Chronic wounds, produced by trauma or pathologic insult, are a frequently encountered problem in elders. Chronic wounds are characterized by loss of skin or underlying soft tissue and do not progress toward healing with conventional wound care treatment. Although the cause of nonhealing wounds is unknown, they consistently present as secondary wounds in that the edges of the wound are not approximated and a tissue defect is evident.
The level of tissue injury determines the path toward healing that the wound will travel. When the level of tissue injury is superficial, limited to the epidermis and superficial dermis with no damage to the dermal blood vessels, the wound is referred to as a partial-thickness wound. Healing occurs by regeneration of epithelial tissue, or reepithelialization. This process is initiated by an inflammatory response, followed by epithelial proliferation and migration of new epithelial cells across the wound and the reestablishment of normal cellular function.
When tissue injury involves loss of the dermis and extends to deeper tissue layers with disruption of vessels, healing becomes more complex. In these wounds, referred to as fullthickness wounds, healing is characterized by the synthesis of several types of new tissue and scar formation. Despite the complexity of healing with full-thickness injury, the repair process occurs in a predictable manner with identifiable phases.
Healing of full-thickness wounds consists of three phases, the inflammatory phase, the proliferative phase, and the maturation phase (Hunt, 1979). The primary purpose of the inflammatory phase is to clean the wound of debris and to stimulate fibroblast cells to produce collagen, the principal structural protein of tissue. White blood cells play a key role during the inflammatory phase.
Figure 1 . A chronic wound with various types of wound surface tissue.
During the proliferative phase, new blood vessels and collagen are laid down in the wound bed. The result of this process is clinically referred to as granulation tissue (Figure 1). Contraction and epithelialization of the wound also occur during the proliferative phase.
The maturation phase of wound healing is characterized by the turnover and remodeling of collagen in the wound. This healing process results in the formation of a scar Elders are plagued by a variety of chronic wounds, including pressure ulcers, venous stasis ulcers, and diabetic foot ulcers. It has been demonstrated that collagen remodeling and wound strength are decreased in the aging individual (Goodson, 1979). Thus, aging-related events may contribute to more frequent occurrence of chronic wounds in this population. In addition, chronic illnesses that often accompany advancing age limit the availability of oxygen and substrates essential to healing. Therefore, providing optimal wound treatment is even more important for elders who have chronic, slow-healing ulcers,
FOUR PRINCIPLES OF WOUND CARE
There are four basic principles of wound care that apply to all chronic wounds:
* Remove debris and cleanse the wound;
* Provide a moist wound healing environment through the use of proper dressings;
* Protect the wound from further injury; and
* Provide substrates essential to the wound healing process.
Removing Debris and Cleansing
Although all chronic wounds are colonized with bacteria, they are not all clinically infected (Bendy, 1964; Ninneman, 1983). Therefore, a central issue in wound care is differentiating wound colonization from wound infection.
Infection of the wound occurs when the bacterial burden overwhelms the immune response of the host and the bacteria proliferate unchecked. Wound colonization refers to the presence of a limited number of bacteria in the wound, which is normal and of no consequence to healing. It is important to recognize that a simple swab culture will not differentiate between infection and colonization. A swab culture informs only of the presence of surface bacteria, not the quantity of bacteria actually present in the wound tissue. Therefore, a swab culture is of no value in diagnosing a wound infection.
Other clinical symptoms of infection must be considered. The critically important signs of wound infection are redness of the skin around the wound edge, purulent drainage, foul odor, and edema (Figure 2) (Garner, 1988). Bacterial overgrowth, or infection, impedes healing by releasing toxins and consuming substrates required for the wound healing process. It has been demonstrated that bacterial counts in excess of 100,000 organisms per gram of tissue impede spontaneous healing (Robson, 1969).
