U.S. patent number 3,771,658 [Application Number 05/190,800] was granted by the patent office on 1973-11-13 for blood transport membrane pump.
Invention is credited to Robert C. Brumfield.
United States Patent |
3,771,658 |
Brumfield |
November 13, 1973 |
BLOOD TRANSPORT MEMBRANE PUMP
Abstract
A slow speed drive rotates a cylindrical exchanger pump which
operates as a blood oxygenator, and also operates alternatively as
a blood dialyser. The pump has a cylindrical rotor permanently
mounted in a closely fitting internally cylindrical stator housing.
The rotor has a coaxial shaft which is eccentrically disposed
parallel to the internal axis of symmetry of the stator housing.
Admitted patient blood is pumped as a thin blood film in laminar
flow between the rotor and stator as the rotor exterior surface
eccentrically approaches the stator surface, and in eddy flow as
the rotor surface recedes from the stator surface. The blood is
introduced into the pump through a manifolded blood inlet having a
longitudinal groove disposed in the inner face of the stator
housing, the groove distributing blood to the annular space between
the rotor and stator. A second similar blood outlet combination
includes a longitudinal groove in the inner stator face,
facilitating blood removal from the pump. The rotor has permanent
shallow depth passageways disposed in its exterior surface parallel
to the rotor shaft axis of symmetry, providing controlled patterned
flow of an admitted secondary fluid. The fluid is secured in the
rotor passageways by a thin fluid-permeable membrane tightly
adjacently covering the passageways. The secondary fluid can be
oxygen gas or a liquid dialysate. When oxygenating gas is used, the
exchanger pump is a blood oxygenator. When a liquid dialysate is
used, the exchanger pump is a blood dialyser. The manifolded and
and jacketed stator housing provides heat transfer means for
controlling the temperatures of treated-blood of the patient.
Inventors: |
Brumfield; Robert C. (Laguna
Beach, CA) |
Family
ID: |
22702835 |
Appl.
No.: |
05/190,800 |
Filed: |
October 20, 1971 |
Current U.S.
Class: |
210/186; 415/90;
210/321.68; 210/321.78; 422/48 |
Current CPC
Class: |
A61M
1/1698 (20130101); A61M 1/267 (20140204); A61M
1/262 (20140204); B01D 63/16 (20130101); A61M
60/205 (20210101); A61M 60/829 (20210101); A61M
2205/3334 (20130101); A61M 60/818 (20210101); A61M
60/113 (20210101); A61M 60/40 (20210101); A61M
60/562 (20210101); A61M 60/50 (20210101) |
Current International
Class: |
A61M
1/10 (20060101); A61M 1/16 (20060101); B01D
63/16 (20060101); B01d 031/00 () |
Field of
Search: |
;23/258.5
;210/321,22,186 ;195/1.8 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Spear, Jr.; Frank A.
Claims
I claim:
1. In an apparatus for treating extra-corporeal patient blood, said
apparatus having a right cylinder rotor coaxially secured on a
rotor shaft, an internally cylindrical stator housing cylindrically
enclosing said rotor, and means providing cooperative bearing
support for said rotor shaft, the blood transport membrane pump
combination comprising:
a pair of rotor shaft bearing supports, each one of said pair of
bearing supports disposed adjacent one shaft terminus, said bearing
supports secured to precise positions on said rotor shaft,
a pair of shaft eccentricity adapters, each one of said adapters
cooperatively securing one of said pair of bearing supports,
disposing said rotor shaft in a precisely fixed eccentricity
parallel with the internal axis of symmetry of said internally
cylindrical stator housing,
a rigid cylindrical rotor shell coaxially disposed on said rotor
shaft, said rotor shaft adaptively disposed in said stator housing,
said shell having an external diameter precisely less than said
internal diameter of said stator housing,
a multiplicity of shallow patterned passageways disposed in the
cylindrical rotor shell exterior face parallel to the rotor shaft
axis of symmetry, providing a patterned secondary fluid flow inside
said passageways from a rotor shell entrance end to a rotor shell
exit end,
a thin membrane, permeable to a secondary fluid, covering the
exterior cylindrical shell surface of said rotor shell, providing a
fluid permeable cover over all said passageways, said membrane and
said rotor shell coaxially flushly secured together by membrane
retaining means, said membrane, said rotor shell and said retaining
means providing a rotor subcombination,
a blood laminar flow arc sector precisely disposed between said
rotor subcombination and said stator housing, said pair of shaft
eccentricity adapters cooperatively fixing the laminar flow arc
sector value, said arc sector providing blood pumping means during
rotation of said rotor subcombination, and
a blood eddy flow arc sector precisely disposed between said rotor
subcombination and said stator housing, said pair of shaft
eccentricity adapters cooperatively fixing said eddy flow arc
sector value, said arc sector providing blood film mixing means
during rotation of said rotor subcombination;
whereby the rotating said rotor subcombination provides laminar
blood flow in said laminar flow arc sector and provides
transitional and eddy flow in the remainder of the pump arc
sector.
