Traumatic wounds and injuries to the skin and its underlying subcutaneous tissues, muscles and bone structures are very common conditions observed and treated in veterinary medicine. A wound is a disruption of the normal continuity of body structure. Wounding may cause injury to structures underlying and collateral to the skin (Waldron and Zimmerman, 2003).
Initial stabilisation and treatment of wounds aims as much as possible to restore the normal anatomical continuity to a damaged area of tissue. By providing prompt patient triage, wound assessments and facilitation of first aid care it is possible to enhance healing and prevent further complications. With multiple factors required by the body to engage optimal healing processes, careful attention to wound management will help to ensure the best patient outcome.
Triage of the trauma patient
For any patient presenting with trauma, the initial physical examination or primary survey and assessment needs to be undertaken with a rapid and systematic approach, which will at times require multiple assessments simultaneously (Figure 1). The primary survey, or broad sweep assessment, is where the most immediate life threatening concerns and overall patient stability are addressed before focusing on wounds. While it is easy to be completely overwhelmed when a patient presents with multiple injuries and systemic failures, it is important to observe one of the most fundamental elements of treatment, A-B-C (Airways, Breathing, Circulation). If any part of the A-B-C survey is not intact, such as with a major haemorrhaging wound, the primary survey should be stopped and complications addressed.
Recording baseline temperature, heart rate, pulse quality, respiratory rate and effort, mucus membrane status, and blood pressure should also be addressed as soon as practicable, to ensure ongoing monitoring of progression or regression in the emergent, at risk patient. Gathering vital information assists in tailoring and implementing a patient specific care plan, where the use of oxygen therapy, fluid therapy resuscitation, analgesia, blood products and assistance with patient thermoregulation will be considered.
The importance of pain assessment and analgesia administration in patient stabilisation should never be underestimated. Ideally pain management is most effective when instituted prior to the painful event (Dahl and Kehlet, 2014); however, patients presenting with a traumatic injury are not afforded this luxury. Subsequent untreated pain causes immediate changes in the neurohormonal axis, which in turn causes restlessness, agitation, increased heart and respiratory rates, fever, and blood pressure fluctuations, all of which are detrimental to the healing and outcome of the animal (Ford and Mazzaferro, 2006). Analgesics should be administered as soon as practicable to improve patient comfort and safety, as well as reduce the risk of patient morbidity and mortality (Gurney, 2012).
Once stabilisation of the patient has been achieved and appropriate pain management has been implemented, orthopaedic, neurological, thoracic, abdominal and wound assessments can commence.
Heamorrhaging wounds
Some wounds such as lacerations have minor bleeding or haemorrhage that requires an immediate bandage until definitive care can be provided. The pressure bandage serves to control haemorrhage but should not be left on for long periods. Pressure bandages that have been left on for too long can impair nerve function and lead to tissue necrosis and slough. Therefore, pressure bandages should be used in hospital only, so that the patient can be observed closely (Ford and Mazzaferro, 2006). Unfortunately measuring of bandage pressures in a clinical setting is impractical, so to reduce the risk of vascular occlusion the bandage pressure must be evenly distributed over the bandaged area. The third phalanges of the central two toes are almost always left exposed. The toes serve as a monitor of blood flow beneath the bandage (Miller, 2003). Check for patient discomfort, swelling, hypothermia, dryness or odour, which may indicate that the area has been bandaged too tightly (Campbell, 2006).
First aid treatment of wounds
Once the patient is stable, further wound assessment and application of a dressing or bandage will assist in providing protection, and stability to any fracture sites, while reducing further tissue damage, secondary pain and inflammation. To help preserve vital tissues, it is important to follow basic initial wound care to help promote optimal conditions for wound healing. Primary considerations of wound first aid are to maintain wound surface moisture and prevent further wound contamination. Before dressing the wound, any large, gross contaminants (e.g. leaves, rocks and stick fragments) should be removed using sterile surgical instruments. Do not attempt to clip the hair or cleanse the wound at this point.
