WO1991008001A1 - Device for controlling and monitoring the flow of cephalorachidian liquid in a drainage circuit - Google Patents

Abstract

The device includes a subcutaneous transplantation valve placed between an upstream duct (1) leading from one of the ventricles of the subject's skull, and a liquid-discharging downstream duct (2). The valve comprises a chamber (4) into which the two ducts (1, 2) open, at least one seat (6$i(b)) located in the chamber at the outlet of one of the ducts, a seal (7) which is movable in relation to the seat, and a driving element (6) which moves the seat and the seal relatively to each other, and which consists of a portion (6) of a tubular ring housed in the chamber (4), one of its ends (6$i(a)) being fixed while the other end (6$i(b)) carries one of the two mutually movable seat or seal elements. The curvature of said portion (6) corresponds to the difference between the pressure in the chamber (4) and the pressure inside said tubular portion (6), so that any variation in this pressure difference will tend to make the seal and the seat move relatively to one another.

Description

 Device for regulating and controlling the flow of cerebrospinal fluid in a drainage circuit.

The present invention relates to a device for regulating and controlling the flow of cerebrospinal fluid in a drainage circuit in a subject suffering from ydrocephaly.

Hydrocephalus is a disease caused in particular by blocking the natural drainage channels of the cerebrospinal fluid. One treatment for this disease is to bypass the flow of fluid from the ventricles of the cranial cavity to another site of resorption such as the heart or peritoneum. This bypass generally consists of a catheter inserted through the skull into one of the ventricles of the brain and connected either to the jugular vein or to the peritoneum. The tubing thus produced comprises a valve for regulating the flow, and the assembly is placed under the patient's skin.

There are currently several types of valves on the market to perform this function. Among the simplest, there will be mentioned valves of the unidirectional valve type. These are valves formed by a notched tube whose slots widen when the internal pressure in the tube overcomes the elastic force of the tube itself tending to close these slots (to which is added or subtracted the prevailing pressure in the tubing part

REPLACEMENT SHEET located downstream of this valve). It can also be a valve applied to a seat by a calibrated spring defining a pressure threshold for opening the valve. One of the major drawbacks of these valves is their lack of possibility of adjustment. However, it is necessary to adapt to each patient the characteristics of the valve according to the natural characteristics of his organism, and to modify the characteristics of the valve over time for the same patient, according to the evolution of his sickness. The replacement of the valve by another with different characteristics, both at the initial setting and during the course of the disease, involves surgical intervention since this valve is implanted under the subject's skin.

Adjustable valves have therefore been developed. These include a return spring for a valve (ball) on its seat, the calibration of which can be modified from the outside without surgical intervention. An actuator is coupled to the spring and can rotate in the valve housing. This organ is sensitive to the magnetic field and can be magnetically coupled through the skin to a motor organ to cause it to change posi¬ tion. These valves are generally complex, therefore of large volume and bulk, reliable questionable and adjustable during shocks. In addition, they include metallic elements which interfere with certain operations such as radiography.

In general, given the low value of the forces used in this type of valve, their construction is very delicate. In addition, the regularity of operation is very random, because the balance of the valve, when a flow is established through the valve, is very sensitive to variations in pressure and viscosity of the liquid. In addition, the extensive miniaturization of this type of

REPLACEMENT SHEET valves in fact αes fragile devices and subject to obstruc¬ tion.

Finally, in general, the known valves are incapable of opposing the effects of overdrainage when the downstream pressure drops as a result, for example, of a change of position of the patient.

The present invention intends to remedy these drawbacks by proposing a valve whose degree of opening is essentially a function of the pressure of the liquid to be drained, in a simple manner with adjustment of an opening threshold at different values, which does not significantly influence the characteristics of the valve opening law when this threshold is exceeded.

To this end, the subject of the invention is therefore a device for regulating and controlling the flow of cerebrospinal fluid in a drainage circuit in a subject suffering from hydrocephalus, comprising a valve for subcutaneous transplantation at the level of the subject's cranial box, inserted between an upstream duct from one of the ventricles of the subject's cranial box and a downstream duct for discharging the liquid into an appropriate organ of the subject, in which the valve has a chamber into which open the two conduits, at least one seat situated at the outlet of one of the αes conduits in the chamber, a shutter movable relative to this seat and a drive member, for relatively moving the seat and the shutter, which is constituted by a portion tubular ring housed in the chamber and one end of which is fixed, while its other end carries one of the two seat or obturator elements movable relatively, the courbur e of this portion being a function of the difference between the pressure prevailing in the chamber and that prevailing in the interior volume of this tubular portion, so that a variation of this difference in pressures tends to displace the shutter and the seat, l one over the other.

