |
Appl. No.: |
09/904709 |
Filed: |
July 12, 2001 |
Current U.S.
Class: |
210/651 ;
210/321.79; 210/321.8; 210/646 |
Current CPC
Class: |
A61M 1/3437 20140204;
A61M 1/3434 20140204; A61M 1/3672 20130101; B01D 63/02 20130101;
B01D 61/20 20130101; B01D 61/30 20130101; B01D 2313/21 20130101;
A61M 1/342 20130101 |
Class at
Publication: |
210/651 ;
210/646; 210/321.79; 210/321.8 |
International
Class: |
A61M 001/34; B01D
061/00; B01D 061/24; B01D 061/28; B01D 061/14; A61M 001/18 |
Claims
What is claimed is:
1. An extracorporeal filter, comprising: a housing having an inlet
for blood and an outlet for waste and ultrafiltrate; a cap attached
to the housing opposite the inlet, the cap having an outlet port
for blood and an infusion port; and a filter media received within
the housing.
2. The filter of claim 1, wherein the infusion port is radially
adjacent the outlet port for blood.
3. The filter of claim 1, wherein the cap is solvent bonded to the
housing.
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 cap is molded of flexible PVC
and is solvent bonded to the housing.
10. The filter of claim 1, wherein the blood outlet communicates
with a bond socket adapted to receive a flexible tubing.
11. The filter of claim 1, wherein the housing is generally
cylindrical.
12. The filter of claim 1, wherein the replacement fluid port
communicates with a bond socket adapted to receive a flexible
tubing.
13. The filter of claim 1, wherein the blood inlet communicates
with a bond socket adapted to receive a flexible tubing.
14. The filter of claim 1, wherein the waste outlet communicates
with a bond socket adapted to receive a flexible tubing.
15. The filter of claim 1, further comprising a second outlet for
waste and ultrafiltrate.
16. The filter of claim 1, further comprising a second inlet for
blood.
17. A method for filtering blood, comprising the steps of:
providing a housing having a filter, an inlet for blood, an outlet
for blood, a headspace between the filter and the outlet, and an
infusion port communicating with the headspace; passing blood
through the inlet; passing blood through the filter; passing blood
through the outlet; and infusing dilution fluid into the infusion
port to produce hemodilution at the outlet.
18. The method of claim 17, further comprising the step of infusing
dilution fluid into a port adjacent the inlet to produce
hemodilution at the inlet.
19. The method of claim 17, wherein the housing is cylindrical.
20. The method of claim 17, wherein the dilution fluid swirls in a
circular pattern in a gap between the filter and the outlet.
21. The method of claim 17, wherein the housing has an outlet for
waste and ultrafiltrate.
22. The method of claim 17, wherein the blood outlet is mounted on
a cap that is solvent bonded on the housing.
23. The method of claim 17, wherein the step of passing blood
through the filter produces hemoconcentration at the outlet.
24. The method of claim 17, wherein the step of passing blood
through the filter removes waste and ultrafiltrate.
25. The method of claim 17, wherein the dilution fluid is a
physiologic replacement fluid.
26. The method of claim 17, wherein the dilution fluid is
saline.
27. The method of claim 17, wherein the dilution fluid is sterile
filtered dialysate.
28. The method of claim 17, wherein the dilution fluid is Ringer's
lactate.
29. A method for filtering blood, comprising the steps of:
providing a housing having an inlet for blood, an outlet for blood,
and an infusion port adjacent the outlet, the housing having a
filter,; passing blood through the inlet; passing blood through the
filter; passing blood through the outlet; and infusing dilution
fluid into the infusion port adjacent the outlet to produce
hemodilution at the outlet.
30. The method of claim 29, further comprising the step of infusing
dilution fluid into a port adjacent the inlet to produce
hemodilution at the inlet.
31. The method of claim 29, wherein the housing is cylindrical.
32. The method of claim 29, wherein the dilution fluid swirls in a
circular pattern in a gap between the filter and the outlet.
33. The method of claim 29, wherein the housing has an outlet for
waste and ultrafiltrate.
34. The method of claim 29, wherein the blood outlet is mounted on
a cap that is solvent bonded on the housing.
35. The method of claim 29, wherein the step of passing blood
through the filter produces hemoconcentration at the outlet.
36. The method of claim 29, wherein the step of passing blood
through the filter removes waste and ultrafiltrate.
37. The method of claim 29, wherein the dilution fluid is a
physiologic replacement fluid.
38. The method of claim 29, wherein the dilution fluid is
saline.
39. The method of claim 29, wherein the dilution fluid is sterile
filtered dialysate.
40. The method of claim 29, wherein the dilution fluid is Ringer's
lactate.
41. The method of claim 29, wherein there is a headspace between
the filter and the outlet.
42. The method of claim 41, wherein the dilution port communicates
with the headspace.
43. A blood-processing device, comprising: a housing having an
inlet for blood and an outlet for waste; a fiber membrane received
within the housing; and a cap attached to the housing opposite the
inlet, the cap having an outlet for blood, a headspace between the
fiber membrane and the cap, and an infusion port communicating with
the headspace.
44. The blood-processing device of claim 43, further comprising an
inlet for dialysate.
45. The blood-processing device of claim 43, further comprising a
second port adapted to receive dilution fluid radially adjacent the
inlet.
46. A blood-processing device, comprising: a housing having an
outlet for blood and an outlet for waste; a fiber membrane received
within the housing; and a cap attached to the housing opposite the
outlet, the cap having an inlet for blood, a headspace between the
fiber membrane and the cap, and an infusion port communicating with
the headspace.
47. The blood-processing device of claim 46, further comprising an
inlet for dialysate.
48. The blood-processing device of claim 46, further comprising a
second port adapted to receive dilution fluid radially adjacent the
outlet.
49. The blood-processing device of claim 46, wherein the infusion
port is radially adjacent the inlet for blood.
50. A method for processing blood, comprising the steps of:
providing a housing having a fiber membrane, an inlet for blood, an
outlet for blood, a headspace between the fiber membrane and the
outlet, and an infusion port communicating with the headspace;
passing blood through the inlet; passing blood into contact with
the fiber membrane; passing blood through the outlet; and infusing
dilution fluid into the infusion port to produce hemodilution at
the outlet.
51. The method of claim 50, wherein the housing further comprises
an inlet for dialysate.
52. The method of claim 50, wherein the housing further comprises a
second port adapted to receive dilution fluid radially adjacent the
inlet.
53. The method of claim 50, wherein the infusion port is radially
adjacent the outlet for blood.
54. A method for processing blood, comprising the steps of:
providing a housing having a fiber membrane, an inlet for blood, an
outlet for blood, a headspace between the fiber membrane and the
inlet, and an infusion port communicating with the headspace;
passing blood through the inlet; infusing dilution fluid into the
infusion port to produce hemodilution at the inlet; passing blood
into contact with the fiber membrane; and passing blood through the
outlet.
55. The method of claim 54, wherein the housing further comprises
an inlet for dialysate.
56. The method of claim 54, wherein the housing further comprises a
second port adapted to receive dilution fluid radially adjacent the
outlet.
57. The method of claim 54, wherein the infusion port is radially
adjacent the inlet for blood.
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 constructions 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.
* * * * *