Degradation in peritoneal dialysis fluids may be avoided by using low pH and high glucose concentration

Objective: When glucose is present in a medical fluid, the heat applied dur ing sterilization leads to degradation. The glucose degradation products (G DPs) give rise to bioincompatible reactions in peritoneal dialysis patients . The extent of the degradation depends on a number of factors, such as hea ting time, temperature, pH, glucose concentration, and catalyzing substance s. In the present work, we investigated the influence of pH and concentrati on in order to determine how to decrease the amounts of GDPs produced. Design: Glucose solutions (1%-60% glucose; pH 1 - 8) were heat sterilized a t 121 degreesC. Ultraviolet (UV) absorption, aldehydes, pH, and inhibition of cell growth (ICG) were used as measures of degradation. Results: Glucose degradation was minimum at an initial pH (prior to sterili zation) of around 3.5 and at a high concentration of glucose. There was con siderable development of acid degradation products during the sterilization process when the initial pH was high. Two different patterns of developmen t of UV-absorbing degradation products were seen: one below pH 3.5, dominat ed by the formation of 5-hydroxy-methyl-2-furaldehyde (5-HMF); and one abov e, dominated by degradation products absorbing at 228 nm. 3-Deoxyglucosone (3-DG) concentration and the portion of 228 nm UV absorbance not caused by 5-HMF were found to relate to the in vitro bioincompatibility measured as I CG; there was no relation between 5-HMF or absorbance at 284 nm and bioinco mpatibility. Conclusion: In order to minimize the development of bioincompatible GDPs in peritoneal dialysis fluids during heat sterilization, pH should be kept ar ound 3.2 and the concentration of glucose should be high. 5-HMF and 284 nm UV absorbance are not reliable as quality measures. 3-DG and the portion of UV absorbance at 228 nm caused by degradation products other than 5-HMF se em to be reliable indicators of bioincompatibility.