Apparatus for delivering foam

Abstract

Apparatus, e.g. a syringe, for dispensing foam includes means for ensuring that only foam of adequate quality is dispensed. In use, the syringe may be filled from a pressurised canister which generates foam e.g. for therapeutic use in treating varicose veins. An initial quantity of foam dispensed from the canister may be of inadequate quality in which case it should not be used: the syringe includes means to ensure that this initial quantity of foam is diverted to a waste port or to an internal waste chamber e.g. located in the syringe plunger. Foam dispensed after the initial quantity of poor quality foam is stored in the main barrel of the syringe ready for administration to a patient in need of treatment.

1 - 11 . (canceled) 
     
     
         12 . A syringe for dispensing foam comprising:
 (a) a syringe plunger having a front end and a back end;   (b) a syringe barrel having a nozzle and a bore to receive the plunger; and   (c) wherein the plunger includes a foam inlet at the back end and a foam outlet at the front end, which inlet and outlet are in communication with each other.   
     
     
         13 . A syringe as claimed in  claim 12  further comprising a one way valve permitting flow of foam into the inlet. 
     
     
         14 . A syringe as claimed in  claim 12  wherein the foam outlet is located adjacent the nozzle. 
     
     
         15 . A syringe as claimed in  claim 12  wherein the foam outlet is provided in a projection that extends into a bore of the nozzle when the plunger is in a fully depressed state. 
     
     
         16 . An apparatus for dispensing foam comprising a syringe as claimed in  claim 12  and a waste foam container having an inlet with a connector of complementary form to the nozzle of the syringe. 
     
     
         17 . An apparatus as claimed in  claim 16  wherein the waste foam container has flexible walls and is substantially empty before foam is dispensed into it. 
     
     
         18 . An apparatus as claimed in  claim 17  wherein the flexible walls are inextensible. 
     
     
         19 . An apparatus as claimed in  claim 16  wherein the waste foam container is rigid. 
     
     
         20 . An apparatus as claimed in  claim 19  wherein the waste foam container comprises a vent. 
     
     
         21 . An apparatus as claimed in  claim 20  wherein the vent is a simple hole. 
     
     
         22 . An apparatus as claimed in  claim 20  wherein the vent is a hydrophobic vent. 
     
     
         23 . A kit for providing a syringe full of foam, the kit comprising an apparatus as claimed in  claim 16  together with a source of foam. 
     
     
         24 . A kit as claimed in  claim 23  wherein the source of foam is a pressurised canister containing liquid to be foamed and gas under pressure. 
     
     
         25 . A method of dispensing foam using an apparatus as claimed in  claim 16  comprising the steps of:
 (a) connecting a source of foam to the plunger foam inlet, unless a source is supplied already so connected; 
 (b) with the plunger fully depressed, generating a substantially continuous flow of foam from the said source and allowing an initial quantity of foam to flow from the plunger inlet through the plunger foam outlet and thence to exit from the syringe nozzle; and 
 (c) without interrupting the flow of foam from the source, blocking the syringe nozzle and causing the plunger to move back such that foam starts to fill the syringe barrel. 
 
     
     
         26 . A method as claimed in  claim 25  wherein a waste foam container is attached to the syringe nozzle. 
     
     
         27 . A method as claimed in  claim 26  wherein a waste foam container may be filled or substantially filled with the initial quantity of foam, and may provide automatically the syringe nozzle blocking step when so filled or substantially filled.