Healing by first intention or Primary intention healing happens when the wound edges are approximated e.g. by sutures, staples or glue. Healing by second intention or Secondary intention healing takes place when the wound edges cannot be approximated and the wound needs to heal from the bottom. Tertiary intention healing is a combination of both of the above, i.e. the wound cannot be stitched up immediately but it can after a while. Healing by primary intentionThe condition for enabling primary healing is that the wound edges are sharp and completely clean and free of microbes as is the case with a wound produced via surgical incision (in a sterile environment). It is also possible to close some cuts caused by trauma via primary intention but they need to be sutured within 4 to 6 hours after the incident in order for the wound edges not to have become too inflamed, colonised or necrotic. The advantage of primary healing is that the time to closure is short which reduces the risk of infection and, furthermore, the scarring is limited. If the wound edges cannot be approximated, the wound will need to heal by second intention. Healing by secondary intentionSecondary intention healing implicates that the wound edges cannot be approximated. This can be the case if there is not enough skin in order to pull the edges together without causing stasis in the area, as is often the case in venous leg ulcers, or if the tissue loss is extensive with a need for considerable new tissue generation as e.g. in fourth degree burns. It is also the case if the wound area is dirty or colonised or the wound edges are not sharp and clean as both would be the case in blast trauma wounds. Secondary intention healing is almost always necessary in dehisced (sprung open) surgical wounds as the tensile strength of the peri-wound tissue (the wound edges and the tissue just next to them) has proven too weak to sustain the tension of e.g. sutures or staples. Secondary healing will typically be characterised by visible granulation tissue and the scar will be bigger than in wounds healed by first intention. The simple fact alone that wounds healing by second intention will be open for longer will render them at high risk of infection. Furthermore, as they will typically be colonised and often dirty and infected they will be prone to complications. Healing by tertiary intentionIn tertiary intention healing, there is a need for the wound to be open for a period of time before it can be sutured. Examples can be a wound left open to allow drainage and later is closed or a wound that is left to heal by secondary intention but encounters complications, where after a very thorough debridement is performed followed by an approximation of the wound edges. MPPT in wounds to heal by non-primary intentionMPPT is intended for use in secondary and the first part of tertiary intention healing. It supports infection removal and prevention, autolytic debridement as well as granulation and epithelialisation, i.e. the wound healing process itself. Wound healing is a dynamic process of restoring the anatomic function of living tissue. Since damage to the body’s tissue is common, the body is well adapted to utilizing mechanisms of repair and defence to elicit the healing process. Normal wound healing is profoundly influenced by the type of injury and by factors about the wound (intrinsic) and within the patient (extrinsic) (Perry, Potter, & Ostendorf, 2014). There are four distinct phases of wound healing. These four phases must occur in correct sequence and in a correct time frame to allow the layers of the skin to heal (see Figure 4.1). Table 4.1 describes how a wound heals. Phase Additional Information
To determine how to treat a wound, consider the etiology, amount of exudate, and available products to plan appropriate treatment. Wounds are classified as acute (healing occurs in a short time frame without complications) or chronic (healing occurs over weeks to years, and treatment is usually complex). Examples of acute wounds include a surgical incision or a traumatic wound (e.g., a gunshot wound). Examples of chronic wounds include venous and arterial ulcers, diabetic ulcers, and pressure ulcers. Table 4.2 lists the six main types of wounds. Type Additional Information Primary intention is where the edges are sutured or stapled closed, and the wound heals quickly with minimal tissue loss. The healing time for a surgical wound is usually short, depending on the surgery. A surgical wound left open to heal by scar formation is a wound healed by secondary intention. In this type of wound, there is a loss of skin, and granulation tissue fills the area left open. Healing is slow, which places the patient at risk for infection. Examples of wounds healing by secondary intention include severe lacerations or massive surgical interventions. Healing by tertiary intention is the intentional delay in closing a wound. On occasion, wounds are left open (covered by a sterile dressing) to allow an infection or inflammation to subside. Once the wound is closed with staples or sutures, the scarring in minimal. Arterial ulcers account for 5% to 20% of all leg ulcers. Perfusion must be assessed prior to initiating treatment. Venous ulcers account for 70% to 90% of all leg ulcers. Perfusion must be assessed prior to initiating treatment. Wounds require different treatment throughout the phases of healing. There are multiple factors that affect how a wound heals as it moves through the phases of healing. It is important to look at the “whole patient” rather than the “hole in the patient” to identify the correct treatment and work efficiently and effectively from the beginning of the healing process. Table 4.3 lists a number of factors that inhibit the ability of tissues and cells to regenerate, which can delay healing and contribute to wound infections. Influencing Factors Additional Information For example, an older adult’s skin tears more easily from mechanical trauma such as tape removal. Patients who are malnourished are at increased risk for wound infections and wound infection-related sepsis. An obese person is at greater risk for wound infection and dehiscence or evisceration. Adequate oxygenation at the tissue level is essential for adequate tissue repair. Hemoglobin level and oxygen release to tissues is reduced in smokers. Cortisone depresses fibroblast activity and capillary growth. Chemotherapy depresses bone marrow production of white blood cells and impairs immune function. Watch this 30-minute video about how wounds heal from Connecting Learners with Knowledge (CLWK), a provincial resource. Frequent wound assessment based on the type, cause, and characteristics of the wound is necessary to help determine the type of treatment required to manage the wound effectively and to promote maximal healing. The health care professional should always compare the wound to the previous assessment to determine progress toward healing. If there has been no improvement in the healing of the wound, alternative options or consulting a wound care specialist should be considered. Checklist 32 outlines the steps to take when assessing a wound. Common types are pressure, venous, arterial, or neuropathic/diabetic foot ulcers, or surgical or trauma wounds. A partial-thickness wound involves only the epidermal layer. If the wound is a pressure ulcer, use the Braden Scale Interventions Algorithm. Assess for a sinus tract, tunnelling, or induration. Watch this 30-minute Wound Assessment video, a provincial resource from CLWK, to learn how to improve wound-assessment skills.
AttributionFigure 4.1 |