WO2011095766A1

WO2011095766A1 - Manometer and three-way valve

Info

Publication number: WO2011095766A1
Application number: PCT/GB2011/000131
Authority: WO
Inventors: Kate Mandeville; Lisa Stroux
Original assignee: Imperial Innovations Limited
Priority date: 2010-02-02
Filing date: 2011-02-01
Publication date: 2011-08-11
Also published as: GB201001699D0

Abstract

A valve for a manometer for use in lumbar puncture procedures is provided, the valve comprising valve member which is linearly moveable relative to a valve body to define three valve configurations for, respectively, connecting a rise pipe of the manometer to a lumbar puncture needle, dispensing liquid from the rise pipe and dispensing liquid from the rise pipe and lumbar puncture needle. A corresponding lumbar puncture manometer and a lumbar puncture manometer having a telescopic rise pipe are also disclosed.

Description

MANOMETER AND THREE-WAY VALVE

[0001] The present invention relates to a valve for a manometer and to a manometer, in particular although not exclusively for use in lumbar puncture procedures.

[0002] Lumbar puncture (also known as spinal tap in North America) is a routine hospital procedure performed in several medical conditions. The spinal cord lies within the vertebral canal between three layers - the dura, arachnoid mater and pia mater. The dura and arachnoid mater lie in close approximation at the periphery of the canal, whereas the pia mater overlays the spinal cord, thus leaving a space in between the layers called the sub-arachnoid space. This space is filled with cerebrospinal fluid (CSF), which is produced in the brain and contains a number of factors which vary in health and disease. The subarachnoid space extends below the end of the spinal cord, and so can be accessed safely below this level without damaging the spinal cord .

[0003] A lumbar puncture (LP) aims to gain access to the sub-arachnoid space and the CSF using a spinal needle that penetrates the soft tissue and outer layers. Lumbar puncture is commonly used in the clinical setting to draw CSF from a patient for biochemical, cytological and microbiological testing for the diagnosis of a number of diseases. These include suspected meningitis, subarachnoid haemorrhages and rarer neurological diseases like multiple sclerosis. In some instances, the procedure may be used to administer drugs into the CSF (via intra-thecal route) for spinal anaesthesia or chemotherapy, or rarely to therapeutically withdraw CSF.

[0004] An important aspect of the lumber puncture procedure is the measurement of CSF pressure. This has an important diagnostic value, as a rise in CSF pressure may result from inflammatory conditions like meningitis or space-occupying lesions such as a brain haemorrhage which compresses the CSF into the subarachnoid space. It also has a safety role, as some brain abnormalities can be missed on the usual pre-procedure computerised tomography scan, and abnormally high CSF pressure indicates that the procedure must be abandoned. Excessive withdrawal of CSF can lead to the brain dragging down into the vertebral space and death.

[0005] The measurement of CSF is conventionally carried out using a vertical burette system, or manometer. This connects to the hollow cannula of the spinal needle, which is in the subarachnoid space, using a press-fit connection. This allows CSF to flow out of the subarachnoid space up into the hollow burette, until the external fluid pressure equals the internal pressure. The CSF pressure is then read off the vertical scale in mm H2O. A three-way tap at the base of the manometer is then turned to connect the fluid within the manometer to a collecting spout, which dispenses the CSF into specimen bottles held under this spout. A further turn of the three-way tap dispenses further CSF via the cannula within the subarachnoid space. When sufficient CSF has been collected, the manometer is then detached and the stylet replaced in the spinal needle before removal.

[0006] Practitioners in North America, Europe and Asia all typically adopt the manometer system for lumbar puncture. However, regardless of the prevalence of burette-based lumbar punctures, the procedure is wrought with difficulties. Due to initial manufacturing limitations which could not produce a single burette long enough, the manometer is manufactured in two 200mm parts which are connected to each other by a friction-fit connection and likewise to a stopcock and three-way tap by a friction-fit connection. The apparatus itself is cumbersome to operate especially with one hand, usually requiring at least two individuals to collect CSF samples and ensure sterility of the equipment. These manometers thus have a number of design flaws including that the typical readings for CSF pressure often fall within the region of the friction fit between the two parts of the manometer, they are unnecessarily large or long and cumbersome to assemble, and that difficulty in regulating the dispensation of CSF can lead to wastage. Excessive withdrawal of CSF can lead to low-pressure headaches for the patient post-procedure.

