Abstract: Objective To explore the application of the innovative water sampling method for endotoxin and bacterial colony count assays in the quality monitoring of dialysis water. Method The investigation was carried out on 36 units of blood dialysis machine during Nov. 1, 2015 to Feb. 1, 2016. Three water sampling methods for water quality monitoring were used: ①Conventional method taking water sample from the bypass port. After sterilization of the bypass port with iodine volts, water sample was taken by a sterilized syringe from the sterilized bypass port. ②The innovative method taking water sample from water quality monitoring sampler. The bypass port end was filled with dialysate, sterilized with iodine volts and then with ethanol after 2 minutes to take off iodine. A 5ml sterilized syringe was inserted into the sampler end to get water sample. ③ Standard method for water sampling. After the bypass port end filled with dialysate, water sample was taken from the dialyser bypass water outlet end, taking care of the needle not touching the outlet wall. No more than 3 water samples in a week were taken from a dialysis machine. Endotoxin and bacterial colonies in water samples were examined continuously for 3 months. The time used for water sampling was statistically analyzed. The examination accuracy of the samples taken by standard method was recognized as the golden standard to compare with that taken by conventional method and that taken by the innovative method. Results Analysis of variance for single factor and Dunnett t test for further comparison of two variables found that endotoxin increased by 29.7% (n=36, P=0.006) and bacterial colonies increase by 32.2% in water samples by conventional method as compared with those by standard method; endotoxin increased by 4.5% (n=36, P= 0.976) and bacterial colonies increased by 7.6% in water samples by the innovative method as compared with those by standard method. The time used for water sampling reduced by 1.88% by using the innovative method as compared with that by using conventional method. Conclusion Water samples taken by the innovative method and those taken by standard method had no differences in water quality monitoring results. However, the time for water sampling using the innovative method was the shortest among the three water sampling methods. Therefore, the innovative method increased the working efficiency and preserved the same examination accuracy. This method also reduced the working strength and working procedures for the technicians and other professionals in the infection- control department, reduced the false negative and false positive results due to cumbersome procedures, improved the treatment safety for the patients, and also increased the satisfaction of the medical professionals.

Key words: Endotoxin sampler, Dialysate sampling method, Water quality monitoring