Determining an Appropriate To-Keep-Vein-Open (TKVO) Infusion Rate for Peripheral Intravenous Catheter Usage

Abstract

Background: Evidence to support an optimum continuous to-keep-vein-open (TKVO) infusion rate for peripheral intravenous catheters (PIVCs) is lacking. The aim of this study was to simulate typical TKVO rates, in combination with flushing, to better understand TKVO in relation to PIVC patency. Methods: We simulated saline infusion through a 20-gauge PIVC in 2 forearm veins (3.3 and 2.2 mm) using computational fluid dynamics under various venous flow rates (velocities 3.7–22.1 cm/s), with a saline flush rate of 1 mL/s and TKVO infusion rates of 10, 20, and 40 mL/h. We determined TKVO efficacy using the stream of saline clearing the stasis region at the device tip and the shear stress acting on the vein. Results: At 10 mL/h TKVO rate, blood stasis occurs around the PIVC tip as saline is pulled into the faster-moving venous blood flow, creating the blood recirculation (stasis) zone at the device tip. When TKVO increases >20 mL/h, this stasis diminishes, and the likelihood of patency increases. Shear stress on the vein is negligible during TKVO but increases 10- to 19-fold when flushing the small and large veins investigated here. Conclusions: Low TKVO rates (10 mL/h) may not clear the PIVC tip and keep the device patent. Based on our simulations, we propose a TKVO rate of at least 20 mL/h could be used in practice; however, 30–40 mL/h appears most effective across different venous flow rates and peripheral vein sizes. However, this additional fluid load must be carefully considered based on the needs of each patient.