[0007] Aspects of the invention are set out in independent claims 1 and 16. Optional features of embodiments of the invention are set out in the claims dependent thereon.

[0008] Embodiments of the invention are now described by way of example only with reference to the accompanying drawings in which:

Figures 1A, IB and 1C depict a perspective view, a front elevation and a cross-section along the line A-A in Figure IB, respectively;

Figures 2 A and 2B depict a detailed view of a portion of the cross- section of Figure IB illustrating a telescopic rise pipe and an alternative arrangement, respectively;

Figure 3 A depicts a detailed view of the cross-section of Figure 1C illustrating a first three-way valve arrangement;

Figures 3B and 3C depict cross-sectional views along, respectively, lines G-G and F-F in Figure 3A;

Figure 4A depicts a cross-sectional view of a second arrangement for a three-way valve; and

Figure 4B depicts a cross-sectional view along the line D-D in Figure 4A.

[0009] With reference to Figures 1A, IB and 1C, a manometer for measuring CSF pressure and dispensing CSF is now described. The manometer comprises a rise pipe 2 secured to a valve body 4 at one end and having an open end 6 through which the rise pipe communicates with surrounding air. The rise pipe 2 has first portion 8 which comprises the open end 6 at one end. The first portion 8 is disposed within a second portion 10, which is secured to the valve body 4 at one end. The first portion 8 is slideable within the second portion 10 to provide a telescopic rise pipe which can be extended to provide an appropriate length for pressure measurement during use and collapsed for shipping and packaging.

[0010] With reference to Figures 2A and 2B, an end of the second portion 10 adjacent to open end 6 in the collapsed state of the rise pipe 2 has a tapered surface 12 forming, in some embodiments, an angle of approximately 1° relative to the longitudinal direction of the rise pipe, as indicated by the arrows in Figure 2. An end of the first portion 8 opposite the open end 6, has a complimentary tapered surface 14 so as to engage the tapered surface 12 when the rise pipe is fully extended (the first portion 8 being slid out of the second portion 10 as far as possible) and thereby to form a sealed connection between the first portion 8 and the second portion 10 by virtue of an interference fit between the tapered surfaces 12 and 14.

[0011] With reference specifically to Figure 2 A, in some embodiments, a stopper ring 7 is provided around the first portion 8 at the open end 6 to prevent withdrawal of the first portion 8 into the second portion 10 and to provide a grip surface for sulling out the first portion 8. In some embodiments, described with referenced to Figure 2B, the first portion 8 is dimensioned so that the open end 6 protrudes from the second portion 10 in the fully collapsed configuration to provide the grip surface.

[0012] Returning now to Figures 1A, IB and 1C, the valve body 4 comprises a connector portion 16 for connecting the manometer to a lumbar puncture canula, a securing portion 18 for securing the rise pipe 2 to the valve body 4 and an outlet 20 through which CSF can be dispensed into a suitable receptacle on actuation of the push button 22, as described in more detail below. The rise pipe 2 is secured to the securing portion 18 by an interference fit, thermal bonding or adhesive bonding, although in some embodiments the second portion 10 and valve body 4 may be integrally moulded or co-moulded. The connector portion 16 is shaped to connect to a corresponding canula, for example by a Luer of Luer lock connection, although other connections are of course equally possible.

[0013] With referenced to Figures 3A, 3B and 3C, the valve body 4 defines a chamber 24 which can be connected to the connector portion 16 through a connector port 26, to the rise pipe 2 through a rise pipe port 28 and to the outlet 20 through an outlet port 30. The connector port 26 is defined between an inner surface 32 of the chamber 24 and a leading portion 34 adjacent to the connection portion 16 of a moveable valve member 36. A trailing portion 38 of the valve member 36 is disposed through an orifice in a separating wall 40 located between the outlet 20 and the chamber 24. The outlet port 30 is defined between the trailing portions 38 of the valve member 36 and the orifice in the separating wall 40.

