Instrument Selection and Use

Instruments used for rodent surgery are delicate and typically designed for a specific function. Incorrect use of these instruments will damage them and make it difficult, if not impossible, to use them correctly. For example, hemostatic forceps are designed to grasp and hold tissue such as blood vessels or skin. While they can be used to hold a needle for suturing in an emergency, routine use of hemostatic forceps instead of a surgical needleholder is not recommended. These forceps are not designed to securely grasp the needle and using them for suturing will damage the tips making them useless for their intended purpose.Instruments should also be of the appropriate size for rodent surgery. Using instruments that are too large will exaggerate hand motions and decrease surgical precision resulting in poor technique and increased tissue trauma.

It has been reported that repeated use of glass bead sterilizers will make instruments brittle and dull over time. Any instrument that is used frequently, handled roughly or cleaned with abrasive materials can be damaged or dulled. Instruments should be assessed on a regular basis and replaced when necessary. Scissors and other sharp instruments can sometimes be re-sharpened to prolong life. Instruments must be gently cleaned after each use to ensure that all blood and tissue is removed. An ultrasonic cleaner can assist in this process. Proper care will extend the life of your instruments and help preserve your investment.

Instrument Sterilization

Prior to surgery, instruments and other supplies are placed in a ‘surgical pack’. The surgical pack must not only hold the instruments and supplies during the sterilization process, but also maintain the sterility of the contents until used in surgery. A variety of packing methods exists, including:

• Instruments, with or without an instrument tray, are packed inside a folded cloth or paper wrap and sealed with tape designed to indicate when sterilization has been achieved. Other types of sterilization indicators may be placed inside the pack.
• Peel packs –self-sealing ‘envelopes’ used for steam or gas sterilization. A sterilization indicator is included on the envelope.
  

Keeping Instruments Sterile During Surgery

Use an extra piece of sterile drape material or the inside of the surgical wrap or envelope as a sterile space to place instruments during surgery. One of the most common errors for an inexperienced surgeon is setting instruments down on an unsterile surface.

Sterilization Procedures

Surgical instruments and other material or equipment that will contact the surgical site must be sterile prior to use.  The process of sterilization kills all forms of life, including bacterial spores and viruses. Chemical disinfection is not the same as sterilization and is not acceptable as the primary method of instrument preparation for surgery. Methods of instrument sterilization include steam (autoclave) and gas (ethylene oxide) sterilization. Dry heat sterilization using a glass bead sterilizer is not acceptable for initial sterilization of instruments prior to surgery but may be used during ‘batch’ surgeries.

Steam Sterilization

• Steam or autoclave sterilization is the most common method of instrument sterilization.
• Instruments are placed in a surgical pack and exposed to steam under pressure.
• A sterilization indicator (required) such as autoclave tape or an indicator strip is used to identify instruments that have been sterilized.

Ethylene Oxide

• Ethylene oxide gas is used to sterilize items that cannot withstand the high temperature and steam of an autoclave.
• Ethylene oxide is highly toxic. Items sterilized with ethylene oxide must be aerated before use to allow the gas to dissipate.
  

Dry Heat Sterilization

When steam cannot penetrate an instrument or can destroy it, your next logical option is dry heat. Dry heat is a strong but slow technique requiring high temperatures and time. Because of this, it’s not suitable for many materials, but it’s often still more reliable than various other options. Dry heat sterilization uses air of around 340 degrees F to kill microbial life.

Plasma Gas Sterilizers

This type of sterilization uses low temp hydrogen peroxide-based gas plasma inside a chamber to kill any microorganisms on dental and medical equipment, including spores, bacteria, fungi and viruses. When you add vaporized hydrogen peroxide to the chamber, it sterilizes the enclosed equipment. Once you remove the vapor from the chamber, it produces a plasma of a lower temperature, which ensures total sterilization for all equipment.

Oxygen and water are the remainder of this process and make these sterilizers safe for both the environment and medical staff. While this is a more costly method, it’s extremely effective and an excellent option for medical equipment and tools that are moisture sensitive.

Glass Bead Sterilizers:

• Glass bead sterilizers may be used to re-sterilize instruments during a surgical procedure but are not acceptable as an initial method of sterilization.
• Glass bead sterilizers have a central well filled with glass beads heated to high temperature (approximately 5000F). 
• After removal of blood and tissue, the tips of surgical instruments are placed into the hot glass beads for approximately 10-15 seconds.
• Only the tips of the instruments are re-sterilized in this process.
• Instrument tips become extremely hot and must be cooled before use.
• Glass bead sterilizers may be used between animals when one set of initially autoclaved instruments is used on a group of up to 5 animals.
  

Reusing Instruments

When surgical procedures are to be performed on multiple rodents, the same set of instruments may be used on more than one animal under the following conditions.

• The instruments must be initially sterilized by autoclaving or gas sterilization.
• Blood and tissue particles on instrument tips must be removed using alcohol before placement in the glass bead sterilizer.

• The tips of instruments must be placed in a hot bead sterilizer between animals.
• A new set of sterile instruments must be used after every 4-5 animals.
• If the instrument tips have become contaminated by contact with a non-sterile surface or non-sterile portions of the body (such as contents of the gastrointestinal tract) a new sterile set of instruments must be used on subsequent animals.
  

Benefits of Sterilizing Equipment

With invasive procedures, there’s contact between a patient’s mucous membranes or sterile tissue and a surgical instrument or medical device. A significant risk of these types of procedures is introducing pathogenic microbes, potentially resulting in infection. When you don’t properly disinfect or sterilize medical equipment, it increases the risk of infection due to the breach of host barriers.

For both hospital staff and patients alike, germs need to be destroyed to reduce the spread of infections. A prime example of this is fighting against healthcare-associated infections (HAIs), which are infections hospital patients get due to their hospital stay. Surgical instruments, contaminated equipment or improper staff hygiene can cause HAIs.

Some benefits of sterilizing medical equipment include:

1. It eliminates pus, blood, foreign particles and dirt left behind that could lead to dangerous complications for the next patient requiring surgery where the medical practitioner uses the instrument.
2. It decreases bioburden — the number of non-sterilized bacteria living on a surface.
3. It prevents the corrosion of expensive and highly precise tools that have delicate pivots and hinges.
4. It removes the breeding ground for the surviving germs.
5. It ensures the safe transport of equipment needing to be packed and assembled for sterilization or disinfection.

Sterilization and disinfection, when properly used, can ensure the safe use of non-invasive and invasive medical devices.