Helpful Tips For Managing Wounds In Veterinary Patients
David Dycus, DVM, MS, & Jennifer Wardlaw, DVM, MS, Diplomate ACVS Successful wound management depends on taking the correct approach to the lesion, including deciding whether to close it or manage it as an open wound. This article reviews this critical decision-making process and offers tip and techniques for wound management.
Successful wound management depends on taking the correct approach to the lesion, including deciding whether to close it or manage it as an open wound. This article will:
- Review the decision making process regarding wound management
- Provide some tips and techniques for managing open wounds.
SKIN ANATOMYIn order to understand wounds and how to best treat them, it is important to understand the anatomy of the skin, which consists of 3 layers: 1. Epidermis 2. Dermis 3. Hypodermis (commonly referred to as subcutaneous tissue). The most important component for wound management is the vascular supply, which is separated into 3 divisions: 1. Superficial (subpapillary) plexus 2. Middle (cutaneous) plexus 3. Deep (subdermal or subcutaneous) plexus. Dogs and cats have direct cutaneous vessels, which are found in the deep plexus, rather than musculocutaneous vessels, which are present in humans.1
Ten Tips for Wound Management
- Effective wound irrigation is determined by amount of solution used, not by solution type.
- Irrigation pressure should remove bacteria from the wound but not damage the tissue.
- Necrotic tissue should undergo debridement; if tissue viability is questionable, wait and reassess in a few days.
- If unsure whether to suture a wound or keep it open, always err on the side of caution.
- Topical agents applied at the right time are essential to healing; incorrect agents applied at the wrong time are detrimental.
- Cover the wound by a contact layer/bandage after application of a topical agent.
- Honey and sugar have unique antibacterial qualities that make them ideal topical agents.
- Tie-over bandages provide the perfect covering for hard-to-bandage areas.
- A butterfly catheter can be converted to an active drain if a Jackson Pratt active closed drain is unavailable.
- Correct placement and management of Penrose drains is critical for efficient fluid drainage and minimization of complications.
PATHOPHYSIOLOGYIn simple terms, a wound occurs when there is a loss in integrity of the skin and underlying tissues. The ultimate goal of wound healing is restoration of the epithelial surface, and this process involves several physiologic steps:
- Formation of a fibrin-platelet clot
- Recruitment of white blood cells (neutrophils followed by monocytes and macrophages)
- Neovascularization and cellular proliferation
- Tissue remodeling.
INITIAL WOUND CAREIn any traumatic wound, the bacteria burden and degree of foreign material can be quite extensive. The initial goals of wound care are to: • Lessen the bacteria load • Remove foreign material • Remove any necrotic tissue.
Wound Care Steps
- First apply a sterile lubricant to the wound, which allows the hair around the area to be clipped.
- After the hair has been clipped, copiously lavage the wound.
- Once irrigation is complete, differentiate between healthy and necrotic tissue:
- Viable tissue has a red or pink appearance and bleeds when incised.
- Necrotic tissue has a dark purple to black color and fails to bleed when incised.
- Use an aseptic debridement technique (sharp excision with scalpel blade or scissors) to remove necrotic tissue; debride until tissue begins bleeding or healthy tissue is encountered.
- If tissue is pale, bluish, and/or light purple, its viability is difficult to assess—leave it in place until viability can be determined.
Irrigation SolutionsA common discussion regarding irrigation solutions revolves around which type is best to use; common examples include:
- Sterile saline
- Diluted chlorhexidine (0.05% solution; 25 mL of 2% solution in 1 liter of fluid)
- Diluted betadine (0.1% or 1% solution; 1 or 10 mL of 10% solution in 1 liter of fluid).
Irrigation PressureThere is a fine balance between using the pressure of irrigation application to remove bacteria and damaging the tissue. Pressures as low as 1.6 psi can reduce bacteria contamination5; although, 7 to 8 psi is commonly cited.5 Recently, a study found that a 1-liter saline bottle with a hole in it generates 3.9 psi, while a 35-mL syringe, with a 16- or 18-gauge needle, produced 18 or 16 psi, respectively. A 1-liter bag, within a cuff that was pressurized to 300 mm Hg consistently, produced a pressure of 7 to 8 psi, regardless of needle size.6 The preferred pressure needed for effective, but not traumatic, irrigation is 7 to 8 psi. The recommended method of application is use of a 1-liter bag pressurized to 300 mm Hg. Connect the IV tubing to a hypodermic needle to thoroughly lavage the wound.
WOUND MANAGEMENT TECHNIQUESClosure Approaches The decision to close a wound or keep it open depends on several factors. This decision is not always a black and white process, but always err on the side of caution if in doubt. Closing a wound helps increase the speed of healing by bringing the wound edges closer together. There are numerous factors to consider when closing a wound (Table 1). If these factors are not favorable, a decision to close the wound might result in slow wound healing or a non-healing wound. One important aspect is species differences between dogs and cats. In general, primary closure in cats has less strength than primary closure in dogs. Also, in cats, less epithelialization occurs, less granulation tissue is produced, and open wounds heal more slowly.7,8
Wound Closure: Infection ConsiderationsAn overall goal of wound management is to facilitate healing without infection, and this consideration plays a part in the decision whether or not to close a wound. Timing of closure is important but does not necessarily determine the potential for wound infection. A bacteria count of 105 colony-forming units per gram of tissue is considered indicative of infection, and the time required to achieve this bacterial population is approximately 6 or more hours.9 In addition, other factors, such as virulence of the organism, tissue trauma, and the presence of foreign material, can lead to a large bacteria burden in more or less time.