REPLACEMENT SHEET In a first embodiment, the tubular ring portion constitutes an extension in the chamber of the upstream duct, the aforementioned seat being carried by the free end of this annular portion, the shutter being in the form of a fixed plug on which the seat seals tightly when the pressure difference between the chamber and the annular portion is less than a determined threshold.

In a second embodiment, the tubular ring portion is constituted by a blind bypass of the upstream conduit inside the chamber, the free end of which is situated substantially opposite the outlet of this upstream conduit in the chamore, equipped of the aforementioned seat, this end constituting or carrying the movable closure member applied to the seat when the difference in the above pressures is less than a determined threshold.

While the two above embodiments are of the type reacting to the differential pressure between the upstream and downstream conduits, a third embodiment of the invention reacting only to the pressure in the upstream conduit is such that the volume inside the tubular ring portion is isolated from the conduits and the chamber, the aforementioned seat being carried by the outlet of the downstream conduit in the chamber on which the fixed shutter bears at the free end of the annular portion, when the difference in the above pressures is less than a determined threshold.

In order to be able to adapt the device to each particular case that constitutes each subject, the free end of the tubular ring portion is coupled to a return member whose effect tends to apply the shutter to the seat and whose intensity is adjustable.

In a first variant, the return member consists of a helical spring arranged in the chamber, one end of which is coupled to the free end of the tubular ring portion, its other end being coupled to a controlled winding mechanism mechanically by

REPLACEMENT SHEET the outside of the valve.

In a second variant, the elastic return member consists of a second portion of tubular ring doubling the first and whose volume is in permanent communication with a sealed chamber, delimited in a wall made of a perforated material, which covers its seal after perforation, inside which the pressure is adjusted to adjust the value of the opening threshold. Other characteristics and advantages of the invention will emerge from the description below of exemplary embodiments given by way of indication, without limiting intention.

Reference will be made to the appended drawings in which: FIG. 1 is a schematic view in horizontal section of a first embodiment of the invention,

FIGS. 2 and 3 are diagrammatic sectional views of a second embodiment of the invention,

FIG. 4 is a schematic view of a third embodiment of the invention,

FIGS. 5 and 6 illustrate by schematic sectional views an alternative embodiment of the device according to FIGS. 2 and 3,

FIGS. 7, 8 and 9 illustrate, in sectional views, an alternative embodiment of the device according to FIGS. 2 and 3.

FIG. 1 represents a valve for regulating the flow of cerebrospinal fluid in an external drainage duct of which only the terminal part of an upstream duct 1 from a cranial ventricle has been shown and the start of a downstream conduit 2 which can terminate either in the jugular vein or in the peritoneum for absorption of this liquid.

The valve essentially consists of a closed housing 3 which delimits an interior chamber 4 substantially

REPLACEMENT SHEET circular. The conduit 1 communicates with this chamber through a nozzle 5 on which is fitted one of the ends 6a of a portion of tubular ring 6, the other open end 6b of which is pressed in a sealed manner on a fixed shutter 7 under conditions of equilibrium explained below. The duct 2, meanwhile, communicates directly with the chamber 4.

The tubular ring portion 6 is, at rest, curved so that the shutter 7, here forming an integral part of the housing 3, closes its end 6b. This portion then behaves like a Bourdon tube, that is to say that its curvature will depend on the pressure differential between the chamber 4 and its interior volume. If the pressure increases in the duct 1, due to the production of cerebrospinal fluid, the tube 6 tends to open and the end 6b, which forms the valve seat, leaves the obturator 7. The liquid can therefore reach the chamber 4 and the drainage duct 2, with a flow rate which will depend on the passage section between the seat 6b and the shutter 7 and of course, on the pressure and elastic characteristics of the curved tube 6. It will be the same if the pressure in the chamber 4 comes to decrease, which is particularly the case during a change of position of the subject. There may be in this case a risk overdrainage that can fight in various ways, one ^of them being the establishment, at for example the mouthpiece 5, a restriction limiting the flow rate would be too important.

