U.S. patent number 3,769,162 [Application Number 05/175,182] was granted by the patent office on 1973-10-30 for blood oxygenator and thermoregulator apparatus.
Invention is credited to Robert C. Brumfield.
United States Patent |
3,769,162 |
Brumfield |
October 30, 1973 |
BLOOD OXYGENATOR AND THERMOREGULATOR APPARATUS
Abstract
Venous human blood flows into a base distributing manifold of a
blood oxygenator, whose operating components are cooperatively
vertically coaxially disposed. The blood is distributed into
vertically aligned multiple, controlled small diameter oxygen
exchange tubes, each exchange tube having a coaxial oxygen
injection tube disposed at the exchange tube base. Oxygen gas flows
through each injection tube, maintaining two-phase flow of
oxygen-blood up through the exchange tubes. After oxygenation and
separation of excess oxygen and exchanged carbon dioxide gas in a
gas separator, the blood is further defoamed in an external coaxial
defoamer bed. The defoamed blood then descends a coaxial annular
ring in a spiral flow path over a spiral metal tube heat exchanger
which contains temperature controlled circulating heat transfer
fluid. The oxygenated defoamed blood is thermoregulated to the
necessary temperature, exiting from the oxygenator base blood
outlet conduit, returning to the patient's body.
Inventors: |
Brumfield; Robert C. (Laguna
Beach, CA) |
Family
ID: |
22639283 |
Appl.
No.: |
05/175,182 |
Filed: |
August 26, 1971 |
Current U.S.
Class: |
435/2; 128/DIG.3;
261/124; 261/DIG.28; 261/122.1; 422/46; 607/106 |
Current CPC
Class: |
A61M
1/325 (20140204); A61M 1/32 (20130101); A61M
1/369 (20130101); Y10S 261/28 (20130101); Y10S
128/03 (20130101) |
Current International
Class: |
A61M
1/32 (20060101); A61M 1/36 (20060101); A61m
001/03 () |
Field of
Search: |
;23/258.5 ;195/1.8
;128/DIG.3,400 ;261/123,124,DIG.28 ;55/255,256 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
norman E. Shumway et al., "A Mechanical Pump-Oxygenator For
Successful Cardiopulmonary By-Pass;" Surgery; Vol. 40, No. 5,
11/56, pp. 831-839.
|
Primary Examiner: Richman; Barry S.
Claims
I claim:
1. In a process suitable for exchanging oxygen for carbon dioxide
in patient extra corporeal circulating blood, the improvement
combination comprising:
flowing a pro rata volume portion of said blood into a first
terminus of each one of a multiplicity of small diameter blood-gas
exchange tubes coadjacently disposed in a tube array, said tube
array ranging from 4 to 24 inches long and said tubes ranging from
one-sixteenth to five-sixteenths inches in a single internal tube
diameter, said tube array disposed in a blood oxygenator apparatus,
each one of said first terminus secured adjacent the apparatus base
end,
separately injecting into each said flowing pro rata volume portion
of blood from one to four volumes of oxygen gas, forming a
two-phase bubble dispersion of said gas and blood in each one of
said blood-gas exchange tubes, providing absorption of said oxygen
by said blood and release of said carbon dioxide gas by said blood,
and,
flowing said two-phase bubble dispersion from the second terminus
of each one of said blood-gas exchange tubes into a single common
gas separation chamber disposed adjacent the multiplicity of said
second terminus.
2. In an extra corporeal blood oxygenator apparatus suitable for
oxygenating venous blood and removing carbon dioxide therefrom, the
combination comprising:
a. a plurality of elongated oxygen exchange small diameter tubes
disposed in a closely juxtaposed array, each exchange tube having
an open venous blood inlet base end and an open arterial blood
outlet top end, and being of substantially uniform cross section
between said ends,
a first common manifold encompassing and communicating with all
said tubes inlet base ends, for delivering venous blood
thereto,
c. an oxygen supply tube extending into the inlet end of each
exchange tube having a terminal discharge orifice disposed inwardly
from the inlet base end thereof, adapted to discharge oxygen gas in
the direction of the blood flow,
d. a second common manifold encompassing and communicating with all
the oxygen supply tubes for delivering oxygen gas thereto,
e. an annular defoaming chamber disposed above and in flow
communication with said array and axially coaligned therewith
and,
f. an annular blood filter surrounding and in flow communication
with the aforesaid defoaming chamber.
3. Apparatus in accordance with claim 2 wherein said array has an
integral single connecting tube array wall.
4. Apparatus in further accordance with claim 2 wherein said tubes
in said array are uniformly spaced through the tube array cross
section; an annular volume surrounding said array; a helical heat
exchange tube disposed within aforesaid annular volume, providing a
helical flow channel between its convolutions, the arterial blood
adapted to flow through the helical flow channel.
5. Apparatus in further accordance with claim 4 including an
annular blood reservoir surrounding said array, the lower end of
the helical flow channel communicating with said reservoir.
6. Apparatus in further accordance with claim 3 wherein the helical
flow channel surrounds said blood reservoir.
