Flow Control System For Physiological Drainage

Abstract

A flow control system for the positive control of drainage of fluid from a region of the body to be drained to a drainage site at another location. It provides means for the controlled positive shut-off of said drainage. The system includes a flow valve having an internal flow cavity with an inlet and an outlet. A partition divides the cavity into a pair of chambers, the inlet and outlet opening into different respective ones of the chambers. A port is formed in the partition, and a fluid actuated valving member is adapted to open and to close the port. A reservoir has a plenum chamber defined by a bounding wall portion which is movable to change the volume of the plenum chamber. A manually actuable control valve which has an open condition and a closed condition interconnects the plenum chamber of the reservoir to motive means for moving the valving member for opening and closing the flow valve.

Description

This invention relates to a flow control system for the positive control of drainage of fluid from a region of a body to be drained to a drainage location.

There are many ailments wherein the natural physiological means for draining a region of the body (such as the cranium) do not function correctly Then the fluid builds up, causing pain and damage to the patient. A classical example of such an ailment is hydrocephalus wherein the cerebral fluids are not properly drained through the natural mechanism, but instead accumulate. They exert pressure on the brain, constricting its growth and enlarging the skull. Serious brain damage and even death frequently occurs unless the fluid is drained.

Drainage of such fluids by means of a shunt is a well-known technique for alleviating the symptoms of hydrocephalus. A classical example of a drainage system for this purpose is shown in Schulte U.S. Pat. No. 3,111,125 issued Nov. 19, 1963, wherein the collector (distal) end of a region to be drained, passes through a pump, and extends as a shunt tube to the heart where it is drained into the blood stream. It is customary to include a check valve, such as a slit valves in the shunt tube so that the flow is unidirectional away from the brain, and cannot back up.

The alleviation of the symptoms of hydrocephalus and of other ailments involving the accumulation of body fluids has been dramatic. Thousands of persons are alive and normal today who would otherwise be dead or mentally retarded. There has, however, arisen the undesirable consequence that the person might become dependent upon the shunt throughout his entire life, and could never be without one. It would, of course, be preferable were the body encouraged to form its own drainage passages which it might be able to do were the dangerous and damaging symptoms resulting from too great an accumulation to be alleviated. Maintaining pressure at a safe level, but one which is high enough to encourage the body to form its own drainage paths offers the possiblity that a person might one day be free of dependence on the shunt. Thus, the shunt would exist to prevent a dangerous level of fluid accumulation from occurring, but would still leave sufficient fluid in the region to be drained that a continuing pressure would be exerted.

The precise pressure at which the body would be encouraged to form its own drainage paths must be determined for the individual person. It is possible to design different shunts to open at different respective pressures, but this involves the unacceptable requirement to remove and to replace an already-installed shunt which might open at which proves to be an incorrect pressure. It is evident that any more than the minimum number of procedures involving the heart and the brain must be avoided. Furthermore, it is as undesirable to drain too much fluid as it is to drain too little. An excessively-drained brain will lead to fever and malaise. Therefore, it is desirable to give the surgeon a valve which can positively shut off flow so as to permit pressure to build up to a given level, and which can be opened to release just enough fluid to drop the pressure to some selected level.

It is an object of this invention to provide a flow control system which can be externally controlled that exerts a positive control on fluid drainage in the sense of off-on control, wherein the surgeon can by visual observation of symptoms and even of measurement of cranial pressure adjust the pressure level in the region to be drained to a level which is acceptable to the patient and which is likely to improve his condition over a period of time.

It is an advantage of the flow control system according to this invention that it is entirely controlled from the outside of the body, that the condition of the valve (whether it is open or closed) can be determined from outside the body, and that it can be constructed flat and thereby be unobtrusive when laid against the skull and under the scalp.

A flow control system according to this invention includes a flow valve having an internal cavity. A partition divides the cavity into a pair of chambers and an inlet and an outlet open into different respective ones of the chambers. The inlet is connected to the region from which fluid is to be drained, and the outlet is directed to the drainage region where the fluid is to be disposed of. The partition has a port therethrough which interconnects the two chambers. A fluid actuated valving member is disposed in one of the chambers and includes a closure element which is movable toward and away from the port so as to close it or to open it. Motive chamber means is provided which has a movable wall portion that moves the closure element for this purpose.

A reservoir has a plenum chamber defined by a bounding wall. A portion of the bounding wall is movable in order to change the volume of the plenum chamber.

A manually actuable control valve has an open condition and a closed condition. It interconnects the plenum chamber of the reservoir to the motive chamber means of the valving member so that a liquid can flow back and forth between them under control of the control valve, whereby to maintain the flow valve in a selected condition.

