U.S. patent number 3,841,837 [Application Number 05/295,175] was granted by the patent office on 1974-10-15 for oxygenator.
This patent grant is currently assigned to Tecna Corporation. Invention is credited to Sotiris Kitrilakis, Thomas C. Robinson.
United States Patent |
3,841,837 |
Kitrilakis , et al. |
October 15, 1974 |
OXYGENATOR
Abstract
An oxygenator primarily for human blood has a stator with a
cavity partly defined by a first substantially flat wall and a
peripheral wall and has a rotor with a second substantially flat
wall facing the first wall. On their facing sides both walls have
supports highly permeable to gas. Both supports are covered by
gas-permeable, hydrophobic membranes between them defining a
passage for liquid extending from near the center of the cavity to
near the peripheral wall. Gas is conducted through the supports and
membranes on the stator and on the rotor. Blood is supplied through
the stator to the cavity near the center thereof and, without an
external pump, is impelled to flow through the passage and out an
outlet in the peripheral wall, the membranes having irregularities
or vanes acting as centrifugal impellers.
Inventors: |
Kitrilakis; Sotiris (Berkeley,
CA), Robinson; Thomas C. (Berkeley, CA) |
Assignee: |
Tecna Corporation (Emeryville,
CA)
|
Family
ID: |
23136556 |
Appl.
No.: |
05/295,175 |
Filed: |
October 5, 1972 |
Current U.S.
Class: |
422/48;
128/DIG.3; 210/321.68; 210/321.75; 261/DIG.28; 261/87 |
Current CPC
Class: |
B01D
63/16 (20130101); B01D 69/00 (20130101); A61M
1/262 (20140204); A61M 1/267 (20140204); A61M
1/1698 (20130101); A61M 60/113 (20210101); B01D
2315/02 (20130101); A61M 60/40 (20210101); A61M
60/205 (20210101); A61M 1/26 (20130101); Y10S
128/03 (20130101); Y10S 261/28 (20130101) |
Current International
Class: |
A61M
1/16 (20060101); A61M 1/10 (20060101); A61m
001/03 () |
Field of
Search: |
;23/258.5 ;210/321
;261/87,DIG.28 ;128/DIG.3 ;195/1.8 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Richman; Barry S.
Attorney, Agent or Firm: Lothrop & West
Claims
What is claimed is:
1. An oxygenator comprising a stator having a disc-like cavity
defined by a pair of side walls and a peripheral wall; a shaft;
means for journalling said shaft in said stator; a rotor on said
shaft and having a rotor wall disposed in said cavity; first
support means permeable to gas in substantially all directions and
extending from said side walls; first membranes permeable to gas
but not readily permeable to liquid in contact therewith and
disposed against said support means on the side thereof opposite
said side walls; second support means permeable to gas in
substantially all directions and extending from said rotor wall on
the side thereof toward said side wall; second membranes permeable
to gas but not readily permeable to liquid in contact therewith and
disposed against said second support means on the side thereof
opposite said rotor wall and spaced from said first membranes to
leave a passage therebetween extending from adjacent the center of
said cavity to the periphery thereof; means in said stator for
conducting gas into said stator, through said first support means
and out of said stator; means in said rotor for conducting gas into
said rotor, through said second support means and out of said
rotor; inlet means in said stator for conducting liquid into said
cavity and into said passage adjacent the center of said rotor; and
outlet means in said peripheral wall for conducting liquid out of
said cavity.
2. An oxygenator as in claim 1 including an irregularity on said
second membranes effective to produce pumping of said liquid from
said inlet means to said outlet means upon rotation of said rotor
in said stator.
3. An oxygenator as in claim 2 in which said irregularity is a
radial vane.
Description
In U.S. Pat. No. 3,674,440 for an "Oxygenator" issued to one of us
(Kitrilakis) on July 4, 1972 there is disclosed in considerable
detail an arrangement for transferring oxygen to blood. The device
is substantially pressure balanced so far as blood inflow and
outflow are concerned and in use requires the blood to be impelled
through it by some sort of external pump. It has developed in
practice that it would be highly desirable to afford a comparably
effective and efficient oxygenator but which could function without
the necessity of an external blood pump.
It is therefore an object of the invention to provide an oxygenator
that contains within itself a way of circulating blood through
it.
Another object of the invention is to provide an oxygenator having
the attributes of the oxygenator in the mentioned patent but which
does not require an external blood pump.
Another object of the invention is to provide a generally improved
oxygenator.
Other objects, together with foregoing, are attained in the
embodiment of the invention described in the accompanying
description and illustrated in the accompanying drawings, in
which:
FIG. 1 is a cross-section on a diametrical plane through an
oxygenator constructed pursuant to the invention;
FIG. 2 is a detailed cross-section to an enlarged scale through one
of the wall, support and membrane assemblies; and
FIG. 3 is a cross-section, the plane of which is indicated by the
line 3--3 of FIG. 2.
Reference is had to the above-identified patent for many details of
construction of the present oxygenator since they are identical in
many particulars. In the present instance the oxygenator includes a
stator 4 forming a housing made up of a pair of cover plates 6 and
7 of generally similar construction and fastened together around
their peripheries by spaced fasteners 8 and clamping between them a
plurality of separate layers to form, in effect, a sandwich. The
stator housing encloses an interior cavity defined largely by one
side wall 9, a second side wall 11 and a peripheral wall 12 made up
by the sandwich members.
Designed to operate within the stator is a rotor 16 having a shaft
17 provided with a pulley 18 or other means for connecting the
rotor to a motor for turning the rotor on bearings 19 and 21 in the
stator and for rotation about a central axis 22. The rotor includes
not only an enlarged portion 23 of the shaft 17 but likewise
includes a central disc 24 bounded by a rotor wall 26 on one side
and by a rotor wall 27 on the other side.