2. An apparatus in accordance with claim 1 wherein a heat transfer
shell jacket covers the external cylinder face of said stator
housing, said jacket having a fluid inlet conduit and a fluid
outlet conduit secured to said jacket, said inlet conduit, said
jacket and said outlet conduit together providing a serial
passageway for a heat transfer fluid suitable for controlling
patient blood temperature.
3. A blood transport membrane pump combination comprising:
a slow speed drive and a hollow rotor shaft means coaxially secured
together,
a cylindrical pump rotor coaxially mounted on and secured to said
rotor shaft means, together providing a blood pump rotor means,
a multiplicity of shallow patterned passageways permanently
disposed in the exterior cylindrical rotor shell face parallel to
the rotor shaft axis of symmetry, providing a patterned flow inside
said passageways for a secondary fluid flow from a first rotor
cylinder end to a second opposed cylinder end,
a thin secondary fluid-permeable membrane completely covering the
exterior cylindrical shell surface of said pump rotor, membrane
retaining means flushly securing said membrane and said rotor
together, providing a fluid permeable cover for said passageways,
said membrane, said membrane retaining means, and said pump rotor
forming a rotor subcombination,
an internally cylindrical stator pump housing fitting around and
cylindrically enclosing said pump rotor and membrane
subcombination, said rotor shaft means secured to said
subcombination being eccentrically disposed parallel to the
internal axis of symmetry of said stator pump housing, said pump
housing and said pump rotor proportioned and cylindrically axially
copositioned providing a substantial thin annular laminar flow arc
area during rotor rotation, and cooperatively providing a
substantial eddy flow arc sector area during rotor rotation.
means providing cooperative bearing support, securing said rotor
shaft means and said stator housing,
means providing cooperative blood sealing support, securing said
rotor shaft means and said stator housing,
means providing heat transfer control disposed in the wall of said
stator pump housing, providing temperature control of blood
pumped,
means conductively secured to said satator housing, adjacent to
said area of laminar flow of blood, providing a blood inlet
conduit,
means conductively secured to said stator housing disposed in said
area of laminar flow of blood, providing a blood outlet
conduit,
means conductively secured to said hollow rotor shaft means,
adjacent said blood inlet conduit means, providing a secondary
fluid inlet conduit,
means conductively secured to said hollow rotor shaft means,
adjacent said blood inlet conduit means, providing a secondary
fluid inlet passageway to said shallow passageways disposed in the
exterior face of said rotor,
means conductively secured to said hollow rotor shaft means,
adjacent said blood outlet conduit means, providing a secondary
fluid outlet passageway from said shallow passageways in the
exterior face of said rotor, and
means conductively secured to said hollow rotor shaft means,
adjacent said blood outlet conduit means, providing a secondary
fluid outlet conduit,
whereby the rotating said rotor subcombination provides laminar
blood flow in said laminar flow arc sector and provides
transitional and eddy flow in the remainder of the pump arc
sector.
