Aseptic techniques must be used when performing survival surgery. This requires the use of procedures to prevent the introduction of pathogenic organisms. To perform aseptic surgery, appropriate facilities, sterile instruments, trained and properly garbed personnel, pre-operative preparation of the patient, and adherence to the principles of asepsis throughout the surgery are required. Following any survival surgery, it is necessary to assure post-operative complications are addressed promptly. Record keeping to detail anesthesia, surgery, and post-operative care are required and become part of the animal’s individual health record. References provided are not intended to be comprehensive, but rather to introduce readers to several sources for additional information.

The Guide suggests that for most surgical programs, the functional components of an aseptic surgery area should include areas for surgical support, animal preparation, surgeon’s scrub, operating room, and postoperative recovery. Separation of functional areas is best achieved by physical barriers, although it might be possible to achieve separation by timing activities and appropriate cleaning/disinfection between these activities. Below is a list of facilities, facility feature, and equipment necessary to support aseptic surgery involving nonhuman primates:

• Single-use operating room with limited access

• Ventilation to surgery rooms should be positive to surrounding areas

• Surgical lights that can be focused on the patient from two directions

• Numerous electrical outlets

• Minimal nonessential equipment and storage in the operating area to allow for easy clean-up and thorough sanitization

• Separate surgical pack preparation/sterilization area with steam sterilizer

• Surgeon’s prep area with foot, knee or electric eye surgical sinks (usually separate from the storage and pack prep area)

• Patient prep area (containing oxygen source, sink, clippers, vacuum cleaner, suction set-up, anesthesia supplies, and drug storage cabinet)

• Dressing room area or multipurpose room that can be used for personnel to change clothes

• Adjustable-height surgical tables, kick buckets, vacuum lines for suction

• Oxygen source, either in-line and serviced from a central location, or from individual compressed gas tanks

• IV stands, IV fluid warming units, circulating warm water or air blankets

• Inhalant anesthetic machine with exhaust gas scavenging device

• Anesthesia monitoring equipment such as pulse oximeter, capnometer, arterial blood pressure, rectal temperature, and ECG

• Post-operative recovery room that allows close patient monitoring without physically disturbing them, with the capability to increase ambient room temperature or provide safe supplemental heat sources for animals in recovery cages

Surgeon and assistant (if necessary). Proper surgical attire includes scrub clothes, eye protection, disposable cap, and mask. Watches, jewelry, and nail polish should be removed beforehand. A surgical scrub using a povidine-iodine scrub solution or chlorhexidine scrub solution should be performed. These solutions are usually provided in sterile packages containing a plastic scrub brush and nail cleaner. First, the area under each nail is inspected and cleaned with the nail cleaner. The scrub is performed by starting at the fingertips under the nails and working toward the hand and forearm to include the elbow. Each surface is scrubbed a minimum of 10 times, rinsed and repeated for a total of three times on each hand and arm, and for a minimum of 10 minutes. The hands are then dried on a sterile towel, which is usually provided with the gown. Gowns are often packed inside-out to allow the surgeon to pick-up and put on the gown without touching the outside surfaces that are to remain sterile. Sterile surgical gloves must be put on in a manner to prevent contamination of the surgical gown, and several techniques may be used according to the surgeon’s preference and availability of personnel to assist them. Once the gowns and gloves are on, the hands should be kept above the waist and in sight at all times. If powdered gloves are used, the powder should be wiped off with a sterile cotton gauze sponge and sterile saline prior to starting surgery. Surgeons and their assistants must be vigilant about not handling or coming into contact with any nonsterile item or surface throughout the operation.

Person administering anesthesia. Attire includes scrub clothes, eye protection, cap, mask, and examination gloves. If this is the same person who preps the animal pre-operatively, he/she should wear a lab coat or disposable isolation gown over his/her scrub clothes while clipping and handling the animal outside the surgery room. This outer wear is discarded before the animal is prepped in the surgery room.

