U.S. patent number 3,769,982 [Application Number 05/183,463] was granted by the patent office on 1973-11-06 for physiological drainage system with closure means responsive to downstream suction.
Invention is credited to Rudolf R. Schulte.
United States Patent |
3,769,982 |
Schulte |
November 6, 1973 |
**Please see images for:
( Certificate of Correction ) ** |
PHYSIOLOGICAL DRAINAGE SYSTEM WITH CLOSURE MEANS RESPONSIVE TO
DOWNSTREAM SUCTION
Abstract
A physiological drainage system for draining liquids from a
source of the human body to a region where it is disposed of. The
latter region is at a different elevation from the source region.
The system is provided with a control which is responsive to
downstream suction. When the suction is excessive, the control
closes the system to flow so as to prevent over-drainage of the
source region. The control comprises a valve which remains open to
flow at normal rates and downstream suction levels, and which
closes when the downstream suction level is above some
predetermined level.
Inventors: |
Schulte; Rudolf R. (Santa
Barbara, CA) |
Family
ID: |
22672896 |
Appl.
No.: |
05/183,463 |
Filed: |
September 24, 1971 |
Current U.S.
Class: |
604/10 |
Current CPC
Class: |
A61M
27/006 (20130101) |
Current International
Class: |
A61M
27/00 (20060101); A61m 027/00 () |
Field of
Search: |
;128/35V,35R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Laudenslager; Lucie H.
Claims
I claim:
1. A suction control for a physiological drain wherein the control
closes in response to excessive downstream suction, said control
comprising: a body having an internal cavity, a first and a second
flow port through the body into the cavity, a flexible diaphragm
extending across the cavity; a first sealing surface in said cavity
on said diaphragm; and a second sealing surface in the cavity
adapted to make a closure with the first sealing surface between
the flow ports as a consequence of the exertion of sufficient
suction at one of said ports to cause at least one of said sealing
surfaces to move toward and against the other, the diaphragm being
imperforate throughout its entire area which lies outside of that
portion of the second sealing surface which is occluded when the
said sealing surfaces abut one another.
2. A suction control according to claim 1 in which the diaphragm 41
across the cavity to divide it into two chambers, there being a
third flow port through said diaphragm interconnecting the
chambers, and in which the first sealing surface surrounds the
third flow port, and the second sealing surface comprises a wall of
one of the chambers, each of the first and second flow ports
entering a different respective flow chamber outside the area
bounded by a sealing surface.
3. A suction control according to claim 2 in which a third sealing
surface is provided which comprises a wall of the other of said
chambers.
4. A suction control according to claim 3 in which at least one of
said walls is flexible.
5. A suction control according to claim 1 in which the diaphragm
extends across the cavity to divide it into two chambers, there
being a third flow port through said diaphragm interconnecting the
chambers, in which the first sealing surface surrounds the third
flow port, each of the first and second flow ports entering a
different respective flow chamber outside the area bounded by a
sealing surface, in which a flexible complementary diaphragm
extends across the cavity in one of said flow chambers, with one of
the first and second flow ports entering the flow chamber between
the two diaphragms, a surface of said complementary diaphragm
forming a sealing surface, and a support member in the other flow
chamber supporting the diaphragm away from the wall of the
cavity.
6. A suction control according to claim 5 in which the support is
tubular, axially aligned with the third flow port, and perforated
to permit flow inside the support and through its wall.
7. A suction control according to claim 5 in which a vent passage
interconnects the flow chamber entered by the other of said first
and second flow ports to a relief chamber located between the
complementary diaphragm and the wall of the cavity.
8. A suction control according to claim 7 in which the support is
tubular, axially aligned with the third flow port, and perforated
to permit flow inside the support and through its wall.
9. A suction control according to claim 8 in which spacer means
prevent adherence of the complementary diaphragm to the wall of the
cavity.
10. A suction control according to claim 1 in which the diaphragm
extends across the cavity to divide it into two chambers, its
sealing surface facing one of said flow ports and adapted to close
the same, the other of said flow ports entering the same chamber as
the said one of said flow ports.
11. A suction control according to claim 10 in which bias spring
means is mounted in the chamber which does not receive the flow
ports, and biases the sealing surface toward the first-named flow
port.
12. A suction control according to claim 1 in which a pair of said
diaphragms is provided, said diaphragms being substantially flat
sheets laid against one another and sealed to each other to form an
internal flow chamber when fluid pressure is exerted between the
diaphragms, the flow ports opening into said flow chamber at
linearly spaced-apart locations, each of said diaphragms carrying
one of said sealing surfaces.
13. A suction control according to claim 12 in which a body
surrounds said diaphragms to form a cavity receiving the same and
permitting their distention by insertion of fluid under
pressure.
14. A physiological drainage system provided with a control for
resisting over-drainage as a consequence of downstream suction
comprising: a drainage catheter adapted to drain fluid from a
source region; a shunt tube to dispose of fluid collected by said
catheter; and a suction control comprising: a body having an
internal cavity, a first and a second flow port through the body
into the cavity, a flexible diaphragm extending across the cavity;
a first sealing surface in said cavity on said diaphragm; and a
second sealing surface in the cavity adapted to make a closure with
the first sealing surface between the flow ports as a consequence
of the exertion of sufficient suction at one of said ports to cause
at least one of said sealing surfaces to move toward and against
the other, the catheter being connected to one flow port and the
shunt tube to the other; the diaphragm being imperforate throughout
its entire area which lies outside of that portion of the second
sealing surface which is occluded when the said sealing surfaces
abut one another.