4. The blood transport membrane pump combination comprising:
a tubular rotor shaft, cooperatively adapted to a rotative drive,
having each one of a pair of rotating sealing glands disposed at
one shaft terminus, each said gland adapted to conducting the flow
of a secondary fluid,
a pair of rotor shaft bearing supports, each one of said pair of
bearing supports disposed adjacent one shaft terminus, said bearing
supports secured to precise positions on said rotor shaft,
a rigid tubular pump base having precisely positioned securing
means for said pair of bearing supports, the precise internal
diameter of said tubular base adaptively providing an internally
cylindrical stator housing,
a pair of shaft eccentricity adapters, each one of said adapters
cooperatively securing one of said pair of bearing supports,
disposing said rotor shaft in a precisely fixed eccentricity
parallel with the internal axis of symmetry of said internally
cylindrical stator housing,
a rigid cylindrical rotor shell coaxially disposed on said rotor
shaft, said rotor shell adaptively disposed in said stator housing,
said shell having an external diameter precisely less than the
internal diameter of said stator housing,
a multiplicity of shallow patterned passageways disposed in the
cylindrical rotor shell exterior face parallel to the rotor shaft
axis of symmetry, providing a patterned secondary fluid flow inside
said passageways from a rotor shell entrance end to a rotor shell
exit end,
a thin secondary fluid-permeable membrane completely covering the
exterior cylindrical shell surface of said rotor shell, providing a
fluid permeable cover over all said passageways, said membrane and
said rotor shell coaxially secured by membrane retaining means,
said membrane retaining means flushly securing said membrane to
said rotor, said membrane, said rotor shell and said membrane
retaining means together providing a rotor subcombination,
means associated with said shaft providing a pair of removable
circular end plates, each one of said end plates coaxially securing
one rotor shell end fluid tight,
means internally secured on said tubular stator housing providing a
pair of fluid seals, each one of said seals cooperatively sealing
one said removable end plate,
a pair of fixed circular end plates, one being a fixed inlet end
plate and one being a fixed outlet end plate, said plates being
permanently coaxially secured and positioned on said rotor shaft
providing a pair of index support positions, one plate disposed
inside a rotor subcombination inlet end and one plate disposed
inside a rotor subcombination outlet end, each said index position
providing a secondary fluid flow passageway through wall aperture
means in the tubular wall of said rotor shaft, then conducting
through aperture means in one said fixed end plate, then conducting
through a distributing manifold passageway disposed in the inner
face of said rotor shell, venting into said multiplicity of shallow
patterned passageways disposed in said rotor shell exterior face,
the above subcombination of said fluid flow passageways, blocked by
a fluid flow plug disposed in said rotor shaft between the inlet
wall aperture means and the outlet wall aperture means, providing a
reversible secondary fluid flow passageway subcombination through
said membrane pump,
a blood laminar flow arc sector precisely disposed between said
rotor subcombination and said stator housing, said pair of shaft
eccentricity adapters cooperatively fixing the arc sector value,
said laminar flow arc sector providing blood pumping means during
rotation of said rotor subcombination,
a blood eddy flow arc sector precisely disposed between said rotor
subcombination and said stator housing, said pair of shaft
eccentricity adapters cooperatively fixing said eddy flow arc
sector value, said eddy flow arc sector providing blood mixing
means during rotation of said rotor subcombination,
a blood inlet manifold conductively secured on said stator housing
parallel to said stator axis of symmetry, conductively venting
blood into said housing adjacent laminar blood flow arc sector,
and
a blood outlet manifold conductively secured on said stator housing
parallel to said stator axis of symmetry, conductively venting
blood exiting from said housing adjacent said laminar blood flow
arc sector;
whereby the rotating said rotor subcombination provides laminar
blood flow in said laminar flow arc sector and provides
transitional and eddy flow in the remainder of the pump arc
sector.
5. An apparatus in accordance with claim 4 wherein a heat transfer
shell jacket completely covers the external cylinder face of said
stator housing, said jacket having a fluid inlet conduit and a
fluid outlet conduit secured to said jacket, said inlet conduit,
said jacket and said outlet conduit together providing a serial
passageway for a heat transfer fluid suitable for controlling
patient blood temperature.
Description
BACKGORUND OF THE INVENTION
A patient's blood can be treated to saturate venous blood with
oxygen and remove carbon dioxide, as during advanced patient
treatment and during radical cardiopulmonary surgery. Likewise,
there is well established need for blood dialysis, to remove waste
products accumulating in blood during renal failure.
Apparatus for treating blood are classified in Class 23 Subclass
258.5. Blood oxygenerators are listed in this class. Kidney
dialysers are also listed in Class 23 Subclass 258.5.
