Canister Device for Producing Sclerosing Foam

Abstract

The present invention relates to a canister device that is suitable for producing sclerosing foam for intravenous injection, in the treatment of varicose veins and other venous disorders. The canister device for producing therapeutic foam, the device comprises a pressurisable chamber containing sclerosant liquid and physiologically acceptable gas; a foam pathway through which the liquid and the gas may pass from the chamber to the exterior of the device, the pathway including a gas-liquid interface at which the liquid and the gas are mixed and foam is formed; and a mechanism by which the pathway can be opened or closed, such that, when the chamber is pressurised and the pathway is open, the liquid and the gas are forced to pass along the pathway to the exterior of the device; characterised in that an expandable compartment is located within the chamber, the compartment comprising an internal space that is in fluid communication with the exterior of the device through a fluid inlet located on the exterior of the device and that is not in fluid communication with the liquid or the gas, wherein in use fluid is introduced through the fluid inlet to expand the compartment and pressurize the chamber. The device is only pressurized at the point of use and therefore avoid problems associated with shipment and storage of pressurized medical grade gases.

Claims

1. A canister device for producing therapeutic foam, the device comprising: a pressurizable chamber containing sclerosant liquid and physiologically acceptable gas; a form pathway through which the liquid and the gas may pass from the chamber to the exterior of the device, the pathway including a gas-liquid interface at which the liquid and the gas are mixed and the foam is formed; and a mechanism by which the pathway can be opened or closed, such that, when the chamber is pressurized and the pathway is open, the liquid and the gas are forced to pass along the pathway to the exterior of the device; characterized in that the expandable compartment is located within the chamber, the compartment comprising an internal space that is in fluid communication with the exterior of the device through a fluid inlet located on the exterior of the device and that is not in fluid communication with the liquid or the gas, wherein in use fluid is introduced through the fluid inlet to expand the compartment and pressurize the chamber.

2. A canister device according to claim 1, wherein the expandable compartment is made at least partly of an elastic membrane selected from silicone, poly vinyl chloride (PVC), polyethylene terephthalate (PET), polyesters and polyurethanes.

3. A canister device according to claim 1, wherein the fluid inlet is adapted to connect with a source of gas.

4. A canister device according to claim 1, wherein the fluid inlet comprises a one way valve.

5. A canister device according to claim 1, wherein the fluid inlet comprises a vent to allow emptying of the expandable compartment.

6. A canister device according to claim 1, further comprising a pressure indicator to inform a user when the chamber is pressurized to a desired level.

7. A canister device according to claim 2, wherein the fluid inlet is adapted to connect with a source of gas.

8. A canister device according to claim 2, wherein the fluid inlet comprises a one way valve.

9. A canister device according to claim 3, wherein the fluid inlet comprises a one way valve.

10. A canister device according to claim 2, wherein the fluid inlet comprises a vent to allow emptying of the expandable compartment.

11. A canister device according to claim 3, wherein the fluid inlet comprises a vent to allow emptying of the expandable compartment.

12. A canister device according to claim 4, wherein the fluid inlet comprises a vent to allow emptying of the expandable compartment.

13. A canister device according to claim 2, further comprising a pressure indicator to inform a user when the chamber is pressurized to a desired level.

14. A canister device according to claim 3, further comprising a pressure indicator to inform a user when the chamber is pressurized to a desired level.

15. A canister device according to claim 4, further comprising a pressure indicator to inform a user when the chamber is pressurized to a desired level.

16. A canister device according to claim 5, further comprising a pressure indicator to inform a user when the chamber is pressurized to a desired level.

Description

[0031] Further features and advantages of the invention will be apparent from the following description of specific embodiments, which is made with reference to the accompanying drawings.

[0032] FIG. 1 shows a schematic view of an embodiment of the invention with the inner container in an empty conformation.

[0033] FIG. 2 shows a schematic view of an embodiment of the invention with the inner container in a filled conformation.

[0034] A device of the invention is shown in FIG. 1 having a canister body [1] with an inwardly domed bottom surface [2] and having an aerosol valve cup [3] clinched at its top. The canister contains a solution of 1% (v/v) polidocanol [7] and a volume of physiological gas [8] equal to seven times the volume of sclerosant liquid. Within the canister is provided an inner container [10] that is separated from the sclerosant fluid [7] and the physiological gas [8] by an elastic membrane [11]. The elastic membrane [11] is attached via a one way valve [21] to a fitting [20] that is suitable for gas tight connection to a source of gas (not shown) mounted on the domed bottom surface [2].

[0035] The valve [3] comprises a gas-liquid interface [4] which includes holes [4a] that permit entry of gas to the interface [4] and mounts a dip-tube [5] that extends below the surface of the sclerosant fluid [7] to allow it to enter the gas-liquid interface. The valve [3] also includes a stem valve [6] that is depressed to activate the aerosol valve [3] and open the foam pathway to the external atmosphere.

[0036] In use, the inner chamber [10] is filled by attaching a source of gas (not shown) to the fitting [20] and introducing a volume of air through the one way valve [21]. As shown in FIG. 2, the elastic membrane [11] stretches as the inner chamber [10] is inflated with air. The inflated inner chamber [10a] reduces the available volume in the canister and thereby increases the pressure of the physiological gas [8]. The one way valve [20] prevents air from exiting the inflated inner chamber [10a].

[0037] On depression of the valve stem [6], the pressure provided by the inflated inner chamber [10a] forces sclerosant fluid [7] and physiological gas [8] through the foam pathway toward the stem valve [6]. Physiological gas [8] enters the gas-liquid interface [4] through holes [4a] where it mixes with sclerosant fluid [7] that enters via the dip tube [5]. The gas [8] and fluid [7] are forced through the gas-liquid interface under pressure and foam is formed and delivered to a syringe that can be attached directly to the valve stem [6]. Alternatively, a transfer device such as that described in WO 2005/048977 is attached to the valve stem [6] to enable secure, sterile connection of a syringe for dispensing of foam.