15. A physiological drainage system according to claim 14 in which
the shunt tube is provided with a check valve at a location removed
from its connection to the control.
16. A physiological drainage system according to claim 14 in which
a pump is connected into the system between the catheter and the
control.
17. A physiological drainage system according to claim 16 in which
the shunt tube is provided with a check valve at a location removed
from its connection to the control.
18. A physiological drainage system according to claim 14 in which
the diaphragm extends across the cavity to divide it into two
chambers, there being a third flow port through said diaphragm
interconnecting the chambers, and in which the first sealing
surface surrounds the third flow port, and the second sealing
surface comprises a wall of one of the chambers, each of the first
and second flow ports entering a different respective flow chamber
outside the area bounded by a sealing surface.
19. A physiological drainage system according to claim 14 in which
the diaphragm extends across the cavity to divide it into two
chambers, there being a third flow port through said diaphragm
interconnecting the chambers, in which the first sealing surface
surrounds the third flow port, each of the first and second flow
ports entering a different respective flow chamber outside the area
bounded by a sealing surface, in which a flexible complementary
diaphragm extends across the cavity in one of said flow chambers,
with one of the said first and second flow ports entering the flow
chamber between the two diaphragms, a surface of said complementary
diaphragm forming a sealing surface, and a support in the other
flow chamber supporting the diaphragm away from the wall of the
cavity.
20. A physiological drainage system according to claim 19 in which
a vent passage interconnects the flow chamber entered by the other
of said first and second flow ports to a relief chamber located
between the complementary diaphragm and the wall of the cavity.
21. A physiological drainage system according to claim 14 in which
the diaphragm extends across the cavity to divide it into two
chambers, its sealing surface facing one of said flow ports and
adapted to close the same, the other of said flow ports entering
the same chamber as the other of the said flow ports.
22. A physiological drainage system according to claim 14 in which
a pair of said diaphragms is provided, said diaphragms being
substantially flat sheets laid against one another and sealed to
each other to form an internal flow chamber when fluid pressure is
exerted between the diaphragms, the flow ports opening into said
flow chamber at linearly spaced-apart locations, each of said
diaphragms carrying one of said sealing surfaces.
23. A suction control according to claim 1 in which the diaphragm
forms a bounding wall of said cavity, and is so disposed and
arranged as to shut off flow between the flow ports as a
consequence of exertion of sufficient suction on the control.
24. A suction control according to claim 23 in which the said
diaphragm forms an outer wall of the control.
25. A suction control according to claim 24 in which the control is
generally circular in plan view, and in which a seat surrounds the
second flow port at the center of the control, the diaphragm
overlaying the said seat and the entry of the first flow port into
the cavity.
26. A suction control according to claim 25 in which the diaphragm
is fabric-reinforced.
27. A suction control according to claim 14 in which the diaphragm
forms a bounding wall of said cavity, and is so disposed and
arranged as to shut off flow between the flow ports as a
consequence of exertion of sufficient suction on the control.
28. A physiological drainage system according to claim 27 in which
the said diaphragm forms an outer wall of the control.
29. A physiological drainage system according to claim 28 in which
the control is generally circular in plan view, and in which a seat
surrounds the second flow port at the center of the control, the
diaphragm overlaying the said seat and the entry of the first flow
port into the cavity.
30. A physiological drainage system according to claim 29 in which
the diaphragm is fabric-reinforced.
Description
This invention relates to physiological drainage systems of the
type used for draining excess liquid from a source region of the
human body to a drainage region. An example is found in the
alleviation of the symptoms of hydrocephalus, in which ailment the
natural drainage systems from the cranium fail to provide
sufficient drainage. It is necessary to drain excess fluid from the
cranium in order to prevent brain damage and death.
Drainage systems for alleviation of the symptoms of hydrocephalus
and of other ailments of the body in which unwanted quantities of
fluid remain in some source region of the human body are well
known. A classical example of one such system is shown in U.S. Pat.
No. 3,111,125, issued to Rudolf R. Schulte on Nov. 19, 1963. In
thus shunt system, a drainage catheter is inserted in a source
region to be drained, the ventricles of the brain, for example. The
catheter is connected to a shunt tube which extends along a
selected route to another region of the human body, such as to the
heart, where the excess fluid is disposed of. It is common practice
to provide a check valve at the free end of the shunt tube in order
to prevent fluids from backing up into the system. it is also
common practice to provide a pump in the system to assist the
system's functioning. The pump means ordinarily remains open to
forward flow, may act as a reverse flow check valve, and can also
impel fluid in one or both directions depending on how the valve is
manipulated.
Systems according to the foregoing arrangement are in widespread
use throughout the world, and have provided dramatically successful
results in alleviating the distress of hydrocephalus. In this
ailment, before such shunt systems were devised, brain damage and
death were frequent consequences. Because such systems have been
used, thousands of persons today are alive and leading normal
lives.
Of course, over the years during which systems of the above type
have been in use, a number of problems have developed which, while
not serious enough to contra-indicate the usage of the system,
still indicate that there is room for improvement of the system.