7. A disposable blood oxygenator apparatus suitable for exchanging
oxygen for carbon dioxide in patient extra corporeal circulating
blood, wherein the improvement combination comprises:
a multiplicity of small diameter oxygen exchange tubes coadjacently
disposed in a closely packed, parallel, equal length upstanding
tube array, said tube array disposed in an oxygenator apparatus,
the tube array first terminus secured adjacent the apparatus base
end,
a first tube case means permanently coaxially closely securing said
tube array, said first case means having a case length longer than
said tube array, said tube array coaxially disposed relative to
said first case means the required spaced distance from said case
means first terminus,
a multiplicity of short oxygen gas injection tubes having internal
gas passages therein, said injection tubes equal in number to the
number of multiple oxygen gas exchange tubes, a first terminus of
each one of said multiplicity of injection tubes disposed inside
and adjacent a single exchange tube terminus in said exchange tube
array first terminus, a second terminus of each one of said
multiplicity of injection tubes terminating in an injection tube
manifold plate, said manifold plate disposed the residual injection
tube length from said tube array first terminus, providing
therebetween an inlet blood reservoir volume,
an annular defoamer bed concentrically disposed around said first
tube case means, having a bed depth required to defoam oxygenated
blood, said bed having foamed blood escape aperture means
adjacently disposed in aforesaid case means, said bed having a bed
base annular closure supportively externally sealed around said
first case means at a bed first terminus, and the second bed means
terminus coplanar with said first case means second terminus, said
defoamer bed having a first open cell plastic foam packing disposed
therein, the packing surface having a silicone defoaming
composition thin film disposed thereon, thereby accelerating the
separation of oxygenated blood and gas,
a thin annular shell blood filter means coaxially surrounding said
defoamer bed and a gas separation chamber disposed above said tube
array, said annular shell blood filter having a dense open cell
plastic foam composition filter medium cylindrically disposed
therein and a thin fine weave filter cloth disposed over the filter
medium exterior, the blood filter means length being not less than
the defoamer bed depth, said filter cloth permanently exteriorly
secured to said foam filter medium, said shell blood filter snugly
secured to said bed base annular closure, and,
a shell filter closure plate internally supportively disposed in
and snugly secured to said shell blood filter at the second
terminus of aforesaid filter opposed to the filter terminus secured
to the bed base annular closure.
8. An apparatus as set forth in claim 7
wherein the further improvement combination comprises:
an annular tube second case means concentrically disposed around
said first tube case means having an internal tube diameter
substantially equal to the shell blood filter external diameter,
said second case means having a first terminus supportively
securing said bed base annular closure, and said annular shell
blood filter, and a second terminus securing a first annular
oxygenator case closure plate, said second case means having a
length required to provide the necessary oxygenated blood reservoir
in the annular volume between said first and second case means,
said second case means having at least one blood reservoir aperture
disposed in the tube wall thereof contiguous said second case means
second terminus.
a tubular heat exchange means snugly concentrically disposed around
said second case means, a heat exchange thermoregulating fluid
circulating through said heat exchange means, said exchange means
having a blood circulating path externally disposed thereon
providing a controlled temperature range of 50.degree. to
108.degree.F for the oxygenated blood flowing from said blood
filter over said exchange means, said tubular means having a fluid
inlet conduit and a fluid outlet conduit,
a tubular exterior third case means snugly concentrically disposed
around said heat exchange means, providing an exterior boundary
surface for the blood circulating annulus enclosing said heat
exchange means, said third case means having a length at least
equal to the combined lengths of said second case means and said
blood filter, a first terminus of said third case means permanently
completely sealed by said first oxygenator case closure plate and
the second terminus of said third case means sealed by said second
oxygenator closure plate, said second oxygenator closure plate
having gas escape aperture means disposed therein, said heat
exchange means fluid inlet conduit and said fluid outlet conduit
conductively disposed outside of said blood circulating annulus, to
the blood oxygenator exterior, and
at least one oxygenated, temperature regulated blood outlet conduit
exteriorly disposed from said first oxygenator case closure
plate.
9. A combination as set forth in claim 8 wherein said tubular heat
exchange means further comprises a spirally wound tubular coil
snugly concentrically disposed around said second case means.
