The surgeon’s role in wound healing - Veterinary Practice
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The surgeon’s role in wound healing

ROBIN FEARON reports on a session at the London Vet Show in which delegates were advised that if they stick to basic surgical principles and medical treatments there are few wounds that will not heal well

WOUND healing is one of the bugbears of veterinary surgery. Patients who heal slowly or have infected wounds test the patience of even the most experienced practitioner.

So it was refreshing to hear Gert ter Haar, senior small animal surgery lecturer at the RVC, give a no-nonsense approach to healing. Evidence based literature reveals little about controlling wounds, said Gert, so his approach relies on method, adhering to general principles of surgery and wound management, rather than investing in specialist equipment, bandages or topical medication.

Whether wounds are surgical or accidental, the most common complication is delayed healing. Either individual patients do not heal well or have complications caused by predisposing factors such as diabetes, old age or infection.

“There are no magic tricks,” he said. “When we know how long a normal wound takes to heal then we know when to intervene.”

Surgeons inevitably hope wounds will heal rapidly without granulation tissue formation and get upset when wounds open up and they have to wait for second intention healing, said Gert. “Second intention healing is the body’s normal response to injury. Wounds that are not sutured by a surgeon will heal, it just takes longer.”

The entire process of inflammation, debridement, repair through granulation tissue formation, contraction and epithelialisation inevitably takes weeks. “How many would wait three weeks before you intervene?” asked Gert. “How many would start getting nervous within two or three days? It is completely normal, it just takes that long.

“If there are problems in one of those phases then we have to realise that it takes longer. Just explain it to the owner, be frank with them.”

Inter vene too soon at the inf lammator y phase, when the body is combatting infection, and the immune response can be interrupted. “Without those inflammatory cells we get infected wounds,” said Gert. “Let them do their work.”

Using antibiotics during granulation tissue formation is unnecessary. “Most do not need anything and topical medicines will definitely decrease the rate of granulation tissue formation,” he said. “Once you have granulation tissue then you are quite sure things will go right: it will lead to normal wound contraction and epithelialisation from the edges.”

Unfortunately, most clinicians do intervene too soon, he said. Surgeons are not patient people and they like to close patients up and send them home quickly. “When we do have a problematic wound, we want it to be solved within two or three days and of course that is not going to happen. No matter how brilliant a surgeon or hospital is, some things you cannot change.”

Six steps to success

Observe William Halsted’s six steps in the principles of surgery and most complications disappear. “Work aseptically, be gentle with the tissues, avoid damage to the blood supply and any tissues that we leave in the body and healing will be successful,” he said. “Avoid dead space formation and, finally, avoid tension on the tissues.”

Primarily, the surgeon is the main factor affecting wound healing. Surgical trauma creates complications and potential infection. “The surgeon’s experience is important and mainly because we know that anaesthetic duration and the surgery itself are the main factors in whether or not we get wound infection. Surgeries that take too long will become infected.”

Assess the patient’s medical condition and if the patient is prone to wound complications then address those problems. Anaemia or hypervolaemia affect clot formation in the inflammatory phase. Chronic endocrine disease, kidney disease and Cushing’s disease decrease granulation tissue formation and slow down epithelialisation.

Any neoplastic disease in the wound delays healing, but also drug therapies, cytotoxic drugs, corticosteroids, nonsteroidal anti-inflammatories, even vitamins and minerals affect the process. Address these factors, treat disease with care and problems are minimised, said Gert.

Using topical stimulants to promote healing can appear attractive, he said, and there is some impact, yet: “At this stage I cannot recommend them. There is not a lot of evidence to suggest that it is better at promoting good healing and it is expensive.”

What surgeons dread most of all is infected wounds, said Gert. But contaminated wounds do not necessarily mean infection. For that to happen bacteria must multiply inside the wound and this occurs in less than 5% of normal wounds.

“The most important factor influencing infection is contamination of the tissues at the time of surgery or trauma,” he said. “We should then examine how much tissue damage there is. If we have less wound contamination but lots of necrotic tissue and poor blood supply, that is a disaster waiting to happen.”

Traumatic and open wounds require a fast response to avoid infection. Road traffic accident wounds are often contaminated and marked by abrasions where animals have been dragged.

Older wounds that look necrotic or infected, where the injury took place at least a day ago, also need a different approach.

Whenever you are in doubt, treat it like an infected wound, he said. “There is nothing wrong with waiting for a day or more before doing an invasive procedure. Make sure you know what type of wound you are dealing with.”

On the question of using antibiotics, he said that for normal surgeries there is no reason to use them unless surgery takes a long time. “Use them as prophylaxis only, it does not mean that you need to continue treating with antibiotics. When there is a low infection risk it can make matters worse, delay healing and cause antibiotic resistance. Don’t overdo it.”

Ultimately there is no single product that can help tackle all infected wounds. Best principles – removing necrotic tissue and foreign material, careful handling, lavaging and applying drains where necessary – should be adhered to.

Finally, he said, avoid wounds reopening by avoiding tension when suturing. An animal should be able to cough or go to the toilet without it popping open.

Reliance on tension-reducing sutures is a surgical cul-de-sac. “Assess the tension and when you have doubts use a tension relieving technique but do not rely on your suture material for that.”

Healing takes time, he concluded, and all surgeons can do in the meantime is make sure that the underlying tissues are healthy. “Be patient, use second intention healing and your patients will be fine.”

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