Wound Healing Flashcards
Describe the appropriate tissue layers involved in simple wound closure and the essential properties that allow for closure.
- Where are sutures placed?
- When do wounds epithelialize?
- What percent of normal is tensile strength at 3 wks? 6 wks? What is max achievable?
- With clean lacerations and surgical incisions, deep sutures are placed in collagen-rich areas such the fascia and dermis. Closure of such layers allows for primary intention healing.
- Collagen-rich areas are able to hold sutures with a high degree of tension.
- Fatty tissue layers, such as subcutaneous fat, do not have significant collagen and cannot hold sutures under tension; thus, such layers are typically not closed.
- Closed wounds epithelialize within 24 to 48 hours, at which point water barrier function has been restored.
- In closed wounds, tensile strength is only 20% of normal skin at 3 weeks and 70% at 6 weeks. Maximal tensile strength achieved by scar is 75% to 80%.
Describe the essential differences in healing of an open wound vs closing a wound. What can infection do to an open wound?
- Open wounds heal using the same processes of closed wounds, including hemostasis, inflammation, proliferation, and remodeling (maturation). However, it is a much longer process.
- Healing in open wounds is referred to as secondary intention, with greater granulation tissue and contraction.
- Infection can disregulate the repair and transform the wound into a clinically nonhealing wound.
Identify important factors that should be considered when evaluating an acute wound.
- Consider the mechanism, age, and extent of injury.
- Assess for contamination.
- Assess the wound for neurovascular and tendon compromise.
- Assess the need for tetanus prophylaxis.
- Be sure to identify patient risk factors that may delay healing, such as immunocompromise; diabetes mellitus; and peripheral vascular disease, including ischemic arterial disease, venous insufficiency, and previous radiation to the wound site.
Understand the different classes of surgical wounds and the associated risks of surgical site infection (SSI). What are the different rates of infection? How do you manage different classes?
- Surgical wounds are classified as clean, clean-contaminated, contaminated, or dirty. An appendectomy without perforation is classified as clean-contaminated.
- The rates of infection are 1% to 5% for clean cases, 2% to 9% for clean-contaminated cases, and 3% to 13% for contaminated cases. Dirty cases already have an established infection.
- Surgical incisions that are high risk for SSI should be left open after surgery. These can be closed with either delayed primary closure or left to heal by secondary intention.
- Primary closure of contaminated midline abdominal incisions leads to more wound failures than delayed primary closure.
Identify and describe the different types of nonhealing wounds in different patient populations.
Chronic or nonhealing wounds are open wounds that fail to epithelialize and close in a reasonable amount of time. They can be categorized into pressure sores, lower extremity ulcers, and radiation skin injuries.
- Pressure sores develop over bony prominences, usually in immobile patients. They present with an area of skin ulceration overlying a large area of fat and muscle necrosis.
- Leg ulcers arise from arterial or venous insufficiency that impairs the normal process of healing. The presence of an arterial pulse indicates adequate arterial flow.
- Radiation skin injuries result from external-beam radiation through the skin to treat deep pathology. They can manifest acutely as self-limiting skin erythema or later as skin ulcerations or nonhealing wounds.
Know the common indications for primary repair of simple wounds. When can tissue adhesives be used? How long can a laceration be open and still allow for primary repair?
- Primary repair of wounds, such as suture repair, is appropriate when the depth of the wound will lead to excess scarring if the edges are not approximated. This typically applies to lacerations that violate the dermis.
- Tissue adhesives may be considered for small wounds not under tension.
- Clean, uninfected lacerations may be closed primarily for up to 18 hours following the injury.
- Facial wounds may be closed primarily up to 24 hours following the injury.
Know the common contraindications for primary repair of simple wounds.
- Wounds with high concern for infection - allow to close with secondary intention
- Wounds grossly contaminated with debris or infected tissue that can’t be removed
- Late noncosmetic wounds.
- Human and animal bites
- Deep puncture wounds
- Wounds with a high degree of tension
- Actively bleeding wounds
- Superficial epidermal wounds
Describe the appropriate steps that should be performed in simple wound closure to optimize healing.
- Inflammation can influence the length and quality of healing - should be minimized.
- Sterile technique and meticulous hemostasis limit inflammation
- Decreases scar formation, risk of infection, and healing time
- Use of fine forceps and skin hooks avoids crush injury to the epidermis and dermis - limits necrotic tissue at the wound edge and reduces inflammation. This allows for smaller surgical scars.
