Abstract: 【Abstract】Objective To compare the effectiveness and safety of the two different disinfection methods, high concentrations of sodium hypochlorite and peracetic acid with no solution immersion every night, and low concentrations of sodium hypochlorite and peracetic acid with solution immersion every night, and to analyze the advantages of low concentration disinfectant immersion method at night in the disinfection of central dialysis fluid delivery system (CDDS). Methods During the period from November 2017 to November 2019 in the First Medical Center of the General Hospital of the Chinese People's Liberation Army, the CDDS
used two disinfection methods, each for 12 months. The levels of bacteria and endotoxin at different sampling points in CDDS and the changes of disinfectant concentration during night immersion were compared between the two disinfection methods to evaluate the effectiveness. The washing time required to the safe residual concentration of the two low disinfectants was measured to evaluate the safety of the disinfection method. Results Compared with the high concentration washing disinfection, the low concentration immersion disinfection at night resulted in the decreases of bacterial colonies (Z=-2.041, P=0.041) and endotoxin (t=4.761, P=0.032) at the outlet of dialysate supply device, and the decreases of bacterial colonies (Z=-2.178, P= 0.029) and endotoxin (t=5.405, P=0.027) at the end of system pipeline. There were no significant differences in the levels of bacteria colonies (Z=-1.069, P=0.285) and endotoxin (t=2.621, P=0.086) at the outlet of dialysis machine between the two disinfection methods. After the disinfectant dwelled in pipeline ever night, the effective concentration of sodium hypochlorite decreased by 15.78% to the concentration of 43mg/L, and peracetic acid decreased by 5.88% to the concentration of 160mg/L. The residual concentrations of the two disinfectants reached safe levels after washing for 14 min and 16 min respectively. Conclusion Night low concentration disinfectant immersion method is safe and effective for CDDS disinfection and can be used clinically.

Key words: Immersion disinfection, Central dialysate supply system, Bacterial culture, Endotoxin detection