10. In a disposable blood oxygenator apparatus suitable for
exchanging oxygen for carbon dioxide in patient extra corporeal
circulating blood, the combination comprising:
a multiplicity of small diameter oxygen exchange tubes coadjacently
disposed in a solidly packed, parallel, equal length tube array,
said tube array ranging from 4 to 24 inches long and said tubes
ranging from one-sixteenth to five-sixteenths inches in a single
internal tube diameter, said tube array vertically disposed in an
oxygenator apparatus, the tube array first terminus secured
adjacent the apparatus base end,
a first tube case means permanently coaxially closely securing said
tube array, said first case means having a case length
substantially longer than said tube array, said tube array
coaxially disposed inside said first case means the required spaced
distances from each of the first and second case means
terminus,
a multiplicity of short oxygen injection tubes having clear
internal gas passages therein, said injection tubes equal in number
to the number of multiple oxygen gas exchange tubes, a first
terminus of each one of said multiplicity of injection tubes
disposed inside and adjacent a single exchange tube terminus in
said exchange tube array first terminus, a second terminus of each
one of said multiplicity of injection tubes terminating in an
injection tube manifold plate, said manifold plate planarly
disposed normal to the first case means axis of symmetry and the
manifold planar area completely sealing said first tube case means,
said manifold plate disposed the residual injection tube length
from said tube array first terminus, providing there between an
inlet blood reservoir volume,
an annular defoamer bed concentrically disposed around said first
tube case means, having a bed depth required to defoam oxygenated
blood, said bed having foamed blood escape aperture means
adjacently disposed in aforesaid case means, said bed having a bed
base annular closure supportively externally sealed around said
first case means at a bed first terminus, and the second bed means
terminus coplanar with said first case means second terminus, said
defoamer bed having a first open cell plastic foam packing disposed
therein, the packing surface having a silicone defoaming
composition thin film disposed thereon, accelerating the separation
of oxygenated blood and gas,
a thin annular shell blood filter means coaxially surrounding said
defoamer bed and a gas separation chamber disposed above said tube
array, said annular shell blood filter having a dense open cell
plastic foam composition filter medium cylindrically disposed
therein and a thin fine weave filter cloth disposed over the filter
medium exterior, the blood filter means length being not less than
the defoamer bed depth, said filter cloth permanently exteriorly
secured to said foam filter medium, said shell blood filter snugly
secured to said bed base annular closure, and,
a shell filter closure plate internally supportively disposed in
and snugly secured to said shell blood filter at the second
terminus of aforesaid filter opposed to the filter terminus secured
to the bed base annular closure.
11. In a disposable blood oxygenator apparatus suitable for
exchanging oxygen for carbon dioxide in patient circulating blood,
and for regulating the blood temperature, the combination
comprising:
a multiplicity of small diameter oxygen exchange tubes coadjacently
disposed in a solidly packed, parallel, equal length tube array,
said tube array ranging from 4 to 24 inches long and said tubes
ranging from one-sixteenth to five-sixteenths inches in a single
internal tube diameter, said tube array vertically disposed in an
oxygenator apparatus, the tube array first terminus secured
adjacent the apparatus base end,
a first cylindrical tube case means permanently coaxially closely
securing said tube array, said first case means having a case
length substantially longer than said tube array, said tube array
coaxially disposed inside said first case means the required spaced
distances from each of the first and second case means
terminus,
a multiplicity of short oxygen injection tubes having clear
internal gas passages therein, said injection tubes equal in number
to the number of multiple oxygen gas exchange tubes, a first
terminus of each one of said multiplicity of injection tubes
disposed inside and adjacent a single exchange tube terminus in
said exchange tube array first terminus, a second terminus of each
one of said multiplicity of injection tubes terminating in an
injection tube manifold plate, said manifold plate planarly
disposed normal to the first case means axis of symmetry and the
manifold planar area completely sealing said first tube case means,
said manifold plate disposed the residual injection tube length
from said tube array first terminus, providing there between an
inlet blood reservoir volume,
a first closure means, permanently completely sealing said first
tube case means at said case means first terminus, providing an
oxygen inlet reservoir volume between said first closure means and
said manifold plate,
at least one foamed blood escape aperture means provided in said
first case tube means adjacent the second terminus of said tube
array,
a gas separation chamber means disposed in said first case means
above said at least one foamed blood escape aperture means,
extending to said first case means second terminus,
at least one blood inlet conduit means disposed in said first case
means providing direct conduction of blood into said blood
reservoir volume,
at least one oxygen inlet conduit means disposed in said first case
means providing direct conduction of oxygen into said oxygen
reservoir volume,
an annular defoamer bed means concentrically disposed around said
first tube case means, having a bed depth required to defoam
oxygenated blood flowing from said foamed blood escape aperture
means, said bed means having a bed base annular closure means
supportively externally sealed around said first case means at a
bed means first terminus supportively securing said bed means to
said first case means, and the second bed means terminus coplanar
with said first case means second terminus, said defoamer bed
having a first open cell plastic foam packing means disposed
therein, the packing surface having a silicone defoaming
composition thin film means disposed thereon accelerating the
separation of oxygenated blood and gas,
a thin annular shell blood filter means coaxially surrounding said
defoamer bed and aforesaid gas separation chamber, said annular
shell blood filter having a dense open cell plastic foam
composition filter medium means cylindrically disposed therein and
a thin fine weave filter cloth disposed over the filter medium
means exterior, the blood filter length being not less than the
defoamer bed depth, said filter cloth permanently secured to said
foam filter medium means, said shell blood filter snugly secured to
said bed base annular closure,
a shell filter closure plate means internally supportively disposed