According to a preferred but optional feature of this invention, the motive chamber means comprises a flexible wall whereby the volume of the motive chamber means is variable as a consequence of fluid injected into it. When expanded sufficiently, it causes the closure means to close the port.

According to still another preferred but optional feature of the invention, the motive chamber means is an elastic balloon, and the manually actuable control valve is a unidirectional check valve which permits fluid to flow toward the flow valve except when it is mechanically distorted to permit reverse flow to the reservoir.

According to still another preferred but optional feature of the invention, a flexible diaphragm is provided in the chamber between the port and the closure element, whereby to make the flow valve itself a unidirectional check valve which permits flow only from the inlet to the outlet, and prevents the reverse flow.

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 is a plan view of the presently preferred embodiment of the invention;

FIG. 2 is a cross-section taken at line 2--2 of FIG. 1 in one valving condition;

FIG. 3 is a view similar to that of FIG. 2 showing the device in another valving condition;

FIG. 4 is an axial cross-section of a fragment of FIG. 2 shown in another valving position;

FIG. 5 is a perspective view of a portion of FIG. 2;

FIG. 6 is an enlarged axial section taken at line 6-6 of FIG. 1; and

FIG. 7 is an enlarged axial cross-section of another embodiment of a portion of the system of FIG. 1.

FIG. 1 shows the presently preferred flow control system 10 according to the invention. It is constructed so as to be laid flat against the skull and beneath the scalp. Its major components are a flow valve 11 having an inlet 12 and an outlet 13, a manually actuable control valve 14, and a reservoir 15. It is the function of flow valve 11 to provide for a positive shut-off of fluid flow from the inlet to the outlet, and in one embodiment of the invention, to limit such flow to movement from the inlet to the outlet and to prevent movement from the outlet to the inlet. It is the function of the system to control the flow valve.

Flow valve 11 includes a base 20 and a dome-shaped cover 21. The base and the cover are joined to form a continuous body which encloses an internal flow cavity 22 across which there extends a partition 23 which divides the cavity into a first and a second chamber 24, 25, respectively. A port 26 through the partition fluidly interconnects the two chambers. A valve seat 27 surrounds the port in the second chamber and projects into this chamber.

The flow valve is customarily made of the same material throughout. A suitable material is medical grade silicone rubber and the flexibility of a member will largely be determined by its thickness. The partition is preferably made stiffly flexible. The cover is also stiffly flexible and includes a plurality of internal ribs 28 to prevent the cover from making a sealing contact with the upper surface of the partition. The flow valve therefore tends to retain its shape, although it can be temporarily collapsed by mechanical pressure when needed to expel fluid from it. Fluid flow can always occur between the inlet and the port without impedance from contact between the cover and the partition, because of the flow channels formed by the ribs.

Inlet 12 enters first chamber 24. Outlet 13 is connected to second chamber 25. Therefore, positive flow from the region to be drained to the region to receive the drainage fluid will be from the inlet through chamber 24, port 26, chamber 25, and outlet 13.

A fluid actuated valving member 30 (FIG. 6) is formed in the base and operated in second chamber 25. For this purpose, the base includes a cloth reinforced closure sheet 31 at the bottom of a motive chamber 32 which comprises a cylindrical sink in the base. It is overlaid and closed by a wall 33 which has a movable central portion as will later be discussed. It carries a closure element 34 which in the embodiment shown is the upper surface of wall 33.

Closure sheet 31 is inelastic because of its reinforcement while wall 33 is flexible and elastic, with the properties of the wall of a balloon. A conduit 35 enters motive chamber 32 from control valve 14 to admit actuating fluid to it. It is the purpose of wall 33 to deflect so that closure element 34 can close port 26 at valve seat 27, (see FIG. 3) and upon release of pressure return to the condition shown in FIG. 6. The combination of motive chamber 32 and wall 33 is sometimes called "motive chamber means." The movable part of wall 33 is sometimes called the "movable wall portion" of the motive chamber means.

Manually actuable control valve 14 is shown in full detail in FIGS. 2, 3, 4 and 5. It includes a cover 40 which is stiffly flexible. It encloses a cavity 41 which is divided into a chamber 42 that is connected to conduit 35 and another chamber 43 that is connected to the reservoir through a conduit 44. A manually deformable valve element 45 (see FIG. 5) comprises a dome-shaped body 46 with imperforate peripheral upper and lower zones 47, 48. At least one slit, but preferably four slits 49, extend as lines of longitude along and through the dome-shaped body, thereby interconnecting the inside and outside walls of the dome. They extend from zone to zone. These slits are formed by cutting the material without removal of the material so that when the body is undistorted, the slits will remain closed.

