Background: The ability of an infusion set to deliver a specific amount of drug to the patient can be directly related to the presence of an antireflux valve and dead-space volume. In this study we quantified separately the impact of these 2 components on drug delivery.
Methods: Various infusion sets were assessed differing in length, in dead-space volume, and with or without an antireflux valve. Noradrenaline was infused with a syringe pump simultaneously with a carrier flow. Effluent drug concentration was measured using ultraviolet spectrophotometry. Flow change efficiency (FCE) was calculated from the ratio of the area under the experimental mass flow rate curve to the area under the theoretical instantaneous mass flow rate curve.
Results: The FCE for infusion sets with or without antireflux valves were significantly different 10 to 15 minutes after the start of an infusion at flow rates of 7 mL/h for noradrenaline and 35 mL/h to 70 mL/h for the carrier fluid. They were not different with a carrier flow of 115 mL/h.
Discussion: These findings suggest that antireflux valves have a significant impact on FCE when the ratio of drug flow rate to carrier fluid flow rate is high. Infusion sets with very low dead-space volume connectors yield better FCE. There is a nonlinear relationship between dead-space volume and FCE 5 to 10 minutes after the onset of drug infusion.
Conclusion: Care providers must consider dead-space volume and the presence of an antireflux valve when choosing their infusion sets.