One such problem is a tendency to over-drain the source region,
even though the shunt system may be set to open only at a
relatively high positive pressure within the cavity. It is
undesirable to remove too much fluid from the ventricles of the
brain, because then fever and listlessness are apt to result, and
the possibility that the body may develop its own drainage system
as a consequence of the maintenance of some positive pressure level
in the brain is frustrated.
It is an object of the system of this invention, instead of
over-draining the source region, to leave the proper amount of
fluid therein, and as a consequence, a proper pressure level.
Analysis indicates that one cause of the over-draining effect is
that, because the shunt system ordinarily remains full of liquid,
and because the person in whom it is implanted moves to various
angular positions relative to the vertical, the "hanging" fluid
column which develops in the shunt tube will vary from position to
position, and a siphoning-pumping action results. Therefore, even
though the system, when in static equilibrium at one body attitude
may drain the source region to exactly the right degree, still this
equilibrium can suddenly be upset merely by a change in body
position, and a different drainage condition could result. This
variability cannot be controlled, because it results from the
normal body movements of the user. Accordingly, it is an object of
this invention to provide a means which will close down the system
to fluid flow so as to protect the source region against excessive
drainage due to downstream suction so that, no matter what the
position of the user, the suction effect will not tend to
over-drain the source region. Instead, the system will drain only
when suction below a given level exists (i.e. when excessive
suction does not exist), accompanied by sufficient positive
pressure to cause expulsion of fluid from the source region and
through the system.
This device is, in one sense a "siphon breaker," but is not to be
confused with ordinary siphon breakers which are widely known. The
classical type of siphon breaker, which seeks to avoid siphoning
from a region as the consequence of an upstream break in a line,
ordinarily functions to admit gas into a fluid stream so as to
break the suction. Of course, it is impossible to introduce gases
into a system in the human body, where the system connects to the
brain and to the bloodstream. Accordingly, while this device acts
to break a suction force, it is not to be confused with classical
suction or siphon breakers, because it does not relieve the suction
force. Instead, it blocks it.
Another classical device utilized in controlling unwanted movement
of fluids is a common check valve which operates on a differential
pressure concept, usually being spring-loaded to a closed position,
and opened in the direction of forward flow by a differential force
which overcomes the spring bias. The device of this invention needs
carefully to be distinguished from the classical check valve. In
the check valve, there is an impediment to flow in one direction
and free flow in the opposite direction under a suitable or
sufficient differential pressure. It is to be noted that, in this
device, however in some respects it may physically resemble a check
valve, it closes to stop the flow of fluid in the intended
direction of forward flow when excessive downstream suction is
exerted. Such suction would open the classical check valve because
it would contribute all the more to the differential pressure
needed to open the same. Accordingly, the usual considerations of
stopping flow with check valves and with siphon breakers are not
pertinent to this invention.
This invention provides a control which permits the free flow of
fluid from a source region to be drained to a receiving region to
receive the same which will close to the forward direction of flow
when an excessive downstream suction exists. In some embodiments of
this invention, the control will remain closed regardless of the
upstream pressure, and will not open again until the downstream
suction is relieved, such as by the person's assuming a position in
which a lesser suction exists.
In the use of this device it may, at first blush, appear that this
closure means might tend to keep the system closed for an
unwarranted length of time. As will later be apparent, the ordinary
motions of turning over in bed, of sitting up, standing up, sitting
down, and leaning over will of themselves cause changes of suction
level which are likely to permit the control to open and again
permit drainage. Accordingly, it is another object of this
invention to provide a control responsive to downstream suction
which will permit drainage to occur under predetermined suction and
differential pressure conditions, stop the drainage when an
excessive downstream suction is exerted on the system which might
over-drain the region to be drained, and still be open in a number
of normal positions of the human body such that proper drainage
will in fact occur with sufficient frequency to meet the needs of
the user.
A device according to the present invention includes a body having
a pair of flow ports entering a cavity, and between them flexible
means which is adapted to move to close the outlet which is
downstream as to direction of flow when excessive suction exists
downstream.
According to an optional feature of the invention, the flexible
means is so disposed and arranged that, when once it closes the
control, the control remains closed until the suction is
sufficiently relieved, regardless of the upstream pressure,
assuming it to be greater than the suction level, of course.
The above and other features of this invention will be fully
understood from the following detailed description and the
accompanying drawings in which:
FIG. 1 shows a reclining person with a system according to the
invention implanted in him;
FIG. 2 shows the same person in an erect position;
FIG. 3 is a schematic view of a system according to the
invention;
FIG. 4 is an enlarged fragmentary view of a portion of the system
of FIG. 3;
FIG. 5 is a cross-section taken at line 5--5 in FIG. 2;
FIGS. 6 and 7 are cross-sections taken at lines 6--6 and 7--7,
respectively, in FIG. 4;
FIG. 8 is an axial section of an embodiment of a control according
to the invention in one operating position;
FIGS. 9 and 10 are views similar to FIG. 8 showing the device of
FIG. 8 in other operating conditions;
FIG. 11 shows an optional feature which may be embodied in the
device of FIG. 8;
FIG. 12 is a cross-section taken at line 12--12 in FIG. 8;
FIG. 13 is a fragmentary cross-section taken at line 13--13 in FIG.
8;
FIG. 14 is a fragmentary cross-section taken at line 14--14 in FIG.
