Changes in umbilical catheters' microstructure in vivo: A prospective study

Umbilical vessels present after birth allow a unique central access for both venous and arterial catheterization, yet the catheterization complications can be misdiagnosed as the complications of prematurity per se.

A prospective observational study of 41 used polyurethane umbilical catheters, both venous and arterial was conducted in a tertiary neonatal intensive care unit. The study consisted of bedside ultrasound imaging and post-removal microbiological and microstructural analysis to assess the in vivo catheters' changes and their clinical significance.

The study has shown that catheters' surface thrombosis and bacterial colonization happen more often within umbilical venous than within arterial catheters (31% vs 8% in both cases) and are inversely proportional to the patient's gestational age (thrombosis: Me: 28 weeks vs no thrombosis: 32 weeks; p = 0.05, bacterial colonization: 27 weeks vs no colonization: 30 weeks; p = 0.013), respectively. The clots formed near the catheter's tip are correlated with catheter's bacterial colonization. Chemical analysis with energy dispersive spectroscopy showed a higher calcium composition in used catheters (19.89% vs 0%, p = 0.016) and structure analysis in the scanning electron microscopy proved that within hours catheters become covered with an external coating of a constant thickness, not affected by the catheterization time.

The following observations give a better insight to the complex in vivo interactions and call for a more intense bedside-monitoring of the indwelling devices.