We quantitatively studied factors influencing the environment cleanness for intravenous hyperalimentation (IVH) admixing. The environment cleanness was evaluated by measuring the counts of particles (>0.5μm) and bacteria floating in 1 ft3 of the air inside the clean room (23.6m3) and in the clean bench built in the department of pharmacy, The University of Tokyo Hospital in 1998. The number of particles at the center of the clean room during IVH admixing by 4 pharmacists was higher than that at the medicine passing area (150±50/ft3 vs. 260±60/ft3; mean±S.D., n=12). The cleanness inside the clean room was improved as the measurement point became higher from the floor (600±180/ft3, 150±50/ft3, and 35±15/ft3 at 50, 100, and 150 cm height, respectively) and the number of persons working inside the room decreased. The changes in the counts of floating bacteria were similar to that of floating particles under the same conditions. In addition the effect of disinfection on the counts of bacteria was clearly observed. When the cleanness of the room became lower by turning off the air conditioning, the particle counts inside the clean bench became lower along with the distance from the front glass becoming deeper (i.e., 1400±550/ft3, 140±70/ft3, and 40±30/ft3 at 0, 5, and 15 cm, respectively). From these lines of evidence, the following items were suggested in order to maintain the environment cleanness for IVH admixing. First, the number of persons residing in the clean room should be kept to be minimum. Second, the clean bench should be set up in the center of the clean room. Finally IVH admixing operation should be performed at more than 15 cm depth inside the front glass surface of the clean bench. Moreover, the effect of mopping-up of the clean room with 0.1% benzethonium chloride clearly demonstrated the importance of disinfection on a routine basis.