- The embodiment of Figures 2 and 3 is a variant of that of Figure 1 on which we find most of the elements already described with the same references.

'In this case, the curved tube 6 is blind at its end 6b and carries a valve (here a ball 8) which rests at rest on a seat 9 through which the conduit 1 opens into the chamber 4. It will be noted that the valve resting on its seat, the force tending to move it away from its

REPLACEMENT SHEET seat, due to the exercise of the pressure prevailing in the conduit 1 on its useful surface, is negligible compared to the force generated by the deformation of the tube 6, due to the action of this same pressure inside this tube . The outlet of the conduit 2 in the chamber 4 is equipped with a unidirectional valve 10 passing in the chamber-conduit direction. We see in Figure 3 that the housing 3 is closed by a cover 11 in the form of a dome which is made of an elastically deformable material. The advantage of this arrangement lies in the possibility that it gives the valve to be able to function as a manually actuated pump. It will be recalled in fact that in most cases, the valve is implanted under the patient's skin with the face 3a of the housing in contact with the cranial box. The dome 11 is therefore directly accessible through the skin. By pressing on this dome, part of the liquid contained in the chamber 4 is driven into the duct 2. The elastic return of the dome 11 in its position creates a depression in the chamber 4 which forces the opening of the valve 8, 9 ( the tube 6 tending to open) and the chamber 4 is refilled. The surgeon only has to monitor the return of the dome to its initial position to note the proper functioning of the valve and the circuit if the dome returns correctly to its position, or the malfunction of the device, if the return of the dome is not done in good conditions.

In FIG. 4, a third embodiment of the invention is shown. It is a valve which avoids overdrainage in the event of a pressure drop in the downstream duct. We know that a change in the patient's position modifies the relative altitudes between the skull and the resorption organ of the cerebrospinal fluid (heart or peritoneum).

At the terminals of the valve, there is therefore a variable pressure parameter corresponding to this variable difference in altitude. To obtain a regulation of the

REPLACEMENT SHEET intra-cranial pressure independent of the patient's position, in the case of a proximal valve, i.e. a valve implanted near the skull, it is necessary to control the opening of this valve according to a differential pressure independent of the pressure prevailing at the outlet of the valve. Thus in the embodiment of FIG. 4, the duct 1 opens directly into the chamber 4 through a one-way valve 15 passing in the direction of the duct 1-chamber 4. The curved tube 6 is then completely closed, filled a gas whose pressure is adjusted to adjust the curvature of the tube so that the shutter 16 which it carries at its end 6b rests on the seat 17 which is fitted with the end of the conduit 2 opening into the chamber 4. The variation in curvature of the annular tube 6 depends on the differential pressure prevailing in the tube and the chamber 4. An increase in the pressure in this chamber following an arrival of cerebrospinal fluid leads to an increase in the curvature of the tube annular 6 (reduction of its initial radius) tending to move the shutter 16 away from the seat 17. A flow of the fluid is therefore possible. As a result of a change in position of the subject who, for example, gets up, the pressure in the tube 2 can drop suddenly. If the valve 16, 17 is open, the pressure drops in the chamber 4 which causes the reduction in the curvature of the tube 6 (increase in its radius) which results in the closing of the valve 16, 17. The drainage is thus stopped until a new pressure is established in chamber 4 which can lead to a reopening of the valve. The opening threshold of this valve depends on the construction characteristics of the tube 6 and on the setting of the assistance spring, if this valve is equipped with it. The presence of the valve 15 ensures the pumping function explained above.

The valves according to the preceding figures, are without possibility of adjustment and their opening threshold depends on the

REPLACEMENT SHEET physical and geometrical characteristics of the curved tube 6. It is however very useful to be able to act on this parameter to adjust the operation of the device at the request of the patient, in order to increase the comfort of the latter, without however resorting to a another intervention that involves changing the valve.

Figures 5 and 6 are the diagrammatic representation that of an alternative embodiment of the device according to Figures 2 and 3 which comprises auxiliary means for returning and calibrating the valve. The elements already described have the same references as with reference to the previous figures.