It is evident that the slits can be distorted and thereby opened by a sufficient differential positive fluid force or by manual deformation such as by a vertical axial push along axis 50 of the body (See FIGS. 3 and 4). This is merely one form of a valve suitable for this purpose. An advantage of the illustrated dome-shaped body is that it opens readily to flow from inside to outside, but tends to close tightly to prevent reverse flow when the differential is reversed. It would take an unexpectedly high pressure to open the valve to reverse flow. This valve therefore functions as a check valve which can be opened by manual deformation caused by exerting a mechanical force sufficient to distort the body and open the slits.

It will be understood that valves other than slit valves could be used instead of the illustrated valve, and that the slits could instead be provided in a flat wall instead of in a dome structure, which would render the valve as easily opened in both directions by fluid differential, which if the required differential pressure to open it were high enough would still be acceptable. It will further be noted that this valve is essentially a check valve which absent manual distortion will readily permit flow from its inner chamber 43 to outside chamber 42 when a suitable differential pressure is exerted, but will not permit the reverse. Similarly, it operates as a positive valve preventing any flow at differential pressures below that required to open the slits unless there is a mechanical deformation. The construction shown is especially suitable for physiological uses because it permits the flow valve to be retained in its positively closed condition and opened only as a consequence of the intentional manipulation of the control valve.

Reservior 15 is connected to chamber 43 by conduit 44. The reservoir has a base 51 and a stiffly flexible dome 52 which form an internal plenum chamber 53 whose volume is variable by virtue of the fact that the wall of the dome is movable and flexible.

The embodiment of FIGS. 1-6 constitutes the presently preferred embodiment of the invention in which the system provides positive off-on control of the drainage of fluids. FIG. 7 illustrates an additional feature which may be utilized in the same system invention if desired. It utilizes the same elements as in FIGS. 1-6 and like numbers are therefore used in FIG. 7. It adds a check diaphragm 55 which is a thin, very flexible diaphragm which is made of shape and size such that its normal position is that shown in FIG. 7 wherein because of its structure it normally bears against valve seat 27 and closes port 26. The diaphragm includes a perforation 56 so that there is equal pressure on both sides. It will be noted that when the pressure in the inlet is higher than that in the outlet, the diaphragm will be deflected away from the port and flow will occur. Should the reverse pressure differential occur, then by virtue of its inherent mechanical tendency to return to the shape and position of FIG. 7 and also by virtue of the unbalanced area of the diaphragm within the valve seat 27, the diaphragm will close and hold closed the port and prevent reverse flow into the region intended to be drained. This can constitute an important advantage when the valve is open, because in the event that the person is inverted a reverse differential pressure will result, and this valve will prevent back flow. It is evident that the closure element 34 of the fluid actuating valve member 30 will press against the diaphragm to press it against the valve seat 27 in order to make the same class of valve closure as occurred in FIGS. 1-6, and this is the full equivalent of the closure of FIGS. 1-6.

The operation of this device will now be discussed with initial reference to FIG. 2 which shows the device in its relaxed, open to flow condition. While it is possible to use any class of fluid including gases in this device to control its action, there is an undesirable tendency of gases to be absorbed in any system over a period of time and therefore the system will usually be filled with liquid such as a saline solution. Should this liquid leak into the body it will do no harm. The displaceable volume of the reservoir should be substantially equal to the volume needed in the fluid actuated valving member 30 for closing the flow valve, and no greater, in order that over-extension of wall 33 will not occur. This is a design parameter which is easily determined by the designer.

Accordingly, the reservoir, the control valve, conduits 44 and 35 and motive chamber 32 are filled with saline solution in FIG. 2 and the device may be installed in the user in that condition, the valve being in its relaxed and open condition which can be observed by feeling the reservoir's tumescent condition. While the reservoir is fully extended to its normal position as shown, there will be no closure of the flow by valving member 30 and the system is open to flow.

To close the flow valve, a distortive force will be exerted on the reservoir as indicated by arrow 57 in FIG. 3 so as to deflect the dome wall 52 of the reservoir and reduce the volume of the plenum chamber. Fluid is therefore driven through conduit 44 and into chamber 43 where the differential pressure causes the slits 49 to open and bow out as shown, and liquid flows through them into chamber 42. From chamber 42 it flows through conduit 35 to motive chamber 32. The increased pressure (or more precisely the increased volume of incompressible liquid in chamber 32) will cause wall 33 to balloon upwardly and contact seat 27 to close the port 26. The valve is now positively closed to flow. The closed condition can positively be determined by feeling the surface of the reservoir and observing that it is depressed, because there is no way for the wall of the reservoir to return to its original dome-like condition unless liquid is returned to it.