11;
FIGS. 15 and 16 are axial cross-sections of another embodiment of
the invention, shown in two operating positions;
FIGS. 17 and 18 are axial cross-sections of another embodiment of
the invention in two different operating positions;
FIGS. 19 and 20 are axial cross-sections of still another
embodiment of the invention in two different operating
conditions;
FIGS. 21 and 22 are cross-sections taken at lines 21--21 and 22--22
in FIGS. 19 and 20, respectively;
FIG. 23 shows an optional type of diaphragm useful in this
invention;
FIGS. 24 and 25 are axial cross-sections of the presently preferred
embodiment of the invention in two operating positions;
FIG. 26 is a perspective view of the device of FIG. 24;
FIG. 27 is a top plan view of the device of FIG. 24; and
FIG. 28 is a cross-section taken at line 28--28 of FIG. 24.
FIG. 1 illustrates a person 30 afflicted with hydrocephalus having
a cranium 31 enclosing a brain 32, the ventricles of which are
surfeited with fluid because the normal drainage passages of the
body are not draining the same. As a consequence, development of
this brain would be retarded unless the resulting fluid pressure
were relieved. The person's skull would be distended, and in
general, he would be subjected to intense pain, mental retardation,
and possibly death.
It is for the purpose of draining the excess fluid that the system
35, according to the invention, is provided. The system shown
drains fluid from the ventricles of the brain to the heart 36, from
which it is carried in the bloodstream to be disposed of by normal
physiological functions of the purification of the blood. This
system includes a drainage catheter 37 which has, as best shown in
FIGS. 2 and 5, a tubular cylindrical wall 38 with a plurality of
drainage ports 39 therethrough near one end. The catheter is
inserted so that these ports are placed in the source region. The
other end passes through the burr hole in the skull through which
the drainage end of the catheter was inserted.
A pump 40 according to the aforesaid Schulte U.S. Pat. No.
3,111,125 is connected to the drainage catheter. This pump is
optional. It exists to flush either the upstream or the downstream
portions of the system, and to create pumping surges should such be
desired. This is a very useful additional feature for use with this
invention, but it is not essential to the practice of this
invention.
The pump has an inlet 41 connected to the drainage catheter and an
outlet 42 connected to the control 45 according to this invention.
Both the pump and the control may be formed with flat bottoms and
low profiles so they can be laid against the skull and fit beneath
the scalp. The control has a first and second flow port 46, 47,
respectively, the first upstream flow port (46) being connected to
the outlet of the pump and the second downstream flow port (47)
being connected to a shunt 50 of the type shown in the aforesaid
Schulte patent and also shown in FIG. 4. If the pump is not used,
the control is connected directly to the catheter. The term
"upstream" is used to mean the direction from which flow
originates. In some embodiments of this system, both ends are
regarded as potentially upstream. However, speaking generally,
"upstream" means toward the source region from the control, and
"downstream" means toward the disposal region.
The shunt may be a simple open-ended tube, but it is usually best
for it to include check valve means at its free end so that reverse
flow of fluids will not occur into the shunt from the disposal
region. The shunt is tubular and has a cylindrical wall 51
extending to a closed end 52 adjacent to which there is a check
valve 53 in the form of a slit 54. Slit 54 is cut through the wall
of the tube without removal of material so that a differential
pressure derived from a greater pressure on the outside than on the
inside will tend to press the edges of the slit together and close
the valve, while a reverse differential pressure will tend to bow
the wall outward, opening the slit and permitting drainage.
Were shunt 54 to be held freely in the air, hanging vertically as
shown in FIG. 4, liquid 55 would fall to a given level 56 which
indicates the differential pressure required to open the slit
valve. Liquid above that level would open the slit and drain out.
In the system as schematically shown in FIG. 3, it would be the
more usual thing for the system to remain substantially full of
liquid, there being few if any breaks in the column; however, such
might be in the form of a vacuum break downstream of the control,
whose length depends on the length of column supported above the
level 56. It is this additional column of liquid hanging from the
control which exerts the suction that it is the function of this
control to resist.
As schematically shown in FIG. 3, the system taps a region 57 to be
drained by the drainage catheter 37. Pump 40, if used, passes fluid
from the catheter to control 45 and shunt 50, and then into a
disposal region where the fluid is disposed of. In order to
illustrate the different suction conditions in the system which are
derived from changes in posture of the person, reference should now
be made to FIG. 1 wherein the person is shown reclining. It will be
seen that the maximum pressure in the system is derived from a
column of fluid whose height is shown by dimension A. This is the
height of a vertical column measured from the inlet end of the
drainage catheter to the discharge end of the shunt. It will be
noted that there is substantially no suction exerted below the pump
or the control. In fact, but for the check valve 53, there would
actually be a reverse pressure at the control from the outlet end.
It will also be recognized that the dimension A would "disappear"
were the person to lie on his side with tip 58 of the drainage
catheter at the same elevation as the tip 59 of shunt 50.
An extreme but common situation, and one which it is the function
of this invention to control, is shown in FIG. 2 with the person in
the erect position. A dimension B represents the column between the
two tips. In this case, the hanging column of fluid in shunt 50 is
very long, perhaps 12-18 inches in length, and its effect would be
to siphon liquid out of the brain, perhaps excessively. The means
whereby this has been resisted in the past has been to make the
slit valve 53 open at a relatively high pressure, thereby lessening
the effective sunction column above level 56 as heretofore
discussed. However, this makes the system less sensitive, and is
something of a "brute force" means of approaching the problem.
