Clinical Biodurability of Aliphatic Polyether Based Polyurethanes as Peritoneal Dialysis Catheters

Abstract

Thermoplastic polyurethane elastomers are the most important implantable grade polyurethanes in medical applications. An aliphatic polyether based polyurethane, Tecoflex (TF; Thermedics, Inc., Woburn, MA), is used in the construction of a proprietary peritoneal dialysis (PD) catheter. Information is limited regarding the biostability of the TF polymer in the clinical environment as a PD catheter. This report presents the clinical experience regarding the biodurability of 104 catheter implants. The extracorporeal tubing segments of all TF catheters eventually developed aesthetically offensive discoloration, opaqueness, and surface tackiness. Catheter breaks in the external segment occurred in 27% of devices that survived longer than 28 months. Mupirocin ointment at the catheter skin exit site caused swelling and deformity of the TF in one case. Three catheters extruded as a result of Dacron cuffs separating from the tubing wall. Catheters removed for other reasons were frequently found to have loose cuffs, especially if the devices were implanted for several years. Causes and possible mechanisms for observed failures are discussed. The durability of biomaterials used in construction of PD catheters is of vital importance for successful long-term functioning. The TF polymer embodied as a PD catheter represents a mismatch of the material and its mission. Fabrication of PD catheters from higher grade polyurethanes possessing greater biostability should be explored. Silicone rubber appears to remain the most durable material to date for PD catheter construction.