Typically, in a rotary blood oxygenator, Thomas, in U.S. Pat.
3,026,871, discloses an apparatus in which a rotating horizontal
cylinder has a peripheral wall formed of silicone coated fabric.
The rotating fabric wall externally dips into a pool of patient
blood, which is then disposed on the cylinder surface. The blood
film is oxygenated by the oxygen diffusing from the cylinder
interior. Additional tubular spray means are provided for spraying
blood on the exterior wall of the cylinder fabric, thus increasing
the oxygenation rate of the blood.
SUMMARY OF THE INVENTION
A slow speed drive rotates a cylindrical exchanger pump which
operates as a blood oxygenator, and also could operate in principle
as a blood dialyzer apparatus, with the required secondary fluid.
The pump has a cylindrical rotor permanently mounted in a closely
fitting internally cylindrical stator housing. The rotor has a
coaxial shaft which is eccentrically disposed parallel to the
internal axis of symmetry of the stator housing. Admitted patient
blood is pumped by the exchanger pump, between the eccentrically
disposed rotor and the stator. The blood flows laminarly in a thin
film as a position on the eccentrically disposed rotor surface
approaches the stator surface. Eddy flow occurs as a position on
the rotor surface recedes from the stator surface. The rotor has
permanent passageways disposed in its exterior surface parallel to
the rotor shaft axis of symmetry, providing controlled patterned
flow of an admitted secondary fluid, which is secured in the rotor
passageways by a thin membrane tightly adjacently covering the
passageways, the membrane being permeable to the required secondary
fluid. The secondary fluid can be oxygenating gas or a liquid
dialysate. When oxygen gas is used, the exchanger pump is a blood
oxygenerator. When a liquid dialysate is used, the exchanger pump
is a blood dialyzer. Typically, the permeable membrane can be a
thin silicone rubber, in a blood oxygenator; or a selected
cellophane, in a blood dialyser. The stator housing is manifolded
and jacketed to provide heat transfer means for controlling the
patient's circulating blood temperature. Hollow shaft means provide
for the admittance of secondary fluid to the passageways and for
the waste fluid exit from the passageways. Blood inlet and outlet
conduits are conductively secured to the stator housing. The blood
is introduced into the pump through a manifolded blood inlet having
a longitudinal groove disposed in the inner face of the stator
housing, the groove distributing blood to the annular space between
the rotor and stator. A second similar blood outlet combination
also includes a longitudinal blood distribution groove for blood
removal from the pump.
Included in the objects of this invention are:
To provide a general type of apparatus for treating patient blood
which can be utilized separately as a blood oxygenator and also as
a blood dialyser.
To provide a blood exchanger membrane pump capable of pumping blood
during treatment in a blood oxygenating procedure, or in a blood
dialysing procedure.
To provide a blood exchanger membrane pump utilizing separately
oxygen gas in blood oxygenation procedure, or utilizing a blood
dialysis fluid in a blood dialysis procedure.
To provide an effective thin blood film for rapid mass transport of
oxygen and carbon dioxide in a blood oxygenation pump.
To provide rapid transport of urine excreta products from the blood
in a blood dialyser.
Other objects and advantages of this invention are taught in the
following description and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The description of this invention is to be read in conjunction with
the following drawings;
FIG. 1 is an elevational sectional and partial perspective view of
the blood transport membrane pump.
FIG. 2 is an enlarged perspective partial sectional view through
2--2 of FIG. 1.
FIG. 3 is a cross sectional view through 3--3 of FIG. 1
illustrating the overall cross sectional configuration of the blood
transport membrane pump .
