U.S. patent application number 11/163703 was filed with the patent office on 2006-05-04 for blood treatment dialyzer/filter design to trap and remove entrained gas.
This patent application is currently assigned to NXSTAGE MEDICAL, INC.. Invention is credited to James M. BRUGGER, Martin STILLIG.
Application Number | 20060091057 11/163703 |
Document ID | / |
Family ID | 36319501 |
Filed Date | 2006-05-04 |
United States Patent
Application |
20060091057 |
Kind Code |
A1 |
BRUGGER; James M. ; et
al. |
May 4, 2006 |
Blood Treatment Dialyzer/Filter Design to Trap and Remove Entrained
Gas
Abstract
A configuration of a blood microtubular filter/dializer used in
many kinds of renal replacement therapy systems can provide highly
a effective mechanism for removing air from the blood circuit of
such systems. In embodiments, for example, the invention takes
advantage of the slow flow rate that usually occurs where blood
exits the microtubules into a header area of the filter to provide
a settling area and, preferably, a air release mechanism.
Inventors: |
BRUGGER; James M.; (Boxford,
MA) ; STILLIG; Martin; (Dransfeld, DE) |
Correspondence
Address: |
PROSKAUER ROSE LLP;PATENT DEPARTMENT
1585 BROADWAY
NEW YORK
NY
10036-8299
US
|
Assignee: |
NXSTAGE MEDICAL, INC.
439 South Union Street 5th Floor
Lawrence
MA
|
Family ID: |
36319501 |
Appl. No.: |
11/163703 |
Filed: |
October 27, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60622863 |
Oct 28, 2004 |
|
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|
Current U.S.
Class: |
210/321.88 ;
210/321.89; 210/323.2; 210/420; 210/436 |
Current CPC
Class: |
B01D 61/20 20130101;
B01D 61/30 20130101; A61M 1/3627 20130101; B01D 19/0042 20130101;
B01D 63/00 20130101; B01D 65/00 20130101; B01D 63/02 20130101; B01D
19/0021 20130101; B01D 2313/06 20130101; B01D 2313/18 20130101 |
Class at
Publication: |
210/321.88 ;
210/321.89; 210/323.2; 210/436; 210/420 |
International
Class: |
B01D 63/04 20060101
B01D063/04 |
Claims
1. A blood treatment apparatus, comprising: a blood dialyzer or
hemofilter processing element including filter media into which
blood comes in contact during use; said processing element having a
header chamber where multiple flows of blood combine; said header
chamber being at a position where blood exits a treatment portion
of said blood purifier, said header chamber having at least one
blood outlet and at least one auxiliary outlet; a holder configured
to support said dialyzer or hemofilter in a position and
orientation such that air can accumulate in said header chamber in
a position in said header space that is adjacent and in
communication with said auxiliary outlet.
2. Apparatus as in claim 1, wherein said auxiliary outlet is remote
from said blood outlet.
3. Apparatus as in claim 1, wherein said auxiliary outlet is
opposite said blood outlet.
4. Apparatus as in claim 1, further comprising a valve connected to
said auxiliary port and pre-connected and sterilized together with
said blood purifier.
5. Apparatus as in claim 1, further comprising a multi-way stopcock
valve connected to said auxiliary port and pre-connected and
sterilized together with said blood purifier.
6. Apparatus as in claim 1, further comprising a multi-way stopcock
valve connectable to said auxiliary port and a syringe connectable
to said multi-way valve, said valve, syringe, and said blood
purifier forming a kit.
7. Apparatus as in claim 1, further comprising a holder, said blood
purifier having a longitudinal axis and said holder being
configured to support said blood purifier with said longitudinal
axis at an angle with respect to the vertical, as defined with
respect to the force of gravity.
8. Apparatus as in claim 1, further comprising a gas release
component connected to said auxiliary port and pre-connected and
sterilized together with said blood purifier, said air release
component being configured to permit gas to egress from said header
space without permitting blood to egress from said header
space.
9. Apparatus as in claim 8, wherein said air release component
includes a hydrophobic membrane.
