Surface morphology and tensile force at breaking point or different kinds of intravenous catheters before and after usage.

Heads of seven different types of unused and used intravenous catheters as well as tips of the corresponding needles for venipuncture, artificially cut and ruptured surfaces were either directly mounted on stubs or previously fixed in 1% phosphate buffered glutaraldehyde (pH 7.4), dehydrated with acidified 2, 2-dimethoxy-propane, dried in a critical point drying apparatus using CO2, mounted with silver-paint and sputter coated with 20 nm gold. In addition tensile tests of unused catheters were carried out. According to the tensile tests and to the SEM findings neither spontaneous breakage nor manufacturing defects may be reason of catheter embolism. Manufacturing defects at the tips of needles for venipuncture, as well as rough surfaces of the introducers or catheter walls may cause endothelial lesions. Settling of formed elements of the blood apparently is related to ruggedness of the catheter wall or to manufacturing defects. Thrombi, grown on he outer surface of the catheters are very rare. In Cavafix catheters thrombus formation is mostly related to the roughness of radio-opaque parts of the catheter wall. Outgrowth of the thrombus via the top to the outer surface could be demonstrated frequently