Circulating personnel. Attire is the same as for the person administering anesthesia. Assistants who must provide equipment and supplies to surgeon’s must utilize techniques to ensure that the operating field and instrument table remain sterile throughout the operation.

Nonhuman primates undergoing surgery require a pre-operative assessment that includes evaluation for the anesthetic, analgesic, and any prophylactic medication requirements. A veterinarian who has experience with nonhuman primates should be consulted by the investigative staff planning experimental surgeries to ensure that animals are appropriately prepared. Personnel supporting the surgery need to be aware of the type of preparation required on the animal, the position required during surgery, the types of anesthetic, analgesics, and other drugs that are to be administered, and surgical instrumentation to be used. If special equipment is needed either for the surgery or supporting the animal during the procedure, staff need to know how to use it and it should be available for use.

• Pre-anesthesia preparation (see previous section).

• Endotracheal intubation (see previous section).

• The surgical site must be clipped sufficiently to ensure that contamination will not occur intra operatively. One should avoid unnecessarily removing too much hair on small animals because hypothermia can result.

• Pre-operative antibiotics and analgesics should be given after consultation with a veterinarian experienced with nonhuman primates.

• IV catheterization should be performed to permit the administration of parenteral fluids and facilitate emergency treatment. Usually, the cephalic or saphenous veins are used.

• The animal is positioned appropriately on the surgery table, and anesthesia monitoring devices such as ECG, thermometer, pulse oximeter, etc., are put in place prior to initiation of the procedure.]

• When electro surgical devices are to be used, it is necessary to make sure that there is good contact between the animal’s skin and the grounding devices. Electro surgical gels for this specific purpose are available. One should not substitute ultrasound or ECG gels. Severe thermal burns can result from improper grounding of electro surgical devices.

Surgical instruments and drapes must be sterilized pre-operatively. Various methods of sterilization are available, and whichever method is used, one should implement appropriate quality assurance methods to ensure that sterilization is consistently achieved.

Steam sterilization (250 F, with the time dependent on the type of pack being sterilized) is a very dependable method. Sterilization by this method depends on the ability of the steam to reach the items to be sterilized. Pressure steam sterilizers and vacuum steam sterilizers are commonly used for sterilizing surgical instruments. Each of these units is a type of autoclave, because the door of the sterilization chamber is held closed by the pressure within the chamber. They differ in the method that is used to evacuate the air from the sterilization chamber. Pressure steam sterilizers often utilize gravity to displace air from the chamber, while a vacuum is used in vacuum steam sterilizers. The disadvantage of steam sterilization is that fine instrument, devices that cannot be disassembled for adequate penetration by the steam, and many heat-sensitive synthetic materials cannot be sterilized using steam.

Ethylene dioxide gas sterilization is safe for nearly all types of materials; however, it is flammable and explosive except when mixed with carbon dioxide. Consequently, it is expensive to maintain sterilizers that utilize this method of sterilization and a high volume of sterilization must be done to offset their cost. Research facilities often arrange to have their sterilization done through formal contractual agreements. This method of sterilization is especially useful for sterilization of items that cannot tolerate steam sterilization. Pre-planning is necessary when utilizing ethylene dioxide sterilization because sterilization cycles require many hours and equipment may not be available for quick turnaround or surgeries scheduled on short notice. For this reason, ethylene dioxide should not be relied upon as a sole method of sterilization.

Liquid sterilants such as 2% glutaraldehyde (Cidexplus, Advanced Sterilization Products, Irvine, CA) can be used for specific equipment, but should not be routinely relied upon as the sole method of sterilization for most surgical instruments. Instruments treated with liquid sterilants must be thoroughly rinsed with sterile irrigation saline prior to use.

Gamma-irradiation is another sterilization method used by some facilities. It is usually used for pharmaceuticals and hospital and surgical materials that are heat sensitive.

