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

Background: 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.

Methods: 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.

Results: 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.

Conclusion: 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.