Note: Descriptions are shown in the official language in which they were submitted.
1153960
BACRGROU~D OF ~HE INVENTION
Capillary fiber dialyzers are sold in larse
cuæntities by various.companies for use as artificial
kicneys for the dialysis of blood. Typical~y, these
5 various commercial devices comprise a bundle of hollow
fibers disposed in a generally rigid tubular housing,
with the bundle and housing having relatively diametrically
enlarged mznifold members adjacent opposite housing ends.
A sealing cap is then placed on each housing.end, with
lO the sealing cap defining a central port for the flow
of blood from end to end of the housing~ passing through
tne bores of the hollow fibers in the bundle
Dialysis solution passes through the bundle of
fibers in contact with the exterior surfaces.of the
lS individual fibers, entering the housing through a side
port in one of the enlarged manifold members, and being
withdrawn from another port in the side of the other
enlarged manifold member. The ends of the bundle of
:~ollow fibers are potted with a urethane material or the
20 like, to stabilize the fibers and to secure them in a
single mass, with the bores of the fibers being exposed
to ?e~it flow communication alons their lengths.
Fr~cuently, an O-ring is provided between the end of the
manifold member and the end closure member, to provide
25 a he~metic seal.
In the conventional techniques of manufac.uring
hollow fiber dialyzers, the bundles of fragile fibers,
1153960
upon assembly into dia~yzers, exhibit a substantial
~umber of instances of fiber breakage, occurence of shoxt
~ibers, &nd the like which results in leaking units which
must be discarded or repaired. Often, some of the fibers
misalign, and flare out into the enlarged manifold member,
whe~ they should remain in a discrete ~undle during the
potting process. This can result in a leakage situation,
for even a single leaking fiber must result in the
scrapping of the entire dialyzer unless it can be
repaired.
The unit cost of dialyzers is incréased by the
need in many designs of a separate O-ring at its end for
sealing. Also, the O-ring is conventionally compressed
2S the end closure member is applied to provide the seal.
~owe~er, in the case of a vinyl O-ring or another material
which is subject to cold flow upon storage, the dialyzer
mzy lose its sealing capabilities provided by the O-ring
because of the cold flow of the ring material in response
to the compressive forces. The result of this is that
_he seal itself is weakened, and small amounts of blood
may leak from the end closure of the dialyzer.
In accordance with this invention, &n improved
se~ling system is provided in which a resilie~t sealing
me~ber is not placed under significant initial compression,
so that sig~ificant cold flow does not take place upon
storage. As a result of this, dialyzers in accord&nce
with this irvention may be stored indefinitely without a
significant diminution of their good end sealing capa~ilities.
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1153960
A capillary fiber diffusion device is provided
herein which may be made with a significantly lower
scrap rate, greatly reducing the uni. cost of the
oi2llyzer, which also has improved shelf life with respect
5 to its end seals, and an intrinsically lower cost because
a separate, preformed o-ring is not necessar~ in the
designs proposed.
DESCRIPTION OF THE INVENTIO~
In this invention, a hollow fiber diffusion
~evice comprises a bundle of hollow fibers disposed in
a generally rigid, tubular housing, with the-housing having
relatively diametrically enlarged manifold members adjacent
opposite housing ends, and being sealed at said opposite ends.
In accordance with this invention, a relatively
resilient plastic sleeve member is carried at each end of
said housing and sealed thereto. Each sleeve member carries
an integral added inner sleeve of less inner diameter than
the inner diameters of the manifold members. The inner
sleeves are spaced radially inwardly of the remainder of
said plastic sleeve member to define a space therebetween
open at one end and coaxially positioned with said housing to
receive, hold and center the ends of said bundle. The inner
sleeve contains a mass of potting compound which is inter-
spersed throughout the exterior surfaces of the fibers ofsaid bundle and the inner sleeve is made of a material which
sealingly adheres to the potting compound.
.
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1153960
Since the inner sleeve is made of a material
which sealingly adheres to the potting compo~nd,
a strong seal is formed between the potting compound
and the inner sleeve. For example, the potting compound
5 may be a compatible urethane material, and the inner
sleeve may be a polyvinyl chloride thermoplastic material.
The relatively resilient plastic sleeve which
carries the inner sleeve also may define an outer
sleeve which fits in telescoping relation into the inner
surface of the enlarged manifold members, and may be
sealed thereto by solvent sealing or the like. Accordingly,
a solid, complete seal of the inner ends of the dialyzer
is provided, forcing all fluid passing from end to end
of the dialyzer to pass through the bores of the fibers,
which are centered and held by the inner sleeve.