As in the mentioned patent, most of the interior stator and rotor
walls are covered by special devices for assisting in the
oxygenation of the blood and for blood flow. On the wall 9, for
example, there is a support wafer 28 typical of others in the
device. This is a ruffled or corrugated sheet of material affording
mechanical support yet being permeable in virtually all directions
to gas, such as oxygen. As an alternate, the wafers can be mounds
or ridges integral with the material of the rotor and stator. An
appropriate support wafer 29 is disposed on the other stator wall
11. Comparable support wafers 31 and 32 are situated against the
walls 26 and 27 of the rotor.
Each support wafer, however formed, is covered with a membrane,
such as 33, having little ability to support itself but being
supported in substantially a planar form by resting against the
adjacent support wafer. The membrane is on the opposite side of the
wafer from the adjacent rotor or stator wall. The membranes are
highly permeable to gases but are not readily permeable to liquid
which contacts the membrane. A comparable membrane 34 is arranged
adjacent the wafer 29 while membranes 36 and 37 lie adjacent the
wafers 31 and 32. Conveniently, some of these various parts are
relatively thin layers which go to make up the sandwich referred
to. In the instance of the rotor, the parts are secured together
for conjoint rotation about the axis 22 by reason of a plurality of
through bolts 38 passing through the various parts of the rotor and
clamping them together.
In order to supply gas, such as oxygen, to the interior of the
mechanism the stator is provided with a branched inlet opening 41.
One portion of the opening connects with a duct 42 leading into
proximity with the support wafer 28 so that gas in the duct 42 can
travel into and through the wafer or around the axis and eventually
can flow through any of a number of passages 43 formed in the
stator. The passages 43 communicate with the wafer 29 so that there
can be gas flow through all parts thereof. Escape of gas from the
wafer 29 is through a passage 44 in the lower portion of the
stator. Flow is from there to any suitable point of
disposition.
The inlet opening 41 also is connected to a duct 46 leading into an
annular chamber 47 between the stator and the rotor and confined by
sealing rings 48 and 49. From the compartment 47 gas flow is
through an opening 51 leading into an upper chamber 52 defined by
the hollow interior of the drive shaft. The chamber 52 is isolated
from a lower chamber 53, also formed in the drive shaft, by the
solid intervening rotor disc 24.
Gas from the inlet 41 flows through the duct 46 into the confined
chamber 47, thence through the opening 51 into the upper chamber
52. From thence the gas flows into and through all parts of the
rotor wafer 31 on one side of the rotor plate 24 and then flows
through any one of several openings 54 in the rotor disc to the
wafer 32. The gas permeates throughout that wafer and then travels
into the lower chamber 53 in the rotor for discharge to any
suitable point.
Most of the gas which is supplied to the wafers diffuses through
the adjacent membranes and into a passage 56 disposed between and
defined by the outer surface of the rotor and the inner wall of the
stator. The passage 56 is duplicated by a comparable passage 57 on
the other side of the rotor, the two sides being connected by a
peripheral passage 58 extending around the interior of the stator.
Also, the passages 56 and 57 communicate with annular chambers 59
and 61 respectively extending around the rotor and within the
stator. The chambers are confined between the packing ring 49 and a
comparable packing ring 62.
Blood from a suitable source enters the stator through a passage 63
opening into the annular chamber 59. Blood in the chamber 59 can
flow to the chamber 61 through any one of several openings 66
formed in each of the sandwich members making up the rotor. In
addition, the stator periphery is provided with a discharge or
outlet passage 67 opening to the passage 58. Blood flows into the
annular chamber 59 and thence into the passage 56 and through the
openings 66 into the passage 57 and then from such passages 56 and
57 through the outlet 67.
We have found that the membranes, such as 33, normally have
sufficient superficial irregularities so that when the rotor is
revolved about the axis 22, the irregularities act upon the blood
in the passages 56 and 57 to exert a centrifugal force thereon. The
force magnitude is great enough to induce blood to flow in through
the entrance passage 63, through the passages 56 and 57 in a
generally radial path and then out through the discharge opening 67
and into whatever connecting ducting may be secured thereto. Thus,
blood is made to flow through the oxygenator without the necessity
of utilizing an exterior circulating pump.
While the irregularities on the membranes are sufficient, as
indicated, to induce flow by centrifugal action, it is sometimes
the case that the flow needs to be accelerated or augmented. In
such instance we provide a membrane 68 generally similar to the
other membranes, such as 33 for example, as shown in FIG. 2. The
membrane 68 has an integrally formed, special irregularity 69 in
the form of an upstanding radial vane. Usually the membrane is of
an elastomeric or plastic material that is readily molded so it is
feasible to mold the radial vane 69 with the membrane. The vane 69
projects from the membrane into the adjacent passageway 56 or 57
and imparts an additional centrifugal acceleration to blood in the
passageways. The result of the vanes is to augment the effect of
the centrifugal force due to the rotating rotor and produces a very
effective pumping of the blood, so that external pumps can be
dispensed with.
The structure as described, particularly when the vanes are
utilized, carries out all of the attributes of the earlier patented
device as to the production of turbulent flow and the reduction in
thickness of boundary layers in the blood. In fact, the transfer of
oxygen to the blood in this structure has proved so efficient in
practice that the oxygenator herein with a single rotor stage can
accomplish substantially the same amount of oxygenation as the
two-stage rotor shown in the patent and has the added attribute of
dispensing with an external pump.
* * * * *