A mechanism for improved talc pleurodesis via foam delivery.

Talcum powder is recognized as the leading drug for pleurodesis, a treatment of choice for malignant pleural effusions. Recently, it was shown that hydrogel foam delivery systems significantly enhanced the number of adhesions between the chest wall and the lung in a New Zealand rabbit model due to the sol-gel transition. However, many questions still remain regarding the cause of improved efficacy, such as: (1) Would only hydrogel foams improve the efficacy of talc pleurodesis? (2) Is it possible to achieve the same efficacy of hydrogels using non-hydrogel foams? 3) What are the physicochemical properties that can be correlated to the efficacy of talc pleurodesis? In this study, we use non-hydrogel foam formulations to determine the efficacy of pleurodesis. Foam stability and rheology of the formulations were correlated to adhesion formation. The results clearly suggest a correlation of pleurodesis efficacy to the viscosity and modulus of the foam delivery system.

An experimental study of the stability of liquid bridges subject to shear-induced closed-flow.

This paper shows via experiments, the effect of closed-flows on the stability of a liquid bridge. Experiments were conducted with a 3M HFE-7500 liquid as the liquid bridge and a mixture of sodium polytungstate solution and glycerine as the outer liquid, which is encapsulated in a cylindrical cavity. Depending on the glycerine content, the Bond number ranged from 0.04 to 0.25. It was shown that a closed-flow in both the encapsulating liquid and the bridge would increase the stability of a non-cylindrical bridge depending on the direction of shear, the Bond number and the bridge volume. It was also shown that, for a given bridge volume and Bond number, there is a capillary number that gives the maximum percentage stabilization. Any further increase in the capillary number flips the direction of the bulge from top to bottom or vice versa thereby decreasing the stabilization and at some capillary number even destabilizing the bridge. The scaling of the problem was analyzed through experimental data.