Comment to: Acute and chronic consequences of polidocanol foam injection in the lung in experimental animals by Grandi L, Grandi RA, Tomasi CD, da Rocha JL, Cardoso V, Dal-Pizzol F. Phlebology 2013;28:441-4.

To assess the occurrence of pulmonary embolism and long-term inflammatory activation after polidocanol foam injection, domestic rabbits, of both sexes, weighing around 2 kg were used: a control group (injection of saline solution, n = 4) and an experimental group (injection of polidocanol foam 1 and 3 mg/kg, n = 4 each dose), administered in the lateral superficial auricular vein as a slow bolus over 1 min. Foam (1 mL polidocanol 3%+ 4 mL air) 0.3 mL and 1.0 mL was injected respectively for the 1 mg/kg and the 3 mg/kg group. Technetium (Tc99m) lung scintigraphy was realized 15 min after injection, then the rabbits were killed and the lungs were removed for histopathological evaluation. A separated group of animals was reserved for histopathological evaluation 30 days after injection. The pulmonary perfusion showed an important reduction of pulmonary perfusion in all injected cases; while in the control group no alterations were found. The pathological exam at earlier times shows the presence of platelet-fibrin clots mainly in the small pulmonary veins, independent of the dose administered and occasional presence of droplets corresponding to fat embolism, and an acute inflammatory response. In later times it was observed chronic thrombus in small veins with mixed chronic inflammatory response, sparse or more limited. This work shows that the injection of polidocanol foam in experimental animals leads to acute and chronic alterations in pulmonary perfusion and lung inflammation. If few amounts of polidocanol foam can be deposited into the lung (in low quantity, not causing significant pulmonary embolism) it can induce inflammation in the pulmonary parenchyma. The use of rabbits does not allow using maneuvers that can reduce the incidence of embolism (leg elevation, immobility). In addition, the veins used to in the rabbits cannot reflect the veins used in humans, with a shorter time than the time needed to inactivate polidocanol.