Because valve element 45 is in effect a check valve, any back pressure derived from an increase in drainage pressure in the flow valve only tends to close it more tightly, and the flow valve will therefore remain closed. An advantage of using a liquid as the motive fluid resides in its incompressibility, because regardless of an increase in the drainage pressure in the flow valve, there will be no opening of the valve as a consequence of shrinkage of volume in chamber 32, for it cannot occur.

Now should it be desired to open the flow valve to drainage flow, a distortive force is exerted as indicated by arrow 58 in FIG. 4 which will cause the cover 40 of the control valve 14 to move downward to contact the top of body 46 to distort slits 49 so as to open them. At this time, there is likely to be sufficient drainage pressure in the flow valve to deflect the wall 33 away from the port and also if desired one may push directly down onto the cover 21 of the flow valve so as positively to expel liquid from chamber 32 back through control valve 14 into the reservoir, thereby restoring it into the condition shown in FIG. 2. The return to the open condition is also assisted by the elasticity of wall 33, which tends to return to the position shown in FIG. 2. When drainage of chamber 32 is completed, the force 58 may be released, and valve 14 will return to the condition shown in FIG. 2 leaving flow valve 11 open to drainage flow.

An advantage of the construction of body 46 can be noted in FIG. 5. The slits extend only between the zones 47 and 48, and not into them. There is no risk of mismatching of the edges of the slits when they close as there would be if the slits were to extend up to the pole of the dome-shaped body and intersect to form leaves with free ends. Similarly, there are edges that may be mismatched at the lower edge.

Therefore, valve 14 is a reliable off-on valve having open and closed positions which can be attained by fluid force in one direction and by mechanical forces in both directions. It will be understood that there is a wide range of equivalent valving means available, but this device, which can so readily be made of materials of construction that are compatible with the human body, constitutes a uniquely desirable construction.

The manually actuable control valve 14 and reservoir 15 together comprise "means for forcing liquid into the motive chamber means and releasably retaining it therein."

The material of the device may conveniently be medical grade silicone rubber which can be cast in individual parts and then cemented or fused together as desired.

In use, the flow valve is shut off, and the surgeon may make such pressure measurements or clinical observations as he wishes in order to determine when a given upper pressure level has been reached. When it has, he simply presses on valve 14, which opens valve 11 until he is of the opinion that enough fluid has been drained to reach a predetermined lower pressure level. Then he presses reservoir 15 to close the flow valve. The condition of valve 11 can always be determined from an examination of the contour of reservoir 15.

This invention provides a desirable and useful means for positive drainage of fluids within the human body which can in one embodiment provide check valve functions (FIG. 7), which is rugged and reliable, and whose condition can readily be ascertained by tactile testing.

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.

Claims

I claim:

1. A flow control system for the positive control of drainage of fluid from a region of the body to be drained to another location, and providing for the controlled positive shut-off of said drainage, said system comprising: a flow valve having an internal flow cavity, an inlet to and an outlet from said flow cavity, a partition dividing the cavity into a pair of chambers, the inlet and outlet opening into different respective ones of said chambers, said partition having a port therein which interconnects the two chambers, a fluid-actuated valving member in one of said chambers comprising a closure element movable against and away from the partition so as to close or to open the port to flow therethrough, and motive chamber means having a movable wall carrying said closure element; a reservoir having a plenum chamber defined by a bounding wall, a portion of which is movable in order to reduce the volume of the plenum chamber; and a manually-actuable control valve having an open condition and a closed condition, interconnecting the plenum chamber of the reservoir and the motive chamber means of said valving member and being adapted to prevent flow between them in at least one direction therethrough while in its closed condition.

2. A system according to claim 1 in which the motive chamber means comprises a motive chamber bounded at least in part by the movable wall which is movable as a consequence of fluid pressure within the motive chamber so as to cause the closure means to close the port.

3. A system according to claim 2 in which the said wall of the motive chamber means is elastic so as to stretch while being moved to close the port.

4. A system according to claim 2 in which the closure means comprises a region of said wall of the motive chamber means.

5. A system according to claim 1 in which a flexible diaphragm extends across the flow valve which is connected to the outlet and is adapted to move against the port to close the same when the fluid pressure in the outlet is greater than that in the inlet and to move away from the port to leave it open when the differential pressure is reversed, the diaphragm being disposed between the closure elements and the port.

