Effect of Arterial Catheter Geometry on Radial Artery Blood Pressure Measurements

Abstract

Blood pressure is a crucial parameter in haemodynamic monitoring, providing an indication of tissue perfusion in critical situations. Commonplace in (paediatric) intensive care units ((P)ICU) are arterial catheters, inserted in the radial artery, which are an invasive means of continuously measuring blood pressure. However, quantifying the degree to which arterial catheter geometries modify the pressure measurement, especially for paediatrics, remains seemingly unexplored in research, while discrepancies between non-invasive and invasive blood pressure monitoring methods have been observed in Erasmus MC (P)ICU departments.

Using FEBio, a computational fluid dynamics (CFD) model was developed to investigate the influence of catheter geometries on the pressure generated at the catheter tip (taken to be the measured pressure) for six age groups ranging from <2 years to 18 years of age. For three age groups (2-5 years, 12-14 years, and 15-18 years), simulations were run with two different catheter gauges (diameters).

Hence, a total of nine different sets of age and catheter gauge were investigated. Apart from comparison between simulations with and without a catheter, the effect of the position of the catheter in the vessel (eccentricity ratio) and changing catheter lengths in the vessel were studied. The results show that arterial catheters (substantially) influence the pressure measured by the catheter. In the worst-case scenarios simulated, namely that in which the catheter is in the centre of the vessel with an intraluminal catheter length equal to 80% of its total length, eight of the nine cases investigated showed systolic pressure values higher than the target values used in the
PICU. Thus, the results suggest that the presence of the catheter may be enough to modify a normal blood pressure into appearing elevated (hypertensive), potentially influencing patient treatment. Shorter catheter lengths were associated with lower pressure overestimations, as was moving the catheter towards the vessel wall. Consequently, these results are clinically significant, and may help physicians in making more informed haemodynamic assessments.