Preparation of bacteriologically safe bicarbonate concentrate for hemodialysis

To determine whether bacteriologic hazards associated with bicarbonate concentrate may be reduced or prevented, evaluation of a system consisting of a mixing tank supplied with R.O. water and two separate storage tanks was undertaken. Bicarbonate was mixed on a schedule specific to usage and dispensed to the storage tanks from which it was drawn off into 2.5 gallon jugs for each treatment. The mixing tank was disinfected with hypochlorite solution (200 ppm) before each use. Storage tanks and 2.5 gallon jugs were disinfected weekly and sampled immediately before scheduled disinfection and after the longest storage time. The mixing tank was sampled for corresponding batches. A 1 ml inoculum of concentrate was plated onto tryptic soy sheep blood agar, incubated for 48 hours at 35 degrees C and colony counts/ml recorded. A total of 225 batches on a 10% sampling schedule were monitored. All cultures have grown less than 50 cfu/ml, which is less than AAMI standards for maximum allowable level for water and dialysate. Bacteriologically safe bicarbonate concentrate can be reliably produced using R.O. water, controlled storage times, and rigid disinfection schedules.