Foam production methods

In this study, the commercially available Varithena 1% varicose vein treatment (referred to as polidocanol injectable foam or PEM) was employed, and its performance compared with physician compounded foams (PCFs) made using different foam generation methods.

With respect to PCFs, POL (Croda, Goole, UK) at a concentration of 1% (v/v in buffered saline) was employed as a surfactant agent. Foams were produced by mixing liquid and room air (at a volume ratio of 1:4, respectively) as this is the most widely used formulation adopted in clinical practice⁴⁸. Two methods of PCF production were investigated: (i) DSS and (ii) Tessari. In the DSS method, foam was produced by passing the POL solution from a 5 mL syringe, ten times into and out of a 10 mL syringe. Silicon-free syringes (BD Biosciences, USA) were connected via a Combidyn adapter (B. Braun Melsungen, Germany). In the Tessari method, the straight connector was replaced with a three-way valve that was set at a 30° off-set. Polidocanol endovenous microfoam (PEM) Varithena is a commercially available microfoam combination produced by Provensis Ltd (a BTG International group company, London, UK) consisting of a proprietary 35:65 CO₂:O₂ gas mixture with ultralow nitrogen content (<0.8%) and 1% POL solution. The foam is contained within a pressurized canister combined with a transfer unit, which can be connected to a 10 mL silicone-free syringe. Once connected, the syringe is filled with 5 mL of foam. Experiments were conducted at room temperature (23 °C), after foam production, and foams were produced by the same operator.