Kinetics of diethylhexyl-phthalate extraction from polyvinylchloride-infusion lines

Background: For infusion therapy, polyvinylchloride (PVC)-infusion lines are commonly used. In this study, we examined the temperature dependency and the dynamics of extraction in the time course of infusion. Methods: PVC-infusion lines used on the newborn ICU were perfused with a typical 24-hour fat infusion. We collected the perfused solution and measured the concentration of DEHP. This procedure was carried out at 27degreesC and 33degreesC. In another experiment, we examined the extraction rate in the time course of a 24-hour infusion. The infusion was collected every 4 hours. Results: We discovered that extraction of DEHP depends highly on the surrounding temperature. Whereas at 27degreesC, the extraction of DEHP was 422.78 mug/mL, the leaching reached 540.78 mug/mL at 33degreesC under other-wise identical conditions. This is important because the temperature on a newborn ICU is between 31 and 37degreesC in an incubator. In the other experiment, we found out that the extraction rate rose from 25.44 mug/mL in the first 4 hours to 478.1 mug/mL after 24 hours. Conclusions: The result of this study is that the actual daily load of DEHP for a 2-kg newborn is 30% higher than measured before. The rate of extraction is dependent on the time of contact between solution and tubing. If PVC-infusion systems ate used, solutions should be as cold as possible, and infusion time should be as short as possible.