Claims for Patent: 7,814,943

Summary for Patent: 7,814,943

Title:	Apparatus and method for dispensing foam
Abstract:	Apparatus for dispensing foam for the treatment of, inter alia, varicose veins. The apparatus includes a source of foam and a dispensing device which has an inlet in communication with the source of foam, a usable foam outlet, and a waste bleed outlet. The waste bleed outlet communicates with the inlet and with the useable foam outlet, and has a higher resistance to flow of foam than that of the usable foam outlet. The useable foam outlet may be blocked off such that foam may flow through the high resistance waste bleed outlet, and the usable foam outlet may be opened such that foam may flow through the usable foam outlet.
Inventor(s):	Harman; Anthony David (Henley-on-thames, GB), Wright; David Dakin Iowerth (High Wycombe, GB), Mijers; Jam Willem Marinus (EH Heemstede, NL), Kay; Stuart Brian William (Ickleton, GB), Hurlstone; Christopher John (Ickleton, GB), Dixon; Julian Richard (Ickleton, GB), Pocock; Andrew Gordon (Ickleton, GB), Hogan; Brendan (Co. Galway, IE)
Assignee:	BTG International Limited (London, GB)
Application Number:	10/571,608
Patent Claims:	1. Apparatus for dispensing foam comprising a source of foam and a dispensing device, the dispensing device comprising: (a) an inlet in communication with the source of foam; (b) a usable foam outlet; (c) a waste bleed outlet communicating with the inlet and with the useable foam outlet, the bleed outlet having a higher resistance to flow of foam than that of the usable foam outlet; wherein the usable foam outlet may be blocked off such that foam may flow through the high resistance waste bleed outlet and the usable foam outlet may be opened such that foam may flow through the usable foam outlet. 2. Apparatus as claimed in claim 1 wherein the waste bleed outlet is located adjacent the usable foam outlet. 3. Apparatus as claimed in claim 1 further comprising a second waste outlet communicating with the usable foam outlet. 4. Apparatus as claimed in claim 3 wherein the second waste outlet has a lower resistance to flow of foam than that of the waste bleed outlet. 5. Apparatus as claimed in claim 3 wherein the communication between the second waste outlet and the usable foam outlet is via a valve arrangement. 6. Apparatus as claimed in claim 5 wherein the valve arrangement comprises a diaphragm member. 7. Apparatus as claimed in claim 1 comprising a substantially enclosed waste chamber with which the waste bleed outlet communicates. 8. Apparatus as claimed in claim 7 wherein at least a portion of a wall of the waste chamber is transparent to allow inspection of foam in the chamber. 9. Apparatus as claimed in claim 7 wherein the waste chamber forms an integral part of the dispensing device. 10. A device for dispensing foam comprising: (a) an inlet for communication with a source of foam; (b) a usable foam outlet; (c) a waste bleed outlet communicating with the inlet and with the useable foam outlet, the bleed outlet having a higher resistance to flow of foam than that of the usable foam outlet; and (d) a connector for mechanically securing the device to a source of foam; wherein the usable foam outlet may be blocked off such that foam may flow through the high resistance waste bleed outlet and the usable foam outlet may be opened such that foam may flow through the usable foam outlet. 11. A device as claimed in claim 10 wherein the waste bleed outlet is located adjacent the usable foam outlet. 12. A device as claimed in claim 10 further comprising a second waste outlet communicating with the usable foam outlet. 13. A device as claimed in claim 12 wherein the second waste outlet has a lower resistance to flow of foam than that of the waste bleed outlet. 14. A device as claimed in claim 12 wherein the communication between the second waste outlet and the usable foam outlet is via a one way valve arrangement. 15. A device as claimed in claim 14 wherein the one way valve arrangement comprises a diaphragm member. 16. A device as claimed in claim 10 comprising a substantially enclosed waste chamber with which the waste bleed outlet communicates. 17. A device as claimed in claim 16 wherein at least a portion of a wall of the waste chamber is transparent to allow inspection of foam in the chamber. 18. A device as claimed in claim 16 wherein the waste chamber forms an integral part of the device. 19. A kit comprising a device as claimed in claim 10 in combination with a foam source, the said source being provided with a connector complementary to that of the dispensing device and with a foam outlet complementary to the foam inlet of the dispensing device. 20. A kit as claimed in claim 19 further comprising a syringe. 21. A kit as claimed in claim 19 or wherein the foam source comprises a first canister containing liquid to be foamed and a second canister containing pressurized gas for charging the said first canister prior to generation of foam. 22. An assembly comprising a device as claimed in claim 10 in combination with a syringe, wherein the nozzle of the syringe is fitted into the usable foam outlet, and wherein the usable foam outlet with the syringe nozzle fitted therein has a lower resistance to flow of foam than that of the waste bleed outlet. 23. An assembly as claimed in claim 22 wherein the syringe nozzle is a standard luer nozzle and the usable foam outlet of the dispensing device is configured as a female luer connector. 24. An assembly as claimed in claim 22 wherein the syringe comprises a plunger having a projection extending into a nozzle of the syringe, whereby dead space in the syringe is minimised. 25. Apparatus as claimed in claim 1 wherein the source of foam comprises a canister charged with liquid and gas under pressure. 26. A method of dispensing foam using an apparatus or device as claimed in claim 1 comprising the steps of: (a) dispensing foam to waste with the useable foam outlet blocked; (b) observing the said foam being dispensed to waste and making a determination as to when the foam is of a predetermined quality; (c) once the foam is of the said predetermined quality, dispensing foam to a separate location for subsequent use, whilst continuing to dispense foam to waste; (d) wherein the rate at which foam is dispensed to waste is lower than the rate at which foam is dispensed to the said separate location for subsequent use. 27. A method of dispensing foam using the apparatus claimed in claim 1 comprising the steps of: (a) providing a syringe fitted to the usable foam outlet of the dispensing device; (b) whilst holding a plunger of the syringe in a fully depressed position, causing foam from the source to flow into the foam inlet of the dispensing device and thence out of the waste bleed outlet; (c) observing the said foam exiting the waste bleed outlet; (d) when the said foam exiting the bleed outlet is observed to have a predetermined quality, releasing the plunger of the syringe, whereby the syringe fills with foam. 28. A method of dispensing foam from a pressurized container using an apparatus or device as claimed in any one of claim 1 comprising the steps of:-- (a) initially dispensing a continuous flow of foam to waste with the useable foam outlet blocked; and then (b) subsequently diverting at least a proportion of the said flow of foam to a vessel for further use, without substantial interruption of the flow of foam from the pressurized container.