Quantification of mechanical properties in long-term in vivo used silicone catheter lines according to DIN 10555-3

BACKGROUND: Totally implantable central venous access port devices are crucial for intravenous application of chemotherapeutics and long-term therapy for chronic disease. Common complications include thrombosis and device fracture related to altered material properties through exposure in situ. This study exhibits whether uniaxial tensile properties (DIN 10555-3) of in vivo used catheters prove inferior to unused catheters.

MATERIAL AND METHODS: 5 unused, originally packed silicone catheters were cut into 6 segments of 50 mm: 3 segments each were cleaned via cleaning solution (n = 15) while 3 segments were left unattended (n = 15). Distal segments (50 mm) of long-term in vivo used silicone catheters were cleaned before testing (n = 33). Overall mechanical behavior was tested in a custom-made self-centering, torsion free carrier. Maximum force stress at failure, strain at failure and Young's modulus were determined and statistically analyzed.

FINDINGS: Unused catheters showed no significant difference in testing. in vivo used catheters exhibited 20% lower maximal force than unused catheters (p < 0.001), strain at break (p 〈0,001), and 7% higher elastic modulus (p = 0.004; power: 0.845). Due to a constant cross section area, stress at failure was proportional to maximum force (p < 0.001). Relation between determined parameters and dwell times was non-significant.

INTERPRETATION: In vivo long-term used silicone catheters showed significantly lower ultimate strength than unused ones. It is likely that in situ altering changes the mechanical properties of catheters and may potentially lead to failure.