Types of ClosureTypes of wound closure can be classified as: 1. Primary closure (first intention healing) allows apposition of wound edges, which then facilitates healing by first intention. Primary closure is indicated most often for:
- Surgically created wounds
- Sharply incised wounds, with minimal trauma and contamination (in our opinion, dog bite wounds do not fall in this category).
- Mildly contaminated wounds that require some debridement
- Those initially treated by open wound management for a short period of time.
- Severely contaminated wounds
- Wounds that require more intensive debridement.
- With resistant bacterial infections
- That run perpendicular to the skin's tension lines.
Step-by-Step: Tie-Over Bandage Application
- Place suture loops, using monofilament, nonabsorbable suture, in healthy tissue around the periphery of the wound, approximately 1 to 2 cm from its edges (Figure 1). These sutures will hold the tie-over bandage material. Note: If the suture loops are too big, tension will be lost; if the loops are too tight, blood flow will be impeded.
- Apply sterile bandage material to the top of the wound; wound type will determine whether this is a wet-to-dry or nonadherent bandage (Figure 2).
- Loop umbilical tape through the sutures and tie it onto itself to secure the bandage material. It is helpful to have at least 5 interrupted sutures placed in a star pattern; however, more are used for larger wounds.
- Use a final outer impermeable layer to prevent nosocomial infections (Figure 3).
ONGOING WOUND CAREOnce the wound has been treated and a wound healing technique (closed vs open) chosen:
- Open wounds should be bandaged after topical treatment to protect healing tissue from further damage, such as self-mutilation, hospital organisms, and the outside environment.
Topical AgentsTopical agents can be a double-edged sword: use of the correct agents at the right time is essential to healing, but application of incorrect agents at the wrong time can be detrimental to healing.
- In general, topical agents, especially antimicrobial agents that have broad spectrum activity, are useful early in the course of wound management.
- Other topical agents, such as honey or sugar, are best used during the inflammatory or early repair phases.
Types of BandagesAfter application of a topical agent, a contact layer must cover the wound. The type of layer and frequency of bandage changes will depend on the expected amount of exudate. Regardless, any open wound should have its bandage changed every 24 hours at a minimum. Bandaging techniques are based on the type of injury and treatment goals. The function of the contact layer varies but may include:
- Exudate absorption
- Topical medication delivery
- Promotion of healing.
Step-by-Step: Creating an Active Closed DrainA butterfly catheter can be converted into an active closed drain by (Figure 4):10
- Cutting off the syringe adaptor
- Fenestrating the end of the tube with a needle
- Passing the fenestrated end into the wound.
- Attaching the butterfly needle to a blood collection tube, which provides the vacuum for suction.
- Ensuring the drain only has a ventral exit through the skin, not an entrance and exit
- Covering the drain while it is in place to prevent secondary infections.
Step-by-Step: Placing a Penrose DrainPenrose drains are commonly placed incorrectly or in inappropriate places (Figure 5). To correctly place the drain:
- Chose the most ventral aspect of the wound for drain placement.
- Place the proximal end of the drain in the most dorsal aspect of the wound, not outside the wound or skin.
- We prefer to insert a monofilament nonabsorbable suture blindly through the skin, which exits from the dorsal aspect of the wound.
- Place a mattress suture through the proximal aspect of the drain; the suture then exits the wound back through the skin where the suture is tied, securing the drain in place in the most proximal aspect of the wound (Figure 6). Removal is made easier by using a different color of suture to secure the drain than the color used to close the wound.
- Place the drain in as much of the wound as possible; then create a stab incision that allows the drain to exit the wound ventrally (Figure 7).
- Monitor drains daily and remove them once drainage decreases or changes to a more serosanguineous appearance. However, do not leave drains in place for more than 3 to 5 days.
- Figures 1 through 3 courtesy Kristen Welch, DVM, Diplomate ACVECC, Charleston Veterinary Referral Center, Charleston, SC
- Figure 4 courtesy Cory Fisher, DVM, MS, Diplomate ACVS, Mississippi State University
- Figure 5A courtesy Rick Hurt, DVM, Mississippi State University
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- Orgill D, Demling RH. Current concepts and approaches to wound healing. J Crit Care Med 1988; 16:899-908.
- Moscati RM, Mayrose J, Reardon RF, et al. A multicenter comparison of tap water versus sterile saline for wound irrigation. Acad Emerg Med 2007; 14:404.
- Owens BD, White DW, Wenke JC. Comparsion of irrigation solutions and devices in a contaminated musculoskeletal wound survival model. J Bone Joint Surg Am 2009; 91:92-98.
- Gall TT, Monnet E. Evaluation of fluid pressures of common wound-flushing techniques. Am J Vet Res 2010; 71:1384-1386.
- Bohling MW, Henderson RA, Swaim SF, et al. Comparison of the role of the subcutaneous tissues in cutaneous wound healing in the dog and cat. J Vet Surg 2006; 35:3.
- Bohling MW, Henderson RA, Swaim SF, et al. Cutaneous wound healing in the cat: A macroscopic description and comparison with cutaneous wound healing in the dog. J Vet Surg 2004; 33:579.
- Robson MC, Heggers JP. Delayed wound closure based on bacterial counts. J Surg Oncol 1970; 2:379.
- Campbell BG. Bandages and drains. In Tobias K, Johnston S (eds): Veterinary Surgery: Small Animal, 1st ed. St. Louis: Elsevier, 2012, pp 227-230.