Sterilization with Ethylene Oxide

Introduction

Sterilization allows for the elimination, or rather a significant reduction, of the biological load that the utensil or instrument may have. In other words, it is the elimination of viruses, bacteria and other microorganisms that are present inside or on the surface of pharmaceutical and hospital utensils or objects such as syringes, gloves, surgical and examination utensils, among others.

The importance of good sterilization in the hospital sector is essential for its success and correct operation, both at laboratory level to avoid obtaining erroneous results, as well as at hospital level to avoid any complications with a patient. Sterilization methods are very varied and also had to evolve with the appearance of "thermosensitive" products. The evolution of the pharmaceutical and medical sector led to the emergence of new products such as prostheses, implants and also products with new characteristics thanks to the composition of their materials such as resin, rubber, plastic, etc. Therefore, sterilization techniques also had to evolve at the same pace as the instruments and products in order to guarantee, on the one hand, total sterilization and, on the other hand, complete integrity after sterilization of these so-called thermosensitive products.

What are thermosensitive products and/or materials?

“Thermosensitive” materials and/or products that are sensitive to temperature changes or that do not resist heat, such as: electric motors, cameras, rubber, plastics, optical instruments, etc.

For this reason, low-temperature sterilization systems were developed. Some are gas-based, such as ethylene oxide and hydrogen peroxide, and others are radiation-based, such as gamma radiation.

Each technique has its advantages and disadvantages, and may be more or less appropriate depending on the characteristics of the materials to be sterilized.

One of the most important and most used due to its high efficiency is sterilization by Ethylene Oxide (ETO) .

What is ethylene oxide?

It is a colorless and odorless gas that allows sterilizing and destroying microorganisms, penetrating and spreading through thermosensitive, porous and difficult-to-access materials, without damaging the materials of the sterilized products.

Its advantages are as follows:

• Propagation in the folds and inaccessible places of the element to be sterilized.
• Sterilization between 25ºC and 60ºC (at low temperature) guaranteeing no deformation or destruction of the elements to be sterilized.
• Pass through the membranes of the packaging containing the elements (for example, polyethylene film).
• Its effectiveness is maximum for heat-sensitive materials, which we remember cannot be sterilized by traditional methods such as water vapor.

What do you need to know about the ethylene oxide sterilization process?

Ethylene Oxide (ETO) gas has great advantages, but it is also important to know that it is explosive and toxic, which is why it must always be used very safely, working with sterilization equipment that ensures the safety of personnel, the work environment and the environment.

The importance of a good optimization of the sterilization process is essential, so it is necessary to find the most appropriate relationship between the variables: gas concentration, humidity, contact time with gas and temperature. This is clearly defined by the ISO 11135 standard, which states that the variables that are set must result in the sterility of all the biological indicators placed in the product in half the time of the process cycle, and it must also be a consistent, documented and auditable process.

The validity of a validation process according to ISO standards for ethylene oxide gas is at least ONE year, at the end of which you can revalidate it for an equal period of time by repeating only a small part of the process.

For the process with ethylene oxide gas, the product can be introduced into the chamber in bulk or on pallets. Therefore, the design of its packaging is neither decisive nor exclusive in optimizing the contents of the chamber.

In addition, it is also important to evaluate the effect of the technology on each of the sterilized materials. Pigmented nonwoven fabrics and plastic polymers packed in medical grade paper bags, or mixed bags, polyethylene with paper windows, when exposed to ethylene oxide gas, do not show any deterioration in the strength and elasticity of their fibers. Unlike exposure to gamma rays in minimum doses of 18 kGys, most of the main manufacturers of medical equipment report that many polypropylene and cellulose nonwoven fabrics show alterations in color and strength, in addition to absorbing a certain “ozone” odor from radiation that in many cases remains for several days.

Benefits of Ethylene Oxide Sterilization.

• Excellent gas diffusion capacity in the products to be sterilized. It has a high penetration rate in most materials and packaging.
• It is a process with a high margin of sterilization safety, since it causes the effective destruction of very resistant spores and almost all types of fungi.
• Compared to other processes such as Gamma Radiation, dry heat and plasma, the EO gas process is more economical and more effective.
• The process with ethylene oxide gas is simpler and cheaper to validate.
• It does not require high temperatures to sterilize since the gas is volatile at temperatures above 10ºC, so it has a wide spectrum of application in sterilization of biomedical supplies.
• Good compatibility with most materials.
• There are no restrictions for sterilization of narrow lumens.

Among the materials that can be sterilized with Ethylene Oxide Gas are:

• Surgical and examination latex gloves
• Latex and cardiac probes
• Catheters
• Endoscopes
• Ventilation and inhalation therapy circuits
• Surgery packages
• Nonwoven fabric gowns
• Polypropylene and cellulose surgical drapes
• Polypropylene glasses or jars
• Disposable syringes Plastic and glass
• Dental instruments
• Collection bags
• Cotton and elastic bandages
• Plastic and wooden cotton swabs
• Gauze and Compresses
• Epidural block equipment
• IV Equipment
• Glass Ampoules
• Ophthalmic Bottles
• Implants
• Prosthesis
• Self-adhesive bandages and patches
• Natural and synthetic sutures

Ethylene oxide gas has been the most reliable method for many years in the sterilization of various healing materials and medical products.