Simulation Analysis of Flow Rate Variability During Microinfusions: The Effect of Vertical Displacement and Multidrug Infusion in Conventional Infusion Pumps Versus New Cylinder-Type Infusion Pumps.

Background: Medication dosing errors can occur during microinfusions when there is vertical pump displacement or multidrug infusion through a single intravenous path. We compared flow rate variability between new-generation cylinder-type infusion pumps and conventional infusion pumps under simulated conditions.

Methods: We evaluated the flow rates during microinfusions using different infusion pumps (syringe pump with 10/30/50-mL syringes, peristaltic pump, and cylinder pump). Two visible dyes were used as model drugs. The study samples were quantified using spectrophotometry. For vertical displacement, the infusion pumps were moved up and down by 60 cm during microinfusions at 0.5 mL·h-1 and 2 mL·h-1. In the multi-infusion study, the second drug flow was added through 4 linearly connected stopcocks either upstream or downstream of the first drug. We compared the total error dose between the cylinder pump and the syringe pump with a Mann-Whitney U test and additionally estimated the effects of the infusion pumps on total error doses by linear regression analysis.

Results: There were repetitive patterns of temporary flow increases when the pump was displaced upward and flow decreases when the pump was displaced downward in all settings. However, the amount of flow irregularities was more pronounced at the lower infusion rate and in the syringe-type pump using larger volume syringes. The total error dose increased in the syringe pump loaded with a 50-mL syringe compared to that of the new cylinder pump (regression coefficient [β] = 4.66 [95% confidence interval {CI}, 1.60-7.72]; P = .008). The initiation and cessation of a new drug during multidrug microinfusion in the same intravenous path affected the lower rate first drug leading to a transient flow rate increase and decrease, respectively. The change in flow rate was observed regardless of the port selected for addition of the second drug, and the total error dose of the first drug did not significantly vary when an upstream or a downstream port was selected.

Conclusions: In the microinfusion settings, attention must be paid to the use of the syringe pump loaded with large-volume syringes. The novel cylinder pump could be considered as a practical alternative to syringe pumps with small syringes given its flow stability without the need for frequent drug replacement.