Swelling of hydrocolloid dressings

Wound healing is promoted by dressings that maintain a moist environment. Specifically, hydrocolloid dressings allow excess fluid to escape without permitting wound desiccation. However, the fluid handling capacity of hydrocolloid dressings depends on many factors such as the physicochemical properties of the gel formulation, and the design of the dressing. We measured the moisture uptake kinetics of different hydrocolloid dressings by placing the gel side of a sample in contact with water. The time evolution of the thickness was measured by means of a video camera linked to a computer. The theory of Tanaka and Fillmore (1979) was used to predict the kinetics of uniaxial swelling of a cylindrical gel sample. The model allows to associate to an experimental curve a total thickness increase hf-h0 (where hf and h0 are respectively the final and initial thickness) and a characteristic time tau. The model also relates hf-h0 and tau to the physiochemical composition of the dressing, and to the initial thickness h0. The influence of h0 is discussed by means of experiments performed on dressings with different initial thickness.