10. A blood treatment apparatus, comprising: a blood purifier
including filter media into which blood comes in contact during
use; said processing element having a header chamber at a position
where blood exits a portion of said blood purifier, said header
chamber having at least one blood outlet and one auxiliary outlet
remote from said at least one blood outlet; said auxiliary outlet
being configured to permit the removal of gas accumulated in said
header chamber and addition and removal of medicament.
11. Apparatus as in claim 10, further comprising a valve connected
to said auxiliary port and pre-connected and sterilized together
with said blood purifier.
12. Apparatus as in claim 10, further comprising a multi-way valve
connected to said auxiliary port and pre-connected and sterilized
together with said blood purifier.
13. Apparatus as in claim 10, further comprising a syringe
connected to said auxiliary port.
14. Apparatus as in claim 10, further comprising a holder
configured to orient said blood purifier such that said at least
one blood outlet is lower, with respect to a direction of gravity,
than said auxiliary outlet.
15. Apparatus as in claim 10, further comprising a gas release
component connected to said auxiliary port and pre-connected and
sterilized together with said blood purifier, said air release
component being configured to permit gas to egress from said header
space without permitting blood to egress from said header
space.
16. Apparatus as in claim 15, wherein said air release component
includes a hydrophobic membrane.
17. A blood treatment apparatus, comprising: a blood purifier
including microtubular filter membranes in a bundle with one end of
said bundle terminating in a first manifold at a lower end of said
blood purifier and a second end of said bundle terminating in a
second manifold, blood flowing in an upward direction through said
filter media during use; said purifier having first and second
header chambers forming respective passages where flow divides and
coalesces in said first and second manifolds, respectively; said
second header having an outlet where a coalesced flow from said
second manifold flows out of said second header; said purifier
being of generally cylindrical construction with a longitudinal
axis parallel to said microtubular membranes; said second header
having an auxiliary port having fitted with a gas release membrane
to allow any gas bubbles in blood in said second header to flow out
of the auxiliary port; a holder configured to hold said purifier in
a preferred orientation in which said longitudinal axis forms an
angle with respect to a direction of gravitation force and with
said auxiliary port at a highest point of said second header and
said outlet being positioned remote from said port, said highest
point being determined with respect to said preferred orientation;
said holder and a body of said purifier having mechanical features
that prevent engagement of said purifier in said holder unless said
purifier is in said preferred orientation with respect to said
holder, thereby ensuring said purifier is used in said preferred
orientation; said holder being fixedly mountable on a blood
processing machine or some other base of reference in a fixed
orientation.
Description
BACKGROUND
[0001] One of the problems with fluid circuits in blood treatment
systems is entrained air (bubbles) in treatment fluids, infusate,
or blood. Treatment systems normally have air detectors to prevent
air from being injected into a patient, either because a venous
line carrying blood back to the patient contains air or because an
infusate line, such as the replacement fluid line of a
hemofiltration system, contains air. It is desirable for the air
detectors to be made sufficiently sensitive to prevent the rare
instances of long trains of air bubbles being injected into a
patient. But sensitivity high enough to prevent long thin trains of
bubbles may be high enough to alarm very small amounts of air which
pose no risk. In other words, sensitive air detectors alarm on a
lot of fall positives if they protect against all possible
risks.
[0002] A prior art approach has been to remove as much air from a
protected fluid circuit as possible. Putting air traps in fluid
circuits, particularly blood lines, has drawbacks. Air-settling
chambers necessarily involve stagnant flow, which creates a risk of
forming clots (e.g., for blood) or sedimentation or other
concentration of entrained material (e.g. medication).
[0003] The inventive embodiments provide various other features and
advantages in addition to or in lieu of those discussed above and
below. Many of these features and advantages are apparent from the
description below with reference to the following drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] FIG. 1 is a cross-section view of a filter usable in a
variety of different types of blood treatment systems oriented to
trap air in one or two header portions of the filter.
[0005] FIGS. 2A through 2C illustrate holders for use with the
filter device embodiment described herein, including a particular
example of application to a blood treatment device such as that of
FIG. 1.
