Many of us overuse antibiotics postoperatively, which can lead to side effects, such as vomiting and diarrhea, and antibiotic resistance in our patients.
There are, however, many other ways to reduce the infection rate in surgical patients. In human surgery, such practices have enabled a 25 percent reduction in nosocomial infections, also called hospital-acquired infections.
The standard for most elective procedures is to give an intravenous antibiotic such as cefazolin 30 minutes before the skin incision, and every 90 minutes under anesthesia. Specific procedures (e.g. colorectal surgery) may require specific antibiotics.
Beyond antibiotics, there are a number of ways to prevent infections.
Good oxygenation of the patient allows killing of bacteria via oxidative processes. Preoxygenation and short-term postoperative oxygenation can therefore be beneficial to fight surgical site infection.
There are other obvious benefits, especially for patients with cardiac or respiratory diseases and brachycephalic patients who will also benefit from postoperative oxygenation.
Enhancing oxygenation also requires good perfusion, which entails giving IV fluids. In most healthy stable patients, lactated Ringer’s solution is administered at 10 ml/kg/hr. We have all experienced the seemingly stable patient undergoing a the most “routine” procedure, such as a spay or a neuter, suddenly having anesthetic complications. IV catheters provide immediate access to a vein to administer emergency drugs—in other words, an IV catheter could save a life.
Control Body Temps
Many studies show that hypothermia is a common cause of infection. Hypothermia causes peripheral vasoconstriction and therefore poor local oxygenation.
Using a fluid pump helps maintain patient perfusion before, during and after surgery
Hypothermia also decreases the patient’s immunity, among other deleterious effects.
Several ways to limit hypothermia include warm-water heating pads covered by a towel, IV fluid warmers, forced-air warming blankets (e.g. Bair Hugger) and covering the patient’s feet (LW Cabell et al., “The effects of active peripheral skin warming on perioperative hypothermia in dogs.” Vet Surg. 1997, Vol. 26, N. 2, p. 79-85).
Control Blood Sugar
Hyperglycemia can also potentiate infections. Glycemia should therefore be monitored closely, especially in poorly regulated diabetic patients, which are at increased risk of infection.
Even non-diabetic pets can become hyperglycemic. These patients should be given the benefit of insulin as needed.
Reduce Anesthesia Time
Duration of anesthesia is statistically correlated to the infection rate. Every additional minute under anesthesia increases the risk of infection by 0.5 percent (MW Beal et al., “The effects of perioperative hypothermia and the duration of anesthesia on postoperative wound infection rate in clean wounds: a retrospective study.” Vet Surg. 2000, Vol. 29, N. 2, p. 123-127).
In other words, each additional hour under anesthesia raises the risk of infection by 30 percent.
Remember that the time under anesthesia can be much longer than the duration of surgery, when you add the time it takes to place an IV catheter, clip hair, take radiographs, position the patient on the surgery table, scrub the skin and patiently wait for the surgeon.
Quickly flushing and debriding grossly contaminated wounds will help minimize later infectious complications.
Technicians play a critical role in minimizing the duration of anesthesia and should also take actions to reduce anesthetic duration.
In a progressive hospital, each one of the above steps could be discussed during a staff meeting to devise ways to shorten the total time under anesthesia.
Here are additional ways to ward off infection without antibiotics:
- Prevent licking or chewing of surgical incisions using an Elizabethan collar or Bite-Not collar.
- Perform sterile IV catheter placement, conscientious patient clipping (i.e., wide enough) and meticulous scrubbing technique.
- Improve the nutritional status of debilitated patients.
- Have constant awareness of asepsis during scrubbing, gowning, gloving and throughout surgery. Actually wearing a gown, cap and mask happens to be standard protocol, just like actually wearing clothes! Wearing booties could be considered optional, if not debatable.
- Convert contaminated wounds into “clean contaminated” or cleaner wounds as soon as possible.
- Avoid elective surgery on immuno-suppressed or immuno-deficient patients, for example, because of steroids or chemotherapy.
- Use gentle tissue manipulation and careful tissue apposition to decrease the risk of hematomas or seromas.
- Treat distant infections such as dermatitis, otitis externa or tooth abscesses if possible before elective surgery.
- Change gloves whenever they are contaminated or perforated. The first step is to be honest with yourself.
- Avoid clipping the patient too long before surgery. Microtrauma by the clippers facilitates entry of bacteria into the skin and triples the risk of incisional infection.
- Limit the use of propofol, which has been associated with a four-fold increase in surgical site infection.
- Avoid dental prophylaxis on the same day as an elective surgery (especially orthopedic). The risk of bacteremia and surgical site infection are well established.
- Meticulously clean the operating room, including the surgical lights and the table. Some veterinarians hide silver dollars in conspicuous places as an incentive!
- Use sharp, good-quality, sterile instruments.
- Establish a comprehensive plan to prevent nosocomial diseases, starting with frequent hand washing, especially after treating each patient. This plan should be implemented by the entire staff—doctors, technicians, technician assistants and kennel helpers. The most perfect plan is only as perfect as its weakest link.
Dr. Zeltzman is a board-certified small-animal surgeon at Valley Central Veterinary Referral Center in Whitehall, Pa. His website is www.drphilzeltzman