Dilution is effective in reducing infusion phlebitis in peripheral parenteral nutrition: an experimental study in rabbits.

To clarify conflicting clinical results that had been reported as to whether dilution is effective or not in reducing infusion phlebitis, this study was undertaken. We undertook two experiments with the different infusion conditions in rabbits to confirm the generality and the reproducibility of the results. To test the effect of dilution, 120 mL/kg of solution A (784 mOsm/kg) was infused into rabbit ear veins at 10 mL.kg-1.h-1 for 12 h, and 144 mL/kg of 1.2-fold-diluted solution A (648 mOsm/kg) was infused at 12 mL.kg-1.h-1 for 12 h. Similarly, 120 mL/kg of solution B (718 mOsm/kg) was infused at 5 mL.kg-1.h-1 for 24 h, and 168 mL/kg of 1.4-fold-diluted solution B (514 mOsm/kg) was infused at 7 mL.kg-1.h-1 for 24 h. The infused veins were sampled 24 h after the end of the infusion and examined histopathologically. After the 12-h infusion, phlebitic changes were observed in six of eight rabbits given solution A but in only one of eight rabbits given diluted solution A, although the same quantities of the same nutrients were infused. Also, after the 24-h infusion, phlebitic changes were observed in six of eight rabbits given solution B but in no animals given diluted solution B. The same result that dilution reduced or eliminated phlebitic changes was confirmed in the different conditions. These results suggest that osmolality of the infusion solution is an important factor in the development of phlebitis regardless of infusion volume or infusion rate and that dilution is effective in reducing the phlebitic potential of infusion solutions.