EFFECT OF REPEATED FORMALDEHYDE LOW-TEMPERATURE STEAM STERILIZATION ON PHYSICOMECHANICAL PROPERTIES OF PVC TUBING

Resterilization of non-reusable medical devices has been proposed for economical reasons in hospitals although one cannot assume that reprocessing such materials does not alter the physicomechanical properties and consequently safety in medical practice. The purpose of this study was to determine whether, and in which way, multiple sterilization cycles could be prejudicious to a material commonly used in medical routine in a number of articles. After 5-50 cycles of sterilization by the low-temperature steam formaldehyde technique at 56-degrees-C, the resistance of plasticized vinyl polychloride (PVC) tubing has been tested using a simple stretching test. The breaking strength decreases with increasing number of cycles, being statistically significant between 10 to 20 cycles with a mean loss of 0.282% per cycle (p < 0.01). The breaking length increases when the number of cycles diminishes being statistically significant between 5 to 10 cycles (p < 0.01), with a mean change of 1.306% per cycle. Since the mechanical properties undergo significant deterioration after five cycles, leading us to suspect that reutilization in medical practice may not be safe for the patients, we cannot recommend multiple resterilization of PVC materials by this method. Nevertheless, if necessary, the hospital pharmacist bears the entire responsibility of reprocessing disposables. In this case, an absolute limit of three cycles should not be exceeded.