[0006] FIG. 2D illustrates an example of a holder feature to
restrict orientations of a filter ensure that the filter is
oriented with respect to the force of gravity.
[0007] FIG. 3 illustrates a filter similar to that of FIG. 1 but
with a header port for removing air and/or disrupting or cleaning
clots.
[0008] FIG. 4A illustrates an assembly for use with the port of
FIG. 3 for removing air and/or disrupting or cleaning clots.
[0009] FIG. 4B illustrates a drip-chamber (or bubble trap)
embodiment similar to the embodiment of FIG. 4A.
[0010] FIG. 5 illustrates a header cap with a hydrophobic membrane
for automatically venting air.
[0011] FIGS. 6A through 9B illustrate a method for manufacturing a
filter having a two-piece header caps that allow the use of a
cylinder for a majority of the filter.
[0012] FIGS. 10A, 10B, and 11 illustrate the filter whose
manufacture is described with respect to FIGS. 6A through 9B.
[0013] FIG. 12 shows an alternative configuration for connecting a
dialysate manifold with a tubular body of the a filter according to
an embodiment of the invention.
[0014] FIG. 13 illustrates a single element header component that
uses a simple tube for the dialysate portion.
DETAILED DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a cross-section view of a filter usable in a
variety of different types of blood treatment systems oriented to
trap air in one or two header portions of the filter. A filter 100,
which may be a dialyzer, hemofilter, hemodiafilter, or any other
compatible blood treatment has a bundle of tubular media 132
connecting an arterial 160 and venous 155 head space which is
isolated from a filtrate space 130. Blood flows through ports 122
and 124 in header caps 110 and 136 as indicated by arrows 118 and
112 into and out of the arterial 160 and venous 155 head spaces,
respectively. A cylindrical filter body 128 encloses the filtrate
space 130 and contains filtrate (e.g., dialyzer) ports 126 and 120.
Arterial and venous headers 142 and 134 isolate the filtrate space
130 from the respective arterial 160 and venous 155 head
spaces.
[0016] The orientation of the filter 100 with respect to the pull
of gravity is shown with the understanding that gravity is assumed
to pull down with respect to the profile orientation of the drawing
page. If any air is entrained in the blood, it may settle in
pockets 151 and 153 in the arterial 160 and venous 155 head spaces
as indicated by air/liquid interfaces 152 and 150. The flow of
blood through the arterial 160 and venous 155 head spaces is
extremely slow due to the very small cross-sectional areas of the
filter fibers in the bundle 132. As a result, the arterial 160 and
venous 155 head spaces are an idea place for air to settle out.
With the indicated orientation, with blood outlet 124 pointing down
and away from the pocket 151. Since the blood moves at a very slow
rate in the arterial 160 and venous 155 head spaces, there is
little risk of reentrainment and air settles out very
effectively.
[0017] Air trapped in pocket 153 may travel through filter fibers
in bundle 132 up to venous head space 155 and accumulate in pocket
151. Since the pocket 153 is located near the top of the arterial
head space 160, air will tend to travel up a few of the fibers
closest to the top and collect in the pocket 151 without mixing in
with blood. This keeps the vast majority of fibers filled with
blood.
[0018] FIGS. 2A through 2C illustrate holder variations for the
filter embodiments of the present patent disclosure. The variations
are intended to illustrate examples and not intended to be
comprehensive or limiting. In FIG. 2A, a holder 175 of a blood
treatment machine orients a filter such as that of FIG. 1 and those
of the further filter embodiments described below. The holder 175
may be attached at a base thereof (not shown separately) to a blood
treatment machine 172 which may contain actuators, sensors, and
control elements as well as a fluid circuit, here illustrated as a
cartridge 180 enclosed between two parts 171 and 172 of the blood
treatment machine 172. A filter 100 that is preconnected to the
fluid circuit can easily be mounted in such an apparatus. The
holder 175 may be articulating to allow for some movement or change
of orientation of the filter 100 and is preferably a
spring-tensioned clamp that allows for one-handed insertion of a
filter 100. In an alternative embodiment, the holder 175 may be
attached to the 180 cartridge such that its orientation is obtained
when the cartridge 180 is positioned with respect to the blood
treatment machine 170. In FIG. 2B, a holder 194 is integrated into
a disposable unit 190 (such as the fluid circuit cartridge of FIG.