[0014] The valve member 36 comprises a substantially rigid core 42 to provide sufficient rigidity for the valve member 36, surrounded by a resilient polymeric material 44 which is shaped to define a dome shaped structure 46 at its trailing end, a protruding seal portion 48 in the region of the leading portion 34 and, in between, a saucer-shaped further seal portion 50 inside the chamber 24 adjacent to the separating wall 40. Overall, the resilient material 44 defines a body of revolution around and centred on the substantially rigid wall 42.

[0015] The domed member 46 seals against a corresponding seat of the valve body 4 to seal the interior of the valve body 4 from surrounding air with only the connector portion 16, outlet 20 and securing portion 18 providing fluidic communication between the interior of the valve body 4 and its exterior. The domed member 46, in effect, provides a push button membrane sealing against the valve body 4. The domed member 46 comprises a ribbed surface on its exterior aspect to provide a non-slip or reduced-slip surface for the push button 22 and facilitate controlled depression/release, with the valve member 36 extending from the domed member 46 into the valve body 4, through the orifice in the separating wall 40 into the chamber 24. In some embodiments, the domed member 46 has a patterned surface other than a ribbed surface, for example or knobbed surface or non-patterned surface.

[0016] Without external forces applied to the domed member 46, the leading portion 34 of the valve member 36 is disposed adjacent to the connector portion 16 to define the connector port 26 with the sealed portion 48 spaced from the inner surface 32. In this configuration, the further sealed portion 50 is resiliency biased against the separating wall 40 around its orifice. Thus, in this configuration, the connection port 26 is connected via the chamber 24 to the rise pipe port 28 via the chamber 24.

[0017] When the push button 22 is fully depressed by a user, the leading portion 34 and the seal portion 48 of the valve member 36 come to rest against the inner surface 32 in the region of the connector port 26 to seal the connector port 26 from the chamber 24. In this configuration, the further sealed portion 50 is spaced from the separating wall 40, thus opening the orifice in the separating wall 40 and connecting the outlet port 30 to the rise pipe port 28 via the chamber 24.

[0018] In intermediate configurations between the two extremes described above, the leading portion 34 and seal portion 48 are spaced from the connector port 26 and the further sealed portion 50 is spaced from the orifice in the separating wall 40, so that all three ports 26, 28 and 30 are connected to each other via the chamber 24, or in other words are in fluidic communication with each other via the chamber 24, in these intermediate configurations. Upon partial or full release of the pushing force, the valve member 36 backs off partially or fully, respectively, due to the resilience of the domed member 46, thus enabling repeated actuation of the valve to select a required configuration of the valve.

[0019] Thus, it can be seen that linear movement of the valve member 36 upon exertion by a user of a pushing force on the push button 22 allows the valve member 36 to be disposed in configurations relative to the valve body 4 so as to selectively connect the connector port 26 to the rise pipe 28 via the volume 24 and seal off the outlet port 30, connect the rise pipe port 28 to the outlet port 30 via the volume 24 and seal off the connector port 26 or to connect all three ports together in respective configurations.

[0020] In use, the manometer is prepared by extending the rise pipe 6 as described above. With the spinal canula in place, the connection portion 16 is connected to the canula and, in the absence of a force exerted on the push button 22, the connection port 16 is connected to the rise pipe port 28 with the outlet port 30 being sealed so that CSF flowing under pressure through the connector portion 16 into the chamber 24 rises against gravity in the rise pipe 6 until the gravitational pressure to the liquid column in the rise pipe 6 balances the CSF pressure in the subarachanoid space, at which point a pressure reading can be taken from the graduated scale of the rise pipe, for example in mmH₂0.

[0021] To dispense CSF into a receptacle through the outlet 20, a user pushes onto the ribbed surface of the domed portion 46 to fully depress the push button 22 so that the valve member 36 opens the outlet port 30 and seals the connector port 26. In this configuration, the liquid column from the rise pipe flows into the receptacle held under the outlet 20. Conveniently, the arrangement of the push button 22 adjacent and above the outlet 20 allows a user with one hand to hold a receptacle under the outlet 20 and actuate the push button 22 with the thumb of the same hand.

[0022] For example, the valve body 4 can be held between the index and middle fingers between the rise pipe 2 and connector 16, allowing the thumb to be placed on the push button, in a manner similar to actuating a conventional syringe.

