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Wound Closure- Continued

Chapter 20: Table of Contents

Wounds can be closed primarily or with delayed closure if appropriate. For wound closure, consider the following:

  • Freshen wound edges: dead skin and underlying tissues should be removed during staged débridements but do not freshen the wound edges repeatedly during wound management as this will only serve to remove viable tissue that could be used for closure.  When ready for closure, a 1-2mm strip of epithelium/dermis should be taken to allow fresh wound edges to contact. If the wound is less than 36 hours old, it may not be required to freshen the wound edges.

Plan wound closure: large or irregular wound will require planning prior to closure. Aim to close wounds along tension lines of skin where possible.  This does not always hold true, however, and some hands-on manipulation might be required to find the best closing plane. Using sterile towel clamps (the least traumatic tool in your surgery pack for skin) bring the skin edges together in various orientations. The arrangement that creates the least amount of tension (and often the smallest dog ears) is the one to pick. Towel clamps can be left in place as the remainder of the wound is sutured.

  • Undermining the surrounding tissues may be required to release the skin and allow closure of skin edges without tension. This can be performed in a 360 degree fashion with combination of blunt and sharp dissection. Attempt to preserve arteries and veins, and only undermine as necessary to close the wound (minimize excessive dead space). If skin edges pull easily into apposition undermining is not necessary.  
  • Eliminate dead space prior to wound closure. Any potential space left beneath the wound will fill with tissue fluid and form a seroma that could get infected or prevent adhesion of the tissue layers. Techniques to reduce dead space include bandaging, drain placement, walking sutures.
  • Use of drains is indicated if a large amount of dead space is present or a wound is severely contaminated.  Drains can be classified as passive or active. The most commonly used passive drain is the Penrose drain. Penrose drains are soft and pliable, gravity dependent drains. They are available in various sizes and can be cut to length. Penrose drains are useful for wounds where a bandage can be applied but should be avoided in non-dependent areas or when entry of air into the wound is undesirable (e.g. chest wounds). Passive drains should never be left uncovered. Bandages provide pressure which help prevent fluid accumulation and seroma formation. In addition, bandaging protects drains against early removal by the patient, ascending bacterial infection and contamination of the environment from drain discharge. Bandages also allow clinicians to monitor the quality and quantity of the fluid produced by the wound. Drains typically remain in a wound for 2-3 days. Drain removal is based on decreased fluid production and change in fluid quality (e.g. change from serosanguinous or purulent to serous effusion). If significant discharge is still present after 5 days, the wound may require further surgical exploration and debridement to reduce bacterial contamination, remove foreign bodies or necrotic tissue.  Closed suction drains can be constructed from butterfly catheters and red top vacutainer tubes or purchased commercially (Jackson-Pratt). For a butterfly catheter suction drain, the adaptor tip of the butterfly catheter (end opposite the needle end) is removed so that the plastic tubing is what remains. Multiple, small, oval fenestrations are cut into 1 or 2 inches of tubing (the part of tubing that will be placed within in the wound). The needle end of the butterfly catheter which exits the skin in a ‘normal’ area is stuck into the plastic top of a large vacutainer tube. The vacutainer tube is a vacuum environment and this means that the tubing will act as a suction. As the vacutainer tube becomes filled or if 4-6h have gone by (these tubes lose their suction), it should be replaced. Even the largest of these tubes do not provide much suction.  As such, these drains are more suitable for smaller wounds that don’t have much in the way of necrotic debris. 

Closed suction drains are ideal for areas that are difficult to bandage or when a closed wound cavity is desirable (e.g. deep chest wounds, abdominal wounds that communicate the abdomen and wounds containing metallic implants). Collection of fluid into the ‘grenade’ portion of the drain, allows to quantify, and visually assess the fluid produced. Cytologic evaluation and bacterial culture of the fluid collected can also guide drain removal or wound re-exploration.

  • Walking sutures can be used to tack down the dermis to the underlying fascia. These also help decrease tension on the wound edges. After placement, the wound edges should be in close proximity and under minimal tension.  If tissues are fragile and suture pulls out easily, use cruciate or horizontal mattress pattern instead of simple interrupted suture pattern for less stress on each bite.Massive skin wounds of the trunk and side of thorax can be closed using walking sutures. If a wound is too large to be closed completely using this technique, it can be closed enough to allow the remainder of the wound to heal by second intention or with a secondary surgery. 
  • Multiple layer wound closure should occur especially in larger wounds – i.e. fascia to fascia, subcutaneous tissue to subcutaneous tissue, etc.
  • Suture size will vary depending on size of wound, size of patient and tissues being sutured. Typically, walking sutures/muscle fascia sutures are applied using 2-0 PDS® or Biosyn®  (3-0 in patients <15kg, or occasionally 0 in larger dogs). Subcutaneous tissues closed using 3-0 PDS®, Biosyn® or Monocryl® (4-0 in smaller patients). Dermal closure is performed using 3-0 Monocryl® or Biosyn®  (4-0 in smaller patients) and skin apposed using 3-0 to 4-0 Prolene®, Surgipro®, Nylon or skin staples. If tissues are fragile and suture pulls out easily, use cruciate or horizontal mattress pattern instead of simple interrupted suture pattern for less stress on each bite.
  • Additional wound closure techniques. Releasing incisions, advancement and rotational flaps, or punch grafts can be used to close difficult wounds. Several good references exist to guide surgical decision-making.

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