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Principles of Operative Technique

Proper surgical technique is important to prevent wound infection, promote wound healing, and ensure likelihood of a satisfactory outcome to the surgical procedure.

"GOOD" SURGICAL TECHNIQUE INCLUDES:

  • asepsis, asepsis, asepsis
  • gentle tissue handling
  • effective hemostasis
  • maintenance of sufficient blood supply to tissues
  • proper use of surgical instruments
  • accurate tissue apposition
  • appropriate use of monitoring equipment
  • support of vital organ functions
  • expeditious performance of the surgical procedure

"Asepsis is a chain which is only as strong as its weakest link." Aseptic technique is required at all times and all team members are responsible for monitoring for breaks in aseptic technique. Potential sources of contamination include the team members, the patient, all articles used in the procedure, the surgical room or area, and other personnel entering the surgical area.

BASIC ASEPTIC PRINCIPLES

  • All articles must be sterilized before use in procedure.
  • If in doubt about sterility of item or person, it is not!
  • All persons who touch sterile articles must be sterile.
  • Non-sterile persons never reach across a sterile field.
  • Draped tables are sterile only above the table level.
  • Gown front is sterile only from waist to shoulder level.
  • Moisture causes contamination.

Gentle handling of tissues will help minimize postsurgical pain. Tissues should not be cut or separated without reason and tissue dissection is usually done along fascial planes. Exposed tissue must be protected from drying or contamination.

Effective hemostasis and maintenance of blood supply allows visualization of the surgical field while preserving the total blood volume. Hemostasis is achieved by ligation, pressure, electrocoagulation and avoiding damage to major vessels. Only the vessel to be occluded should be incorporated in a ligature or clip. In using electrocoagulation, a high frequency current is applied to a small area of tissue (the bleeding vessel) and electric energy is converted to heat, resulting in coagulation of tissue and sealing of the vessel. To avoid excessive tissue damage, only the vessel to be occluded is in contact with the electrode. Electrocoagulation can be used for minor hemorrhage; large vessels should be ligated.

Proper use of surgical instruments minimizes trauma. For example, vascular forceps are used to occlude blood vessels when flow is to be reestablished; hemostatic forceps, which crush, are applied to vessels through which blood will no longer flow.

Accurate tissue apposition enhances healing and promotes rapid return to normal function. Retraction and dissection of tissue can produce pockets known as dead space. Dead space can delay healing and serve as a site for bacterial growth and fluid accumulation. As tissues are returned to their normal positions, dead space needs to be obliterated by careful suture placement to appose tissue and/or placement of drains to prevent fluid accumulation. Tissues are replaced to their normal anatomic positions with minimal amount of tension by sutures to prevent tissue devitalization. Type of suture material and pattern to be used will be dictated by the tissue involved and forces applied to those tissues.

Behavior of animals also might influence the choices; some animals are more prone to chew or remove certain types of suture materials or devices such as surgical staples. Because physicians normally work with cooperative human patients, they must re-evaluate surgical materials and methods to be used with animals.

Most animals will be fully mobile within 12 hours after a surgical procedure and the incision line must be able to withstand the twisting, bending, and stretching which will occur!

Intraoperative patient support and monitoring - Accepted medical and veterinary surgical practice requires assessment of the physiologic status of the animal on a regular basis. Vital time for resuscitation can be lost by failure to notice life threatening physiologic or metabolic problems.

The degree of monitoring sophistication depends on the species, the extent and duration of the surgical procedure, and whether it is a survival or terminal procedure. Monitoring can be qualitative, using the anesthetist's sense of touch, sight and hearing to evaluate the patient; or quantitative, using instruments for periodic measurement of specific vital organ performance.

The anesthetic record provides a detailed account of the course of anesthesia and intraoperative events, Blank record forms are available from the Office of Veterinary Resources. Whether you use one of these forms, or one of your own design, it is important to record data from the pre-operative period, the induction period, the anesthetic/surgical period and the immediate post-operative period. Later measurements may be written on the individual animal's chart.

Support of vital organ functions is an integral part of any surgical protocol. Many devices are available but they may not be practical or applicable for all species.

  1. Body temperature - This can be measured via rectal or esophageal thermometers. Every effort should be made to combat hypothermia by use of circulating warm water blankets, warm water bottles, heat lamps, or application of insulating materials such as drapes.
  2. Respiratory system support - This can be as simple as appropriate positioning of the animal to ensure an unobstructed airway, endotracheal intubation, or providing supplemental oxygen.
  3. Cardiovascular function - A variety of techniques may be used for assessment: capillary refill time, heart rate monitoring, Doppler Flow probes, EKG, palpation of pulse, and use of esophageal or conventional stethoscopes.
  4. Cardiovascular support - includes fluid therapy and availability of defibrillators (if necessary) and cardioactive drugs.
  5. Hydration Status - Monitoring rate and amount of urine production, as well as subjective assessment of blood loss, and capillary refill time of the oral mucus membranes can indicate adequacy of fluid volume. There are many possible choices for fluid replacement, but normal (0.9%) saline or balanced electrolyte solutions such as lactated Ringer's are common. Intravenous (IV) administered fluid therapy is best for larger animal species, but can be difficult in smaller animals; Subcutaneous (SQ) or Intraperitoneal (IP) fluids may be appropriate for these species. Warming fluids is recommended.

Required Components of a Perioperative Record:

  1. presurgical body temperature measurements
  2. periodic heart rate, respiratory rate
  3. time that drugs or medications were administered
  4. dosage and route for these drugs or medications
  5. any noted responses to the drugs or medications
  6. initials of person who administered drugs


References used for this module:

  • APPLYING PRINCIPLES OF ASEPTIC SURGERY TO RODENTS. T.C. Cunliffe-Beamer. AWIC Newsletter, Vol. 4, No. 2, Apr-June 1993.
  • SPECIAL REPORT Guidelines for animal surgery in research and teaching. Brown, M.J., Pearson P.T., and F.N. Tomson. Am J Vet Res, Vol. 54, No. 9, Sept. 1993.
  • THE DEA: FOLLOWING ITS "10 COMMANDMENTS", JAVMA, Vol 205, No. 10, Nov. 15, 1994
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