Note: Descriptions are shown in the official language in which they were submitted.
The invention concerns a dialyser cartridge parti-
cularly suita~le for extracorporeal dialysis of blood.
Dialyser cartridges of the coil type which comprise
a central hollow core about which a membrane tube and membrane
support material is wound in a s:ingle spiral are in use. In
such devices, the blood inlet (our outlet) leads into the
membrane tube through the central hollow core and the blood
outlet (or inlet) leads out of the membrane tube at or towards
the outer periphery of the spiralled membrane tube and membrane
support material. Connection of the blood inlet and outlet
lines to the membrane tube has, in known devices, involved
practical difficulties in that, for example, a confined space
needs to be worked in when connecting up blood lines to the
membrane tube through the central hollow core.
An object of the present invention is to provide
a coil-type dialyser of a construction enabling both blood
inlet and outlet connection at the outer periphery of the
spiral and furthermore to provide a dialyser of the coil
type in which there are no free spaces through which preferen-
tial flow of dialysate, necessitating recirculation of
dialysate, can take place.
In accordance with the invention, there is provided
a dialyser cartridge comprising a flat membrane tube through
which blood to be dialysed may be passed, membrane support
material over the outer surfaces of the membrane tube, a split
core between which a central portion of the membrane tube and
membrane support material is located and about which core said
membrane tube and membrane support material are outwardly
spirally wound so that the free ends of the membrane tube
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and membrane support material are situated at the outer peri
phery of the winding, a hollow cylindrically walled casing
encasing the split core and spirally wound membrane tube and
membrane support material, two longltudinal slots in said
hollow cylindrically walled casing Eor the passage of said
membrane towards the outside, blood inlet means for connection
to an arterial line and blood outlet means for connection to a
blood venous line leading through the circumferential wall of
the casing into the ends of the membrane tube, and a pair of
end covers fixed to the ends of the hollow cylindrical casing,
one end cover having a dialysate inlet for connection to a
dialysate supply line and the other end cover having a dialysate
outlet for connection to a dialysate take-off line.
The membrane support material may comprise a series
of spaced apart parallel elements lying against the outer
surfaces of the membrane tube, the parallel members against
one side of the membrane tube being at an angle relative to
the series of parallel members against the other side of khe
membrane tube. The membrane support material may comprise bands
of sheet material having on one side a series of spaced apart
parallel ribs which then constitute the parallel members, the
membrane tube being sandwiched between a pair of such bands
with their ribs facing inwardly towards one another. The
parallel members against one side of the membrane tube may be
at an ac~te angle relative to the axis of the cylindrical casing,
and the parallel members against the other side of the membrane
tube may be at the sa~e but opposite acute angle relative to
said axis. The parallel members may have a series of spaced
grooves, the grooves in adjacent parallel members being subs-
tantially parallel to the length of the membrane tube.
The split defined by the split core may be of substan-
tially S-section, and the split core as a whole may be of subs-
tantially circular section. In this maoner, presuming that
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the split core sections are closed-ended, little or no free
space, through which preferential flow of dialysis liquid would
take place is defined.
The hollow cylindrically walled casing may have at
its inner surface a pair of radially directed abutment ~ace of
a breadth corresponding to the thickness of the membrane
support material to abut against the free ends of the membrane
support material at the outer periphery of the spiral. The
purpose of these abutment faces, it will be appreciated is as
with the S-sectioned split core, to eliminate any free space
through which preferential flow of dialysis liquid would take
place.
The blood inlet and blood outlet means may comprise
connector elements having means for connection to an arterial
line and venous line respectively and may have flat convex-
sectioned hollow mouth sections sealingly located in the ends
of the flat membrane tube between its adjacent sheets.
The ends of the membrane tube and the blood inlet
and blood outlet means may be located between seals provided
in the circumferential walls of the casing.
The invention will now be described with reference
to the accompanying drawings showing, by way of example, an
embodiment of the invention.
In the drawings:
Figure 1 shows a perspective exploded view of a coil
dialyser, wherein the membrane tube and membrane support mate-
rial have not yet been wound about the split core;
Figure 2 shows a partly broken away side elevation
of the dialyser cartridge of Figure 1, in assembled condition,
Figure 3 shows an enlarged detail of the membrane
support material,
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Figure 4 shows an edge-on view of the membrane support
material viewing as indicated by IV-IV in Figure 3; and
Figure 5 shows a plan cross-section of the coil
dialyser in assembled condition, the form of the casing being
slightly modified from that shown in Figure 1.
