Effects on instruments of the World Health Organization--recommended protocols for decontamination after possible exposure to transmissible spongiform encephalopathy-contaminated tissue.

It has been recommended by the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC) that rigorous decontamination protocols be used on surgical instruments that have been exposed to tissue possibly contaminated with Creutzfeldt-Jakob disease (CJD). This study was designed to examine the effects of these protocols on various types of surgical instruments. The most important conclusions are: (1) autoclaving in 1N NaOH will cause darkening of some instruments; (2) soaking in 1N NaOH at room temperature damages carbon steel but not stainless steel or titanium; (3) soaking in chlorine bleach will badly corrode gold-plated instruments and will damage some, but not all, stainless-steel instruments, especially welded and soldered joints. Damage became apparent after the first exposure and therefore long tests are not necessary to establish which instruments will be damaged.

Use of containment pans and lids for autoclaving caustic solutions.

As a means of decontaminating instruments possibly exposed to Creutzfeldt-Jakob disease, the World Health Organization has recommended immersion and autoclaving in sodium hydroxide. However, this recommendation has raised concerns of possible damage to autoclaves, and hazards to operators as a result of the caustic vapors. A series of experiments has been conducted that demonstrate that there are containment pan-and-lid combinations in which instruments can be autoclaved in sodium hydroxide without risk to the autoclave or the operator.

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.

Evaluation of substrates for 90 degrees peel adhesion--a collaborative study. II. Transdermal drug delivery systems.

In a previous study on peel adhesion for medical tapes, it was shown that a stainless steel (SS) substrate better discriminated among medical tapes than a high-density polyethylene (HDPE) substrate. The objective of this study was to determine if a SS substrate would also better distinguish among transdermal drug delivery systems (TDDSs). Five TDDSs (Vivelle Dot, Climara, Catapres-TTS, Duragesic, and Mylan Fentanyl) were evaluated on three different substrates (SS, HDPE, and human cadaver skin). All measurements were made using a dwell time of approximately 3 min, a peel angle of 90 degrees, and a peel speed of 300 mm/min. Differences among TDDSs were greater for SS than for HDPE, using the F statistic for testing for differences among TDDSs means as a measure of heterogeneity, thereby indicating greater discrimination by SS.

Evaluation of substrates for 90 degrees peel adhesion--a collaborative study. I. Medical tapes.

As part of a method development for peel testing, an interlaboratory comparison among Food and Drug Administration-Center for Drug Evaluation and Research, Food and Drug Administration-Center for Devices and Radiological Health and Southwest Research Institute was conducted using medical tapes. The aim was to determine which readily available substrate [stainless steel (SS), high density polyethylene (HDPE) or Vitro-Skin(R)] would best distinguish among various medical tapes. Five medical tapes (3M 1523, 3M 1525L, 3M 1776, Mepiform(R) and Mediderm(R) 3505) were evaluated on four different substrates (SS, HDPE, Vitro-Skin, and human cadaver skin) using the following peel parameters: approximately 3 min dwell time, 90 degrees peel angle, and 300 mm/min peel rate. No substrate mimics cadaver skin for all five tapes. SS had the best ability to distinguish among the medical tapes. Overall, for quality control purposes (yielding good discrimination and precision), SS would be the optimal substrate.