- Steri-Strips, fibrin glue, or other biologic sealants may be used to close the epidermis to avoid suture material that can generate an inflammatory response.
Identify appropriate suture material to be used in different types of clean wounds or surgical incisions.
- Nonabsorbable suture such as nylon and polypropylene can be used to close skin anywhere.
- Staples may be used on scalp wounds and wounds greater than 5 cm - permit faster closure.
- Absorbable suture material must be used for dermal or buried sutures.
- Absorbable sutures under significant tension, such as abdominal fascia, should retain significant tensile strength for at least 6 weeks until maximal tensile strength of the wound is achieved.
Identify closed infected wounds and determine the need for incision and drainage.
- SSI: categorized into superficial, deep, or organ/space infections; involve purulent drainage
- Signs of wound infection include fever, tenderness, erythema, edema, and drainage
- Closed erythematous wounds without draining or loculated fluid - antibiotics ok
- If pus or necrotic tissue is present - open the wound, remove sutures, consider I&D
How do you manage different types of open wounds?
- Necrotic
- Dry
- Open
- Large
- Necrotic - debride; accumulates, source for bacteria
- Dry, chronic - assn w/ arterial dz - revascularize then I&D
- Open - cover, keep moist to prevent desiccation, necrosis.
- Daily dressing changes with plain wet-to-dry gauze.
- Large open - consider negative pressure WV therapy
- Large open wounds where healing will not be complete for at least 2 to 3 weeks - consider skin grafting
- sufficient bed of granulation tissue - ready for grafting
- primary intx, secondary intx, and graft impossible - flap coverage
Describe the basic principles of skin grafting and associated techniques for managing wounds that may not be amenable to primary closure, secondary closure, or negative pressure wound therapy.
- Grafts - full (complete dermis) or split (portion of dermis)
- Other tissues (tendon, nerve, fat, bone) may be grafted for small defects
- Skin grafts require a healthy recipient bed for survival.
- Skin grafts revascularize through two processes:
- First 24-48 hrs: grafts obtain nutrition/perfusion through the wound bed plasma - imbibition.
- After 48 hrs: new capillaries grow from the bed to the graft to begin neovascularization - inoculation
- STSG: more secondary contracture - avoid over function/cosmesis critical areas (ie, joints, face).
- STSG: less primary contracture - preferred when large surface areas need to be grafted (ie, large burns).
- FTSG: preferred when less secondary contracture is desired.
- Full-thickness skin graft harvest sites are closed primarily - the size of the graft is much smaller.
Describe the basic principles of flaps and associated techniques for managing wounds that may not be amenable to primary closure, secondary closure, or negative pressure wound therapy.
- Flaps have an immediate blood supply at the time of transfer.
- Flaps can be local, regional, or distant (free flaps), can include muscle, bone, tendon, nerve, and fascia.
- May be classified by the type of movement necessary to relocate the tissue (ie, advancement, rotation, transposition).
- Flaps are transferred with a blood supply.
- Local and regional flaps maintain an intact blood supply.
- Free flaps require microsurgical techniques to reestablish the blood supply at the recipient site by anastomosing the artery and vein of the flap to an artery and vein at the recipient site.
- Flaps are commonly used in previously radiated or oncologic reconstruction wounds - vasculature is compromised
- Extremity reconstruction and salvage after trauma may also require use of flaps.
Describe essential steps in the management of different types of different types of chronic or nonhealing wounds.
- Pressure sores: control factors that lead to increased pressure - periodic rotation, low-pressure beds
- Nonhealing wounds in ischemic extremities: revascularization.
- Patients with wounds in irradiated areas: consider hyperbaric oxygen therapy or tissue flaps.
- Identification and control of infection, diabetes, or malnutrition is often necessary.
Describe the standard postoperative care for uncomplicated wounds closed with primary intention to ensure proper healing and avoid potential complications.
- Closed wounds should be kept sterile for 24 to 48 hours until epithelialization is complete. Patients are allowed to shower and wash after 24 to 48 hours of wound closure.
- Gentle cleansing removes old serum and blood, reducing potential bacterial accumulation and risk of infection.
- In patients who have undergone closure of deep structures, such as abdominal fascia, heavy activity should be limited for a minimum of 6 weeks while healing of deep fascial structures occurs.
