The University of Tennessee Health Science Center - Department of Comparative Medicine

Surgical Considerations

I. SURGERY FROM WHICH THE ANIMAL RECOVERS CONSCIOUSNESS

Individuals performing survival surgical procedures must be knowl-edgeable of aseptic surgical techniques and have adequate training and skills to conduct the procedure to be performed without causing undue postsurgical distress to the animal. Aseptic techniques must be used for all survival surgical procedures. Major surgical procedures on non-rodent mammalian species must be conducted in surgical facilities approved by the IACUC. Minor surgical procedures on non-rodent species and all procedures on rodent species may be conducted in a laboratory. The determination of whether a procedure is "major" or "minor" will be made by the IACUC. The guidelines used by the committee to make this determination are noted below, along with descriptions of facilities and techniques to be applied to each category, and postsurgical care standards.

A. NON-RODENT MAMMALIAN SPECIES

1. Minor Survival Surgery
   
   
   • Definition - "Minor" surgery is any invasive operative procedure in which only skin or mucous membranes and connective tissue is resected, e.g., vascular cutdown for catheter placement, implanting pumps in subcutaneous tissue. Also included are procedures involving biopsies or placement of probes or catheters requiring the entry into a body cavity through a needle or trocar in combination with a "minor" surgical procedure, e.g., the placement of electrodes into the CNS through reflected skin and a burr hole in the cranium, so long as the dura is not resected. Procedures in which the surgical field cannot be effectively disinfected, e.g., tooth extractions and gingival grafts, are considered "minor".
     
     
   • Standards - "Minor" surgical procedures may be performed in a laboratory setting using appropriate aseptic technique. This includes a clean work area; preparation of the surgical site including clipping of the hair, disinfection of the skin and draping of the surgical site with sterile drapes; the use of sterile supplies and instruments; and sterile gloves and a surgical mask worn by the surgeon and any assistants working in the surgical field.
   
   
2. Major Survival Surgery
   
   
   • Definition - "Major" surgery is any invasive operative procedure in which extensive resection is performed, e.g., a body cavity is entered, organs are removed, or normal anatomy is significantly altered. In general, if a mesenchymal barrier is opened (pleurum, peritoneum, meninges) or an extensive orthopedic procedure is involved, the surgery is considered "major". For surgical procedures that do not clearly fall in the above categories, the chance for significant inadvertent infection of the surgical site is to be a primary consideration.
     
     
   • Standards - All "major" survival surgical procedures on non-rodent species must be conducted in facilities intended for that purpose. These facilities must be constructed, maintained and operated to insure a level of sanitation appropriate for aseptic surgery, and directed and staffed by trained personnel. The operating room(s) must be uncluttered and contain only standard surgical equipment and supplies and may also contain essential specialty equipment required to support current reerch and teaching protocols. The operating room(s) must not be used for general storage. Use of the operating room(s) should be limited to aseptic procedures. A separate area, apart from the operating room(s), must be provided for clipping hair from the operative site although the final surgical preparation of the skin may be conducted in the surgery. An area equipped with surgical scrub sinks should be apart from the operating room(s) and the animal preparation area. Other necessary surgical support functions require facilities for cleaning and sterilizing instruments; storing instruments and sterile supplies; a dressing area for personnel to change into surgical attire; and an area for intensive care and supportive treatment of the animals postsurgically. Although it is desirable, it is not necessary for support areas to be contiguous with the surgery room, with the exception of the surgical scrub sinks. Aseptic technique must be used. This includes wearing of sterile surgical gloves, gowns, caps, and face masks; use of sterile supplies and instruments; and aseptic preparation of the surgical field.
   
   
3. Major surgery followed by less than 24 hour survival

   If it is anticipated not to allow the animal to survive more that 24 hours postoperatively, "major" surgical procedures may be conducted in a laboratory using aseptic techniques applicable to "minor" surgical procedures. However, if infection of the surgical site proves to be a significant problem within the 24 hour period, standards and facilities applicable to "major" surgery will be required.

4. Postsurgical Care

   The project director noted on the protocol is primarily responsible for postoperative care of the animal with appropriate input from a DCM veterinarian. However, investigators may, and are encouraged to, request the DCM veterinary staff to assume this responsibilitv. Immediate request the DCM veterinary staff to assume this responsibility Immediate postsurgical care should include observing the animal to ensure uneventful recovery from anesthesia and surgery. Follow-up postsurgical care should include administering supportive fluids, analgesics, and other drugs as required; monitoring of the animal, including daily temperatures; clinical observations for signs of pain, abnormal behavior, appetite, and excretory functions; providing adequate care for surgical incisions; and maintaining appropriate medical records.

B. RODENT SPECIES

This policy applies to surgical procedures on rodent species that are anticipated to have a postoperative survival time of greater than 24 hours.

1. Standards

   Surgical procedures on rodents may be performed in a laboratory setting using appropriate aseptic technique. This includes a clean work area; preparation of the surgical site including removal of the hair, disinfection of the skin and draping of the surgical site with sterile drapes; the use of sterile supplies, instruments and suture materials; and sterile gloves and a surgical mask worn by the surgeon and any assistants working in the surgical field. If infection of the surgical site proves to be a significant problem in procedures carried out in rodents, the standards for non-rodent species must be applied.

2. Survival Rodent Surgery

   Postoperative infections in rodents can and do occur. Such infections, which may not be apparent on casual observations, cause distress to the animals and can affect the results of a study. In accordance with standards to minimize surgically induced infections, set forth in the NIH Guide for the Care and Use of Laboratory Animals, aseptic surgical procedures must be used. A separate room used primarily for aseptic procedures is desirable; however, the IACUC will approve performing survival rodent surgical procedures in a conventional laboratory setting using aseptic technique. The following minimum standards for aseptic procedures have been adopted by the IACUC:

   • A clean uncluttered work area and a sanitized work surface.
     
