Variable flow self-cleaning valve

Abstract: The present valve, employable by persons affected by hydro­ cephalus, permits discharge into suitable offtake branches of the excess cephalorhachidian fluid existing in the ventricles of the brain. The valve basically consists of a hollow cylindrical body (1) having inside a seat (5) with an enlarging triangular shape designed to interact with an aptly-shaped capsule or small piston (6) and placed against an antagonist spring (7). This pattern permits to offset the varying amounts of ventricular fluid pressures, discharging outside any fluid, whether large or small, through suitable offtake branches and at the same time it accomplishes a self-cleaning function which ensures a constant flow efficiency.

Description: The object of the present invention patent is a variable flow valve, preferably applicable in offtake branches for ejection of surplus cephalorhachidian fluid existing in the ventricles of the brain in patients affected by hydrocephalus. As it is known by medical pathology this type of disease is characterized by an increase in the pressure of the cephalorhachidian fluid existing in the ventricles of the brain. This pressure increase is due to a pathological occlusion of the natural paths that permit regulation of this pressure. In these cases it is essential to surgically intervene to form auxiliary channels for the surplus fluid, otherwise the brain will suffer severe and irreparable injuries. Naturally these offtake branches must be maintained functionally in place by the patient because of the cyclic nature of this abnormal phenomenon, therefore it becomes necessary to use a valve for regulation of ventricular pressure. In this regard modern surgical engineering has only an extremely limited number of valves to offer. The most well known and used of them is the diaphragm valve, but this valve is subject to a number of flow and tension problems. This valve, in fact, is manufactured case by case and set for a specific limit pressure that can differ from one patient to another. This means that increases in ventricular pressure that stay below this limit cannot be discharged. This results in a period of brain suffering that can only be relieved when the pressure exceeds the valve threshold setting. This type of valve is also easily subject to occlusions and other similar troubles that quickly make the appliance unserviceable. Other by-pass means have also been developed, such as a constant flow system as discussed in the patent CH 496,445 which is efficient for small pressure variations but which is absolutely inadequate for strong jumps in pressure which require immediate and abundant external discharge. In this solution, in fact, a flow modulation system has been entirely omitted and it is necessary to adjust the discharge pressures exceeding the predetermined calibration through a threaded screw which makes the use of the device not very practical. The main purpose of the present invention is the development of a valve capable of offsetting increases in ventricle fluid pressure of any size by variable flow ejection, thus eliminating all the problems encountered by the state of the art. As part of this general scope the valve that forms the object of the present invention specifically evidences a capacity to maintain its own functional efficiency over long time periods thanks to a constant self-cleaning action caused by suitably shaped movable components. The present valve can be used to offset slight increases in ventricular pressure. It can also, through intermediate channels, offset strong increases in this pressure with immediate and abundant discharge outside. Another advantage offered by the present invention is that this valve eliminates completely the so-called siphon effect. This because any force applied by the fluid but not caused by ventricular bodies immediately causes blockage of the valve element. The reliable efficiency and functional merits of the invention, and the simplicity with which it can be produced, are the prerequisites for quick and widespread diffusion of the same even on a large scale. The invention, in fact, refers to a self-cleaning variable flow valve for offtake channels of ventricular cephalorhachidian fluid consisting of a hollow cylindrical body with inlet and outlet openings, this hollow cylindrical body internally interacting with a sliding piston fitted up against a spring, characterized by the fact that on the inner surface of the said hollow body a flared conical longitudinally-elongated profiled seat is arranged, the said sliding piston being provided with an annular groove and a discharge channel which co-operate with the said seat for ensuring a different outflow rate of fluid depending on the variable pressure rates applied. The invention can be better understood from the following description, as well as from the enclosed drawings where: figure 1 is a schematic exploded view of a type of valve according to the invention with an assembled cylinder; figure 2 is a schematic view of the assembled parts with the piston is its semi-closed position; figure 3 is a detailed view of the sliding piston; figures 4 and 5 are, respectively, schematic cut-away views of the valve in its closed position and in its maximum capacity open position. The number 1, with reference to the enclosed illustrations, is used to indicate the cylindrical or valve body as a whole and that can be made as an enbloc unit but which, for convenience, is obtained in two parts, 2 and 3, where the first part enters completely into the second. Cylindrical section 2, contrary to part 3, which is hollow and offers exclusively an opening 4 for insertion of cylinder 2, includes a characteristic carved part 5 or a basically tapered or flared opening in the direction shown in the illustration. Carved part 5, when cylindrical body 2 is inserted into body 3, forms a closed internal seat serving the purposes we shall illustrate in the following, the said seat being arranged longitudinally along the inner cylindrical surface. Cylindrical body 1 houses movable piston 6 and spring 7 which acts as an antagonist device for the piston itself, which is pushed towards opening A on the cylindrical body. Opening A is connected, in the case in question, to an offtake branch, not illustrated, coming from the ventricular body subject to pathological pressure increases. B is used to indicate the exit section connected to a drainage channel. The piston 6 basically consists of a front tapered section 8 (see fig. 3) acting on an eventual flared profile 8' of opening A and a cylindrical body 9 that forms seal strip 11 and is interrupted by annular groove 10. Inside flow channel 12, with opening 13 and exit from the rear part of the piston near a drain cylinder 14, starts out from groove 10. The assembled valve can be seen as illustrated in figure 4 with piston 6 completely pushed by spring 7 towards flared profile 8' which is internally closed off by the tapered section 8 of same. In this phase the caphalorhachidian fluid is at normal pressures and consequently the piston is not exposed to any force except that of pre-set spring 7. The main characteristic of the present invention consists in the fact that the fluid pressure changes in the inlet opening (A) provoke a movement, more or less wide, of the piston (6) and a consequent proportional discharge variation, due to the passage of the fluid itself through sections, more or less wide, of the flared seat (5). A slight increase in pressure applied by the fluid in opening A will cause piston 6 to start slowly retracting until seal strip 11 crosses the vertex of seat 5. This permits the fluid to penetrate into annular groove 10 and move from here into flow channel 12. This channel leads directly into cylinder chamber 15 going towards exit B. If pressure continues to increase the piston moves further back, permitting an increase in flow rate due to the increase in discharge space provided by flared seat 5. A further increase in fluid pressure will bring the piston to its all-back position as illustrated in figure 5. In this position the cross-section of seat 5 is in its maximum flow rate position with respect to discharge groove 10 and fluid can be expelled at the highest discharge rate. It is evident that under normal operating conditions the piston will move to intermediate positions to permit, for example, an almost constant minimum discharge rate. To do this spring 7 is set to offset all the pressure conditions that can arise, from a minimum pressure, slightly higher than normal, to a maximum level which ensures that a maximum quantity of fluid will be drained off in the least possible time period in order to ensure quick return to normal of ventricular pressure. The seal strip 11 of the piston 6 conducts a self-cleaning action for the inner part of the valve since during the movements of the piston itself, the seal strip drags against the inner walls of the cylindrical element and removes any impurity which may occur. The period of suffering by the brain is practically nil since the valve has the capacity to drain quantities going from just a few droplets per minute up to several deciliters per minute. The example in question described a type of valve formed of two cylindrical bodies one of which enters entirely into the other, with the inner body having a flared opening. However other forms of embodiment can be made that in any case permit achievement of an internal cylindrical chamber with a seat with a flared or increasing profile. One of the advantages of this type of valve is that its design inhibits any abnormal movement of the fluid, preventing suction effects, because spring 7, not exposed to pressure or having pressure that pushes towards opening B, keeps the piston moved towards opening A and consequently checks fluid backflow. Any further pressure above and beyond maximum pressure caused, for example, by the siphon effect caused by the peritoneal discharge tube, is offset by the piston itself which moves to its travel limit where seal strip 11 crosses the edge of the flared opening and stops flow. In one possible variant piston 6 can be modified and have helical grooves carved onto cylindrical surface 9 in place of discharge channel 12. This permits the piston, during its longitudinal movements inside the cylindrical chamber, to make rotary movements about its axis in order to further enhance the self-cleaning action performed by the valve. Other variants or modifications can be made to the invention in question but which should in any case be considered to be included within the realm of protection claimed by the claims.

