A scanning electron microscopy analysis of a spontaneous hemodialysis catheter fracture.

Central venous catheters have become increasingly important in hemodialysis treatment. With their increased use, catheter-related problems will be seen more frequently, and more rare complications may be observed. We describe the first case of asymptomatic spontaneous breakdown of a tunneled cuffed silicone catheter used for long-term hemodialysis treatment. This was discovered on removal of the catheter, leaving behind a catheter fragment in the left lower pulmonary lobe. An extensive scanning electron microscopy study showed accumulation of lumps of nonsilicone material at the place of the fracture, leading to severe disruption of the original cross-linked elastomer structure. Using energy-dispersive X-ray spectral analysis, which shows all elements with an atomic number of 11 or greater in a material, we found the lumps were aggregates of barium sulfate particles used to visualize the catheter on fluoroscopy. We suggest that the use of too small or too many barium sulfate particles led to high viscosity of the raw silicone before polymerization, causing improper mixing of barium sulfate particles in the silicone matrix. This resulted in insufficient removal of admixed air bubbles and unequal dispersion of barium sulfate, with the potential for weak spots after extrusion of the silicone into its definitive shape. With the increasing use of hemodialysis catheters for prolonged periods, catheter-related complications related to materials or manufacturing errors can be expected to occur more often.