in and snugly secured to said shell blood filter at the filter
second terminus opposed to the filter terminus secured to the bed
base annular closure means,
an annular tube second case means concentrically disposed around
said first tube case means having an internal tube diameter
substantially equal to the shell blood filter external diameter,
said second case means having a first terminus supportively
securing said bed base annular closure, and said annular shell
blood filter, and a second terminus securing a first annular
oxygenator case closure plate, said second case means having a
length required to provide the necessary oxygenated blood reservoir
in the annular volume between said first and second case means,
said second case means having at least one blood reservoir aperture
disposed in the tube wall thereof contiguous said second case means
second terminus,
a tubular heat exchange means snugly concentrically disposed around
said second case means, a heat exchange thermoregulating fluid
circulating through said heat exchange means, said exchange means
having a blood circulating path externally disposed thereon
providing a controlled temperature range of 50.degree. to
108.degree. F for the oxygenated blood flowing from said blood
filter over said exchange means, said tubular means having a fluid
inlet conduit and a fluid outlet conduit,
a tubular exterior third case means snugly concentrically disposed
around said heat exchange means, providing an exterior boundary
surface for the blood circulating annulus enclosing said heat
exchange means, said third case means having a length at least
equal to the combined lengths of said second case means and said
blood filter, a first terminus of said third case means permanently
completely sealed by said first oxygenator case closure plate and
the second terminus of said third case means sealed by said second
oxygenator closure plate, said second oxygenator closure plate
having gas escape aperture means disposed therein, said heat
exchange means fluid inlet conduit and said fluid outlet conduit
conductively disposed outside of said blood circulating annulus, to
the blood oxygenator exterior, and
at least one oxygenated, temperature regulated blood outlet conduit
means exteriorly disposed from said first oxygenator case closure
plate. pg,35
12. A combination as set forth in claim 11 wherein said tubular
heat exchange menas is a spirally wound tubular coil snugly
concentrically disposed around said second case means.
Description
BACKGROUND OF THE INVENTION
This invention relates to a blood oxygenator and a thermoregulator
apparatus particularly suitable for saturating venous blood with
oxygen and releasing the carbon dioxide contained in the blood,
together with regulating the temperature of the oxygenated blood
prior to returning the blood to the patient's body. The advent of
more advanced patient treatment and of radical cardiopulmonary
surgery has increased the need for a disposable oxygenator and
thermoregulator apparatus. The apparatus should require a minimum
of priming with blood, plasma, or the like, and the flow of the
blood through the apparatus should produce a minimum trauma to the
circulating blood, so that hazards to the patient are reduced.
Apparatus for treating blood, human and animal are now classified
in Class 23-Subclass 258.5. Blood oxygenators are specifically
listed in the class.
SUMMARY OF THE INVENTION
A blood oxygenator and thermoregulator apparatus is disposed in a
vertical tubular casing, having cooperative operating components.
In the apparatus suitably disposed below the patient, the venous
blood of the patient is distributed through a multiplicity of small
diameter oxygen exchange tubes, coadjacently disposed in a solidly
packed parallel equal length tube array. A first cylindrical tube
case means permanently coaxially closely secures the vertical tube
array the required spaced distance from the first tube case means
terminuses. A multiplicity of short oxygenator tubes equal in
number to the number of multiple gas exchange tubes are each singly
disposed inside and adjacent a single exchange tube terminus in the
exchange tube array. A second terminus of each one of said
multiplicity of injection tubes terminate in an injection tube
manifold plate, the manifold plate being planarly disposed normal
to the first case means axis of symmetry and completely sealing the
first tube case means. The manifold plate is disposed a residual
injection tube length from the tube array first terminus, providing
an inlet blood reservoir volume. An oxygen inlet reservoir volume
is provided in said first tube case means between said manifold
plate and a first closure means for said first tube case means. At
least one foamed blood escape aperture means is provided in the
first tube case means adjacent said tube array second terminus, and
a gas separation chamber is disposed above the blood escape
aperture means, with at least one gas escape aperture means
provided adjacent to the gas separation chamber.
Separate blood inlet conduit means and oxygen inlet conduit means
are disposed in the first case means providing the respective
conduction of blood and oxygen to said tube array. An annular
defoamer bed is concentrically disposed around said first tube case
means extending from a bed base annular closure, disposed
substantially below said foamed blood escape aperture means, to the
top of said gas separation chamber, forming a thin annular shell
blood filter surrounding both the defoamer bed and the gas
separation chamber. An annular tube second case means is
concentrically disposed around said first tube case means, the
second case means having a first terminus supportively securing
said bed base annular closure. The annular tube second case means
has a second terminus securing a first annular oxygenator case
closure plate, and the second case means has a length required to
provide the necessary oxygenated blood reservoir in the annular
volume between the first and second case means.
A tubular heat exchange means is snugly concentrically disposed
around the second case means and contains a circulating heat
transfer fluid, providing a controlled temperature range of
50.degree. to 108.degree.F for the oxygenated blood flowing from
the blood filter over the exchange means. A tubular exterior third
case means is snugly concentrically disposed around the heat
exchange means providing an exterior boundary surface for the
annulus in which blood circulates.
The third case means has a length at least equal to the combined
length of the second case means and the blood filter. A first
terminus of the third case means is permanently completely secured
to the first oxygenator case closure base plate and the second
terminus is sealed to the second oxygenator case closure plate, the
second closure plate having gas escape aperture means disposed
therein. Heat exchange means fluid inlet and outlet conduits are
conductively disposed therein. At least one oxygenated blood outlet
conduit is disposed from the first oxygenator case closure base
plate.