The presence of nonviable tissue and foreign debris provide a culture medium for the growth of bacteria and the ultimate development of a wound infection (Dhingra, 1976; Sapico, 1986). Therefore, removal of nonviable tissue, such as necrotic tissue and slough, and foreign debris, such as residual material from dressings, is the first principle of chronic wound care. The removal of nonviable tissue is referred to as debridement, the removal of foreign debris usually is referred to as cleansing.
Debridement. If nonviable necrotic tissue or slough is present in the wound, wound debridement must be the initial goal. Necrotic tissue refers to dead, devitalized tissue that is adherent to viable tissue. Necrotic tissue, also referred to as eschar, is dark and avascular. Slough is creamy white, stringy tissue that loosely adheres to the wound. There are several methods of wound debridement; autolytic, biochemical, mechanical, and sharp (surgical).
The body's capacity to lyse and dissolve necrotic tissue is referred to as natural or autolytic debridement. Autolytic debridement can be supported through dressings that encapsulate and concentrate white blood cells and enzymes in the wound bed. Occlusive or semi-occlusive dressings are applied and left in place, allowing wound fluids to collect until they actually disrupt the dressing. The time required to disrupt the dressing varies, ranging from one to several days. During dressing changes, the nonviable tissue that has been lysed by the autolytic process can be cleansed easily from the wound bed.
Although autolytic debridement uses the body's own natural defenses for debridement and is relatively safe, the use of occlusive and semiocclusive dressings on the immunocompromised individual requires caution. Normally, during autolysis, the body's white cells control bacterial overgrowth. The immunocompromised individual with deficient white cells, however, may not be able to control or prevent bacterial overgrowth. In addition, the autolytic process can be delayed if there is a large amount of nonviable tissue present in the wound. In these cases, other methods of debridement may be necessary.
Figure 2. A chronic wound with various signs of clinical infection.
Biochemical debridement involves the use of enzymes to dissolve nonviable tissue. There are many enzyme preparations available for debridement (eg, Elase). Although there is limited data to support the effectiveness of biochemical enzymes in promoting healing, they are often used in long-term care settings because sharp debridement is not as readily available (Boxer, 1969; Lee, 1975; Varma, 1973). Because biochemical enzymes specifically act to lyse tissue, they are appropriate only for wounds that contain necrotic tissue. Some frequently used wound healing sprays (eg, Granulex) often are not recognized as products that contain biochemical enzymes. These products should not be indiscriminately used on chronic wounds.
Mechanical debridement is another option for removing nonviable tissue. Mechanical debridement is accomplished by placing moist coarsemesh gauze in the wound and allowing the dressing to dry. These dressings often are referred to as wetto-dry dressings. Upon removal, necrotic tissue adheres to the gauze and is removed. The use of this method is controversial, however, because granulation tissue also adheres to the dressing and is continually disrupted (Alvarez, 1983). Therefore, wet-todry dressings should be discontinued once the wound begins to granulate. A further criticism of this approach is that the pain inflicted with this method is cruel. Adequate pain management must accompany these dressing procedures.
Sharp (surgical) debridement is the most rapid and effective method of debridement. It involves dissecting necrotic tissue from viable tissue with a surgical instrument, such as a scalpel or scissors. Typically, sharp debridement requires the services of a physician or other health care provider with specialized training in this procedure. It is within the legal scope of practice for nurses in some states.
Cleansing. In contrast to debridement, cleansing of the wound refers to the removal of foreign debris or wound surface contaminants, which may be a result of the dressing material itself. The presence of such contaminants, as with nonviable tissue, predisposes the wound to infection.
The first consideration in cleansing the wound is whether to use a vigorous or gentle technique. Generally, vigorous techniques, such as placing the wound in a whirlpool, are confined to those wounds that have large segments of foreign debris or nonviable tissue. Immersion of wounds in water with forceful agitation softens necrotic tissue and makes them more amendable to sharp debridement.