Furthermore, close selection of the level 56 is quite difficult,
and adjustment is impossible in the implanted tube. A better
technique would be to enable the region to be drained at any
desired outlet pressure, but to prevent it from being drained
excessively because of excessive suction forces. That is the
purpose of the control of the instant invention. Incidentally, the
pulsing variations of suction derived from frequent changes of
position cause strong pumping pulses, which could overcome a slit
valve, but which are stopped by the control.
FIG. 8 shows one embodiment of a control 60 according to the
invention which may be utilized at the location shown schematically
by control 45 in the system, as may the other embodiments hereafter
disclosed. Control 60 has a body 61 with a flat base 62 and a dome
63 forming a cavity 64 therein which is divided into two chambers
65, 66 by a flexible diaphragm 67 with a central flow port 68
(sometimes called a "third flow port") therethrough. The intended
downstream flow through this control is from first flow port 69 to
second flow port 70, port 69 being upstream and port 70 being
downstream.
A support 71 projects into the cavity from the dome, to which it is
attached. It has a plurality of passages 72 in its wall and a
central opening 73 in communication with the passages and in
alignment with flow port 68. A seat 74 is formed on the diaphragm
surrounding the flow port and facing into chamber 66. A
complementary diaphragm 75 extends across the cavity adjacent to
the base. It is prevented from adhering to the base by a plurality
of raised buttons 77 which are molded integrally with the base.
Ports 69 and 70 form connectors 78, 79 by means of which the
control may be coupled into the system.
Control 60 is shown in three different positions in FIGS. 8, 9, and
10. The positions of FIGS. 8 and 9 are closed positions and that of
FIG. 10 is its normal open position.
FIG. 11 shows an optional feature which may be incorporated in the
control of FIG. 8, when it is desired to resist suction only if
exerted from the downstream end. In this case a vent passage 80 is
formed interconnecting the first chamber 65 to a relief chamber 81
formed between the base and the complementary diaphragm. The
function of this vent passage will further be discussed below.
The device is shown assembled by layers of cement 82, which are
shown in dotted notation. This control and all other embodiments of
the invention are preferably made out of the same material of
construction, a convenient example of which is medical grade
silicone rubber. The parts may individually be molded and then
cemented together. In some embodiments variuus of the portions may
be vulcanized together without cement. It is to be understood that,
in all of the drawings herein, the parts where joined together to
form continuous structure are fluid-tight at their joints except as
otherwise indicated. The required flexibility of certain parts is
generally secured by selection of their respective thicknesses.
FIGS. 15 and 16 show another embodiment of the invention. A control
85 has a body 86 constructed of a flat base 87 and a dome 88. These
form a cavity 89 between them. The cavity is divided into chambers
90, 91 which are respectively connected to first and second flow
ports 92, 93. Port 93 will ordinarily be the downstream port,
although in this embodiment the selection is immaterial, because
the control functions bi-directionally. The base includes a
dome-shaped inner surface 94, which faces convex upwardly toward a
flexible diaphragm 95. This diaphragm divides the cavity into the
aforesaid two chambers 90 and 91. A flow port 96 (sometimes called
a "third flow port") passes through the diaphragm and a seat 97
extending around this port, facing into the chamber 91.
The device of FIGS. 15 and 16 is shown in these two figures in its
actuated position with the diaphragm flexed. In its unflexed
condition, the diaphragm will assume a position midway between the
two positions, and so there will be free flow between ports 92 and
93 through flow port 96. Exertion of sufficient suction at either
of the two flow ports will cause the diaphragm to assume a
respective one of the illustrated positions.
FIGS. 17 and 18 show another embodiment of the invention wherein a
control 100 has a body 101 with a base 102 and a cover 103. A
cavity 105 is formed in the body. A flexible diaphragm 106 bows
upwardly in the diaphragm with a chamber 107 beneath it. A bias
spring 108 is placed in chamber 107 which tends to force the
central portion of the diaphragm upwardly toward a first flow port
109, which is surrounded by a seat 110 that projects into chamber
111 of cavity 105. A second flow port 112 also enters chamber 111.
This embodiment differs from the previous embodiments in that flow
does not occur through the diaphragm, but instead is always on the
same side thereof. The normal relaxed position of the diaphragm is
that shown in FIG. 17, and its actuated position, when suction does
not occur and sufficient positive pressure exists to open the
control, is shown in FIG. 18, both of which will be more fully
described below.
FIG. 19 shows still another embodiment of the invention wherein a
control 120 includes a body 121 having a cavity 122 therein. The
cavity is vented by vent ports 123 through its wall, although if
desired these may be closed and the cavity filled with a spongy or
springy means for exerting a reference pressure as will later be
discussed. The device is a generally flat lozenge having first and
second ports 124, 125 entering at its ends. Within the body the
ports connect to a flow chamber 126 of variable volume which is
formed between a pair of diaphragms 127, 128 that are generally
flat sheets of elastic resilient material which, under proper
conditions of pressure and flow rates, will bow apart as shown in
FIG. 1 to enlarge the flow chamber 126, or under suction conditions
where closure occurs, draw together to form a closure line 129 as
shown in FIG. 22.
FIG. 23 illustrates a portion of a diaphragm which is flexible, but
not necessarily resilient in the "elastic" sense of the term.
Except for diaphragms such as complementary diaphragm 75, which is
best made elastic, the diaphragms merely need to be movable to
accomplish their purpose. Even in diaphragm 75, a spring could be
substituted for the elasticity as a source of restorative force.