Included in the objects of this invention are:
To provide a simple, relatively inexpensive, disposable blood
oxygenator and defoamer apparatus, with blood thermoregulation
control.
To provide a disposable blood oxygenator and thermoregulator
apparatus which can be quickly placed in operation and which can be
sterilized prior to use.
To provide a blood oxygenator and thermoregulator apparatus which
is substantially transparent, adapting it to constant visual
observation during use with patients.
To provide a blood oxygenator and thermoregulator apparatus
requiring a minimum volume of blood fluid extenders to place the
apparatus in operative condition.
To provide a blood oxygenator and thermoregulator means for
controlling the temperature of oxygenated blood exiting
therefrom.
To provide a blood oxygenator and thermoregulator apparatus which
functionally operates with a minimum damage to the blood
circulating therein.
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 perspective partial sectional view of the
blood oxygenator and thermoregulator apparatus.
FIG. 2 is a sectional view through 2--2 of FIG. 1.
FIG. 3A is another cross sectional view similar to FIG. 2,
illustrating a further modification of an oxygen exchange tube
array cross sectional configuration with the oxygen injection tubes
disposed therein.
FIG. 3B is still another cross sectional view illustrating the
cross sectional geometry of another oxygen exchange tube array
configuration having gas injection tubes disposed therein.
FIG. 4A schematically illustrates a slug mixture of blood and
oxygen gas vertically disposed before two-phase slug flow begins in
an oxygen exchange tube. FIG. 4B is an enlarged schematic
illustration of a flowing mixture of a two-phased slug flow of
blood and oxygen gas in a single oxygen exchange tube.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the elevational perspective partial section view of
FIG. 1 in detail, the blood oxygenator 1 has a multiplicity of
small diameter oxygen exchange tubes 5 coadjacently disposed in a
solidly packed parallel equal length tube array 50. Typically the
tube array 50 ranges from 4 to 24 inches long, and each single tube
5 ranges from one-sixteenth to five-sixteenths inches in a single
internal tube diameter. The tube array 50 is vertically disposed in
the oxygenator apparatus 1. The multiple tubes 5 are closely
packed, preferably being a solidly bonded mass with no interstices
between the tube walls, typically being an extruded plastic tube
array, as 50 or the like. A first cylindrical tube case means 6
permanently coaxially closely secures the tube array 50, the first
case means 6 having a case length 6a, longer than the tube array
50. The tube array 50 is coaxially disposed inside the case means
6, spaced the required distances from each of the first case means
terminus 6b and second case means terminus 6c. A multiplicity of
short oxygen injection tubes 7 have clear internal gas passages,
the injection tubes being equal in number to the number of multiple
oxygen gas exchange tubes 5. A first terminus 7a of each one of the
multiplicity of the oxygen injection tubes 7 is disposed inside and
closely adjacent to a single exchange tube 5 terminus 51 in the
exchange tube array 50. A second terminus 7b of each one of the
multiplicity of oxygen injection tubes 7 terminates in an injection
tube manifold plate 8. The manifold plate 8 is planarly disposed
normal to the first case means 6 axis of symmetry and the manifold
plate area completely seals the first tube case means 6. The
manifold plate 8 is disposed the residual injection tube length 7c
from the tube array first terminus 51 providing an inlet blood
reservoir volume 14 between the tube array first terminus 51 and
the manifold plate 8. A first closure means 11 permanently
completely seals the first tube case means 6 at the case means
first terminus 6b, providing an oxygen inlet reservoir volume 12
between the first closure means 11 and the manifold plate 8.
Multiple foamed blood escape aperture means 17 are provided in the
first case tube means 6 adjacent to the tube array 50 second
terminus 52. A gase separation chamber 16 is disposed above the
multiple foam blood escape aperture means 17 extending to the first
case means 6 second terminus 6c. At least one blood inlet conduit
means 15 is disposed in the first case means 6, providing direct
conduction of blood into the blood reservoir volume 14. At least
one oxygen inlet conduit means 13 is disposed in the first case
means 6 providing direct conduction of oxygen into the oxygen
reservoir volume 12.
An annular blood defoamer bed 21 is concentrically disposed around
the first tube case means 6 having a bed depth 21a required to
defoam the oxygenated blood flowing from the foamed blood escape
aperture means 17. The blood defoamer bed 21 has a bed base annular
closure 18 supportively externally sealed around the first case
means 6 at a bed 21 first terminus 21b, securing the bed 21 to the
first case means 6. The annular defoamer bed 21 has a second
terminus 21c almost coplanar with the first case means terminus 6c.
The defoamer bed 21 has a first open cell plastic foam packing 22
disposed in the defoamer bed, the packing surface having a silicone
defoaming composition thin film 22a disposed on the foam packing.
The silicone defoaming composition is selected to be compatible
with blood and to accelerate the separation of gas phase from the
liquid blood phase, thereby defoaming blood.
