|Title:||Generation of therapeutic microfoam|
|Abstract:||Improved therapeutic sclerosing microfoams and methods and devices for making them are provided that have advantage in producing a consistent profile injectable foam with minimal input by the physician yet using high volume percentages of blood dispersible gases, thus avoiding use of potentially hazardous amounts of nitrogen.|
|Inventor(s):||Osman; Tariq (London, GB), Shilton-Brown; Sheila Bronwen (Brentwood, GB), Wright; David Dakin Iorwerth (Wycombe, GB), Harman; Anthony David (Henley-on-Thames, GB), Boorman; Timothy David (Frinton on Sea, GB)|
|Assignee:||BTG International Limited (London, GB)|
1. A device for producing a microfoam suitable for use in sclerotherapy of blood vessels comprising a housing in which is situated a pressurisable chamber containing an
aqueous sclerosant liquid; a pathway with one or more outlet orifices by which the liquid may pass from the pressurisable chamber to exterior of the device through one or more outlet orifices and a mechanism by which the pathway from the chamber to the
exterior can be opened or closed such that, when the container is pressurised and the pathway is open, fluid in the chamber will be forced along the pathway and through the one or more outlet orifices said housing including one or more of (a) a
pressurised source of physiologically acceptable gas that is dispersible in blood and (b) an inlet for admission of said gas; the gas being contacted with the liquid on activation of the mechanism such as to produce a gas liquid mixture said pathway to
the exterior of the housing includes one or more elements defining one or more passages of cross-sectional dimension 0.1 .mu.m to 30 .mu.m, through which the gas liquid mixture is passed to reach the exterior of the device, said passing of the mixture
through the passages forming a microfoam of from 0.07 to 0.19 g/ml density and having a half-life of at least 2 minutes.
2. A device as claimed in claim 1 further comprising a gas liquid interface junction, prior to the passages, the junction controlling the ratio of gas to liquid passing through it such as to produce the required density microfoam.
3. A device as claimed in claim 1 characterised in that the ratio of gas and liquid in the mixture is controlled such that the microfoam is from 0.09 to 0.16 g/ml density.
4. A device as claimed in claim 2 wherein the housing includes a chamber charged with the blood dispersible gas and the sclerosant liquid, the pathway including a dip-tube with an inlet opening in liquid in the chamber.
5. A device as claimed in claim 4 wherein the dip-tube has an outlet opening at the gas liquid interface junction where the gas has access to the pathway to the pathway to the one or more outlet orifices.
6. A device as claimed in claim 1 wherein the pathway is opened or closed by a valve having an actuator element that is depressed or tilted to open up a pathway to the exterior, whereby said liquid rises up the dip-tube under gas pressure and is mixed in the interface junction with said gas to produce an aerosol, dispersion of bubbles in liquid or macrofoam.
7. A device as claimed in claim 1 wherein the one or more elements having one or more passages of 0.1 .mu.m to 30 .mu.m cross-sectional dimension are mounted inside the chamber in the pathway to the valve, such that the gas liquid mixture passes through the passage or passages and is caused to produce said microfoam.
8. A device as claimed in claim 1 wherein the one or more elements having one or more passages of 0.1 .mu.m to 30 .mu.m cross-sectional dimension are mounted on the downstream side of the valve, such that the gas liquid mixture passes through the passage or passages and is caused to produce said microfoam.
9. A device as claimed in claim 8 wherein the one or more elements are located in a cap mounted on the valve, upstream of the gas liquid interface, the cap including an outlet nozzle.
10. A device as claimed in claim 7 wherein the one or more elements are located within the housing mounted between the gas liquid interface and the valve.
11. A device as claimed in claim 1 characterised in that the gas liquid interface junction comprises holes in the dip tube above the surface of the liquid in use.
12. A device as claimed in claim 4 characterised in that the chamber is pressurised at 0.01 to 9 bar over atmospheric.
13. A device as claimed in claim 1 characterised in that the aqueous sclerosant liquid is contained within a second flexible gas and liquid tight disposed within the pressurisable chamber, the second chamber being sealed around the dip-tube.
14. A device as claimed in claim 13 characterised in that the dip-tube has a one-way valve positioned between the gas liquid interface junction and the dip-tube opening within the second flexible chamber, which when the pathway to the exterior of the device is closed, also remains closed such as to separate the liquid from the physiologically acceptable blood dispersible gas around it in the chamber and on opening the pathway to the exterior, the one way valve also opens and releases liquid up the dip-tube to the gas liquid interface junction where an aerosol, dispersion of bubbles in liquid or macrofoam is produced which is passed through the passages and converted to microfoam.
15. A device as claimed in claim 1 wherein the one or more elements defining one or more passages are provided in the form of porous membranes, meshes, screens or sinters.
16. A device as claimed in claim 1 characterised in that it comprises a series of the elements defining said passages arranged in parallel with their major surfaces perpendicular to the pathway.
17. A device for delivering microfoam to a syringe from a microfoam generating device as claimed in claim 1 characterised in that it comprises an inlet conduit for engaging the outlet of the microfoam producing device in a microfoam tight fashion, the conduit being connected to and leading through a multipath valve for directing microfoam passing down the conduit, the valve being capable of being set to direct microfoam down either of first and second outlet conduits or for closing the inlet conduit, the syringe luer outlet being received by one of the first and second outlet conduits.
18. A device as claimed in claim 17 further comprising one or more elements for engaging the microfoam producing device other than by its outlet nozzle to hold it securely.
19. A device as claimed in claim 1 further comprising a base element, sufficiently stable to mount a microfoam producing device adjacent a multipath-valve said inlet being attachable to the microfoam producing device outlet conduit.
20. A device as claimed in claim 19 further comprising an activating element which operates to cause the pathway within the microfoam producing device to be opened to the inlet conduit.