[0023] Once sufficient liquid has been drawn from the rise pipe 6 into the receptacle through the outlet 20, the push button 22 can be fully released to stop further flow into the receptacle. If all of the liquid in the rise pipe 6 has drained into the receptacle and still further liquid is required, the pressure on the push button 22 can be reduced to an intermediate level to back off the valve member 36 due to the resilience of the domed member 46 to a position intermediate a configuration sealing the outlet port 30 and a configuration sealing the connector port 26, thus allowing CSF to flow directly from the connector 16 through the chamber 24 to the outlet 20 until sufficient CSF has been drawn.

[0024] Since the valve member 36 can be disposed at intermediate positions, between the three configurations mentioned, by adjusting the pressure applied to the push button 22, the flow rate from the rise pipe 2 and connector portion 16 to the outlet 20 can be controlled from dripping only to fully open by gradually spacing the seal member 50 away from the separating wall 40. Once the rise pipe 40 has emptied, the flow rate from the connector 16 only can additionally be controlled by controlling the position of the seal member 48 relative to the connector port 26 by controlling the pressure on the push button 22.

[0025] In some embodiments, now described with reference to Figures 4A and 4B, an alternative valve body and valve member arrangement replaces the one described above with reference to Figures 3A, 3B and 3C. Like parts have been given like reference numerals.

[0026] In these embodiments, the separating wall 40 is removed so that the chamber 24 occupies the entire interior space of the valve body 4 including the inside of the domed member 46 and a single seal portion 52 sealing and connecting ports on linear movement of the valve member 36 as the push button 22 is depressed replaces the separate seal portions 48 and 50 for sealing, respectively connector port 26 and the outlet port 30. The sealed portion 52 comprises first and second wiper plates 54, 55 which, when no pressing force is applied to the push button 22, are disposed inside the chamber 24 in a first region between the rise pipe port 28 and the outlet port 30 (in the direction of linear movement of the valve member 36) the rise pipe port 28 being disposed on top of the chamber 24 in a working orientation and the outlet port 30 being disposed at the bottom of the chamber 24 in a working orientation. The wiper plates 54, 55 are spaced so that a leading wiper plate 54 is disposed with its top adjacent to the rise pipe port 28 and a trailing wiper plate 55 is disposed with its bottom adjacent to the outlet port 30.

[0027] In the first region, the chamber 24 defines a substantially cylindrical shape with the walls of the chamber 24 extending at right angles to a transverse cross-section of the chamber in this region. The wiper plates 54, 55 have a rounded edge 56 which conforms to the inner surface 32 of the chamber 24 in the first region and is a resilient fit with the wall to form a wiping seal in the first region. Thus, when the valve member 36 is disposed in a rest configuration with no pushing force being applied to the push button 22, the chamber 24 is sealed into two portions, one extending towards the connector portion 16 through which the rise pipe 28 and connector port 26 connect and are in fluidic communication with each other and another sealed off portion between the rise pipe port 28 and the outlet port 30, thereby sealing the outlet port 30 from the other two ports.

[0028] The same substantially cylindrical shape of the chamber 24 is continued in a second region beyond the outlet port 28 in the direction of movement of the valve member 36 between the outlet port 28 and the connector port 26 so that both wiper plates 54, 55 of the seal portion 52 can be disposed on the other side of the outlet port 28 in the second region to seal against the inner surface 32. Thus, in this configuration (with the push button 22 partially depressed) the rise pipe port 28 and outlet port 30 are connected to each other and in fluidic communication while the connector port 26 is sealed off from both of the other two ports.

[0029] In yet a further, third, region of the chamber 24, further along in the direction of movement of the valve member 36, the transverse cross-section area of the chamber 24 expands so that the wiper plates 54 of the seal portion 52 no longer seal against the inner surface 32 of the chamber 24, so that fluidic communication is established between all three ports when both wiper plates 54 of the sealed portion 52 are disposed in the third region, when the push button 22 is fully depressed. Thus, in this configuration, all three ports are connected to each other via the chamber 24.