A thin annular shell blood filter is a combination of a thin filter
medium 23 coaxially surrounding the defoamer bed 21 and the gas
separation chamber 16, and a covering filter cloth 24. The annular
blood filter medium 23 is a dense, open cell, plastic foam
composition filter medium. A thin, fine weave filter cloth 24 is
exteriorly disposed as a thin layer over all of the exterior face
of filter medium 23. The blood filter medium length is not less
than the defoamer bed depth 21a. The filter cloth 24 is permanently
secured to the foam filter medium 23, and the combination of 23 and
24 are snugly secured by a nylon cord means 25 to the bed base
annular closure 18 at 27. A shell filter closure plate 19 is
internally supportively disposed in and snugly secured to the blood
filter medium 23 and filter cloth 24 combination at the filter
terminus 21c which is opposed to the filter terminus 21b secured to
the bed face annular closure 18. In this apparatus the filter
closure plate 19 is supportively bonded to the case means. The
oxygen and carbon dioxide gases 20 escape from the defoamer bed 21
and gas separation chamber 16 through the thin annular shell blood
filter combination of filter medium 23 and filter cloth 24. The
cord means 26 secures the combination of filter medium 23 and cloth
24 to closure 19, at 28.
An annular tube second case means 33 is concentrically disposed
around the first tube case means 6 having an internal tube diameter
substantially equal to the shell blood filter medium 23 and filter
cloth 24 combination external diameter. The second case means 33
has a first terminus 33a supportively securing the bed base annular
closure 18 and the annular shell blood filter, and a second
terminus 33b secures a first annular oxygenator case closure plate
3, and is hermetically bonded to the plate 3. The second case means
33 has a length 33c required to provide the necessary oxygenated
blood reservoir 36 in the annular volume between the first case
means 6 and the second case means 33. At least one blood reservoir
aperture 35 is disposed in the wall of second case means 33
contiguous to the second case means 33 second terminus 33b,
providing an aperture for blood to flow into the blood reservoir
36.
A tubular heat exchange means 31 is snugly concentrically disposed
around the second case means 33. A heat exchange thermoregulating
fluid 53 circlates through the heat exchange means 31. In this
specific example, the heat exchange means 31 comprises multiple
spiral turns of an aluminum tube heat exchanger coil 31, the
aluminum coil being completely externally coated with a thin
polyurethane film 54 which is chemically and physically compatible
with circulating blood. The spiral turns of the heat exchanger coil
31 provide an annular blood flow helical path 32 for the blood
exiting from the blood filter shell 23 and cloth filter 24. The
tubular heat exchange means 31 can control the circulating blood
temperature in a typical range of 50.degree. to 108.degree.F as the
blood descends the spiral path 32. A tubular exterior third case
means 2 is snugly concentrically disposed around the tubular heat
exchange means 31, providing an exterior boundary surface for the
blood circulating annulus 55 enclosing the heat exchanger means 31.
The third case means 2 has a length 2c at least equal to the
combined lengths 33c and 21a of the second case means 33 and the
defoamer bed 21. A first terminus 2a of the third case means 2 is
permanently completely sealed by the first oxygenator case closure
plate 3 and the second terminus 2b of the third case means 2 is
sealed by the second oxygenator closure plate 4. The second
oxygenator closure plate 4 has gas escape aperture means 41,
covered by cap 42 disposed therein, allowing escape of carbon
dioxide gas exchanged in the circulating blood, as well as the
excess oxygen gas. The heat exchange means 31 has a fluid inlet
conduit 38 and a fluid outlet conduit 39 conductively disposed
outside of the blood circulating annulus 55. Seals 47 hermetically
secure the inlet conduit 38 and the outlet conduit 39 into the
apparatus 1, utilizing an O-ring 48 disposed in O-ring groove
49.
At least one oxygenated blood outlet conduit 37 is exteriorly
secured to and exits from the first oxygenator closure plate 3.
In this apparatus a hypodermic needle fastening means 45 is
disposed through the closure plate 4, providing for the
introduction of required dosage of medication through a syringe
means during the operation of the blood oxygenator 1.
A foam insulating layer 46 is exteriorly secured on the third case
means 2 providing additional temperature regulation means, as is
necessary.
FIG. 2 is an illustration of the cross sectional view through the
apparatus 1 at two levels in a cross sectional structure of the
apparatus. The left side of FIG. 2 is an illustration of the cross
section of apparatus 1 through the annular shell blood filter, the
defoamer bed, and the tube array. The third case means 2 has a foam
insulating layer 46 exteriorly disposed around the case member 2.
The blood circulating annulus 55 is shown disposed on both halves
of the sectional view. The left half portion of the view
illustrates the filter cloth 24 exteriorly disposed over the
exterior face of the filter medium 23. The defoamer bed 21 has the
open cell plastic foam packing 22 disposed in the bed 21, the
packing surface of 22 having a thin film silicone defoaming
composition 22a disposed thereon. The tubular first case means 6
forms the inner structure member of the defoamer bed and the outer
structure of the tube array 50 disposed in case member 6. The
individual oxygen exchange tubes 5 are disposed in the tube array
50 as integral exchange tube apertures. The right hand side of FIG.