2A). For example, the holder 194 may be made of wire which is
connected to a plastic panel support 191 of the disposable unit.
Examples of such disposable units are disclosed in U.S. Pat. No.
6,955,655 for "Hemofiltration system" and U.S. Pat. No. 6,579,253
for "Fluid processing systems and methods using extracorporeal
fluid flow panels oriented within a cartridge," each of which is
hereby incorporated by reference as if full set forth in its
entirety herein and U.S. patent application Ser. No. 10/650,935
published as US 2004-0069709, which is incorporated by reference
above. The holder 194 supports a filter 192 such that when the
disposable unit 190 is mounted, in a treatment device such as 170,
the filter 192 is held at an angle as shown. Another alternative
arrangement shown in FIG. 2C is to provide a separate support 178
that is attached, or attachable, to a support 176.
[0019] FIG. 2D illustrates an example of a holder feature to
restrict orientations of a filter ensure that the filter is
oriented with respect to the force of gravity. The view is a
sectional view. In the example, the filter 166 has tabs 162 and 164
that prevent the filter 166 from being received fully within a
flexible trough 168 which functions as a holder. This may be
confirmed by inspection. The flexible trough 168 allows the filter
166 body to fit into it fully in only one orientation, the holder
providing an urging force that keeps the filter 166 in place when
inserted. Note that the example illustrated in FIG. 2D is only one
of many devices that may be used to restrict the orientation of the
filter when attached to a holder and is not intended to be limiting
of the scope of any of the inventions described in the present
disclosure.
[0020] FIG. 3 illustrates a filter similar to that of FIG. 1 but
with a header cap 210 having an integrated header port 200 for
removing air and/or disrupting or cleaning clots. Tubing 265 may be
connected to the port and provided with a clamp 260. The clamp 260
may be released, at intervals, by an operator, to vent air from the
air pocket 251 and re-engaged to prevent blood loss. The clamp 260
may be a normally-closed type clamp with a strong spring so that it
reclamps tubing 265 when released. The tubing 265 may be capped
with a microporous filter end cap 253 to prevent any contamination
re-entering the blood in the venous head space 155. The entire
assembly that includes the filter 100, tubing 265, and microporous
filter end cap 253 may be fused, sealed, and sterilized as a unit.
In addition the same may be fused, sealed and sterilized as a unit
with an entire treatment circuit, combining it with the circuit
described in U.S. patent application Ser. No. 10/650,935 published
as US 2004-0069709, which is hereby incorporated by reference as if
full set forth in its entirety herein. With this combination, the
entire circuit may be isolated from contamination.
[0021] FIG. 4A illustrates an assembly 350 for use with the port of
FIG. 3 for removing air and/or disrupting or cleaning clots. The
port 200 has a tube 310 connecting the venous head space 155 with a
multi-way valve (e.g., a stopcock as shown) 312. The multi-way
valve 312 is further connected to a syringe 320 and tubing 375
connecting a supply of blood normal saline 375, heparin, drug, or
other medicament (such as from a tube 360 and bag 365) such as
anticoagulants, drugs, etc. The multi-way valve allows the syringe
to be connected, in a first position, to draw saline from the
source of saline 375 and, in a second position, to draw air from
the venous head space 155. In the second position, saline may be
pushed into the head space 155 to clear clots or for prophylaxis by
injecting medicament, for example, an anticoagulant such as
heparin. In an illustrative usage method, the multi-way valve 312
is set in the second position and air is drawn from the head space
155. Then it is set in the first position and saline is drawn into
the syringe 320. Then the multi-way valve 312 is set in the second
position again and saline (or saline and heparin) is injected into
the venous head space 155. The apparatus including the multi-way
valve 312, syringe 320, tubing 310, 375, 360 and clamp 260 may be
pre-attached to the filter 100 and presterilized as a unit.