The diffusion device of this invention is
typically contemplated to be a dialyzer for blood.
However, it is understood that it may also be utilized
as an oxygenator for blood, an ultrafiltration device, a
reverse osmosis module, a membrane plasmapheresis device,
or the like.
Typically, the ends of the housing may each be
sealed by means of an attached end closure member. The
end closure member may define a central port, ~s well as
an inwardly pointing, annular sealing ring positioned to
sealingly press against the end of the inner sleeve.
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li53~60
The effect of this is to define a manifold in the
interior area of the sealing ring which provides commu-
nication between the central port and the interiors of
the fibers of the bundle and has a very low volume,
S which is particularly desirable in the procéssing of
blood.
Additionally, the end closure m~mhers utilized
in this invention may define a plurality of eccentrically-
positioned sleeves adapted for communication with the
exterior space about the inner sleeve and the sealing
ring. These eccentrically-positioned sleeves can define
access ports to permit extrusion of an 0-ring into the
area about the annular sealing ring, to form ar. 0-ring
seal about said sealing ring which is not substantially
compressively stressed. Thus, the seal will not be
subject to significant cold flow on storage to compxomise
the quality of the seal.
Also, the eccentrically positioned sleeves may
be used as torquing lugs, if desired, to place a threaded
closure on a threaded housing end for sealing, or for
opening the closure member, if such is necessary, for
a repair operation or an inspec~ion during manufacture.
The hollow fiber diffusion device of this inven-
tion may be manufactured by applying the relatively
resilient plastic sleeve member, which has a closed end,
to each end of the housing and sealing it within the
housing end. An end of the bundle of hollow fibers is
inserted into each inner sleeve, which inner sleeve is
spaced radially inwardly of the remainder of the plastic
--6--
llS3~60
sleeve member, and coaxially positioned within the
housing to hold and center the bundle ends. The inner
sleeve preferably defines the closed outer end.
Potting compound is then applied to the ends
5 of the bundle to permeate and enclose the bundle ends
within the sleeve. This may be done by rotating the
dialyzer so that the ends of the housing revolve around
the rotational center, while simultaneously applying
the potting compound through the side dialysate ports
from where it migrates radially outwardly to,the bundle
ends, to fill the closed-end inner sleeves to the desired
level. Conventional potting compounds, such as poly-
urethane formulations, used in the commercial manufacture
of hollow fiber dialyzers may be used in this invention.
After the potting compound has cured, the outer
end of the inner sleeve and the outermost portion of the
fiber bundle end may be sliced away, to expose the open
bores of the individual fibers of the bundle. The inner
sleeve is preferably made of a material such as a polyvinyl
chloride formulation which is easily cut by a slicing
instrument.
After this, the end closure member which defines
a central port and an inwardly pointing, annular sealing
ring may be attached to each end of the housing. In one
specific embodiment, the end closure may be twisted on by
a conventional interloc~ing screw thread arrangement.
However, solvent sealing or other techniques are also contem-
plated for sealing of the closures to the housing.
1153~6~
The sealing ring is proportioned to sealingly
press against the cut end of the inner sleeve. It may
be solvent-sealed against the cut end of the inner
sleeve for permanent and improved sealing, lf desiredr
or sealed by any other means. The effect of this is
to define a manifold chamber within the annular sealing
ring, for c~mmunication between the central port and
the bores of the bundle fibers.
As described above, sealant material may then
be applied through port means in the end closure to
form a sealant ring about the exterior of the sealing
ring. Since the sealant ring may be relatively uncompressed
since it is formed in situ, the quality of its seal does
not significantly deteriorate by cold flow upon storage.
Referring to the drawings, Figure 1 is a
perspective view of a hollow fiber dialyzer in a semi-
finished stage of manufacture, showing the attached,
relatively resilient plastic sleeve member of this inven-
tion carried at the ends of the housing.
Figure 2 is a longitudinal sectional view of an
end of the dialyzer of Figure 1 showina how, after the
potting of the fiber bundle, an end portion of the
relatively resilient plastic sleeve member may be sliced
away to expose the open fibers of the bundle embedded in
pot.ing compound.
Figure 3 is a fragmentary elevational view, taken
partly in longitudinal section, showing how an end closure
member in accordance with this invention may be attached
to the end of the housing to complete the assembly of the dialyzer.
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llS3960
Figure 4 is a fragmentary elevational view,
tæken partly in longitudinal section, of an alternative
e~bodiment of the dialyzer of Figure 1 showing a different
design of the relatively resilient plastic sleeve.