DESCRIPTION OF THE PREFERRED EMBODIMENT
Refer to FIG. 1, FIG. 2 and FIG. 3 is in detail as required. In
FIG. 1 the blood transport membrane pump 10 is shown in side
elevational view detail, having a tubular rotor shaft 11 centrally
disposed substantially throughout a major fraction of the length of
pump 10. A concentric tubular aperture 12 is disposed in the shaft
11. A rotative drive pulley 13 and shaft key 13a are secured
adjacent a first shaft terminus 16. A first rotative sealing gland
14 for a secondary fluid is securely disposed on the shaft terminus
14 and a second rotative sealing gland 15 is disposed on the shaft
terminus 17 at the opposed shaft terminus. Tubular securing nipples
18 and 19 are respectively disposed on rotative sealing glands 14
and 15, supplying means for conducting a secondary fluid into the
pump 10. Typically the flow direction 20 of the secondary fluid is
that shown in the arrow direction indicated. A pair of rotor shaft
bearing supports 21 and 22 are each adjacently disposed to shaft
terminus 16 and 17 respectively. The bearing supports 21 and 22 are
secured in precise positions on the rotor shaft 11, each said
bearing support being removably securely locked to the shaft 11 by
conventional means. A rigid tubular pump base 23 has a precise
internal diameter 35 adaptively providing an internal cylindrical
stator housing for the pump 10. Precisely ground guide pin screws
24 and 25 are shown threaded into precision threaded apertures 28
and 29 respectively in the pump base 23, through the precisely
located apertures 26 and 27 respectively in the bearing supports 21
and 22. As in conventional precision bearing supports, a second
pair of ground guide pin screws secure the pair of bearing supports
21 and 22 on opposed bases of bearing supports, not shown. The pair
of unseen ground guide pin screws likewise are precisely screwed
into threaded apertures in the pump base 23, precisely locating
unseen opposed apertures in the bearing supports 21 and 22
respectively, providing precise location of 21 and 22.
A pair of shaft eccentricity adapters 30 and 31 are adaptively
disposed between the pair of bearing supports 21 and 22
respectively and the rigid tubular pump base 23. The shaft
eccentricity adapters 30 and 31 are secured by the respective guide
pin screws 24 and 25, disposing the rotor shaft 11 in a precisely
fixed eccentricity 32 parallel with the internal axis of symmetry
33 of the precision diameter 35 of the internally cylindrical
stator housing 23. The shaft eccentricity adapters 30 and 31 can be
metal shims, they can also be equivalent well known means for
precisely locating the eccentricity 32 of shaft 11 with respect to
the axis of symmetry 33 of the pump stator housing 23. Thus the
eccentricity 32 of shaft 11 is shown displaced vertically upward.
The eccentricity can equivalently be disposed along any internal
radius of the 360.degree. arc of the pump stator housing 23, for
the purpose of rapidly positioning the shaft 11 in a pre-determined
eccentricity 32 or the equivalent. Other securing means can be
used, replacing shims as shaft eccentricity adapters, such as
securing indexing pins, precisely machined lands or grooves, or the
like.
A rigid cylindrical rotor shell 34 is coaxially disposed on the
rotor shaft 11, the shell 34 having an external diameter 108, a
precisely fixed value less than the internal diameter 35 of the
station housing 23, as will be discussed later. The precision
diameter 108 of the rotor shell 34 is cooperatively related to the
internal precision diameter 35 of the tubular base 23. A
multiplicity of shallow depth patterned passageways 36 are disposed
in the cylindrical rotor shell 34 exterior face 37, providing a
patterned secondary fluid flow inside the multiple patterned
passageways 36 from a rotor shell entrance end 38 to a rotor shell
exit end 39 oppositely disposed on the rotor shell. The passageways
36 are disposed parallel to the rotor shaft 11 axis of symmetry,
with the lands 105 therebetween.
A thin secondary fluid-permeable membrane 40 completely covers the
exterior cylindrical shell face 37 of the rotor shell 34, providing
a fluid-permeable cover over all of the multiple passageways 36.
The tightly drawn fluid-permeable cover membrane 40 is shown in
further enlarged detail in FIG. 2. Typically, the thin membrane 40
is folded over the opposed ends of the rotor shell 34 and the pair
40 and 34 flushly secured by membrane retaining means, being a
slip-fit pair of retaining rings 41 and 42 respectively. Thus the
subcombination 43 consisting of the rotor shell 34, the cover
membrane 40, and a the pair of retaining rings 41 and 42 is a unit
which can be factory assembled, prepared ready for quick
replacement in a blood transport membrane pump. Each one of the
retaining rings 41 and 42 flushly secure the membrane 40 to an
opposed rotor end 38 and 39. Specifically, a pair of slip-fit
retaining rings 41 and 42 are illustrated; however, a pair of
compressible wire retaining rings or other membrane retaining means
can be equivalently disposed flushly in the exterior face 37 of the
rotor shell 34, securing the membrane.