[0030] In the specific embodiment described with reference to Figures 4A and 4B, the cross-sectional area of the chamber 24 on either side of the rise pipe port 28 is generally disc shaped with a substantially circular inner perimeter of the chamber 24 extending over most of its angular extent but with an inwardly raised bump of the inner surface 32 extending into the chamber 24 at its bottom in the working orientation. In the third region adjacent the connector port 26, where the seal portion 52 is disposed on full depression of the push button 22, the bump 56 falls away to give rise to the expanded cross- sectional area, so that an indent 58 of the wiper plates 54 corresponding to the bump 56 provides an increased cross-sectional area of the flow path from the connection port 26, as compared to a fully disc shaped wiper plate shape and cross-sectional area throughout.

[0031] In use, the device is handled substantially as described above, with the rise pipe 2 connected to the connector 16 when no external force is applied to the push button 22 but with the difference that connection of the rise pipe 2 to the outlet 20 while sealing off the connector 16 is achieved not in a fully depressed configuration but in an intermediate configuration, with the push button 22 partially depressed and that all three ports are connected when the push button 22 is fully depressed. A gradual increase of a pressure applied to the push button 22 first leads to a low flow rate, dripping action, from the rise pipe 2, then increases this flow rate and then finally a gradually increasing flow rate from the connector 16 as the valve member 36 is progressively advanced into the chamber 24 of the valve body 4. [0032] In some embodiments related to the embodiments described above with reference to Figures 4A and 4B, the valve body 4 includes an arrangement which provides a user with haptic or tactile feedback allowing a user to discern when the valve member 36 is within the intermediate configuration relative to the valve body 4 so that the rise pipe port 28 is connected to the outlet port 30 but both these ports are sealed off from the connector port 26, and when this configuration is left. In some embodiments, this haptic or tactile feedback is provided by a rib around the perimeter of the chamber 24 in the second region between the rise pipe port 28 and the connector port 26 and positioned so that the leading wiper plate 54 rides over the rib, but not the trailing wiper plate 55 when the seal portion 52 is pushed passed the rise pipe port 28 sufficiently so that the trailing wiper plate 55 rests adjacent to the rise pipe portion 28 on the side towards the connector port 26. On further depression of the push button to connect the three ports, the trailing wiper plate 55 then also rides over the rib.

[0033] Thus, two instances of haptic or tactile feedback in the form of a small resistance to movement of the valve member 36 are provided, once when the push button 22 has been sufficiently depressed to connect the rise pipe port 28 to the outlet port 30, while sealing the connector port 26, and once when all three ports have been connected, and likewise on the return stroke of the valve member 36. It will be understood that other ways of providing haptic or tactile feedback are used in other embodiments, for example the rib can be replaced by one or more nubs or separate feedback features can be provided both on the valve member 36 and the valve body 4, for example separate resilient plates interacting with a separate feature such as a web on the valve body 4. In any event, the resistance to movement due to the feedback providing feature must be sufficiently large to be haptically detected by a user but not so large so as to impede the return stroke of the valve member 36 due to the resilience of the domed member 46. [0034] The manometers described above may be manufactured using any suitable manufacturing technique, for example the parts of the rise pipe 2 are manufactured by extrusion of a clear plastic material, for example PC (polycarbonate) or PVC (polyvinyl chloride), followed by machining of the tapered surfaces 12, 14, with the valve body injection moulded from a clear plastic such as PC (with the separating wall 40 in the Figure 3 embodiment separately moulded, for example injection moulded from PC, and then assembled), and with the resilient polymeric material 44 being TPC (thermoplastic elastomer), shaped by injection moulding. In dependence on the chosen or most appropriate shore harness of the TPE and the final dimensions of the valve member 36, the core 42 may be omitted in some embodiments. In embodiments where a core 42 is included for rigidity, a PVC or PC rod-shaped member could be placed inside the TPE shape using co-injection moulding. While PC is a preferred material in terms of optical clearness, PVC is also transparent and maybe preferred in some embodiments due to the reduced cost of PVC. Equally envisaged are embodiments which use a blend of PVC and PC for the rise pipe 2 parts and the valve body 4 (and, if applicable separating wall 40).