Figure 5 is an end elevational view of the
dialyzer of Figure 4j after the step of slicing away
an end portion of the relatively resilient plastic
sleevo member and application of an end closure for
sealing the dialyzer end.
Referring to the drawings, a hollow fiber
oiffusion device lO, which is specifically shown to be
a dialyzer for blood, comprises a bundle of,hollow
fibers 12 of a conventional type used in hollow fiber
dialyzers, disposed in a generally rigid, tubular housing
15 14 of a d~sign generally similar to co~mercial hollow
fiber dialyzers, except as otherwise described herein.
' ~ousing 14 carries at its opposed ends a pair
o. relatively diametrically enlarged manifold members
16, each of which defines a conventionally designed
20 dialysis solution access port 18, one of which is the
inlet and the other the outlet for dialysis solution.
Manifolds 16 permit the relatively uniform flow distri-
bution and collection of dialvsis solution prior to and
Lmmediately following its trip through the bundle of
25 ~ibers 12 in contact with the exterior surfaces of the
fibers.
In accordance with this invention, a relatively
resilient plastic sleeve member 20 is carried at each
i~
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1153960 --
end of the housing 14 and is sealed thereto conventionally
by solvent sealing or the like at the inter ace betwee~
outer sleeve 22 of sleeve member 20 and the annular end
24 of the tubular housing, as particularly shown in
Figure 2.
Each sleeve member 20 carries an addec inner
sleeve 26, with sleeve member 20 defining, preferably at
inner sleeve 26, a closed end 28. As shown in the
drawings, inner sleeve 26 is of less inner diameter than
~he inner diameters of the manifold members 16, with
inner sleeve 26 being coaxially positioned with housing
~4 to receive, hold and center the ends of bundle 12.
Each inner sleeve may contain a mass of potting
compound 30 which is interspersed throughout the exterior
surfaces of the fibers of bundle 12. Inner sleeve 26 and
preferably tho entire sleeve member 20, which may be a
single molded piece, may be made of a resilient material
such as a polyvinyl chloride plastic formulation which
sealinsly adheres to potting compound 30, whicn in turn,
may be a urethane formulation or a similar material capable
of bonding with the material of inner sleeve 26.
Accordinsly, the ends of bundle 12 are f irmly secured
in a tightly sealed, potted mass.
Preferably, the inner diameter of inner sleeve 26
is essentially the same as the inner diame~er of central
pcr~tions 32 of the tubular housins. Also, it is prefe~able
for at least par. of inner sleeve 26 to be spaced radlally
inwardly from the enlarged maniIold ends 16 o housing 14
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llS3g60
to define an open space 34 about the radlally outer
sur'ace of the inner sleeve 26. This open space can
~e seen in Figure 2, while in Figure 4 i_ is indicated
a~ ~8.
Inner sleeve 26 may define a sligh,t step 27,
while reinforcement members 25 are positioned between
inner sleeve 26 and outer sleeve 22.
Potting compound may be applied to the ends o_
the dialyzer in accordance witn U.S. Patent No. 4,227,295
issued to Bodnar and'Sc'hnell'on'~ctober~14', 1980, which
shows how the sealant may be inserted by spinning the
aiaiyzer so that manifold chambers 16 spin around the
center of rotation while simultaneously inserting the
potting compound through ports 18 until inner sleeve 26
is filled to the desired level. Thereafter, the pottins
co~Dound 30 is allowed to cure. One then transversely
slices through the inner sleeve 26 at point 31 with a
cutting blade or the like, to remove the closed end 28
and the potted end portion 36 of bundle 12, to expose t:~e
open bores of the fibers at the new shortened end 38 of
bu~dle 12.
Following this, an end closure member 40 may ~e
a~Fliec to the end of dialyzer 14, as shown in ~igure 3.
The s~ecific e~bodiment shown for application of the
end closure member 40 are the mating screw threads ~2, ~4,
al~hough other sealing techniques such 25 heat seallns or
solven. sealing may be used as well.
End closure 40 de'ines a central aperture 46 in
the conventional manner of an end closure of a hollow
1~53960
fiber dialyzer. In accordznce with this invention, the
end closure member 40 also includes an inwardly pointing
znnular sealing ring 48, which is positioned as shown in
Figllre 3 to press against the end of the inner sleeve 26.
