Device for producing sclerosing microfoam

Abstract

This invention relates to apparatus and devices that generate sclerosing microfoams for the treatment of venous disorders, such as varicose veins. The invention includes adaptors which provide fluid connections to microfoam generating devices, to enable filling with gas and/or dispensing of the microfoam product. The adaptors are generally cylindrical elements with open ends to enable attachment to pressurisable container on one end and are configured to enable rapid and easy attachment of a filling means or a dispensing means through the other end of the adaptor. A particular configuration comprises three or more circumferentially and downward extending cam tracks which cooperate with corresponding cams on the filling means or dispensing means and which connect a pressurisable container to a fluid path of a filling or dispensing means when the pressurisable container and filling or dispensing means are rotated relative to each other.

Claims

1. An adaptor for connecting a filling or dispensing means to a valve of a pressurisable container, said adaptor comprising: a cylindrical element with open ends and an inner wall and an outer wall therebetween, said open ends comprising a lower open end configured to enable attachment to the pressurisable container and an upper open end configured to enable attachment of a filling means or a dispensing means; an inner bore to accommodate the valve of the pressurisable container and enable engagement of the valve with the filling means or dispensing means when attached through the upper open end of the device; wherein the outer wall of the adaptor comprises three or more evenly spaced cam tracks which circumferentially and downwardly extend from a top initial portion to a bottom terminal end wall at a terminal end of each cam track, which cooperate with corresponding cams on the filling means or dispensing means, and which connect the valve of the pressurisable container to a fluid path of the filling or dispensing means when the pressurisable container and filling or dispensing means are rotated relative to each other.

2. An adaptor according to claim 1 wherein at least one cam track has one or more detents provided in the track to prevent automatic rotation of the containers and/or to enable the user to gauge the progress of the connection.

3. An adaptor according to claim 2 wherein two detents are provided in the top initial portion of the track and which, prior to rotation, are positioned either side of a cam on the filling means.

4. An adaptor according to claim 1 wherein the cam track has mechanical click-stop at the terminal end to prevent further rotation of the filling or dispensing means relative to the pressurisable container.

5. An adaptor according to claim 1 in which the angle of rotation required to connect the valve to the filling or dispensing means and provide a fluid path therebetween is approximately 120 degrees.

6. An adaptor according to claim 1 in which the cam track defines a pathway with gradient of approximately 35 degrees relative to the lower end of the adaptor.

7. An adaptor according to claim 1 wherein the cam track defines a pathway characterised by an initial and a final portion with gradient between 0 and 5 degrees, with a central higher gradient which is in the region of 35 degrees, relative to the lower end of the adaptor.

8. An adaptor according to claim 1 which is provided with a release track, so that the pressurisable container and the filling or dispensing means may be separated again.

9. An adaptor according to claim 8 wherein the release track is defined by the cam track and release is effected by rotation in the opposite direction to that used to connect the valve to the filling or dispensing means.

10. An adaptor according to claim 1 which is configured to snap fit on to the top of an aerosol canister.

11. A device for producing a sclerosing microfoam comprising: a pressurisable container containing a solution of sclerosing agent in a physiologically-acceptable solvent, the pressurisable container being sealed by an aerosol valve through which contents may pass when the container is pressurised and the valve is actuated; a foaming element which is in fluid communication with the aerosol valve; an adaptor as described in claim 1 which is connected to the pressurisable container and which enables attachment of a source of physiologically-acceptable gas or of a foam dispensing means to the pressurisable container; and a source of physiologically-acceptable gas which is adapted to cooperate with the adaptor; wherein, when the source of physiologically-acceptable gas is connected through the adaptor, the valve is opened upon rotation around the adaptor and physiologically-acceptable gas flows into the container until a predetermined pressure is reached.

12. A device according to claim 11 wherein the source of physiologically-acceptable gas comprises a gas outlet positioned within a generally hollow cylindrical element with an open end and comprising on its inner surface three protruding cams arranged to fit into the cam tracks of the adaptor.

13. A device according to claim 12 wherein the source of physiologically-acceptable gas is a pressurised aerosol canister adapted with a hollow cylindrical collar.

14. A device according to claim 11 which further comprises a removable spacer to prevent rotation of the pressurisable container and the source of physiologically-acceptable gas around the adaptor until the spacer is removed.

15. A device according to claim 14 wherein the removable spacer has the form of an annular collar at least partially positioned over the adaptor to prevent movement of the cams in the cam tracks.

