The presence of a non-return valve in an infusion set-up is expected to affect the time-of-arrival of new medication in a patient after syringe exchange. Using Computational Fluid Dynamics (CFD) we have studied the flow through a typical non-return valve, focusing on two separate effects: (A) the overall delay in the time-of-arrival, and (B) timing effects due to the distortion of the Poiseuille flow profile in the non-return valve. The results show that (A) the additional delay in time-of-arrival of new medication, caused by the non-return valve alone, corresponds to the delay that would be caused by 11.2 cm of extra infusion line instead of the valve, and that (B) the non-Poiseuille flow profile inside the non-return valve gives rise to an extra slow wash-out of the last portion of the remnant fluid of the old medication. We conclude that awareness of these extra delays may be important for clinicians in certain time-critical situations.

Konings MK, Gevers R, Mejri S, Timmerman AM. Effect of non-return valves on the time-of-arrival of new medication in a patient after syringe exchange in an infusion set-up. Biomed Tech (Berl). 2022 Dec 16. doi: 10.1515/bmt-2022-0054. Epub ahead of print. PMID: 36520111.