Effect of non-return valves on the time-of-arrival of new medication in a patient after syringe exchange in an infusion set-up.

Abstract

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 theflow 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 11.2cm 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 ofthe remnant fluid of the old medication. We conclude that awareness of these extra delays may be important forclinicians in certain time-critical situations.