[0035] In embodiments described in reference to Figure 2A, the open end 6 of the first portion 8 is slid into the second portion to protrude from it and the stopper ring 7 is placed over and adhered to the open end 6 to prevent the first portion 8 to slide back into the second portion 10. The resulting assembly can then be assembled with the valve body 2 using a press fit connection, either when the manometer is prepared for use or as a pre-assembly step at manufacture. The valve body 2 is assembled by inserting the valve member 36 into the valve body 4 and a joint line of the valve member 36 with the valve body 4 (around the push button 22) is sealed using an adhesive. In the embodiments described with reference to Figures 3A to 3C the separating wall 40 is secured in place by an adhesive or, alternatively, may be secured by ultrasonic welding or a press-fit. The valve member 36 is then forced through the outlet port 30 into position. In some embodiments, in particular with regulatory concerns in mind, adhesive fastening of components is replaced with ultrasonic welding, press fitting or other methods of achieving a sealing fit.

[0036] The above description of specific embodiments of the invention has been made for the purpose of illustration only and by way of example to further the understanding of the invention and is not intended to be limiting on the scope of the invention, as defined in the following claims. Many alterations, modifications and juxtapostions of the features above will be apparent to the skilled person without departing from the scope of the invention and these are intended to be covered by the scope of the claims.

Claims

1. A valve for a manometer for use in lumbar puncture procedures, the valve comprising:

a valve body having a first port for connection to a lumbar puncture canula, a second port for connection to a manometer rise pipe and a third port for dispensing liquid from the first port, second port or both, and

a valve member moveable between a first configuration, a second configuration and a third configuration relative to the valve body, the first and second port being connected to each other and sealed from the third port in the first configuration, the second and third port being connected to each other and sealed from the first port in the second configuration and the first, second and third port being connected to each other in the third configuration,

the valve member being linearly moveable between the first, second and third configurations.

2. A valve as claimed in claim 1 comprising a resilient biasing

arrangement for biasing the valve member to move from the second or third configuration towards the firstconfiguration.

3. A valve as claimed in claim 1 or claim 2 comprising a push button arrangement for transmitting a user's pushing force to the valve member to cause the valve member to move relative to the valve body.

4. A valve as claimed in claim 3 in which the push button arrangement comprises a resiliently deformable membrane to which the valve member is secured.

5. A valve as claimed in claim 4 in which the membrane seals against one end of the valve body.

6. A valve as claimed in claim 3, claim 4 or claim 5 in which the push button arrangement comprises a resilient domed member to which the valve member is secured.

7. A valve as claimed in any preceding claim in which the valve member is moveable from the first configuration to the second configuration via the third configuration.

8. A valve as claimed in any of claims 1 to 6 in which the valve member is moveable from the first configuration to the third configuration via the second configuration.

9. A valve as claimed in claim 7 in which the valve member comprises a first seal portion adjacent one end of the valve member for sealing the first port and a second seal portion adjacent an opposed end of the valve member for sealing the third port.

10. A valve as claimed in claim 9 in which the distance along the valve member between respective sealing surfaces of the first and second seal portions is less than the travel of the valve member between the first and second configurations.

11. A valve as claimed in claim 8 in which the valve member comprises a seal portion for sealing against an inner surface of the valve body between the second and third ports, the seal portion being arranged to travel from one side of the second port between the first and second port to an opposite side of the second port between the second and third port as the valve member travels from the first to the second configuration.

12. A valve as claimed in claim 1 1 in which the valve body has a region adjacent the first port of increased cross-sectional area relative to a region adjacent the third port, the seal portion being disposed in the region of increased cross-sectional area in the third configuration to connect the first, second and third port to each other.

13. A valve as claimed in claim 11 or claim 12, the valve body and valve member each having a respective feature, the features co-operating to provide a haptically detectable resistance to movement of the valve member from the second to the third configuration.

14. A valve as claimed in claim 1 1, claim 12 or claim 13, the inner surface comprising a rib over which the seal member travels between the second and third configurations.

15. A manometer for use in lumbar puncture, the manometer comprising a valve as claimed in any preceding claim.

16. A manometer for use in lumbar puncture, the manometer comprising a rise pipe in which liquid from a lumbar puncture can rise against gravity, the rise pipe comprising a first portion disposed within a second portion, the first and second portion being slideable relative to each other to dispose the rise pipe in an extended configuration in which the first and second portions seal against each other.

17. A manometer as claimed in claim 15 and claim 16.

18. A manometer as claimed in claim 16 or claim 17 in which the first and second portion comprise respective tapered portions arranged to be an interference fit in the extended configuration.