More gentle cleansing techniques, such as wound irrigation, are used for wounds with granulation tissue, in which the goal is to remove surface contaminants and leave granulation tissue unharmed. Gentle irrigation producing 8 pounds of pressure per square inch is effective in decreasing wound inflammation and infection in traumatic wounds (Longmire, 1987). It has been found that solution forced through a 35 ml syringe with a 19 G angiocath delivers this amount of pressure (Stevenson, 1976). The commonly used asepto syringe does not provide 8 lbs of pressure per square inch and has, therefore, limited usefulness in wound irrigation.
Gentle cleansing also can be accomplished by gently wiping the wound surface with a soft, moist gauze, with care being given not to disrupt granulation tissue. When cleansing the wound in this manner, a "patting" technique is preferable to rubbing the wound.
The second consideration in cleansing the wound is what types of solutions and /or cleansers to use. Some antiseptic solutions commonly used for this purpose have been found to be cytotoxic. These include povidoneiodine, acetic acid, hydrogen peroxide, and or Dakin's solution (sodium hypochlorite) (Lineaweaver, 1985). These solutions are toxic to human fibroblasts, thereby inhibiting collagen synthesis and the formation of granulation tissue. These antiseptics also are cytotoxic to lymphocytes and should not be used as a means to control or treat wound infections. This means they should not be employed to cleanse wounds or to moisten gauze dressings.
Many commercially prepared wound cleansers (eg, Shur Clens, Biolex, Saf Clens, Cara Klenz, Ultra Klenz, Clinical Care, Constant-Clens, Dermal Wound Cleanser, Puri-Clens), which are rapidly multiplying in the wound care industry, also have been found to be toxic to cells essential to the wound healing process (Foresman, 1993). Although these products are specifically marketed for wound care, the Food and Drug Administration does not require manufacturers to provide safety and efficacy data before marketing them. Therefore, it is paramount that the clinician inquire regarding the cell toxicity and efficacy of every new product before enlisting it in the treatment of wounds.
Physiologically compatible solutions, such as normal saline and lactated Ringer's, are nontoxic and are effective in removing contaminants from the wound surface. They are the solutions of choice for cleansing and /or irrigating wounds. Because they are physiologically compatible with body fluids, they also are the solutions of choice for moistening gauze dressings. Moreover, these solutions are readily available and are relatively inexpensive.
Although wound debridement and cleansing usually are sufficient to prevent and control most wound infections, an infection occasionally occurs in a wound that is otherwise free of nonviable tissue and debris. In these instances, antimicrobial treatments should be considered. Topical agents, such as Silvadene (silver sulfadiazine), and topical antibiotics have been shown to reduce the bacterial counts of wounds (Bendy, 1964; Kucan, 1981).
The course of topical antimicrobial treatment should be limited, as with any antimicrobial therapy, because sensitization and bacterial resistance may develop with prolonged use. Generally, adrrürüstration of systemic antibiotics is not warranted for an infected chronic wound unless clinical signs of a systemic infection are present. It is important to remember that the goal of antibiotic treatment is not wound sterilization - because wounds cannot be made sterile - but control of bacterial growth. Clean, granulating wounds that are simply colonized with bacteria (but not infected) do not require antimicrobial treatment.
Providing a Moist Wound Environment
The second basic principle of chronic wound care is to provide a moist wound environment. It has been shown that a moist wound environment promotes re-epithelialization and healing (Hinrnan, 1963; Winter, 1963). Therefore, exposing wounds to air for prolonged periods, which dries the surface of wounds, may impede the healing process. Numerous products and dressings are available that support a moist wound healing environment. The most important considerations in selecting a dressing are to be certain that the surface of the wound stays moist while using the dressing selected and that the dressing selected does not disrupt the skin surrounding the wound.
Gauze Dressings. Gauze dressings provide a moist wound environment as long as they are kept moist in the wound with solutions; these often are referred to as wet-to-damp dressings. Generally, a soaked gauze dressing is covered with a dry gauze square to prevent drying of the packing and contamination. In addition to providing a moist wound environment, wet-to-damp dressings also support autolytic debridement and absorb exudate and trap bacteria in the gauze, which are removed when the dressing is changed. Nonetheless, further cleansing during dressing changes usually is warranted.