There is growing concern about antibiotic resistant Staphylococcus spp. bacteria such as meticillin-resistant Staphylococcus pseudintermedius (MRSP), meticillin-resistant S. intermedius (MRSI) as well as a number of different strains of meticillin-resistant S. aureus (MRSA) that have been shown to affect animals (Loeffler and Lloyd, 2010; Vincze et al, 2014). All of these bacterial strains are of some zoonotic concern and pose a significant risk to human health since treatment options are scarce without effective antibiotics to call on. As such, it is important to lightly cover wounds in sterile dressings as soon as possible to protect them from contamination in the hospital environment. It is also imperative to follow strict hygiene protocols and aseptic technique around all wound care to prevent spread of potentially zoonotic strains of resistant bacteria (Monnet, 2008).
Wounds initially should be covered with sterile, non-adherent dressings and secured with a light bandage (Creedon and Davis, 2012). A thorough wound lavage should be left until appropriate analgesia has been administered or the patient is sedated or anesthetised. Any wounds that are over 8 hours old should be swabbed for culture. This is usually done after an initial flush is performed to remove surface contaminants and the sample is taken from deep in the wound (Monnet, 2008).
Wound assessment, classification, and closure
Successful reconstruction of any wound requires careful planning before any decisions can be made regarding open wound management or surgical closure. Evaluation of the patient allows consideration of a variety of modalities used in wound healing, antibiotics, dressings, pain control and sedation, to wound decontamination, debridement techniques and wound closure. Wound assessment and classification takes into account various factors resulting in the overall outcome and treatment of a traumatic wound (Table 1).
| Wound Classification | Criteria (one or more) | Closure option | Wound management |
|---|---|---|---|
| Clean | Non traumatic; elective/surgical wound; no inflammation encountered; respiratory, alimentary, genitourinary tracts not entered; no break in technique | Primary closure | Immediate closure without tension. May require an appropriate flap or grafting technique |
| Clean contaminated | Gastrointestinal, or respiratory tracts entered without significant spillage; oropharynx entered; vagina entered; genitourinary tract entered; biliary tract entered in absence of infected bile; minor break in technique | Delayed primary closure | Lavage and debridement of open wound. Appropriate dressing used. Closure performed 2–3 days after wounding. May require an appropriate flap or grafting technique |
| Contaminated | Gross spillage from gastrointestinal tract; traumatic wound fresh (<4 hours after trauma); entrance into genitourinary tract or biliary tract in presence of infected urine or bile; major break in technique | Secondary closure | Lavage and debridement of open wound. Appropriate dressing used. Closure carried out 5–7 days after wounding. May require an appropriate flap or grafting technique |
| Dirty/infected | Acute bacterial infection encountered; transection of clean tissues for the purpose of surgical access to a collection of pus; traumatic wound with retained devitalised tissue, foreign bodies, faecal contamination and/or delayed treatment (>4 hours after trauma) | Second intention healing | Lavage and debridement of open wound. Appropriate dressing used. Allowed to heal by granulation, contraction and epithelialisation |
Through wound lavage (Figure 2) and debridement a decision is then required on the most appropriate form of closure for the patient. Wound closures fall into three categories, primary, secondary and nonsurgical closure.
Preparation of the surgical site
The skin and hair on animals provides a bacterial breeding ground within the superficial cornified layers and glands of the skin and subcutaneous tissue. Hair removal is best undertaken using well maintained, clean clippers with a size 40 clipper blade using a gentle technique. Razors or depilatories are not recommended methods for hair removal and are known to increase skin trauma and wound infections. To best prepare the surgical site for clipping, communication with the attending veterinarian prior to surgical preparation is important, to establish a suitably sized surgical field and clipping boundaries. When preparing a patient for surgery, veterinary nurses need to take into account the possibility that an extension to the surgical site may be required to allow for wound drainage sites, and the need to debride excess amounts of tissue. Application of a sterile, water soluble lubricant into the wound prior to clipping helps reduce further hair contamination and drying of the tissues. Sterile gloves should be worn at all times when handling the surgical area and particular concern should be paid to not cross contaminating from equipment such as clippers (Shmon, 2003).
