Residual ethylene oxide in medical devices and device material.

Ethylene oxide (EO) gas is commonly used to sterilize medical devices. The amount of residual EO remaining in a device depends partly on the type and size of polymeric material. A major concern is the amount of residue that may be available in the body. With the use of the method described by AAMI for headspace analysis of EO residues, different polymers and medical devices subjected to different numbers of sterilization cycles were examined. Next, the effect of various extraction conditions and extraction solutions on these polymers and medical devices was evaluated. The results showed different polymers desorb EO differently. One polyurethane (PU 75D) had much higher EO residue than a different polyurethane (PU 80A). Repeated extraction of the PU 75D was necessary to quantify total EO residue levels. Different extraction solutions influence the amount and reproducibility of EO detected, whereas multiple resterilizations showed no difference in amount of residual EO. Bioavailability of EO was estimated by extracting the devices and polymers in water. Comparison of total EO residues to EO that was bioavailable showed no difference for some polymers and devices, while others had an almost eightfold difference. Some standard biocompatibility tests were run on extracts and devices, but no significant effects were observed.

Effects of different disinfection and sterilization methods on tensile strength of materials used for single-use devices.

Driven by economic and time constraints, some medical centers and third parties are resterilizing single-use devices (SUDs) for reuse. The steam autoclave is quick, but most plastics used in SUDs cannot survive the temperature. Thus, a number of new methods of cleaning, disinfecting, and sterilizing these complex devices are being introduced on the market. The present study investigated the effects of a range of methods on the tensile strength of latex rubber, silicone elastomer, 2 different formulations of polyurethane, nylon, and high-density polyethylene (HDPE) specimens. The methods used were sodium hypochlorite bleach (Clorox), peracetic acid + hydrogen peroxide (Steris), formaldehyde gas (Chemiclave), low-temperature peracetic acid and gas plasma (Plazlyte), and low-temperature hydrogen peroxide gas plasma (Sterrad). The results showed that silicone elastomer was minimally affected, whereas the strengths of nylon, polyethylene, and latex were reduced by some of the methods. Depending on the formulation, the strength of polyurethane either increased or decreased. The data demonstrated that disinfection and sterilization can affect the tensile strength of certain materials used in medical devices.