Abstract
We investigated two cases with abnormal protuberances on the external segment of CAPD silicone catheters. Case 1. 43 y.o, male. A white protuberance (6mm×3mm) appeare on the catheter 62 months after catheter implantation. Leakage occurred from a pinhole opening in this protuberance. Case 2. 54 y.o, female. A protuberance with a distinctive edge appeared on the catheter 57 months after catheter implantation. The catheter was broken during drainage approximately 63 months after implantation. We studied the cross sectional structure of the two catheters with a Scanning Electron Microscope (SEM). The SE images showed bubbles, appearing consecutively around the middle of the protuberance which were observed on cross sections of the catheters. Furthermore, we performed the following tests to investigate the physical properties of these catheters. The catheters of the above two cases plus unused catheters, as controls, were studied. The following properties were assessed: 1. Hardness of 2. Tensile strength 3. Tensile strength of the radiopaque portion
We found that the hardness of unused catheters varies among manufacturers. The tensile strength of the radioaque portion was lower than that of other portions of the catheter. The catheters from Cases 1 and had lower hardness and significantly lower tensile strength than The unused catheters. Silicone rubber, a hihy biocompatible medical material, is used for CAPD application due to its superior heat resistance, cold resistance and low toxicity. However, our study indicates that silicone rubber may not maintain its integrity under the conditions (temperature, humidity, disinfection and handling) of daily catheter use. Moreover, the SEM results indicate that material degradation occurred at the inner, but not the outer, portion of the catheter. We, therefore, conclude that potential degradation of catheters may occur with long term use of CAPD catheters.
