CONTROL OF MICROWAVE-HEATING OF PERITONEAL-DIALYSIS SOLUTIONS

Objective: To determine if microwave heating of dialysis solutions to 37-degrees-C produced focal overheating (hot spots) and caramelization of dextrose. Design: In vitro determination of conditions for control ling time, temperature, and procedures. Bags had been stored at ambien t room temperature. Main Outcome Measures: Solution and external bag s urface temperature determinations. Dextrose degradation products deter mined spectrophotometrically. Microscopy for potential caramel precipi tates. Results: A microwave oven with no rotation tray produced uneven heating of bags of two commercially available concentrations of dialy sis solutions. The greatest hot spots were evident in spike ports. Ext ernal bag surface temperatures were within 0.20-degrees-C of reservoir temperatures. Initial solution temperatures correlated with temperatu res of the solutions after microwave heating (r = 0.895). No statistic ally significant differences were found between dextrose degradation p roduct concentrations of unheated and heated solutions, including hot spots. No precipitates were observed microscopically. Conclusions: Des pite the presence of solution hot spots in bag infusion ports, 37-degr ees-C temperatures were achievable in the bag reservoirs with no evide nce of increased glucose degradation. This outcome is assured if the i nitial temperature and the microwave conditions (procedure, time, mixi ng of solution) are held constant, and the external bag temperatures a re measured after heating.