Moist gauze dressings are more amendable to packing or wicking sinus tracts and undenrtined areas than are some other dressing materials. The dressing material must be placed in the wound so as to have contact with the entire wound surface. It is important, however, to pack the wound in a manner that avoids placing too much material in the wound, which can apply undue pressure on the newly forming capillary buds and deter healing. Wicking refers to placing dressing material in an obscure tract or undermined area so as to provide moisture and absorb drainage and at the same time avoiding overpacking.
The moisture from gauze dressings may macerate the skin surrounding the wound. Avoiding excessive saturation of gauze dressings and using only enough gauze to maintain contact with the wound surface are ways to prevent inadvertent skin maceration. The use of moisture barriers, such as petroleum jelly, on the skin adjacent to the wound also can help prevent skin maceration. In addition, gauze dressings may remove granulation tissue and disrupt healing. Minimizing diruption of granulation tissue can be accomplished by remoistening gauze dressings immediately before removal.
The use of gauze dressings must be monitored and a change in dressing protocol implemented if injury to skin or granulation tissue becomes a problem. Many products and dressings, however, are available to overcome the problems associated with gauze dressings (ie, trauma to granulation tissue and skin maceration). These products include polyvinyl dressings (eg, Tegaderm, Bioelusive, Op-site), hydrocolloid dressings (eg, Duoderm, Restore, Sween-a-Peel, Johnson & Johnson Ulcer Dressing, ReplicCare), and absorptive dressings (eg, Sorbsan, Kalostat).
Many of these products often are written about extensively when first marketed and then abandoned for new products. These products are an alternative for providing a moist environment and are equally as effective in promoting healing as moistened gauze dressings (Aim, 1981; Alvarez, 1983; Gorse, 1987; Oleske, 1986; Sebern, 1986). Nonetheless, these products are not necessarily better than gauze dressings. From a cost standpoint, they may save labor expenses because dressing changes are less frequent with some of these dressings than with gauze dressings; however, this would be true only when labor costs are relatively high (Xakellis, 1992).
Polyvinyl Dressings. Polyvinyl dressings are transparent, adhesive wound coverings that are semipermeable to oxygen and moisture, and impermeable to bacteria and other contaminants. They maintain a moist wound environment and concentrate the normal defenses of leukocytes, plasma, and fibrin in the wound bed. In this way, they also support autolytic debridement. Polyvinyl dressings can be left on the wound for several days. Caution must be exercised in using these dressings because the adhesive may damage fragile intact skin surrounding the wound. Furthermore, their safety and efficacy with clinically infected wounds remains a point of debate; therefore, polyvinyl dressings generally are reserved for use on partialthickness wounds that are free of signs of localized infection.
Hydrocolloid Dressings. Another type of dressing that maintains a moist wound environment is a hydrocolloid dressing. These wound coverings are impermeable to oxygen, moisture and bacteria, and their hydrocolloid properties maintain a moist wound surface. They also support autolytic debridement and provide some degree of exudate absorption. Their safety for use on clinically infected wound beds, however, has not been established.
Although hydrocolloid dressings are applied directly over the wound, they do not adhere to the wound surface, so they will not disrupt granulation tissue when removed. Some forms of hydrocolloid dressings, however, leave a residue on the wound bed that must be removed with gentle cleansing. This moist dressing residue also can migrate onto the surrounding skin surface, causing maceration. As with polyvinyl dressings, hydrocolloid dressings can be left on the wound for several days, but may disrupt surrounding skin when removed due to the adhesive backing on the dressing.
Absorptive Dressings. Absorptive dressings maintain a moist wound environment by absorbing large volumes of exudate. For this reason they are especially suited to wounds with large amounts of drainage. Calcium alginate dressings (eg, Sorbsan, Kalostat), which are derived from seaweed and appear as a soft fibrous material, are one type of absorptive dressing.
