新生児グルコース·インスリン(GI)療法における投与セットへのインスリン吸着の検討

The adsorption of insulin onto administration sets during its infusion has been reported in many studies.In glucose insulin (GI) therapy for newborn infants in particular,the degree of adsorption is important because the insulin dose is very low.Since this issue had not been clarified,we studied insulin adsorption in this case and examined methods for its prevention.We prepared an insulin fluid with 5% glucose solution (0.02 U/mL) and determined the residual amount of insulin in the fluid with time using an HPLC-UV system after flushing infusion sets for newborn infants with the fluid using a syringe pump.The syringe was made of polypropylene (PP) and the lines of polyvinyl chloride (PVC),polyethylene (PE) or polybutadiene (PB).For the in-line filter,we used posidyne® (PD),an electrically charged nylon 66 membrane.The residual amount of insulin for each type of line decreased to about 20 to 30% of the theoretical value immediately after starting the infusion and gradually increased to about 50 to 60% after 2 hr and then stayed constant.When the PD filter was used with the infusion sets,the residual amount of insulin decreased to below 10% immediately after starting the infusion and had not changed 8 hr later.The actual dose decreased to about 40% for each type of line,and to under 10% when the filter was used.To prevent adsorption,we added a total-vitamin injection containing the nonionic surface-active agent (Tween 80) to the insulin fluid (final concentration : 25μg/mL).The residual amount of insulin recovered to about 100% for the PB line but there was no change when the filter was used as well.In conclusion,our results show that the adsorption of insulin is a critical issue in GI therapy for newborn infants.