When people with diabetes reach end-stage renal disease they must undergo either dialysis or transplantation. About 200,000 Americans need artificial kidney machines to stay alive. These machines rely on sterile dialysis membranes to remove toxic materials from the bloodstream. More than 30 different polymers or polymer blends are used in dialysis membranes, and most of these degrade under conditions of steam or gamma radiation sterilization. Ethylene oxide (EO) remains the sterilant of choice for these membranes. However, the traditional blend used 88 percent CFC-12 as a fire suppressant and propellant, and CFCs have been phased out of production because of their high ozone-depletion potentials (ODPs). Alternatives include explosive 100 percent EO and blends of EO with high global warming potential (GWP) hydrofluorocarbons (HFCs), less effective carbon dioxide, or hydro chlorofluorocarbon (HCFC) compounds facing future phase out. This proposed Phase I effort wilt determine the feasibility of using blends containing EO, trifluoromethyl iodide (CF3I), and HFCs for sterilizing dialysis membranes. Trifluoromethyl iodide is an excellent combustion suppressant and has physical properties similar to CFC-12 with zero ODP and extremely low GWP. Flammability and fractionation tests will be conducted to determine optimal blend compositions. Compatibility and residual CF3I measurements with common membrane materials will be conducted.
The research, if successful, will develop a new nonflammable sterilant gas for dialysis membranes that does not contain ozone-depleting substances, is more effective that current alternatives, and has reduced GWP. The new sterilant gas should also be useful for sterilizing many other types of medical equipment. The new sterilant gas should be marketable worldwide and should allow use of existing EO sterilizing equipment, thus reducing costs of medical care.