[0022] Note that besides using the multi-way valve and bag 365 to
draw air from the header of a filter and inject medicaments into
the filter header, the same devices may be used in connection with
an air trap or drip chamber. Referring to FIG. 4B, a drip chamber
393 (which could also be a bubble trap or other similar device in
which air may accumulate and possibly be vented), has an inlet 391
and an outlet 394. A connection 392 to the top of the drip chamber
393 may be connected to the line 310 shown in FIG. 4A and used in
the manner described for removing air and/or injecting
medicaments.
[0023] FIG. 5 illustrates a header cap 210 with cover 280 sealed to
and covering the header port 200. The cover includes a hydrophobic
membrane 285 that allows air in the head space 155 to vent
automatically while preventing any contamination from entering.
[0024] Referring to FIGS. 6A and 6B, a method for manufacturing a
filter design that incorporates features of the foregoing examples
begins with the insertion of a filter fiber bundle 420 into a
cylindrical tube 405 which forms part of a housing (discussed with
reference to FIG. 11). The tube 405 is a straight tube with no
other structural features, in the present example. As such, the
tube 405 may be a thin walled structure allowing material to be
saved. In addition, it may be made of a material that is not
necessarily injection moldable, as filter housings generally are. A
preferred material is glycol-modified polyethylene terephthalate, a
copolyester (PETG) which may be a clear amorphous thermoplastic
with high stiffness, hardness, and toughness as well as good impact
strength. Other advantages of using a tube for the main part of the
housing will become clear from the further description below. Note
that in the drawing only one end of the tube is shown in the
present and following figures, but a complementary operation may be
performed at an opposite end of the tube 405 such that a
mirror-image structure is obtained.
[0025] The filter fiber membrane bundle 420 may be inserted such
that the fibers 415 extend beyond the end 407 of the tube 405 as
indicated at 445. Referring now to FIGS. 7A and 7B, the resulting
combination 430 of tube 405 and filter fibers 420 may be inserted
in a dialysis cap 435. Note that the term "dialysis cap" is for
convenience is not intended to limit the scope of the invention to
the manufacture of a dialyzer. The outer surface of the tube 405
lies adjacent an inner annular surface 440 of the dialysis cap and
a 450 bond is formed by thermal welding or sealing using adhesive,
solvent, or filling type bonding agent such as urethane to form a
completed structure 480. A symmetrical structure is formed at the
opposite end so that both ends of the tube 405 have a dialysate cap
435.
[0026] Referring now to FIGS. 8A and 8B, potting caps (not shown)
are placed over the ends of the structure 480 and the ends of the
fiber bundle are potted as according methods that are known in the
art of manufacturing filters. A preferred method of potting is
described in U.S. Pat. No. 6,872,346 for a "Method and apparatus
for manufacturing filters," which is hereby incorporated by
reference as if fully set forth in its entirety herein. The result
of potting is the creation of a sealed end of potting material
indicated at 440 which, after hardening, is cut along a planar
surface indicated at 460. The cut 460 is done in such a way that
the end of the filter fibers 420 are open at the surface 465
forming. A portion of the dialysate cap 435 may be trimmed off in
the process of cutting 460, as illustrated, although it will be
apparent to those skilled in the art that this is not essential and
instead, the fibers 420 could extend beyond the end of the
dialysate cap 435 before potting such that the fibers 420 can be
opened by cutting without cutting the dialysis cap 435. The
completed end portion is shown in FIG. 8B, and as discussed, a
symmetrical end portion may be completed at the opposite end (not
shown here).