Although these dressings are not pre-moistened before being used, a moist wound environment is created when they interact with exudate on the wound surface. This process also obliterates dead space. Dead space is tissue injury underlying intact tissue, such as a cavity or tract in the wound bed. These highly absorptive dressings also support autolytic debridement as long as a moist wound surface is maintained. Once the exudate in the wound has decreased, an alternative dressing (that will maintain a moist wound environment) should be used.
Numerous topical agents commonly are used in conjunction with dressings. These topical agents include sugar, antacids, vitamins A and D ointment, and various other creams and ointments (Becker, 1984; Berecek, 1975; Cuzzell, 1986; Settel, 1969).
There is no clear research evidence that supports the effectiveness of these specific agents in wound healing. Positive claims regarding their use, however, may be because most of these products come in an ointment or cream form, which provides a moisture barrier for the wound. Therefore, it may not be the specific ingrethents of a particular product that is of importance, but its moisture retention properties that support the wound healing process.
A final issue regarding the application of wound care products and dressings is whether to use a sterile or clean technique. As stated earlier, chronic wounds are not sterile wounds; they are colonized with bacteria (Bendy, 1964; Ninneman, 1983). Therefore, the use of sterile technique is not warranted and unnecessarily increases the cost of treatment. If principles of clean technique are established and followed, they are sufficient for the care of chronic wounds (Ninneman, 1983). Principles of clean technique include assuring wound care products and dressing materials do not become contaminated during storage and use.
Preventing Further Injury
The third basic principle of wound care is to eliminate or reduce the condition that allowed the wound to develop. Chronic wounds in elders can be the result of a variety of factors. Functional losses in mobility, mental status changes, and deficits of sensation can contribute to the formation of pressure ulcers (Bergstrom, 1987). In addition, sensation and circulatory deficits are responsible for the development of diabetic foot ulcers and venous stasis ulcers.
When the chronic wound is caused by unrelieved external pressure, as with a pressure ulcer, wound care must include measures to reduce pressure. These measures include the use of positioning techniques to keep pressure off the wound area. In patients with pressure ulcers in the sacral region, sitting should be avoided until the wound has healed. Pressure reducing devices, such as mattresses and cushions, can be used to decrease the pressure on bony prominences. Supportive boots, foam wedges, and specially fitted shoes can be used to keep pressure off wounds of the ankle or foot, a common problem area for diabetics.
Treatment of wounds that result from impaired venous circulation, such as chronic venous ulcers, must include interventions to offset diminished venous return. Such modalities as compressive stockings, Unna's paste boots, and pneumatic compression devices have the capability to enhance venous return and, thereby, prevent further tissue injury from venous congestion.
Providing Substrates for Healing
The fourth basic principle of chronic wound care is to provide the substrates essential for healing. Tissue injury can lead to nutritional deficiencies, including hypoalbuminemia and vitamin deficiencies. Conversely, malnutrition has been correlated with the development of tissue injury, namely pressure ulcers (Bergstrom, 1992; Mulholland, 1943).
The necessity of protein in wound healing has long been recognized (Koster, 1940). Proteins are required for repair and regeneration. Deficits of essential amino acids impair angiogenesis, fibroblast proliferation, collagen synthesis, and scar remodeling. In addition to being necessary to build the structural components of wound healing, amino acids are needed to manufacture the enzymes involved in wound healing and play a significant role in supporting the immune response.
Vitamin and Mineral Supplementation and Wound Healing
The pool of amino acids available for wound healing are obtained from the turnover of endogenous protein, such as albumin, and from exogenous protein. Because tissue injury results in increased protein metabolism and use of protein to promote wound healing, additional dietary sources are essential for the patient with a chronic wound. Adequate amounts of carbohydrates and fats are necessary in order to prevent amino acids from being oxidized for caloric needs. Glucose is required to meet the energy requirements of the cells involved in wound repair.