6. A system according to claim 5 in which the motive chamber means comprises a motive chamber bounded at least in part by the movable wall which is movable as a consequence of fluid pressure within the motive chamber so as to cause the closure means to close the port.

7. A system according to claim 6 in which the said wall of the motive chamber means is elastic so as to stretch while being moved to close the port.

8. A system according to claim 1 in which the control valve comprises a check valve which opens to permit flow from the reservoir to the motive chamber means, and which closes to prevent it unless manually manipulated.

9. A system according to claim 1 in which the control valve comprises a wall having a slit therethrough which is closed when the wall is undistorted, and which is opened to flow when the said wall is distorted.

10. A system according to claim 1 in which the control valve comprises a body forming a cavity, a dome-shaped manually deformable valve element in said cavity having slits through its wall which are closed when the valve element is undistorted and open when the valve element is distorted, the inside of said dome being connected to the reservoir, and the cavity at the outside of the dome being connected to the motive chamber means.

11. A system according to claim 9 in which the body of the control valve has an upper and a lower peripheral zone, the slits extending between but not into said zones.

12. A system according to claim 9 in which the motive chamber means comprises a motive chamber bounded at least in part by the movable wall which is movable as a consequence of fluid pressure within the motive chamber so as to cause the closure means to close the port.

13. A system according to claim 12 in which the said wall of the motive chamber means is elastic so as to stretch while being moved to close the port.

14. A system according to claim 12 in which the closure means comprises a region of said wall of the motive chamber means.

15. A system according to claim 9 in which a flexible diaphragm extends across the flow valve chamber which is connected to the outlet and is adapted to move against the port to close the same when the fluid pressure in the outlet is greater than that in the inlet and to move away from the port to leave it open when the differential pressure is reversed, the diaphragm being disposed between the closure elements and the port.

16. A system according to claim 15 in which the motive chamber means comprises a motive chamber bounded at least in part by the movable wall which is movable as a consequence of fluid pressure within the motive chamber so as to cause the closure means to close the port.

17. A system according to claim 16 in which the said wall of the motive chamber means is elastic so as to stretch while being moved to close the port.

18. A system according to claim 9 in which the control valve comprises a check valve which opens to permit flow from the reservoir to the motive chamber means, and which closes to prevent it unless manually manipulated.

19. A system according to claim 8 in which the motive chamber means comprises a sink in the flow valve on the same side of the partition as the outlet, and a flexible and elastic sheet laid across said sink to form a motive chamber connected to the manually-actuable control valve.

20. In combination, a flow valve for the positive control of drainage of fluid from a region of the body to be drained to another location which flow valve provides for the controlled positive shut-off of said drainage, comprising a body having an internal flow cavity, an inlet to and an outlet from said flow cavity, a partition dividing the cavity into a pair of chambers, the inlet and outlet opening into different respective ones of said chambers, said partition having a port therein which interconnects the two chambers, a fluid-actuated valving member in one of said chambers comprising a closure element movable against and away from the partition so as to close or to open the port to flow therethrough, and motive chamber means having a movable wall portion carrying said closure element; and means for forcing liquid into said motive chamber means and releasably retaining it therein.

21. A system according to claim 20 in which the motive chamber means comprises a motive chamber bounded at least in part by the movable wall which is movable as a consequence of fluid pressure within the motive chamber so as to cause the closure means to close the port.

22. A combination according to claim 21 in which the said wall of the motive chamber means is elastic so as to stretch while being moved to close the port.

23. A combination according to claim 21 in which the closure means comprises a region of said wall of the motive chamber means.

24. A combination according to claim 20 in which a flexible diaphragm extends across the flow valve chamber which is connected to the outlet and is adapted to move against the port to close the same when the fluid pressure in the outlet is greater than that in the inlet and to move away from the port to leave it open when the differential pressure is reversed, the diaphragm being disposed between the closure elements and the port.

25. A system according to claim 24 in which the motive chamber means comprises a motive chamber bounded at least in part by the movable wall which is movable as a consequence of fluid pressure within the motive chamber so as to cause the closure means to close the port.

26. A combination according to claim 25 in which the said wall of the motive chamber means is elastic so as to stretch while being moved to close the port.

27. A system according to claim 20 in which the motive chamber means comprises a sink in the flow valve on the same side of the partition as the outlet, and a flexible and elastic sheet laid across said sink to form a motive chamber connected to the manually-actuable control valve.