Again referring to FIGS. 1 and 2 in detail, a pair of removable
circular end plates 44 and 43 are respectively disposed at opposed
rotor shell entrance end 38 and exit end 39. Each of the end plates
44 and 45 precisely fit respectively into the rotor entrance end 38
and rotor exit end 39, coaxially disposed inside the pair of
retaining rings 41 and 42 respectively. Two pairs of removable
securing bolts, the pair of bolts 46 and 47 together with the pair
48 and 49 are shown securing the removable circular end plates 44
and 45 respectively. The pairs of bolts 46 and 47 together with the
pair of bolts 48 and 49 are shown threaded into the fixed inlet
plates 62 and 63, as will be discussed later. Obviously each
removable end plate 44 and 45 can be secured with the required
number of removable securing bolts as is necessary to secure the
rotor shell end fluid tight.
To maintain the removable end plates 44 and 45 fluid tight during
rotation, a pair of removable fluid seals 50 and 51 are
respectively secured against the plates 44 and 45. Securing means
52 and 53 applied against the pair of removable fluid seals 50 and
51 respectively are disposed internally in the tubular stator
housing 23. Typically the securing means 52 consists of an annular
support ring 54 precisely disposed in the tubular stator housing
23, the support ring 54 being locked in position by a removable
retainer ring 56, which in turn holds multiple spring guide pins
58, each guide pin 58 being loaded by one of multiple expansion
springs 60. In a similar manner the removable fluid seal 51 is
secured in position by the means 53. The means 53 comprising as
above, the annular rigid support ring 55 located in position by the
removable retainer ring 57, which in turn positions the multiple
spring guide pins 59, each one of the guide pins having a single
expansion spring 61 disposed thereon.
A pair of fixed circular end plates, the fixed circular end plate
62 and the fixed circular outlet plate 63 are permanently coaxially
secured in position on the motor shaft 11, providing a pair of
precisely fixed index support positions. The fixed inlet plate 62
is disposed inside a rotor subcombination inlet end 38 and the
fixed outlet plate 63 is disposed inside a rotor subcombination
outlet end 39. The plate 62 is secured to the tubular shaft 11 as
by the weldment 64, and the outlet plate 63 is secured to the shaft
11 by the weldment 65. The fixed inlet plate 62 has at least one
inlet plate passageway 66 radially disposed therein, providing a
secondary fluid flow passageway through a wall aperture 67 in the
tubular shaft 11, through the at least one radial passageway 66 and
then through a manifold groove 68 in the rotor shell 34. The serial
plurality of secondary fluid flow passageways form a subcombination
74, providing secondary fluid flow through the tubular shaft
aperture 12, thence through the wall aperture 67, thence through
the radial passageway 66, thence through the manifold groove 68,
finally into the multiplicity of shallow depth passageways 36 at
the rotor shell entrance end 38. After the secondary fluid is
distributed through all of the shallow passageways 36, it flows
through the passageways 36 into the manifold groove 71 in the shell
34, thence through the at least one radial flow outlet passageway
69 into the wall aperture 70 in shaft 11, and thence out the shaft
aperture 12. The direction of the secondary fluid flow is
ordinarily that indicated by the arrow 20; however; the fluid flow
subcombination 74 may be utilized providing for fluid flow in the
opposed direction.