Without nutritional support, albumin levels will fall in the individual with serious tissue injury. Albumin is a major plasma protein and an amino acid donor for protein synthesis outside the liver. Albumin synthesis decreases and albumin catabolism increases in proportion to the extent of tissue injury (Powanda, 1981).
Furthermore, plasma proteins are required to maintain an adequate oncotic pressure wimin the vascular system. A drop in oncotic pressure contributes to tissue edema and has been reported to impair wound healing (Rhoads, 1942). The need for additional dietary protein is accentuated by the fact that many elders may be, to some degree, malnourished.
Wound Assessment Parameters and Characteristics
The single most important indicator of malnutrition is a drop in serum albumin, because it is sacrificed to provide essential amino acids in the event of inadequate protein intake. It is important to note that the half-life of albumin is 20 days; a low albumin is indicative of chronic malnourishment (Sodeman, 1974). Sporadic deficiencies in dietary intake do not result in perceptible changes in serum albumin. Another indicator of severe malnourishment is a lymphocyte count of less man 800 (Gianino, 1993). Body weight, an inexpensive and easily obtained assessment parameter, has only marginal value in detecting malnourishment.
Although specific protein requirements for the individual with a chronic wound are unknown, it is generally agreed that in the presence of tissue injury, amounts greater than the recommended daily allowance are needed to support repair. Generally, in the absence of contraindicating disease, the individual with a wound should receive 1.25 to 1.5 g of protein per kg of body weight per day and 30 to 35 calories per kg of body weight per day (Kaminski, 1976; PinchcofskyDevin, 1989). Ideally, the protein/ calories should come in the form of oral intake of food; however, in the presence of inadequate food intake, high nutrient supplements should be used to meet the need for essential substrates.
Wound healing also requires additional vitamins and minerals to support collagen synthesis and immune competence. Table 1 outlines specific vitamins and minerals, their relation to wound healing, and supplement guidelines. Although the specific amounts needed to support wound repair are not known, patients with chronic wounds should receive, at a minimum, a multivitamin daily. Unfortunately, mineral supplementation is not as straightforward as vitamin supplementation. Zinc supplementation is necessary only if a zinc deficiency exists, and iron supplementation should be withheld if an active infection is present because iron increases bacterial virulence (Bullen, 1991; Lee, 1976; Levenson, 1979).
Underlying the care of chronic wounds is the necessity to assess the wound on an ongoing basis. Changes in wound care must be based on changing wound parameters. Therefore, it is paramount that timely, complete, and accurate wound assessments are documented.
Parameters to be included in the assessment are wound location and size, level of tissue involvement, characteristics of the wound surface, and characteristics of the periwound surface (skin around the wound) (Table 2). Measurement of wound size includes calculations of surface area based on measures of length and width. Measurement of wound depth is accomplished by placing a cotton-tipped applicator in the deepest portion of the wound and marking it at the surface of the wound edge. In assessing the wound surface, it is important to identify the various types of tissue and the extent that each type of tissue covers the wound surface.
For example, the wound in Figure 1 contains necrotic tissue and slough in the center of the wound bed and granulation tissue around the wound edges. Each of these tissues comprises approximately one third of the wound bed. This wound also has newly formed epithelial tissue on the wound border. Exudate and the presence of undermining are important wound characteristics to note as they influence dressing and other treatment choices.
Additionally, as stated earlier, characteristics of the periwound surface are valuable in recognizing the presence of infection. By assessing the wound on an ongoing basis, the wound healing progress can be documented and modifications made in treatment as the wound progresses toward healing.
Although the characteristics of chronic wounds vary greatly, they share the common characteristic of impaired healing. Therefore, supporting the wound healing process must include focusing on the many facets of the healing process. The role of the nurse in this process is to regularly assess the wound and to change wound care treatments according to this assessment. Following the four basic wound care principles provides a comprehensive approach to wound care that supports healing in the dynamic environment of the chronic wound.
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Vitamin and Mineral Supplementation and Wound Healing
Wound Assessment Parameters and Characteristics