In this variant, the tube 6 which communicates with the conduit 1 is doubled by a tube of the same length, which is completely closed to it and in communication with a central enclosure 19 completely isolated from the chamber 4. This tube 18 can be coupled to the tube 6 by its entire length or only by its end 18b perpendicular to the end 6b of the tube 6. The material in which the dome 11 of the valve and the walls of the enclosure 19 are made such that a perforation does not affect the seal it provides. Thus, by means of the needle 20 of a syringe, it is possible to adjust the pressure in the chamber 19, therefore in the tube 18, and thus to adjust the characteristics of the opening threshold of the valve controlled by the tube 6. FIGS. 7, 8 and 9 illustrate the use in a valve of the type of that of FIG. 2, of calibration means adjusting the opening threshold of the valve and of its elastic characteristics. We will find in these figures elements already described bearing the same references. FIG. 7 is a diametrical sectional view of the valve similar to that of FIGS. 3 and 6.

Figure 8 is a horizontal sectional view of the valve at the valves.

Figure 9 is a section along line IX-IX of Figure 7.

REPLACEMENT SHEET Thus, as in FIG. 2, the conduit 1 issuing from the cranial ventricle opens into the chamber 4 through the valve 8, 9. The bottom of the housing has, in the center, a sort of pivot 21 on which is mounted a wheel 22 having rotating on a sector 23 of its periphery of the teeth 24.

This wheel extends axially above the toothed sector by an axis 25 for winding a spiral spring 26 whose inner end is coupled to the axis 25 and whose outer end is coupled to the end 6b of the tube 6 which carries the shutter 16. It is understood that, by maneuvering the wheel 22, the spring 26 is more or less bandaged, thus adjusting the stiffness of the tube 6.

The operation of this adjusting member must be possible from outside the valve which, transplanted under the patient's skin, has its covering dome 11 directly on this skin. This dome is flexible and elastically deformable. The means for maneuvering the wheel 22 in one direction or the other consist of a pallet 27, articulated on the upper part of the housing 3 around a diametrical axis 8. In the rest position, this pallet 27 is located under the dome parallel to itself. By pressing on one side or the other of the axis 8, the tilting of the pallet is controlled through the dome 11. This pallet 27 has two lower parts 29a, 29b which are symmetrical with respect to a vertical plane passing through the axis 28 and which extend under the pallet, in a vertical plane perpendicular to the previous one and which is substantially tangent to the circle primitive toothing 24.

These legs 29a and 29b converge towards one another and in the rest position of the pallet, do not reach the toothed sector 23. When the pallet is tilted to one side, one of the legs is lowered and its end describes a vertical arc which meets a tooth in sector 24. Continued tilting creates the drive of the wheel around the pivot 21. By repeating this operation,

REPLACEMENT SHEET the wheel is turned step by step. The reverse rotation step by step is obtained by pressing the opposite wing of the pallet. The device further comprises a spring 30 which allows, thanks to a lug 31, which is resiliently housed in each interdental space of the wheel, to index and stop the wheel relative to the housing to fix the adjustment position. .

Finally, in order to facilitate the operation of these adjustment means, the dome 11 has protuberances 32 above each of the wings of the pallet 27 to locate these by touching them through the skin of the patient. These protuberances can themselves include distinctive reliefs indicating to the manipulator in which direction the adjustment is modified when they are pressed. Of course the movement of the wheel 22 is limited to an angular sector, for example by abutment of an extension 22a of this wheel against internal protuberances of the housing. One of the terminals of this angular sector, defined by these stops, will correspond to a fully closed position of the valve. The other position will be reached from this first after a certain number of "rattles" generated by each jump of the elastic lug 31 when a tooth 24 passes. The number of these rattles, limited by construction, will be the sign by which the operator can adjust the valve calibration or modify it. Each modification will involve a return to the closed position, then a count of "clicks" up to the number indicated by the manufacturer, corresponding to the desired setting.

The device of the present invention has the advantage of a simple industrial manufacture in a material perfectly tolerated by the body (silicone elastomer) and which can be miniaturized easily, taking into account the fact that the motor device in the form of a hollow tube curved allows in a small space to obtain a displacement and a force important for a variation of pressure

REPLACEMENT SHEET low. There is therefore a large range for making precise adjustments and adjustments in a simple manner. Finally, note that the adjustment device described in Figures 7 to 9 can be transposed to the anti-siphon valve of Figure 4, which constitutes, thus equipped, the most completed embodiment of the invention.