16. A device according to claim 11 wherein the foaming element comprises one or more passages of cross sectional dimension 0.1 m to 30 m, through which physiologically-acceptable gas is passed when the source of physiologically-acceptable gas is connected to the pressurisable container and through which the solution of sclerosing agent and physiologically-acceptable gas is mixed when the container is pressurised and the valve is actuated, such that a microfoam is formed which has density in the range of from 0.07 to 0.19 g/ml density and has a half-life of at least 2 minutes.

17. A device for producing a sclerosing microfoam comprising: a pressurised container containing a solution of sclerosing agent in a physiologically-acceptable solvent and a physiologically-acceptable gas mixture comprising nitrogen in the range of from 0.1-0.8% by volume, the remaining gas consisting essentially of at least 10% carbon dioxide with the remainder oxygen, the pressurised container being sealed by an aerosol valve through which the contents may pass when the container is pressurised and the valve is actuated; a foaming element which is in fluid communication with the aerosol valve; an adaptor as described in claim 1 which is connected to the pressurisable container; and a foam dispensing means which comprises a cylindrical element, the internal surface of which comprises three cams to cooperate with the cam tracks on the adaptor to enable fluid connection with the valve, wherein the foam dispensing means comprises a valve actuation means to open the valve and dispense foam.

Description

FIGURES

(1) FIG. 1 shows a 3D representation of an adaptor according to the present invention (FIG. 1a). FIGS. 1b and 1c show side and cross-sectional views, respectively, of the adaptor of FIG. 1a and further described in Example 1 below.

(2) FIG. 2a shows an exploded view of the adaptor and collar for connecting the adaptor to the source of pressurised gas, FIG. 2b shoes the components connected, in cross-section.

(3) FIG. 3a shows an exploded view of a canister device of the second aspect of the invention with the source of pressurised gas connected to the pressurisable container.

(4) FIG. 3b is an assembled view of the components of FIG. 3a.

(5) FIG. 3c is a cross-sectional view of the components of FIG. 3a connected.

(6) FIG. 4 shows an exploded view of a canister device of the second aspect incorporating the microfoam dispensing device.

EXAMPLES

(7) FIG. 1 illustrates a typical adaptor of the first aspect of the invention. The adaptor [1] is generally cylindrical with an upper open end with a generally circular rim [2] and a lower open end with a generally circular lower rim [3]. The lower open end enables simple mechanical attachment of the adaptor to a pressurisable container, such as an aerosol canister, through snap-fit mountings [5] which are integrally formed inside a hollow portion [7] at the lower end of the adaptor (shown in FIG. 1b). The snap-fit mountings [5] are configured to engage a cup valve, such as the type which is typically crimped onto the mouth of a standard aerosol can (not shown in FIG. 1). The teeth of the snap fit mountings clip are pushed under the rim of the valve cup with high frictional force to hold the adaptor in place. Elongate ribs [6] are provided around the internal circumference of the hollow element which rest against the canister shoulder and support the adaptor such that movement of the adaptor relative to the canister is minimised. The upper portion of the adaptor comprises an inner bore [8] which extends through the inner section of the adaptor and is approximately at the centre of the adaptor to accommodate a valve and/or outlet stem of the pressurised canister. When connected to a canister, the valve stem (or container outlet) protrudes through the adaptor outlet [4].

(8) The adaptor enables easy connection between a pressurised canister and a filling means for simple filling of the pressurised canister through the valve stem, easy removal thereafter and subsequent attachment of a dispensing means directly to the valve stem of the pressurisable canister through a male-female connection.

(9) In this example the adaptor is provided in the male configuration and the filling means or dispensing means is adapted to provide a female counterpart, as described below.

(10) The outer surface of the upper portion of the adaptor comprises three circumferentially and downward extending cam tracks [9] which are equally spaced around the circumference of the adaptor. The cam tracks are designed to cooperate with correspondingly spaced cams on the inner surface of the filling means or dispensing means. The cams will move along the cam tracks as the filling or dispensing means is rotated clockwise relative to the adaptor. The cam tracks are designed to ensure that as the cam travels to the end of the track, complete connection is achieved between the canister valve and the filling means.

(11) The upper (i.e. initial portion of the cam track relative to the direction of travel) part of the cam track comprises two small rib-like protrusions [10] which act as a detent or catch ensuring that, after the cam of the filling means contacts the cam track, it can be held in position and rotation will only begin when additional force is required to force the cam over the protrusions. Two protrusions spaced apart by a distance that is just slightly larger than the diameter of the cams, enables the device to be provided with the filling means pre-attached to the adaptor but held securely between the two protrusions such that connection only occurs when the user applies sufficient force to move the cam over the second protrusion.

