Aging of Silastic Peritoneal Catheters

Abstract

Increasing the survival of patients on CAPD is related to the long-term reliability of the peritoneal access. Six silicone Tenckhoff catheters (with strip or diffuse barium sulphate inclusion) removed after 39-69 months because of the appearance of external segment fissures, were analysed by scanning electron microscopy (SEM) and infra-red spectroscopy with attenuated total refractance (ATR). The extracorporeal portion of the catheters showed (by ATR) a more prominent oxidation peak on the external than the internal surface; SEM showed marks and cracks on the external surface and exfoliation and flattening of the silastic reticle on the intraluminal surface. No evidence of oxidation was found in the intra-abdominal portion of the catheters but biofilm was found. We suggest that barium sulphate may render the silastic brittle and physiological and environmental long-term factors (such as uv-rays, temperature, sweat and disinfectants) could cause oxidation and loss of physico-chemical properties, with critical aging of the silastic and loss of catheter resistance to mechanical injury.

Spontaneous Fracture of the Intraperitoneal Portion of a PD Catheter

“…However, spontaneous ruptures of silicone catheters are occasionally reported (6,7). Silicone rubber catheters have been observed to stretch, crack, or become brittle with age or after repeated exposure to povidone-iodine (1,2,8). Compared to silicone rubber, polyurethane is more likely to be damaged with ageing because of so-called environmental stress cracking or ointment (1,3).…”

Oxidation of Silicone Elastomer Finger Joints

“…Long-term in vivo use leads to oxidation of the silicone elastomer implants, although shortterm studies showed no such effect. 10 Oxygen attacks during long-term in vivo implantation can profoundly degrade the silicone elastomer. Hopkins and Keim 11 stated that even a minuscule amount of oxygen, as little as 1%, can render the elastomer useless for most applications as a result of loss of physical properties.…”

Stretching and breaking characteristics of cerebrospinal fluid shunt tubing

“…4 Silastic shunt catheters have a tendency to weaken over time. 16 Also, calcium deposits on CSF tubing may act as a tether on the apparatus and potentially predisposes such catheters to fracture. 8 The objective of our study was to define more completely the stretching and breaking characteristics of silastic CSF shunt tubing by using mechanical testing.…”