REPLACEMENT SHEET

Claims

1. Device for regulating and controlling the flow of cerebrospinal fluid in a drainage circuit in a subject suffering from hydrocephalus, comprising a subcutaneous transplant valve, interposed between an upstream conduit (1) coming from the one of the ventricles of the subject's cranial box and a downstream conduit (2) for discharging the liquid into a suitable organ of the subject, characterized in that the valve comprises a chamber (4) into which the two conduits (1, 2), at least one seat (6b, 9, 17) located at the outlet of one of the conduits in the chamber, a shutter (7, 8, 16) movable relative to this seat and a drive member (6) for relatively move the seat and the shutter, consisting of a portion (6) of tubular ring housed in the chamber (4) and one end (6a) of which is fixed while its other end (6b) carries one of the two relatively movable seat or shutter elements, the curvature of this portio n (6) being a function of the difference between the pressure prevailing in the chamber (4) and that prevailing in the interior volume of this tubular portion (6), so that a variation of this difference in pressures tends to displace the shutter and seat relative to each other. 2. Device according to claim 1, characterized in that the portion of tubular ring (6) constitutes an extension in the chamber of the upstream duct (1), the seat (6b) aforesaid being carried by the free end (6b) of this annular portion, the shutter being in the form of a fixed plug (7) on which the seat bears in leaktight manner when the difference in pressures between the chamber (7) and the annular portion (6) is less than a determined threshold . 3. Device according to claim 1, characterized in that the portion of tubular ring (6) is constituted by a blind bypass of the upstream conduit (1) inside the chamber whose free end (6b) is located sensi- REPLACEMENT SHEET squarely opposite the outlet of this conduit (1) upstream in the chamber, equipped with the seat (9) above, this end consti¬ killing or carrying the movable member (8) shutter applied to the seat when the pressure difference above is less than a determined threshold. 4. Device according to claim 1, characterized in that the internal volume of the tubular ring portion (6) is isolated from the conduits (1, 2) and from the chamber (4) and is filled with a gas, the aforesaid seat (17) being carried by the outlet of the downstream conduit (2) in the chamber on which the shutter (16) carries fixed at the free end of the annular portion (6) when the difference in the above pressures is less than a determined threshold. 5. Device according to any one of the preceding claims, characterized in that at least the free end (6b) of the tubular ring portion is coupled to a return member (18, 26), the effect tends to apply the shutter on the seat and whose intensity is adjustable. 6. Device according to claim 5, characterized in that the return member is constituted by a spring (26) helical disposed in the chamber (4), one end of which is coupled to the free end (6b) of the tubular ring (6), its other end being coupled to a drive member (22) mounted rotating in the chamber (4), comprising a toothed sector (23) cooperating with pawls (29a, 29b) driving in one or the other direction. 7. Device according to claim 6, characterized in that the chamber (4) of the valve is delimited by a wall (3) in a bowl closed by a dome (11) upper in flexible material, the pawls (29a, 29b) being constituted by tabs located under a tilting pallet (27) around a median axis (28), located under the deformable dome (11), and in that a snap lug (31) cooperates elastically with the toothed sector . 8. Device according to claim 5, characterized REPLACEMENT SHEET in that the elastic return member consists of a second portion of tubular ring (18) doubling the first (6) and the volume of which is in permanent communication with a sealed chamber (19) delimited by a wall of material perforable, which covers its sealing after perforation, inside which the pressure is adjusted to adjust the value of the opening threshold. 9. Device according to any one of the preceding claims, characterized in that the other conduit (1, 2) is equipped at its outlet in the chamber with a one-way valve (10, 15) whose direction passing from the chamber (4) to the conduit (2) if it is the downstream conduit or from the conduit (1) to the chamber (4) if it concerns the upstream conduit. 10. Device according to claim 9, caracté¬ ized in that the valve body has a flexible wall (11) elastically deformable in the shape of a dome, which is, when the valve is transplanted, immediately under the skin of the subject, this wall forming a pumping membrane which can be actuated by pressure through the skin. REPLACEMENT SHEET