Once the animal is moved into the surgery room, it is necessary to prepare the surgical site for surgery. This involves the use of the aseptic techniques described below. Surgeons and all operating room personnel should be trained and should adhere to aseptic technique rigorously throughout the surgery.

To prevent the introduction of pathogenic organisms during a surgical procedure, the surgical site on the patient must be prepared by cleansing and disinfecting the skin. Aseptic technique involves disinfection of the area to reduce any pathogens present. This includes the application of an antiseptic to inhibit or prevent the growth of bacteria during surgery after the site is disinfected, and the utilization of techniques to prevent contamination by microorganisms of the site.

The attendant doing the preparation should wear scrub clothes, cap, mask, protective eyewear, and gloves. Surgical preparation of the patient involves scrubbing in a circular pattern, starting at the center of the intended incision site and gradually working outward, never going back over the previously scrubbed area (Figure 4.12). A povidone-iodine based scrub solution diluted with sterile irrigation saline and applied with sterile cotton gauze sponges should be used. New sponges should be used for each scrub cycle. After each scrub, 70% ethyl alcohol is applied in the same circular, concentric manner as used for the scrub. The area is cleansed a minimum of three times and then povidone-iodine antiseptic solution is applied to the surgical site and allowed to dry prior to surgery. To reduce patient hypothermia, the amount of saline and alcohol that are used during the scrub should be kept to a minimum.

Sterile surgical drapes are used to prevent contamination of the surgical site by contact with nonsterile areas, persons, and instruments. These may be disposable drapes with an adhesive strip on them or reusable towels. If towel clamps. A fenestrated sterile drape is used (over the disposable adhesive drapes or towels) to isolate the surgical site from nonsterile areas.

Anesthesia monitoring during surgery is usually performed by technical support personnel with special training in veterinary anesthesia. In addition, a veterinarian with experience in nonhuman primate anesthesia should be available to assist the support personnel when surgeries on nonhuman primates are scheduled. Monitoring parameters and methods have been previously outlined in Table 4.6. Additional information can be obtained from the references.

Post-operative care begins when the surgery ends and concludes when the surgical incision is healed. Patient monitoring during the immediate recovery period (from the end of surgery until the patient regains consciousness) is similar to that used intra-operatively. Fewer parameters can be monitored once the animal is extubated and placed into a recovery cage.

Temperature, pulse, rate, and respiratory rate

Mucous membrane color and capillary refill time

Return of reflexes, including withdrawal (pedal), palpebral, shivering, jawtone, and gag

Additional information regarding post-surgical considerations is provided for readers in the references.

Parameters monitored should be recorded until the animal is conscious. Once the animal is able to move around normally, it can be returned to the home cage, although group housed nonhuman primates should remain singly housed until the veterinarian releases them to return to their group. Inspection of animals should occur daily and the veterinarian should examine any animals that appear sick, painful, do not eat, or have unusual redness, swelling, or discharge from the surgical incision. Post-operative records should indicate the date, an assessment of the animal’s behavior, appetite, fecal output, hydration, and the condition of the incision site, and all treatments. In cases in which the investigative staff may be administering treatments, it is important that the veterinarian communicate regularly with these staff and that records be assessable for examination by all. Post-operative records are complete when the incisions are healed, sutures have been removed, and animals are ready to return to group housing, if appropriate.

Euthanasia is the act of inducing a humane death in an animal. The American Veterinary Medical Association (AVMA) has published recommended methods of euthanasia for animals, including nonhuman primates. Nonhuman primates are usually sedated with an anesthetic such as ketamine and subsequently euthanized via intravenous administration of a saturated sodium pentobarbital solution. For some research applications, to preserve tissues for histological examination or other in vitro techniques, it may be necessary to anesthetize the animal with an injectable anesthetic such as sodium pentobarbital to the perfuse the animal’s tissues. In either case, both methods are approved by the AVMA.