5 If desired, an organic solvent such as methylisobutylket~ne
may be applied to the sealing ring 48 and/or the end o
inner sleeve 26 to provide a solvent seal bond between
the outer closure 40 and the inner sleeve 26. Outer
closure 40 may be made of a polystyrene-based plastic
10 material, with other copolymer ingredients added as desired,
which material is readily solvent sealable to the preferably
vinyl plastic material of inner sleeve 26.
As the result of this, a small manifold chamber
for blood 50 is provided, for communication between central
aperture 46 and the interiors of the bores of fiber bundle
12, in which manifold chamber 50 is of substantially less exter-
nal diameter than the overall internal diameter of end clos~re
m~ber 40. The effect of this is to reduce the blood
volume of the dialyzer, which is clearly desira~le, as well
as to avoid peripheral, stagnant areas, where bloo~ in a
mznifold faces a wall of po.ting compound which surrounds
bundle 12. Also, in accordance with this invention, t:~e
~mcunt of potting compound which is needed at each end is
greatly reduced, since the potting compound is retainea by
,he inner sleeve, which is spaced radially inwzrdly from
the inr.er wall of the manifold chamber.
End closure 40 may zlso define a plurality OL
ecce~trically positioned projecting me.~bers or pre-erably
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11~3~6~ _
sleeves 52, which are adapted for communication with t~e
exterior space about sealing rins 48 within end closure
40.- Projecting members 52 may be used 2S torquing lugs
to ~acilitate the application of the end closure 40.
5 ~owever, when desired, partitions 54, which are found in
sleeves 52, may be broken through (or not provided i~ the
fi2st place) to permit injection nozzles 56 to communicate
with the annular exterior sp2ce 51 positioned outside of
i~ner sleeve 26 and sealing ring 48, to extrude an O-ring
10 53 made of sealant, to fill exterior space 51. This O-
rin~ 53 in space 51 can reliably exercise its sealing
f~ction without being under such a level of compression
that it may tend to cold flow upon storage. As a result,
the dialyzers of this invention can exhibit a longer shelf
; 15 li e.
~ owever, in the embodiment of Figure 3, it may
not ~e necessary to utilize O-ring 53, since the sol~e3t
seal be.ween sealing ring 48 and inner flange 26 can provide
an adequate hermetic seal for the blood flow path thro~gh
zper.ure 46.
Referring to Figures 4 and 5, a different e.~od~ment
cf dialyze- and seal is disclosed i~ accordance with this
invention. 3ialyzer housing 14ahaving enlarged mani~olc
encs 15a 2nd access ports 18a are disc~osed as in the
previous design. A different design of preferably pol~Lnyl
chloride plastic sleeve member 60 is used, having a closed
end 62 as be~ore, and defining an outer sleeve 64 and æ~
inner sleeve 66, defining an annular aperture 68 pOCi.iChe~ i
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11~3960
between them which faces inwardly toward housing 14a, rather
than outwardly in the manner of the corresponding space
34 in the embodiment shown in Figure 2. Fiber bundle
12a is present, as is potting compound 30a, applied in th~
5 manner of the previous embodiment, and shown to fill annu-
lar aperture 68 as well as inner sleeve 66.
In this instance, after curing of the potting
compound 30a, plastic sleeve member 60 may be transversely
severed across both of its sleeves 64, 66 at slicing line
10 70-70, to separate the portion of sleeve member 60 which
contains closed end 62 from the rest of the dialyzer, a~d
to expose S~ves 64, 66 and sealant 30a therebetween.
Thereafter, an end closure member 40a which may be of a
design identical to closure member 40, is applied by
rotation about screw threads 42a to bring sealing ring 48a
into sealing contact with the end of inner sleeve 66~ as in
the previous embodiment.
It may be desired to not use a solvent seal between
ring 48a and inner sleeve 66, but instead to rely u?on
an extruded O-ring 72, which may be inserted into the
area outside of sealing ring 48a under end closure 40a by
extrusion through ports 52a in the manner previouslv
desc i~ed. O-ring 72 communicates with the sealant i~
annular space 68, and may form a tight adhesive bond wi.h
it, as well as bonding to the peripheral interior areas
of~end closure 40a, providing a firm, relatively uncomnressed
end seal, in which the sealant flows into exact sea~inc
conformity with every irregularity of shape present, tr.us
eliminating the need for a pressure seal which may colc -7OW.
i
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11S3~6(~
The above has been offered for illustrative
purposes, and is not intended to limit the invention
of this application, which is as defined in the claLms
below. ;
This is a division of Canadian Patent Application
Serial No. 354,353, filed June 19, 1980.
:; .