This illustrative diaphragm 135 has a fabric reinforcement 136
which will prevent stretching. However, a number of
bellows-convolutions enable the seat 137 to move axially relative
to the rim edge of the diaphragm. Such a construction can generally
be substituted for the other diaphragms shown in the drawings.
Furthermore, a certain amount of freedom to move is provided by the
rim supports for the various diaphragms. These controls usually do
not measure more than between about 9 to 15 mm. across, and some
resilient yielding of structure will be expected to occur, which
frees up the diaphragm for movement.
The presently preferred embodiment of the invention is shown in
FIGS. 24-28. It is a variation of the device of FIGS. 17 and 18,
and illustrates that the diaphragm need not be movable freely and
separately within a body cavity, but can instead be used to form a
body wall for the cavity. An advantage of such an arrangement is
that a biasing force or pressure can be derived from the body
region surrounding the control, such as from pressure-contact with
fatty tissue in various regions, or even from exposure to fluids in
this region.
Control 140 includes a body 141 having a flat, relatively rigid
base 142 with a peripheral rim 143 around the top of it. A flexible
diaphragm 144, preferably having a fabric reinforcement 145 to
reduce or eliminate stretch, is peripherally attached to the rim
and sealed thereto in order to form a cavity 146 in the body. Thus
the diaphragm is both a cover and a diaphragm, and its operative
part for flow control is its surface which is exposed in the
cavity.
Another fabric reinforcement 147 is cemented to the base to reduce
or eliminate stretching of the base. A first and a second flow port
148, 149, respectively, pass through the body. Flow port 148 will
be connected to the region to be drained, and flow port 149 to the
receiving region.
Flow port 149 rises in the cavity at the center of the cavity, and
is surrounded by a seat 150 which projects into the cavity (this
cavity will sometimes be called a "flow chamber" in the same sense
as chamber 111 in FIGS. 17 and 18).
Flow port 148 rises into the cavity at a point laterally spaced
from the seat. The diaphragm, when it contacts the seat as in FIG.
25, closes the control to flow. It is open in FIG. 24. FIG. 24
illustrates the relaxed condition of the control in the absence of
distortive forces.
The terms "first sealing surface" and "second sealing surface" are
sometimes used herein. The first sealing surface is a portion of a
diaphragm which faces toward another sealing surface, which
surfaces can make contact with one another to close the control to
flow. The diaphragm is imperforate outside of the area occluded
when the sealing surfaces abut one another.
As an example of the usage of this terminology, in FIG. 8,
diaphragm 67 has a sealing surface 74a formed as the crown of seat
74. Surface 74a is on the diaphragm and in the cavity 64.
Complementary diaphragm 75 has a "second" sealing surface 75a which
faces first sealing surface 74a. In FIG. 9, the area bounded by
surface 74a is occluded as a consequence of abutment of the two
sealing surfaces.
In FIG. 15, a first sealing surface 97a is formed as the crown of
seat 97, and second sealing surface 94 (the dome-shaped inner
surface) is formed on the base. Both are in the cavity, and they
face one another. Also, the upper surface of diaphragm 95 faces the
bottom surface of dome 88, for the same purpose. In both cases, the
area occluded is defined by the outer boundary of the area of
abutting contact, and the area of the diaphragm which is not
occluded is imperforate. Like considerations apply to the
construction of FIG. 17.
In FIG. 19, the first and second sealing surfaces are surfaces 127a
and 128a.
In FIG. 24, the first sealing surface is surface 144a which is on
the diaphragm and in the cavity. It faces a second sealing surface
150a formed as the crown of seat 150. The diaphragm is imperforate
outside of the area occluded when the sealing surfaces abut one
another, that is, outside of the crown.
The operation of the system and of the controls according to the
invention will now be described. The system will have been
implanted in the patient as shown by the use of conventional
surgical techniques. A burr hole is formed in the skull after
peeling the scalp back to expose the skull. Then, using a stylette,
the drainage end of the catheter is thrust into the ventricles of
the brain so that the drainage ports stand in the source region.
The pump, if one is used, is connected to the catheter, and the
control is connected to the pump. The shunt tube is passed through
the channels in the body to the heart, is trimmed to the proper
length and connected to the control. Then, the connections are
sutured as required, and the scalp is closed over the system. The
pump itself usually forms a closure for the burr hole. The system
is now installed and ready for operation, and any of the controls
of FIGS. 8 through 28 may be utilized at the location illustrated
generically by control 45 in FIG. 3, with its respective flow ports
connected in that system instead of flow ports 46 and 47.
The function of the system is to drain the ventricles of the brain,
or whatever source region is being drained, while resisting
excessive suction forces. The control behaves as though the pump is
not present, because the control acts to shut down the system in
response to downstream suction. The upstream pressure produced by
the pump does not upset the operation of the control.
The configuration of FIGS. 8-10, without the modification of FIG.
11, will first be discussed in detail. When the system is in steady
flow condition, with gradual drainage in progress, diaphragms 67
and 75 will assume the positions shown in FIG. 10, and there will
be free flow from flow port 69 to flow port 70. This is the
preferred direction of downstream flow to be controlled, wherein
flow port 69 occupies the position shown by flow port 46 in FIG.
3.