(12) A wall is provided at the terminal end of the cam track to prevent over-rotation beyond the point of complete connection (approximately 120 degrees rotation). Towards the end of the cam track, and just before the end wall, a mechanical click-stop [12], in the form of a ramp-like protrusion, is provided such that the cam moves up and over the ramp easily and provides an audible click when the cam passes to provide feedback to the user that the connection is complete. The ramp shape of the click-stop also ensures that greater force is required to move the cam back along the cam track, such that the connection is maintained until the user is ready to disconnect. The dimensions of the ramp are selected such that a slightly increased force is required to disconnect the filling means from the canister by moving the cam backwards over the ramp as the filling means is rotated anticlockwise relative to the adaptor.

(13) As indicated above, the cam track also acts as a release mechanism, for simple removal of the filling means, with additional force required to move the cams over the click-stop ramp and the detents to enable complete removal. Subsequent attachment and removal of a further filling means or a dispensing means operates in exactly the same way and attachment and detachment of the filling means.

(14) FIG. 2 shows a configuration where the adaptor [1] is provided with a corresponding female adaptor [13] attached (but not fully connected). The corresponding female adaptor [13] which is snap-fitted to a canister comprising gas in a similar way as described above for the adaptor [1]. Ribs [17] are provided on the internal surface of the hollow female adaptor.

(15) The adaptor is provided in the form shown is FIG. 2b in which the cams of the filling means are held in place between the detents [10] and further secured through the attachment of a removable spacer [14] which prevents rotation until it is removed. Additional security is provide by location lugs [15] which fit in corresponding arches in the filling means adaptor.

(16) The same male-female connection is utilised for the attachment of a dispensing means, as discussed in more detail below.

(17) FIG. 3 shows a device for producing a sclerosing microfoam. FIG. 3b shows a corresponding configuration to that shown in FIG. 2b but where a canister comprising physiologically acceptable blood-dispersible gas [18] is connected to a canister comprising an aqueous sclerosant liquid, [19] through the adaptor [1]. The device is provided in this form, with the removable spacer [14] holding the canister apart. The spacer is removed and the canister rotated, the same way as described above, to ensure complete connection of the two canisters through the adaptor. Once connected, the valve of the canister comprising physiologically acceptable blood-dispersible gas [18] is actuated and transfers its contents into canister comprising aqueous sclerosant liquid [19], through a mesh-stack shuttle component [21] which is connected to the valve [20] of the canister comprising aqueous sclerosant liquid [19].

(18) The mesh-stack shuttle [21] is comprised of four injection moulded disk filters with mesh size of approximately 5 microns. These are pre-assembled within the casing. The mesh-stack shuttle is important for conditioning and controlling bubble size of microfoam later produced by the device but does not affect the transfer of gas from one canister to the other.

(19) FIG. 3c shows a cross section of the device, when complete connection has been made and gas has transferred from the upper canister [18] into the lower canister [19] comprising sclerosant liquid [23]. This action produces a pressurised gas mix in the sclerosant liquid canister [19] at approximately 3.2 bar absolute pressure when the sterile gas transfer is completed. In this example, the canister [19] is prefilled with approximately 18 ml of polidocanol solution in buffer.

(20) Each canister [18], [19] is a standard 200 to 350 ml design with an aluminium wall, the inside surface of which is coated with an epoxy resin resistant to action of polidocanol and oxygen (e.g. Hoba 7940, Holden UK). The bottom of the canister is domed inward. The dome provides a perimeter area around the bottom of the inner chamber in which a level of polidocanol solution is retained sufficient for the bottom open end of a dip tube [24] to be submerged therein when the top of the dome is no longer covered with the solution.

(21) It takes about 30 seconds for the gas pressure to equilibrate between the two cans to a level of 3.15 bar0.15 bar.

(22) After transfer of the gas, the depleted canister may simply be removed by rotating it in the opposite direction until it becomes detached. The pressurised/filled canister is then ready for use directly or through attachment of a suitable dispensing device.

(23) This is shown in FIG. 4: FIG. 4a shows detachment of the gas canister after transfer of the gas, by simply twisting the gas canister in the opposite (anticlockwise) direction. Increased force will be required by the user to force the cams over the click-stop ramp [12] and the detent protrusions in the reverse direction but is readily achievable within normal pressures ranges when applied by hand. FIG. 4b shows attachment of a microfoam dispensing device to the filled canister through the adaptor.