Skin preparation techniques do not sterilise the skin; approximately 20% of resident bacteria resides in the deeper layers of the skin, where they are inaccessible to antiseptic solutions (Shmon, 2003). Overzealous scrubbing must be avoided as it causes abrasions to the skin as well as bringing bacteria to the skin surface in the hair follicles that are rapidly colonised by bacteria (Shmon, 2003).
Wound decontamination
Wound lavage is the principle method of initial wound decontamination, assisting to remove both visible and microscopic wound contaminants. Irrigation of a wound is best achieved using a 35 ml syringe and a 19 gauge needle, providing the ideal lavage pressure of 8 psi to be maximally effective. An effective method for wound irrigation can be seen in Figure 2, whereby a 1 litre bag of Lactated Ringers solution and a drip set is attached to a 3 way stop cock (Waldron and Zimmerman-Pope, 2003). This method is excellent for helping to maintain sterility and provides a constant source of irrigation fluid that can be easily quantified.
Lactated Ringers crystalloid is the wound lavage solution of choice, as it is a fluid that has a similar osmotic pressure to that of living cells and causes minimal damage to fibroblasts (Buffa et al, 1997; Aldridge, 2013). The addition of concentrated antiseptics such as chlorhexidine gluconate (CHG) to lavage fluid can have cytotoxic effects on important cells involved in healing, such as keratinocytes and fibroblasts. If CHG is used in a wound, it should be used at low concentrations (25 ml of 2% CHG solution to a 1 litre bag of Lactated Ringers will produce an optimal lavage solution of just under 0.05% CHG); at 0.05% dilution CHG has been found to cause no significant difference in wound contraction or epithelialisation compared with sterile saline or Lactated Ringers (Lozier, 1992; White, 2006) and it also has additional benefits of residual antiseptic activity which prevents further bacterial colonisation (Lozier, 1992; White, 2006; Aldridge, 2013).
Types of dressings and suitability for different wounds
There are various types of primary layer wound dressings commonly used to treat wounds, and each plays a specific role in aiding wound healing conditions, dependent on the stage or phase of a wound. Topical dressings come in the form of gels, lotions and dressing sheets. The primary layer of most bandages is usually a wound dressing which provides the wound with the optimum conditions for healing (Table 2).
| The primary layer of most bandages is usually a wound dressing which gives the wound the optimum conditions for healing. Materials may be as follows: | |
|---|---|
| Wet-to-dry dressings using gauze | A wet-to-dry dressing requires the primary layer of bandage, usually a wide mesh gauze swab, to be moistened with lactated ringers or a sterile saline solution. Exudates are diluted and absorbed into the secondary bandage layer, and as the fluid evaporates the bandage dries and adheres to the wound. When the adhered dressing is removed, adhered necrotic tissue is also removed. A wet-to-dry dressing is used to remove damaged and/or necrotic tissue to debride the wound and promote granulation |
| Perforated film dressing, e.g. Melolin (Smith & Nephew), Telfa (Kendall) | Commonly used for surgical wounds (first intention healing). A non-adherent dressing, allows for rapid drainage of exudate, reducing trauma to healing tissue |
| Foam dressing, e.g. Allevyn (Smith & Nephew) | A non-adhesive, dry, sterile, foam dressing that promotes a moist environment and good absorbency |
| Hydrogels, e.g. Intrasite (Smith & Nephew) | A moist gel, high in water content, applied into and onto wounds to rehydrate hard, necrotic tissue. Loosens and absorbs slough and exudate, creates an optimum environment to allow for re-epithelialisation |
| Hydrocolloids, e.g. Granuflex (ConvaTec), Tegasorb (3M) | A non-adherent, moist, sterile dressing that rehydrates the wound and promotes debridement and granulation. For moderate to heavy exuding wounds. Contraindicated in active infection |
| Calcium alginates, e.g. Kaltostat (ConvaTec) | A moist, haemostatic dressing derived from seaweed, for moderate to highly exuding, chronic or acute wounds. A gel is formed over the wound which promotes wound healing by stimulating macrophages and fibroblasts |