Claims: Self-cleaning variable flow valve for offtake channels of ventricular cephalorhachidianfluid comprising a cylindrical hollow body (1) with inlet (A) and outlet (B) openings and a sliding piston (6), placed against a spring (7), said sliding piston (6) being provided with an annular groove (10) and a discharge channel (12) between the end of the piston facing the outlet opening and said annular groove co-operating with the a seat (5) characterized by the fact that the seat is conical, has a longitudinally-elongate profile and is provided on the inner surface of the said hollow body (1), for ensuring a different outflow rate of fluid depending on the variable pressure rates applied. Variable flow valve as previously claimed, characterized by the fact that said cylindrical body (1) consists of two parts (2) (3) one of which telescopes into the other, the inner part (2) being provided on its cylindrical surface with a conical or flared opening which, when the parts are assembled, forms the said conical longitudinally-elongated profiled seat (5). Valve as previously claimed, characterized by the fact that said piston (6) consists of a front conical section (8), which penetrates into a flare (8') of the cylindrical body (1), a cylindrical part (9) and a seal strip (11). Valve as previously claimed, characterized by the fact that the said piston (6) shows an internal discharge channel (12), arranged between a rear drain cylinder (14) and the said annular groove (10). Valve as previously claimed, characterized by the fact that the said annular groove (10) is arranged between the cylindrical part (9) and the seal strip (11) of the piston (6). Valve as previously claimed, characterized by the fact that the conical part (8) of said piston (6) is designed to close the opening (A) of cylindrical body (1) when no pressure is applied other than that of spring (7). Valve as previously claimed, characterized by the fact that the retraction of the piston (6), caused by an increase in fluid pressure in the opening (A) of the cylindrical body (1), makes the passage of the cylindrical body itself possible towards the outlet opening (B) whereby at first the fluid enters in the seat (5) of the cylindrical body (1), and then, the fluid enters in the annular groove (10) and in the internal discharge channel (12) of the piston (6) and then, the fluid goes out of the latter and the outlet (B). Valve as previously claimed, characterized by the fact that the variations in cephalorhachidian fluid pressure in the opening (A) cause a movement, more or less wide, of piston (6) and a consequent proportional discharge variation, provoked by the passage of the fluid itself through sections, more or less wide, of the flared seat (5). Valve as previously claimed, characterized by the fact that the seal strip (11) of the piston (6) permits a self-cleaning action of the inner part of the valve since during the movements of the piston itself, the seal strip (11) drags itself against the inner walls of the cylindrical element and removes eventual impurities. Valve as previously claimed, characterized by the fact that, in lieu of internal channel (12), helicoidal grooves are obtained on the outer surface of the cylindrical part (9) of said piston (6) and said helicoidal grooves permit an axial rotation by the piston during its longitudinal movements.

Inventors: RANCANI CLAUDIO, RANCANI, CLAUDIO
Applicants: MONTINI FIORENZA, RANCANI ALESSANDRO, RANCANI SILVIA, MONTINI, FIORENZA, RANCANI, ALESSANDRO, RANCANI, SILVIA
Application year: 1990
Main classification: A61M1
IPC codes: A61M27, A61M1