(24) The dispensing device [25] is similar to that described in WO 2005/023678 (the contents of which are hereby incorporated by reference). The dispensing device comprises a lower skirt portion [25] and an upper dispensing and waste chamber portion [26]. The skirt portion [25] is generally hollow and adapted to comprise cams on its inner wall, to enable cooperation with the sunken cam tracks on the adaptor [1] and is attached to the pressurised canister [19] through the adaptor in the same way as described above. The upper portion [26] comprises an inlet [27] which is arranged generally in the centre of the device to enable direct communication and provide a gas-tight seal with the valve of the pressurised container when the dispensing device is attached. The inlet is connected to a usable foam outlet [28] in the form of an aperture sized so as to accommodate a syringe nozzle to enable direct transfer of microfoam from the dispensing device to a syringe and also to a valved waste outlet [29] which provides fluid communication with a waste chamber [30] which is enclosed within and forms an integral part of the upper portion of the device. Situated adjacent the usable foam outlet [28] and in communication with the inlet [27] is a waste bleed outlet [31] which has a higher resistance to flow of foam than that of the usable foam outlet and acts as an overflow valve into the waste chamber [30]. With the dispensing device is fitted to the pressurised canister, and a suitable syringe attached via its nozzle to the useable foam outlet [28], microfoam may be generated and dispensed as follows: With the syringe maintained in a fully depressed position, the entire dispensing device [25] is pressed down to depress the nozzle of the canister and thereby open the canister valve and start the flow of foam. This causes foam to flow from the canister valve [20], into the dispensing device via the canister valve [20] and the inlet [27] (which forms a gas-tight seal). Foam coming out of the canister is pressurised and the pressure of the foam forces closed the valved waste outlet [29] such that foam is directed towards the useable foam outlet [28]. However, foam cannot flow out of the usable foam outlet [28] because the syringe is blocking the outlet and so the foam flows out of the waste bleed outlet [31] and enters the waste container [30]. The quality of the initial foam will be of lower quality and will include air that is pushed out from dead space within the valve and dispensing device. Once a suitable quantity of foam has been directed to waste, the user can then simply release the syringe plunger, while continuing to depress the dispensing device. Foam may now flow through the usable foam outlet [28] into the syringe. A certain amount of resistance to flow of foam will be offered by the bore of the syringe nozzle (in this case a standard luer nozzle) and the passage usable foam outlet (that term being understood to include the passage leading from the valve chamber to the syringe nozzle). Further resistance will be offered by the syringe plunger as it is pushed back by foam entering the syringe. The dimensions of the waste bleed outlet [31] are designed with this in mind so that the resistance to flow offered by the bleed outlet is higher than the resistance encountered by the foam entering the syringe. Therefore, although foam will continue to flow into the waste chamber during this stage of the procedure, that flow will be considerably smaller than the flow into the syringe. It is of course desirable to minimise waste. In practice the dimensions of the waste bleed outlet [31] will be a compromise between minimising waste of foam, minimising the duration of the start up period before foam of acceptable quality is produced, and providing sufficient flow through the bleed port to prevent the device from stuttering and producing out of spec. foam after the initial purge to waste.

(25) Once a quantity of good quality foam has been introduced into the syringe, the pressure on the dispensing device is released thereby shutting off flow from the canister. The syringe will then contain good quality foam, but also a bubble of air and/or poor foam caused by the dead air space in the usable foam outlet and syringe nozzle being pushed into the syringe by flow of foam. This air bubble or region of poor foam will normally be located adjacent the syringe plunger; therefore one option is for the user is to avoid fully emptying the syringe when using the foam, thus avoiding the injection of poor quality foam. The dead space can be minimised by using a design of syringe with virtually zero dead space, in which the plunger incorporates a projection which fills the nozzle. As an alternative, dead air space may be eliminated by flushing the dispensing device with good quality foam. This is achieved by simply depressing the syringe plunger to push foam back out of the syringe, through the usable foam outlet [28]. The pressure of the foam being pushed back into the dispensing device opens the valve on the valved waste outlet [29] and foam flows through it into the waste chamber. A small quantity of foam may also flow through the waste bleed outlet [31]. In this case, the initial quantity of foam allowed to enter the syringe can be minimised (to a few millilitres) as it will be used only to flush the system. After the initial purge and flush has taken place, the process is repeated without any flushing required and the syringe may be filled to the desired amount, the dispensing device released and the syringe containing the desired quantity of good quality foam is released and may be injected directly into the vein of a patient.