Optimal initial management of traumatic wounds can make an enormous difference to the end outcome. They are often a component of polytrauma and stabilising the animal takes priority even though the wound can be eye catching. Exceptions may include life threatening haemorrhage and open thorax or abdominal injury.
Early provision of analgesia and protection of the wound from contamination in the hospital is essential. Use of personal protective equipment (particularly gloves) and covering the wound with a clean material (eg fresh incontinence sheet, cling film) can minimise debris and bacteria being introduced to the wound surface.
Once the animal is stabilised, thorough patient assessment is required. A holistic approach to consider the possibility of concurrent pathology (such as pneumothorax, diaphragmatic rupture, urinary tract injury, fractures) and provision of supportive nursing care (for example enteral nutrition or managing expected recumbency) often means that a general anaesthetic or sedation for early treatment and appraisal of the wound is combined with imaging studies and consideration of central lines, feeding tubes and urinary catheters.
Pragmatically, even at this early stage, some thought should be given to the strategy for final closure of the wound to help an owner make decisions that they are emotionally and financially able to pursue. A large degloving injury of a limb with multiple complex fractures may be amputated to facilitate prompt and successful treatment if the possibility of orthopaedic surgery and then potentially several weeks of wound management with final reconstructive surgery are not conceivable.
Veterinary surgeons should temper their primal urge to primarily close a wound immediately because thorough decontamination is essential to reduce the risk of infection. Also, declaration of local tissue viability can take several days as a result of contusion, avulsion and vascular trauma. Once debris, bacteria and non-viable tissue has been removed from the wound, then more predictably successful surgical closure can be performed before or after granulation tissue develops (delayed primary and secondary closure respectively). That is not to suggest immediate closure is never successful if it is a recent clean wound (and ensuring that client expectations are appropriately managed, warning them of the risk of infection or dehiscence if skin subsequently declares itself ischaemic and non-viable) but more often, several days of repeated cleaning and debridement are required. Primary closure may be a pragmatic method to protect the underlying tissues and then monitoring tissue viability pending a definitive procedure (Figure 1).
An overlooked and valuable alternative is to facilitate the normal processes of tissue healing (second intention closure); however, this generally takes at least three to four weeks in healthy dogs and can be slower in cats or for very large wounds. Second intention closure is unlikely to be an option if a wound traverses a joint or is greater than approximately 50 percent the circumference of a limb, since contraction of the wound can impair function or act as a physiological tourniquet.
The aetiology of a wound influences the extent of injury and expected sequelae. Burns can result in deeper tissue damage than expected, especially over bony prominences. Lacerations are generally less contaminated than abrasions. Bite injuries are complicated by dramatic contusion, a potential for localised ischaemic necrosis that develops over subsequent days and considerably worse deeper tissue injury than tends to be visible on the skin. Bites over the abdomen and thorax should be carefully evaluated in case they enter a body cavity (Figure 2).
A standardised team approach
Adopting a largely standardised approach to wound management can help the clinical team to follow an appropriate well-evidenced routine and avoid inadvertent suboptimal treatment. All members of a team should be educated, empowered and encouraged to identify when a colleague forgets an important consideration (eg wearing gloves to handle a wound should be recognised to be as important as a break in aseptic technique in theatre).
- Wear gloves! – not necessarily sterile
- Protect the wound from the hospital environment: a clean incontinence sheet on the table or directly beneath a limb can be useful
- Cover the wound with water-soluble gel (eg sterile sachets of lubricant)
- Clip widely. Limbs should be clipped circumferentially and all of the area that is expected to finally be bandaged should be clipped. Haired skin carries three times the bacterial load and including this underneath a dressing increases contamination and the risk of subsequent infection
- Clean skin around the wound with chlorhexidine skin preparation (or similar) as if for a surgical procedure. Aseptic preparation of the peri-wound decreases bacterial load and a source of potential future infection (exactly the same as for a surgically created incision)
- Change gloves/incontinence sheet/towel
- Heavily contaminated wounds can first be showered with tepid tap water if necessary. Large volume dilution is the key to wound decontamination rather than the type of fluid
- Flush wound with 1l of sterile Hartmann’s solution (more for larger wounds) using either:
- A fluid bag attached to a giving set and a three-way tap with a 20ml syringe and 21G needle (Figure 3)
- A fluid bag inside a pressure infusion cuff (pumped up to maximum pressure) attached to a giving set and a 21G needle screwed on to the end. This “hose” system achieves optimal fluid lavage pressure and avoids the clinician getting bored with using a syringe and stopping before a suitable volume is applied
- Considerable recent and ongoing research into novel wound lavage solutions (largely driven by a need to find alternatives to systemic antimicrobial therapy) is yielding interesting results. Hypochlorous acid can be an effective bactericidal agent and probably has no negative effects on wound healing. The duration of efficacy of hypochlorous acid preparations (once opened) varies between brands
- Consider collecting swabs/tissue samples for bacteriology. Start antibiotics after sample collection if there is concern regarding bacterial contamination or evidence of infection and choose a broad-spectrum drug until culture/sensitivity results are obtained (eg potentiated amoxicillin). Topical wound cytology to determine the bacterial cellular morphology can be extremely useful and is very cost effective; rods or cocci can help determine which systemic and topical antimicrobial and bactericidal agents are more likely to be effective (and improve antimicrobial stewardship)
Removal of dead tissue is vital for progression of normal wound healing. This can be performed by:
- Sharp selective surgical removal of dead or contaminated tissue, being careful to preserve vital anatomy (nerves, tendons, ligaments)
- Mechanical debridement using dressings (eg wet-to-dry) to tear off debris and dead tissue that sticks to the dressings when changed daily. This is non-selective but very effective, particularly for small particulate debris
- Autolytic debridement, using dressings to maintain a moist environment that facilitates the body’s natural debridement process and lavage away the debris during dressing change
- Enzymatic (rare): proteolytic enzymes applied to the wound surface
- Biosurgical (uncommon): biological grade maggots, five to eight per cm2, that remove necrotic tissue, disinfect the wound and promote granulation tissue
Initially, sharp debridement under general anaesthesia is often performed in the prep room, wearing sterile gloves and a scrub top (not necessarily full gown, etc). Unless necrotising fasciitis is suspected, only clearly devitalised tissue is generally cut away. If in doubt, leave questionable tissue and it will declare its viability in subsequent days and can then be removed (staged debridement). Topical wound dressings are then applied and secured using a bandage, if delayed surgical management or second intention healing is planned.
Optimal treatment of a wound at initial presentation is essential to reduce topical contamination (from the injury or the hospital environment) thereby minimising the risk of infection, delayed wound healing, patient morbidity and cost. The most common and easily avoided breaches in wound care are failure to wear gloves, not clipping enough hair off and using insufficient volumes of lavage fluid. These are cheap, easy and simple considerations that make the world of difference in daily wound management.