Should a downstream suction surge be exerted at flow port 70, the
pressure in flow chamber 66 will drop, and it will not
instantaneously be relieved by pressure from flow chamber 65. In
fact, the size of flow port 68 is selected so as to comprise a flow
restriction so as to delay equalization of pressure between the two
chambers. Diaphragm 67 will therefore deflect to the position shown
in FIG. 8 and, depending on the resilience and fluid content of the
region beneath complementary diaphragm 75, diaphragm 75 may also
rise. The result will be an adherence between the seat 74 and the
complementary diaphragm, thereby sealingly separating flow chambers
65 and 66 from each other. The force tending to hold these
diaphragms together is, in this and all embodiments except that of
FIGS. 19-22, distributed over the annular area, these controls
being circular in plan. The only unbalanced force will be that
exerted over the area of the complementary diaphragm within the
perimeter of seat 74 which, however, has some pressure behind it,
too. The effect in a practical system is that the seat, while
adherent to the complementary diaphragm, can shift axially (up and
down in FIG. 8), but will remain in firm sealing contact with the
complementary diaphragm so as to close the flow port as long as a
sufficient degree of suction is exerted downstream to make this
closure. It will be noted that this closure will not be broken by
upstream pressure because this upstream pressure also exerts a
compressive effect over the entire diaphragm in opposition to the
suction, thereby tending to hold the two diaphragms together, and
within practical limits, any differential force on the
complementary diaphragm inside seat 74 will be insufficient to
cause opening. Accordingly, this control is locked shut to flow
until the suction is relieved.
It is also shown in FIG. 9 that control 60 can be used with its
connections reversed from those described, or can protect against
suction surges in either direction of flow. If suction is exerted
at flow port 69, both of the diaphragms 67 and 75 will have been
brought up until they are stopped by support 71, at which time the
sealing contact is made at seat 74. Again, the negative suction
pressure is exerted over the full area of the diaphragm, including
that within seat 74, and initial suction in the entire cavity will
have caused both diaphragms to move before flow through port 70
appreciably raises the pressure in chamber 66. Pressure within flow
chamber 66 is opposed by the support, and upstream pressure exerted
at flow port 70 will not separate the diaphragms within a wide
range of relationships between pressure and suction. The device as
shown in FIGS. 8-10 is, therefore, bi-directional in effect should
such be desired. Because of the dimensional relationships, it is
preferably connected to the likelier source of suction at flow port
70.
Should only a uni-directional suction control be desired, then the
function of the device may be made even more positive by the
improvement shown in FIG. 11, wherein a vent passage 80
interconnects flow chamber 65 to relief chamber 81 beneath
complementary diaphragm 75. Now, consider FIG. 8 with this
modification, and with suction exerted at flow port 70. In such
event, pressure is exerted on the outside of both diaphragms, and
suction is exerted in the region between them. Accordingly, there
is no differential pressure effect between the diaphragms within
seat 74, and there is a strong, compressive force locking both
diaphragms together over their full annular areas outside of seat
74 so long as there is suction downstream, and there is no way that
positive pressure in flow chamber 65 can break this firm lock. It
is necessary for the suction to be relieved before this valve can
open again.
Re-opening of the valve is assured by making the diaphragm 67
somewhat springily flexible so that it tends to return to the
position shown in FIG. 10, and initially laying diaphragm 75 flat
so that it tends to return to the position shown in FIG. 10. Both
diaphragms are also so flexible, and in the case of diaphragm 75,
so elastic, that the differential pressures involved will readily
bring them toward each other so as to close and lock the control.
Accordingly, the vent passage 80 is optional, but does provide a
significant improvement in the function of the device when only
uni-directional suction control is desired. It will be noted that
the use of this modification would be unsuitable were suction to be
exerted at flow port 69 because then the differential pressure on
diaphragm 75 within seat 74 would be nullified, and the diaphragms
would be drawn apart by suction and forced apart by pressure.
FIG. 15 shows a flow control 85. Its diaphragm 95 is made of
flexible material which tends to occupy a position intermediate
between those shown in FIGS. 15 and 16. When fluid flows at gradual
rates and low suction (which is the normal situation), it flows
through the control without impediment. The dome, in this case, is
also flexible and forms, in effect, a complementary diaphragm and
is shown deflected somewhat in FIG. 16.
FIG. 15 shows closure of the control when excessive suction is
exerted at flow port 93. In such event, pressure will have dropped
in flow chamber 91 and, because of the fluid flow restriction
through flow port 96 and past the outer edge of seat 97, pressure
will have dropped in flow chamber 91 enough that diaphragm 95 will
be drawn down so that seal 97 seals on dome-shaped inner surface
94. Now it will be seen that the control is locked and remains
locked. This effect is also helped by any upstream pressure which
continues to exert a locking downward pressure on the diaphragm,
and the pressure cannot by-pass the seat to relieve the suction.
This differential pressure (which must, of course, be sufficient to
overcome any springiness in the diaphragm) will prevent the control
from opening until the suction is relieved.
FIG. 16 illustrates locking of the device should sufficient suction
be exerted at flow port 92. In this event, pressure in flow chamber
90 will have dropped so as to draw down the dome and draw up
diaphragm 94 to make a seal between them, thereby separating the
two flow chambers and preventing flow until the suction is again
relieved. The closure remains, as in FIG. 15, except that in the
condition of FIG. 16 there is a small additional differential
pressure to be considered on the surface bounded by the seat.
