Objective: Fluids for peritoneal dialysis (PD) cause cytotoxic reactions in many different in vitro systems. The low pH, the high osmolality of the fluids, and the glucose degradation products formed during heat sterilization have been considered responsible. In the present study, we investigate the influence of temperature and time during heat sterilization of PD fluids and glucose solutions on glucose degradation and cytotoxicity of the solutions.
Design: Ampoules containing PD-fluid or glucose solution were heated in an oil bath to predetermined F0 values (combinations of time and temperature giving equal energy/bacterial lethality). Cytotoxicity of the solutions was measured as growth inhibition of cultured L-929 fibroblasts. Glucose degradation was measured as UV absorbance at 228 and 284 nm.
Results: The same general pattern was seen in both PD fluid and glucose solution. Cytotoxicity decreased from 90% to 15% when the sterilization temperature was increased from 115 degrees to 140 degrees C and concomitantly the length of time shortened in order to maintain equal bacterial lethality. Under the same conditions, degradation products, measured as UV absorbance at 284 nm, decreased from 0.2 to 0.02.
Conclusion: To minimize the development of cytotoxic breakdown products, high temperatures over short periods of time should be used to heat-sterilize PD fluids. Even as small an increase as 5 degrees C at around 120 degrees C will improve the quality of the solutions.