Microfoam

Commonly the liquid sclerosants, sodium tetra-decyl sulphate (STS) or polidocanol, are agitated with a gas to produce foam ready for administration into veins. The optimal ratio of sclerosant to gas is controversial as is the type of gas used. Ambient air is popular and readily available but contains nitrogen which seeps into the general circulation. Carbon dioxide is rapidly absorbed and potentially safer but the stability of the resulting foam is poor resulting in a rapid coalescence of bubbles. Thus injection has to be immediate and rapid following its preparation. The advantages of a stable, ready-made microfoam is that the sclerosant-gas ratios and bubble size are pre-determined. Consistent small bubble size has the potential to optimise foam preparation which would otherwise be left to the individual operator.