FIGS. 17 and 18 show still another flow control which is intended
for operation at somewhat higher pressures than the other
embodiments. FIG. 17 shows the device in its normally closed
condition. It is also the condition which would occur when
sufficient suction is exerted at flow port 109. In the event that
strong suction exists in flow port 109, its negative force on the
diaphragm caused by an abrupt drop in cavity pressure, combined
with the mechanical force of the spring, will close the valve
unless and until unusually high pressures are exerted in flow port
112. Should, however, there be no excessive suction, and there be
normal drainage pressure at flow port 112, the effect is to build
up sufficient force over the diaphragm outside the seat 110 to move
the diaphragm to the position shown in FIG. 18, thereby opening the
valve to flow as shown. This opening will not be particularly large
because of the effect of the spring. Therefore, should sudden
negative surges of suction be exerted in flow port 109, there will
be a quick lowering of pressure over the diaphragm below and at a
region surrounding the region just beneath seat 110 which will be
adequate to unbalance the situation and close the valve. While this
device is more responsive to upstream pressure than the other
embodiments of the invention, still it has significant utility for
the purposes described.
The device of FIG. 19 comprises a pair of housing parts that
enclose a pair of contiguous flat, resilient sheets. These sheets
in repose act as diaphragms that tend to lay against one another,
and which will be bowed apart by sufficient pressure exerted
between them. Should there be enough pressure at the upstream end
and an absence of excessive suction at the downstream end, then a
flow chamber 126 will open up, as shown in FIGS. 19 and 21, and a
continuous channel will be formed between the two flow ports. If,
however, a sufficient suction is exerted at the downstream port,
then the lesser pressure will cause the diaphragms to move together
and seal to form a closure plane between them, along which fluid
will not flow. This closure can be overcome only by a very
substantial upstream pressure which must overcome not only the
ambient surrounding pressure that tends to force the diaphragms
together, but also to peel them apart where they are pressed
together by the differential between suction and ambient pressure.
The practical effect in a shunt installed in a human body is that
the device remains closed so long as suction is exerted downstream
and is not opened by practical levels of upstream pressure. The
effectiveness of this device may also be improved by providing
means to vary the force which tends to bias the diaphragms
together. Vents 123 admit body fluids under ambient pressures, and
the device could also be packed with springy sponge-like material,
or even with springs, which would exert a restorative force tending
to keep the device closed against incoming pressures and to amplify
the effect of downstream suction.
The device of FIGS. 24-28 operates like that of FIGS. 17 and 18.
Instead of a bias spring, it utilizes force derived from the
surrounding region such as body tissue to resist movement of the
diaphragm away from the seat. Normally, it leaves a small-area flow
channel above the seat, and the outside force and inside fluid
forces about balance in order to permit slow flow. In the event
excessive suction is applied downstream, the lowered pressure at
the center of the diaphragm will pull it down to close the control
as shown in FIG. 25, and the control tends to remain closed because
the outer annular region retains about the same pressure
relationship between inside and outside as it had before, but the
central portion is under a strong closing force. Of course, this
can be overcome by a sufficient upstream pressure, but it must be
substantial, and by the time it is exerted, the user will probably
have changed his position and relieved the suction.
Incidentally, it should be noted that in FIG. 25 some yielding of
the rim has been shown to illustrate means whereby the flexible
diaphragm, although drawn fairly tightly across the rim, can move
down to close the seat even though there may be little, if any,
stretch in the diaphragm itself.
While at first glance it might appear that the devices of this
invention, when once closed could not be re-opened, a consideration
of the practical use of the system will show otherwise. A
reasonably active person will, within the course of a few hours,
roll over, stand up, sit down, or assume other positions which will
create widely varying dimensions A and B (FIG. 1 and 2), with both
positive and negative differential pressures, and without any at
all. Accordingly, even though the control might interrupt flow
through the system for brief periods of time, such an interruption
in a slow-draining device is not critical, and it does overcome a
still more critical problem, namely that of over-drainage.
In addition to the line-seal made at the respective seats by the
diaphragms, it can also be expected for there to be some area
contact between diaphragms which are brought into contiguity, which
makes a more positive seal. In order to simplify the drawings, this
area seal has not specifically been illustrated. Where it occurs,
it tends to make the closure more certain.
In the devices of FIGS. 8-16, the control should be built so that
its normal tendency, absent any differential pressure through it,
is to be open.
Furthermore, in all of the embodiments, relative flow port sizes
may be selected to provide restrictions which delay change of
pressure in respective flow chambers so as to make the operation of
the valve even more reliable. This is an optional consideration for
the designer's use.
This is a practical control and system. It must have a long life,
and be simple in construction and operation. All parts (except the
spring in FIGS. 17 and 18) can be made of medical grade silicone
rubber, which the body will accept. The relative stiffness of the
various parts is determined as a function of their thickness.
In controls of this type, a certain amount of cut-and-try is
necessary. However, after making a few of any type, the values of
the design parameters can readily be determined. Accordingly, this
device provides a means for preventing over-drainage of source
regions in the human body, thereby providing a system which drains
to a datum level and no farther, and providing the individual with
a constant livable condition rather than one which varies from time
to time in a manner which might upset him.
This invention is not to be limited by the embodiments shown in the
drawings and described in the description, which are given by way
of example, and not of limitation, but only in accordance with the
scope of the appended claims.
* * * * *