   • Appropriate preparation of the surgical site including removal of the hair and disinfection of the skin.
     
   • The use of sterile instruments, supplies, and wound closure materials (see IACUC Guidelines titled "Sterilization of Instruments Surgical Supplies for Aseptic Surgery Procedures").
     
   • Draping the surgical site with sterile drapes to avoid contamination of the incision, instruments and supplies.
     
   • Sterile gloves and a surgical mask worn by the surgeon and any assistants working in the immediate surgical field.

   Surgical procedures may be performed on multiple animals during a single session using one sterile surgical pack, providing care is taken to minimize contamination and the instruments are soaked in an approved sterilant and rinsed in sterile saline, or flamed with 95% alcohol between animals. If appropriate precautions are taken to minimize contamination of surgical gloves, it is adequate to rinse the gloves with a sterilant between animals. If surgical gloves become contaminated by handling non-sterilized items, they should be replaced with sterile gloves.

3. Postoperative Care

   Appropriate postoperative care must be given including the administration of fluids, analgesics, and other drugs as indicated; clinical observations for signs of pain, abnormal behavior, appetite, and excretory functions; and providing care for surgical incisions.

   
   

C. MULTIPLE SURVIVAL SURGERY

Generally speaking, multiple survival surgical procedures on a single animal are discouraged. However, under special circumstances, more than one major surgical procedure on a single animal may be permitted with the approval of the IACUC, provided both surgeries are essential related components of a research project. Occasionally, unanticipated additional operative care may be necessary to correct complications that arise following the primary surgical procedure. Such follow-up procedures may be justified as long as the second procedure does not cause an inordinate degree of distress to the animal. In addition, such procedures should receive prior approval of a DCM veterinarian whenever possible. Major multiple survival surgical procedures for teaching protocols are prohibited. Cost is not an adequate reason for performing multiple survival surgical procedures on an animal.

D. STERILIZATION OF INSTRUMENTS ~ SUPPLIES FOR ASEPTIC SURGERY PROCEDURES

Surival surgical procedures on all mammalian species must be conducted using aseptic technique, which requires the use of sterile instruments and supplies. Many supplies such as gloves, surgical blades and suture materials are commerically available in sterile packs. However, it is frequently necessary to sterilize inhouse items such as surgical instruments, drapes, gowns, and instrumentation and catheters or chronic implants.

In considering methods for sterilization procedures, it is important to differentiate between sterilization and disinfection Sterilization kills all viable microorganisms while disinfection only reduces the number of viable microoranisms. High level disinfection will kill most vegetative microorganisms but will not kill the more resistant bacterial spores. Commonly used disinfectants such as alcohol, iodophors, quaternary ammonium and phenolic compounds are not effective sterilants and, therefore, are not acceptable for use on items intended to be used in survival surgical procedures.

The preferred methods of sterilization are high pressure/temperature (in autoclaves) for items that can withstand high temperature, and ethylene oxide gas for items that cannot withstand high temperature. However, cold chemical sterilants may be used effectively for many items. The following are approved sterilization procedures:

1. High pressure/temperature steam sterilization using an autoclave and appropriate monitoring systems to assure sterility. The Department of Comparative Medicine (DCM) will provide this service upon request at no charge.
   
2. Gas sterilization with ethylene oxide using an approved gas sterilizer and appropriate monitoring systems to assure sterility and personnel safety. DCM will provide this service upon request at a nominal charge.
   
3. Cold (chemical) sterilization used properly:
   • Effective and proper use of cold sterilization is dependent on many factors including:
     1. The use of chemicals classified as "sterilants." Those classified only as "disinfectants" are not adequate.
        
     2. The physical properties of the item being steri-lized. It must be relatively smooth, impervious to moisture, and be of a shape that permits all surfaces to be exposed to the sterilant.
        
     3. Exposure.
        
        • All surfaces, both interior and exterior, must be exposed to the sterilant. Tubing must be completely filled and the materials to be sterilized must be clean and arranged in the sterilant to assure total immersion.
          
        • The items being sterilized must be exposed to the sterilant for the prescribed period of time.
          
     4. Use of fresh solutions. The sterilant solution must be clean and fresh. Most sterilants come in solutions consisting of two parts that when added together form what is referred to as an "activated" solution. The shelf life of activated solutions is indicated in the instructions for commercial products. Generally this is from one to four weeks
        
     5. Rinsing chemically sterilized items. Instruments, implants and tubing (both inside and out) should be rinsed with sterile saline or sterile water prior to use to avoid tissue damage
        
   • There are many acceptable commercial sterilants available and their use is encouraged over making up solutions from basic ingredients. Only products classified as sterilants are to be used for sterilizing instruments and implants for surgery and they must be used according to the manufacturer's recommendations for sterilization.
   • The following chemicals classified as sterilants by the Centers for Disease Control (CDC).* Generally, these are the chemical ingredients of the commercial sterilants.
     
     1. Glutaraldehyde (2%) for a minimum of 10 hours.
        
     2. Formaldehyde (8%)-Alcohol (70%) solution for a minimum of 18 hours.
        
     3. Stablized hydrogen peroxide (6%) for a minimum of 6 hours.
        

   Discretion is required in using these agents to assure that they are compatible with the items being sterilized.

   The use of sterilization procedures other than those listed must be approved by the IACUC.

   *Simmons, Bryan P., "CDC Guidelines for the Prevention and Control of Nosocomial Infections: Guideline for Hospital Environmental Control" American Journal of Infection Control, 1983, Vol. II, No. 3, pages 97-120.

   
   
   

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