2 illustrates the cross section structure of the apparatus 1 at a
lower level in the apparatus, wherein the blood reservoir 36 is
formed between the case member 6 and the case member 33. Again the
blood circulating annulus 55 is shown disposed between case member
33 and case member 2. A cross sectional view of the tubular heat
exchange means 31 is shown having circulating heat transfer fluid
53 disposed in tube 31. A thin polyurethane film 54 is shown
disposed exteriorly on the tube 31 preventing physical and chemical
reaction of the circulating blood with the aluminum tubing. The
foam insulating layer 46 is shown exteriorly secured on the third
case means 2.
FIG. 3A illustrates in cross sectional view a multiple oxygen
exchange tube array 60 formed in one piece. Each single oxygen
exchange tube 61 is triangular in cross section, having a common
wall 64 with the adjacent oxygen exchange tubes 61. The solid,
integral tube array can be provided by extruding a suitable plastic
composition, providing parallel tube arrays of the desired length.
Integral solid plastic tube array exterior wall spacer 63 provides
a circular cross section for the tube array 60, enabling the tube
array 60 to be tightly and securely disposed in a first cylindrical
tube 6 case means as taught above. The multiplicity of short oxygen
injection tubes 62 are shown coaxially disposed, equal in number to
the number of multiple oxygen exchange tubes 6
FIG. 3B further illustrates another cross sectional configuration
which is equivalent to the cross sectional configuration of FIG.
3A. In this second configuration the small diameter oxygen exchange
tubes 71 are also coadjacently disposed in a solid, integral tube
array configuration 70, a single oxygen exchange tube 71 being
hexagonally in cross section. Again, a multiplicity of short oxygen
injection tubes 72 having internally clear gas passages are shown
disposed equal in number to the number of multiple oxygen gas
exchange tubes 71. An external solid plastic spacer 73 is shown
integrally disposed around the regular hexagonal shaped oxygen
exchange tubes providing a circular perimeter for the tube array
configuration so that it may be disposed in a first cylindrical
tube case means. The oxygen exchange tube can have a wide variety
of cross sectional shapes, preferably being regular symmetrical
shapes adapted to close packing and providing a large cross
sectional area for flow of fluid. The thin wall 74 is disposed
around the hexagonal tubes 72.
The blood oxygenating apparatus of this invention is operated in a
concurrent two-phase flow of gasesous oxygen and circulating blood.
The mass transport of blood and oxygen and the exchanged carbon
dioxide gas is upward through the apparatus 1. The oxygen exchange
tube array 50 or the like can be designed for blood circulating
flows ranging from that of newborn infants to adults undergoing
radical cardio-pulmonary surgery. In order to avoid massive blood
trauma during the oxygenating process, it is desirable that the
circulating blood be oxygenated with as little blood turbulence as
possible. To this end blood transport should be through an optimal
number of oxygen exchange tubes, providing a maximum amount of
blood oxygenating exchange surface. In the mass transport of blood
upward through the tube array 50, or the like, local fluid
circulation occurs in each oxygen exchange tube. The local
circulation of the blood during this transport process is wall
stabilized, providing constantly renewed blood fluid surface as the
blood is pumped up by the oxygen bubbles. The oxygen gas may flow
in true bubble flow, or in slug flow as the gas velocity through
the oxygen exchange tube is increased.
Typically, the blood flow rate through the oxygenator and
thermoregulator apparatus 1 can vary from 500 ml/min to 7,500
ml/min. This wide variation in flow rate in the apparatus 1 can be
produced by varying the number of oxygen exchange tubes disposed in
a solidly packed tube array. Typically, a tube array 50 for the low
flow rate can contain 85 tubes, each one-fourth inch in diameter.
At the other end of the flow rate range an apparatus requiring a
flow rate of 7,500 mililiters/min. can have 1,360 oxygen exchange
tubes disposed in a tube array 50, each single tube having a
diameter of one-sixteenth inch. The gas-blood flow ratio can vary
over the range of 1-4 times the blood flow rate. The oxygenating
gas typically contains 98 percent oxygen and 2 percent carbon
dioxide.
Comparative studies have shown that blood trauma can be produced in
bubble oxygenators and conventional disc oxygenators. In order to
minimize the blood trauma during the oxygenation process, the
oxygen flow rate should be the minimum value required to maintain
the oxygen transfer rate required. This invention minimizes the
blood trauma by minimizing the turbulence in the oxygenating
process and minimizing the external work done on the circulating
blood during the flow through the oxygen tube exchange array. In
this apparatus compressed oxygen gas forms a two-phase mixture of
blood and oxygen gas within the single oxygen gas exchange tube.