Referring to FIGS. 1 and 3 together in detail, a blood inlet
conduit 80 is shown conductively secured to a blood inlet manifold
81. The manifold 81 in turn is permanently secured to a heat
transfer shell jacket 82 which cylindrically encircles the rigid
tubular pump base 23 over that length of the pump base 23 which
comprises the stator housing. The multiple blood inlet vents 83 are
radially disposed through the heat transfer jacket 82 and the
stator housing 23 providing sealed vents 83 from the blood manifold
81 into the inlet blood groove 108 distributing blood into the
blood laminar flow arc sector 75, shown in FIG. 3. Thus patient
blood can be conductively flowed through the conduit 80, serially
through the blood inlet manifold 81, then through the multiple
blood inlet vents 83 and inlet groove 108, into the blood laminar
flow arc sector 75. When the rotor shell subcombination 43 rotates
in the direction of the arrow 77, blood laminar pumping means 76
are generated over the blood laminar flow arc sector 75 for the
length of the rotor shell subcombination 43. The blood laminar flow
arc sector 75 is mechanically activated by disposing the rotor
shell subcombination 43 eccentrically on the bearing support
combinations 21 and 22, the shaft eccentricity adapters 30 and 31
cooperatively fixing the arc sector 75 value, thus providing a
relatively thin blood laminar pumping means 76. The blood pumping
means 76 is a gap of thickness t, formed between the subcombination
43 and the internal diameter 25 of the stator housing 23. The
Reynolds number defining the above flow conditions is further
modified to a Reynolds-Couette number, as for a coaxial cylinder
viscometer apparatus, wherein the Reynolds-Couette number R.sub.c
is
R.sub.c = .rho..omega.t.sup.2 /.mu.where .rho. is the blood
density, .omega. is the angular velocity of the rotor
subcombination 43, t is the gap, and .mu. is the effective dynamic
viscosity of the blood. At low values of R.sub.c the flow between
the cylindrical surfaces of the rotor subcombination 43 and the
stator housing 23 in the gap 76 = t will be laminar. At high values
of R.sub.c local eddy currents will be generated in the gap 79.
Thus the eccentricity 32 produces laminar pumping of the blood in a
non-uniform pressure distribution, in addition to providing a
transition to a mixing effect at the wider annular gap 79 by the
eddy flow in arc sector 78, as illustrated in FIG. 3. Typically,
the mixing gap thickness value 79 = t in the eddy flow arc sector
78 has a value of 0.050 inches, as compared to the value of the gap
thickness 76 = t in the laminar flow arc sector 75 of 0.010
inches.
As is known in pumping technology, the laminar flow arc sector 75
expands to the transitional arc sectors 111 and 112, over the
laminar arc sector 113. It is difficult to precisely limit the arc
sectors in which laminar, transitional and mixing flows begin and
end. A graphical pressure representation 110 of the outlet conduit
86 blood pressure performance is shown, illustrating the arc sector
required position of conduit 86 for maximum blood outlet pressure
flowing in the direction 85. The blood manifold outlet 87
conductively secured to the blood outlet conduit 86, is in turn
disposed parallel along the external surface of the heat transfer
jacket 82, as is the blood inlet manifold 81. The multiple blood
outlet vents 88 are similarly disposed through the heat transfer
jacket 82 venting into the outlet groove 109. The pair of heat
transfer fluid inlet and outlet conduits 89 and 90 respectively are
attached to the jacket 82 as shown in FIG. 3. The conduits 89 and
90 permit the desired heat transfer fluid to be circulated in the
jacket 82, as will be later discussed, maintaining the patient's
blood at the desired temperature.
Further details of the blood transfer membrane pump construction
are outlined below. The O-ring grooves 91 and 92 are respectively
disposed in the fixed inlet plate 62, sealed by the O-rings 93 and
94, preventing leakage of secondary fluid flow. The snap retaining
ring 95 fits in the retaining ring groove 96, providing an index
position for the shell rotor subcombination 43. At the opposed end
of the pump 10 a second pair of O-ring grooves 97 and 98 are filled
by the O-rings 99 and 100 respectively, again providing seals,
preventing leakage of the secondary fluid. The snap retaining ring
101 is disposed in the retaining ring groove 102, which in turn is
located in the rotor shell subcombination 43, providing a second
indexing position for the shell 34. Conventional O-rings and groove
combinations 103 and 104 are disposed in the seals 50 and 51
respectively, providing sealing means. In more detail, the lands
105 are shown in FIGS. 2 and 3, providing rotor shell 34 structure
between the multiple passageways 36. The stator housing extension
106 can be that length which is required to provide a working
platform for work on the assembly and dis-assembly of the pump 10.
The internal cylindrical surface of stator housing 23, defined by
the stator diameter 35, can be coated with a polyurethane coating
physiologically compatible with patient blood. The support base
107, extending the length of the stator housing provides a support
base for the pump.