| Semipermeable film dressing, e.g. Opsite (Smith & Nephew), Bioclusive (Johnson & Johnson), Tegaderm (3M) | A sterile film dressing which retains moisture within the wound. No absorbency, can be used as a secondary dressing, good for superficial wounds. Can be left in place for longer periods |
| Sodium chloride dressing 20% hypertonic saline, e.g. Hypergel (Molnlycke) | Use on heavily infected highly exudative wounds, indicated for the softening and removal of dry necrosis in wounds |
| Manuka Honey e.g. Kruuse Manuka Honey Wound Dressings | Available in impregnated dressing or in a tube. Bacteriostatic properties, aid in inhibiting growth and reproduction of bacteria |
| Silver-impregnated dressings e.g. Atrauman Ag (Hartmann) | Broad-spectrum antimicrobial and effective against meticillin-resistant Staphylococcus aureus (MRSA) |
Dressings should be changed at least once daily, or more, based on the amount of strike-through, soiling, loosening or slipping of the dressing, patient interference, distal swelling, pain, skin wounds, tissue maceration or odour (Creedon and Davis, 2012).
Factors affecting wound healing
Almost immediately after a wound develops, the process of healing begins. Injured tissue goes through four temporal (time) phases to repair the wound (Table 3). These phases occur in this sequence but may progress at different rates. Even in one lesion site, different areas may be in different phases of repair (Zachary and McGavin, 2012).
| Haemostasis | Occurs immediately after injury, unless there is a clotting disorder. Characterised by initial stopping of blood and then later mild seeping |
| Acute inflammation | Occurs 24 hours after vascular injury, and can last up to 96 hours or longer if the healing process is disrupted by infection, trauma, or some other perturbation. Characterised by redness, swelling, heat and pain |
| Proliferation (granulation) | Can last up to 3 to 4 weeks or longer depending on the size of the wound. This phase is characterised by the generation of new endothelium angiogenesis (blood vessel healing), epithelium (epithelialisation), and connective tissue stroma, fibroplasia/desmoplasia (fibrous and connective tissue growth) to restore normal structure and function to the injured tissue |
| Remodeling (maturation, contraction) | Begins approximately 3 to 4 weeks after injury, but only after the inflammation and proliferation phases have been successfully completed. This phase includes remodeling of granulation tissue by immature connective tissue and the conversion of immature connective tissue to mature connective tissue through extracellular collagen formation. Remodeling can last for 2 or more years |
Successful reconstruction of any wound requires careful planning and the presence of important elements necessary for optimal wound healing by providing a warm, clean wound environment with an adequate blood supply; critical elements can be categorised into sources of physical, endogenous and exogenous factors (Demaria et al, 2011).
With optimal nursing care, most of the factors that negatively affect wound healing can be mitigated and the patient can be offered the best chances for rapid recovery and return to function.
Conclusion
Trauma patients will present in a clinical setting in a wide range of conditions and it is essential to be prepared and ready to initiate immediate patient stabilisation. While triage provides baseline information on a patient's status it is important to continue to monitor patients thereafter for subtle changes in vital parameters in order to ensure treatment plans follow the needs of the patient. Covering the wound early ensures protection for the patient as well as the staff who could otherwise be exposed to resistant bacteria. Cleaning and debriding the traumatic wound involves initial removal of foreign material as well as careful lavage, and culturing in the case of older wounds. Promoting optimal wound healing conditions takes on many modalities from analgesia, nutrition and fluid therapy to blood products and wound closure techniques, all helping to increase wound healing resources available to the body.