Low frequency ultrasound as a potentially viable foaming option for pathological veins

An investigation was carried out on bubble size distributions of sclerosing foams exploiting different methods of production. A lot of effort has been dedicated by researchers over the past two decades in producing foams with better safety profiles to reduce the risk of ischemic events. There are manual and automated techniques, and the state-of-art suggests that an optimal foam has not yet been produced. Herein, a comparison is performed on sclerosing foams produced using the marketed Easyfoam® kit or low frequency ultrasound. Each technique provides a final foam with specific physical characteristics, such as bubble size distribution and stability. This is the first characterization about the bubble size distributions on foams using the manual method clinically available. In this paper, foam bubble sizes were investigated using 4% polidocanol solutions, and different power levels in the case of the ultrasound technique. Specific comparisons were made of the size distributions, the changing bubble diameter over time (up to 2 min) and the liquid fraction. In the formal theoretical analysis, a simple model was proposed with the aim of estimating the number of bubbles that would be required to provoke occlusion events after foam injections. As for the experimental novelty, the foam characterization evidenced that ultrasound generated considerably smaller bubble diameters, producing very wet foams with narrower distributions. Moreover, sonicated foams were less prone to ageing, generating more stable bubbles over time. Such a foam may be applicable to the treatment of small pathological veins (e.g., cosmetic veins or reticular veins), which are currently most often treated with liquid injections.