The oxygen gas reduces the density of the mixture of blood and gas
and the mixture is pumped upward through the exchange tube. Bubble
flow occurs at the lowest gas superficial velocity and slug flow
occurs at the next higher range of gas velocity. During both bubble
and slug flow a thin film of blood is exposed to oxygen gas,
maximizing the rate of oxygen transfer into the blood, with the
concurrent release of carbon dioxide gas. The bubbles flowing up
the exchange tube crowd against one another and against the tube
wall, exposing a large ratio of surface to gas volume as the
bubbles rise. Slugs tend to form at higher gas flow rates, the gas
slugs moving at higher velocity than the liquid, slip through the
liquid, constantly exposing fresh blood surface for oxygen-carbon
dioxide exchange. The blood fluid transported by the slugs and the
bubbles tend to flow laminarly due to the thin film structure. The
apparatus is operable and flow is stable over a wide range of
liquid and gas flow rates, providing safety in patient treatment.
The apparatus can be operated disposed at angles to the vertical,
and can be even operated disposed horizontally, in an emergency. By
simply varying the number of oxygen exchange tubes disposed in a
tube array, one can easily vary the capacity of the apparatus for
oxygen exchange capacity. As the alternate slugs of gas and blood
ascend an exchange tube during upflow, there is considerable
slippage between the liquid and the gas phase.
FIG. 4A illustrates in vertical cross sectional view a static
mixture of blood and oxygen gas disposed in an oxygen exchange
tube. The liquid 81 is alternately interphased with the oxygen gas
bubble 82 in the exchange tube 80.
In FIG. 4B the upward flowing mixture of blood 85 is shown with
interphased oxygen gas bubbles 86 disposed in the oxygen exchange
tube 80. The slippage between gas and liquid is illustrated by the
arrows 89 indicating local relative downward flow of blood film on
the side of the tube 80 while the gas bubbles 86 are ascending the
tube. It is this laminar phenomenon in blood flow which accelerates
the exchange of oxygen gas solution in the blood and the rapid
evolution of carbon dioxide from the blood during this rapid gas
exchange process.
The integral heat exchange means provides temperature control of
the perfused blood, providing precise control of an important
medical variable during a medical treatment. Thus the perfused
blood can be varied in the range of 50.degree. to 108.degree.F as
is required for the optimum treatment condition for the patient.
The blood can be medicated routinely as required prior to the final
temperature regulation of the blood and its return to the patient's
circulatory system.
In operation, the apparatus 1 is disposed below the patient and the
heat transfer fluid 53 is programmed for the scheduled temperature.
Prior to the induction of the patient's circulating blood, the
apparatus 1 may be primed with transfusion blood, plasma, saline
solution, or the like, as is required. The patient's blood or the
alternate substitute fluid is saturated with oxygen flowing through
inlet conduit 13 into the oxygen reservoir 12, then up through the
oxygen injection tube 7. Venous blood flows through the blood inlet
conduits 15 into the blood reservoir 14 and up through the oxygen
exchange tube array 50. The oxygen saturated blood fluid exits the
tube array 50 at 52 and flows through the aperture 17 into the
defoamer bed 21. A heat exchange means 31 helically disposed
provides a spiral descending flow path 32 for the blood, provides
heat transfer for the blood, and equilibrates the the blood to the
desired exit temperature. The blood exits from the annulus 55
through the apertures 35 to the blood reservoir 36. The blood
collected in the annular blood reservoir 36 exits through the blood
exit conduit 37, thence through the means required to place the
blood back in the patient's circulating system.
For the patient's safety it is necessary that the chemical
composition and the physical structure of the components of the
blood oxygenator apparatus of this invention be compatible with the
patient's circulating blood. Consistent with the above requirements
for the defoamer bed composition, the open cell elastic plastic
foam medium can typically be selected from polyurethane foam of the
open cell reticulated modification, polyester fiber felts, silicone
rubber foam of the open cell type, and polypropylene fiber foam of
the open cell construction. These foams can contain in the expanded
state, prior to compression, up to 80 pores per linear inch of
foam. Likewise, for the filter function of the annular shell filter
23, the foam can contain open cell pore openings ranging typically
from 25 to 150 microns in diameter. The mechanical structure of the
rigid oxygenator components can be rigid polyvinyl chloride, high
density polyethylene, polypropylene, polycarbonate, and other rigid
plastic compositions which meet the required chemical and physical
compatibility requirements. The fine weave filter cloth required
for filter cloth 23, or the like, can be a nylon knit or woven
cloth of the required porosity. Silicone defoaming agents are well
known, one which is compatible with the defoaming requirement for
the defoamer bed is a Dow-Corning silicone no. 2003, applied as a
very thin coating to the foam structure disposed in the defoamer
bed.
The oxygenator apparatus of this invention is precisely assembled
and the joints carefully bonded to minimize blood leakage problems
both within components of the apparatus as well as external leakage
from the apparatus as a whole. Hermetic sealing of the external
case, as well as for selected internal components, is necessary.
The bonding can be accomplished by well known cementing procedures,
ultrasonic sealing, dielectric sealing, or conductive heat sealing,
as are applicable and necessary. In conformance with well known
principles, the plastic components selected for sealing together
must be chemically and physically compatible. It is desirable that
the selected components be chemically and physically stable under
standard medical steam sterilization conditions, or other medically
accepted sterilization conditions.
Many modifications and variations in the improvement in a
disposable blood oxygenator and thermoregulator apparatus 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 specifically described.
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