The implication of altitude in foam stability of polidocanol and lapyrium chloride

BACKGROUND: Foam sclerotherapy is a minimally invasive technique to treat chronic venous insufficiency. Foam stability influences the effectiveness of the treatment, determining the degree of endothelial injury induced by the sclerosant. Unstable foam will require higher concen-trations of sclerosant to achieve the same effect compared to a more stable foam, increasing the probability of adverse events. Several variables have been studied to determine foam stability; however, little is known about the impact of altitude. This study aims to evaluate the effect of altitude on the foam stability of polidocanol (PD) and lapyrium chloride (LC). METHODS: We compared the foam stability PD and LC at different altitudes. We used the Tessari method to prepare foam with a liquid drug and room-air ratio of 1:4 for both sclerosants. We performed five trials for each sclerosant agent at three different altitudes. After foam preparation, the syringes were put vertically to compare the half-life of each one.RESULTS: We conducted 15 trials for each foam. LC showed more stability compared to PD at every altitude. An inversely proportional rela-tionship between altitude and foam stability was observed. Regression analysis ran a slope of-0.0064 for PD and-0.0052 for LC. According to our results, LC half-life is almost three-fold the half-life of PD.CONCLUSIONS: The influence of several factors on foam stability has been previously studied. However, little is known about the impact of altitude. LC was three times more stable than PD at any altitude; Boyle's law appears to impact foam half-life. Finally, our results match the current literature reports regarding improving foam stability at lower altitudes.