Referring to the drawings, reference numeral 10
refers generally to a dialyser cartridge, which comprises a flat
membrane tube 12 through which blood to be dialysed may be
passed, and membrane support material 14 over the outer surfaces
of the membrane tube 12. The membrane support material com-
prises bands of sheet material having on one side a series of
spaced apart parallel ribs 16. The ribs 16 against one side
of the membrane tube 12 are at an angle relative to the series
of ribs against the other side of the membrane tube. In the
embodiment shown, the ribs are at an acute angle relative to
the axis of the cylindrical casing, the one set of ribs against
the one side of the membrane tube 12 being at the same but
- opposite acute angle relative to said axis as the other set of
ribs against the other side of the membrane tube.
Referring to Figures 3 and 4 of the drawings, the
ribs 16 have a series of spaced grooves 18, the grooves being
substantially parallel to the length of the membrane tube 12.
These grooves 18 allow small ~uantities of blood to flow pa-
rallel to the length of the membrane tube 12 instead of only
in the well-known criss-cross turbulent flow which arises in
dialyser arrangements having membrane supports comprising ribs
or strands at an angle relative to one another on either side
of the membrane tube 12.
A split core referred to generally by reference
numeral 20 is provided at the centre of the dialyser cartridge
10, between which a central portion of the membrane tube 12
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and membrane to support material 14 is located. The membrane
support material 14 is outwardly spirally wound about the split
core 20 (refer Figure 5) so that the free ends of the membrane
tube 12 and membrane support material 14 is situated at the
outer periphery of the winding. I'he split defined by the split
core is of substantially S-section, and the split core as a
whole is of substantially circular section. As can be seen
from Figure 5, no free spaces, through which preferential flow
of dialysate can take place, are formed.
A hollow cylindrically walled casing 22 encases the
split core 20 and spirally wound membrane tube 12 and memhrane
support material 14. Reinforcing elements 24 are provided to
strengthen the cylindrical casing and to prevent such from
bulging or collapsing under positive or negative pressure.
The hollow cylindrically walled casing 22 comprises
two longitudinal slots 29 the purpose of which is to enable said
membrane 12 to pass to the outside.
Blood inlet means 26 and blood outlet means, also
numbered 26 since blood inle,t and blood outlet are interchange-
able, are provided for connection to an arterial line and venousline respectively. The blood inlet and blood outlet means lead
through the circumferential wall of cylindrical casing 22 into
the ends of the membrane tube 12. The cylindrical casing 22
comprises a pair of wedge-sectioned cover plate 28 which mate
with and are secured to the wall of the cylindrical casing by
means of screws 30. The wall of the cylindrical casing and
cover plates 28 in combination form a seat for seating the blood
inlet and blood outlet 26, and furthermore each carry a seal 32
to seal the free ends of the membrane tube 12 with the blood
inlet and blood outlet means 26 at the ends of the membrane tube
between its adjacent sheets. A pair of end covers 34 ( see
Figure 2) are fixed to the ends of the hollow cylindrical casing
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22, one end cover having a dialysate inlet 36 (normally at the
top) for connection to dialysate supply line (not shown) and
the other end cover 34 having a dialysate outlet 38 for connec-
tion to a dialysate take-off line (not shown).
The hollow cylindrical walled casing has at its
inner surface, in the embodiment shown on the cover plates 28,
a pair of radially directed abutment faces 40 corresponding to
the thickness of the membrane support material 14 to abut
against the free ends of the support material at the outer
periphery of the spiral. As can be seen from Figure 5, no free
spaces through which preferential flow of dialysate can take
place, are formed.
The dialyser cartridge of the invention can be employ-
ed in conventional manner. Thus, blood is pumped through the
membrane tube 12, whilst dialysate flows over the outer sur-
faces thereof through the passages defined by the surface of
the membrane tube itself and the surface of the membrane support
material 14, between adjacent ribs 16. Blood flows through
the membrane tube 12 spirally inwardly to the centre of the
split core 20 and then spirally outwardly to the blood outlet
at the outer periphery of the winding~
