KINETICS OF FLUID DELIVERY FROM METHYLCELLULOSE SPONGES

Purpose: The authors quantitatively evaluate the kinetics of fluid tra nsfer from microsurgical sponges in a laboratory model to understand t he kinetics of mitomycin C (MMC) delivery. Methods: The amount of flui d transferred from soaked methylcellulose (Weck-cel, Week Inc., Durham , NC, U.S.A.) sponges to small pieces of hydrated or dry filter paper used to simulate episcleral tissue and Tenon fascia was measured as a function of time, sponge size, hydration status of the filter paper, a nd technique of sponge application. Results: The time course of fluid delivery from methylcellulose sponges to filter paper was nonlinear an d characterized by a rapid delivery phase over the first 15 to 30 seco nds, followed by a slow phase extending to at least 5 minutes. Sponge size and baseline hydration of the paper significantly influenced the rate and amount of fluid delivered, as did replacing the sponge every minute with a new sponge. Conclusion: The transfer of fluid from a mic rosurgical sponge displays nonlinear kinetics, with the majority of de livery occurring in the first 15 to 30 seconds. Sponge sizer hydration of the recipient tissue, and technique of sponge application are sign ificant variables influencing the amount of fluid, and therefore mitom ycin C, delivered.