In application, the blood transport membrane pump can be operated
as a blood oxygenator, or, separately alternatively, it can also be
operated as a blood dialysis apparatus. When the pump 10 is
operated as a blood oxygenator the thin secondary fluid permeable
membrane 40 is typically a thin flexible membrane permeable to
oxygen and carbon dioxide. When the pump 10 is operated as a blood
dialysis apparatus, the thin permeable membrane 40 is typically
permeable to aqueous dialysis solutions, and to the wate products
exchanged from patient blood. For both types of operative procedure
the thin fluid permeable membrane is typically 0.002-0.003 inches
thick. Typically the rotor shell 34, the selected desired permeable
membrane 40, and the pair of retaining rings 41 and 42 are
assembled at a factory, ready for placement in a pump 10 as
required. The subcombination 43 is to be used as required in a
medical procedure and then discarded, the remainder of the pump
cleaned as necessary, and a second subcombination 43 replaces the
first subcombination 43.
Typically in a patient blood dialysis a selected cellophane
membrane 40 is disposed on the rotor shell 34 secured in the pump
10. The patient's arterial blood secured from a hand, arm or leg,
conductively flows through the blood inlet 80, the blood manifold
81, vents 83, into the blood gap 76 where the blood is rotatively
pumped in the direction 77 to exit through the multiple vents 88
into the blood manifold 87, out through the outlet conduit 86 into
the patient's body. While the blood is in the pump it is in contact
with the membrane 40 where the blood is subjected to the
diffusional washing of the secondary dialysis fluid flowing through
the fluid flow passageway subcombination 74, on the opposite face
of membrane 40. Thus the patient may be subjected to blood
dialysis, utilizing well established blood dialysis fluids as a
secondary fluid in the apparatus 10, removing waste products from
patient blood. The dialysis procedure can be carried on for the
length of time required. In the dialysis procedure the patient's
blood circulating through the pump 10 will be held at approximately
37.degree.C by the required heat transfer fluid flowing through the
heat transfer jacket 82. The pump 10 can be refrigerated in storage
between dialysis procedures, eliminating the requirement that the
machine be cleaned every time it is used consecutively by a
selected patient.
When the machine is used as a blood oxygenator, a selected silicone
type rubber is commonly used as a semi-permeable membrane,
permeable to oxygen and to the exchange of carbon dioxide from the
blood. Other selected oxygen and carbon dioxide permeable membranes
may be used, such as a dimethyl silicone-polycarbonate block
copolymer. When used as a blood oxygenator pump, the secondary
fluid input is typically oxygen gas containing the requisite amount
of carbon dioxide, flowing through the fluid flow passageway
subcombination 74. The blood is conductively circulated as
indicated above for blood dialysis. Since the membrane is freely
permeable to oxygen gas and carbon dioxide gas, oxygen flows
through the membrane and is fixed by the blood, releasing in turn
carbon dioxide gas, which flows out through membrane 40 as part of
the exhaust gas from the passageway subcombination 74.
A pump 10 having a rotor subcombination 43, whose diameter is
approximately 4 inches and whose length is approximately 8 inches,
provides a membrane suitable for continuous dialysis at typically
100 RPM of an adult patient. Such a size machine, used as a blood
oxygenator is most suitable for perfusion of an organ, such as a
heart or kidney, prior to surgical transplant procedure. When
required, as in transplant procedure or the like, a refrigerant
such as water or a Freon as is necessary, can be used to cool blood
and organs to temperatures typically 28.degree.C or less for
hypothermia. Likewise warmer water can be provided to warm patients
and patient's blood as becomes necessary. The machine stores small
amounts of patient's blood during medical procedures and has the
advantage of decreasing patient blood loss under critical
conditions. It is possible to bloat the permeable membrane 40
slightly at the end of the medical procedure, squeezing blood out
of the pump cavity, further decreasing the blood loss.
The pump 10 can be a permanent apparatus suitable for use in
medical procedures, with a replaceable essentially single use
plastic rotor hell, membrane and pair of retaining rings
subcombination 43. The subcombination 43 can be separately prepared
in a factory for use as required in a specific medical
procedure.
Many modifications and variations in the improvement in a blood
transport membrane pump can be made in the light of my teaching. It
is therefore understood that within the scope of the appended
claims, the invention may be practiced otherwise than as has
specifically been described.
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