[0027] Referring now to FIGS. 9A through 11, the two ends 600A and
600B of a single tube structure are indicated. Respective blood
caps 505 and 605 are fitted to the ends 600A and 600B of the
structure 480. Each blood cap has a respective blood port 510, 610
and one of the blood caps has a secondary port 610 which will be
recognized from the discussion of embodiments such as shown and
discussed with respect to FIGS. 3 through 5. The blood caps 505 and
605 have respective header spaces 645 that are preferably
hydraulically shaped to ensure that no, or a minimal number of,
dead (stagnant flow of blood) spaces arise when in use. In the
embodiment shown, a rim 515 fits into an annular recess 470 (or rim
615 into annular recess 471). Prior to fitting the blood caps 505
and 605, a bead 605, 606, 607, 608 of adhesive or sealing material
may be applied or injected in the annular recesses 470 and 471 to
form a bond between the structure 480 and the respective blood caps
505 and 605. The bonding may be done by thermal, friction, solvent
welding, compression bonding, or other technique. Dialysate ports
30 and 531 in the dialysate caps 435 and 425, respectively, allow
dialysate to flow into and out of the space occupied by bundle 420
and in contact with the external surfaces of the filter bundle 420.
For a hemofilter or other kinds of filters, such as sterile
filters, reverse osmosis filters, ultrafilters, etc.; only one
"dialysate" port would be required. Blood ports 510 and 610 in
blood caps 505 and 605, respectively, supply blood into, and be
recovered from, the header spaces 545 and 645, respectively. Air
can be removed from air removal/access port 610. As explained
above, removal/access port 610 can also be used for injection of
anticoagulants, drugs, or other medicaments.
[0028] As best seen in FIGS. 10A and 10B, a small gap 685, 686 is
provided between the end 407 (FIGS. 6A, 7A, 8A) of the tube 405
(FIGS. 6A, 6B) and the surface of the potting 440 to allow
dialysate to flow into the space occupied by the filter bundle 420.
The dialysate (or filtrate, depending on the application) is
distributed by an annular dialysate manifold space 626, 626.
Referring momentarily to FIG. 12, it is noted that instead of
providing for the gap 685, 686 in the manner described, the fiber
bundle may be extended all the way to the end 407 of the tube 405
and openings 705 can be provided to perform the function of the
openings 685, 686. The same features provide for extraction of
filtrate or dialysate or other fluid depending on the application.
FIG. 11 shows a complete filter unit. One of the benefits of the
design is that it makes it possible to confine the capital expense
associated with injection molding to the dialysate and blood header
reducing first costs in new filter designs. In addition, the design
allows the tubular portion to be lengthened and shorted without
requiring major design and manufacturing changes. Note that
although injection molding is not contemplated to be a requirement
for the practice of the invention or all its embodiments, it is a
preferred means for achieving the high precision and economies of
scale for articles of manufacture such as dialyzers, filters, and
hemofilters, as well as other applications of the disclosed
embodiments.
[0029] Referring to FIG. 13, the benefit of using a tube for the
filtrate/dialysate portion of the filter can be obtained by using a
single-element header cap rather than separate "dialysate" and
"blood" caps. In the example shown, a one-piece cap 725 has an
annular dialysate manifold 740 that is sealed by O-rings 747
against the surface of a tube 760. A blood header space 732 is in
communication with a blood port 730 and the dialysate manifold 740
is in communication with a dialysate port 735. Slits 750
(configured such as illustrated in FIG. 11) allow fluid
communication between the dialysate manifold 740 and the external
surfaces of the fiber bundle 733. A potting plug 745, in addition
to performing its normal function, serves to reinforce the
cylindrical structure of the tube 760 against the pressure of the
O-ring 747 seals. In this embodiment, a tube is permitted to be
used with a single-element cap 725 structure providing many of the
benefits of the inventions discussed above.
[0030] A tension band 757 may be used to ensure a good seal and
provide a final shape to the one-piece cap 725 if made of a
somewhat compliant resin to allow it to be removed from an
injection mold despite the recess defined by the dialysate manifold
740. Alternatively, the one-piece cap 725 may have a discontinuous
dialysate manifold that allows it to be created without requiring
the cap to yield, the cap could be machined rather than molded, or
the cap could be made of two molded pieces that are assembled into
a single cap. Many variations are possible.
[0031] It will be understood that while the invention has been
described above in conjunction with a few exemplary embodiments,
the description and examples are intended to illustrate and not
limit the scope of the invention. That which is described herein
with respect to the exemplary embodiments can be applied to the
measurement of many different formation characteristics. Thus, the
scope of the invention should only be limited by the following
claims.
* * * * *