Chronicles about the care and management of open wounds go back to early civilization’s use of natural remedies to treat injuries of unfathomable causes. One of the oldest medical manuscripts known to man is a clay tablet dated circa 2100 bc that contains a collection of prescriptions described as “three healing gestures,” which even in modern times is the basis for wound treatment.^1,2 These gestures were washing the wound, making plasters, and bandaging the wound.

The Ebers Papyrus, circa 1500 bc, detailed the use of lint, animal grease, and honey for the management of open wounds. The lint provided a fibrous base that promoted wound site closure, the animal grease provided a barrier to environmental pathogens, and the honey served as an antibiotic agent. The Egyptians believed that closing a wound preserved the soul and prevented the exposure of the spirit to “infernal beings,” as was noted in the Berlin papyrus. The Greeks, who had a similar perspective on the importance of wound closure, were the first to differentiate between acute and chronic wounds, calling them “fresh” and “non-healing,” respectively. Galen of Pergamum, a Greek surgeon who served Roman gladiators circa AD 120–201, made many contributions to the field of wound care. The most important was acknowledgment of the importance of maintaining wound-site moisture to ensure successful wound closure.

There were limited advances that continued throughout the Middle Ages and the Renaissance, but the most profound advances, both technological and clinical, came with the development of microbiology and cellular pathology. In the 19th century, Pasteur advocated that wounds be covered and kept dry because he believed this would keep them “germ” free. The dressings developed at this time (made from cloth, cotton, and gauze) have dominated wound management in recent history, and in some countries, they continue to be the main products used.

The first manufactured dressings were probably Gamgee wadding and tulle gras. Gamgee discovered that degreased cotton wrapped in bleached lint would absorb fluids, and he introduced his first dressing in the 19th century. During the 1914–1918 war, Frenchman Lumiere developed cotton gauze that was impregnated with paraffin to prevent the dressing from sticking to the wound. Wound management technology did not progress significantly beyond these early developments until the 1960s when comparisons were made of wound healing in dry and moist environments.³

In 1962, Winter⁴ published his landmark paper about the effect of occlusion on wound healing. He made experimental wounds on the backs of domestic pigs, covered half of the wounds with occlusive film, and left the other half exposed to the air. The occluded, and hence moist, wounds had an epithelialization rate twice that of those left open to form a scab. The concept of moist wound healing was accepted, and a variety of dressings have become available since the late 1970s to deliver and maintain a moist healing environment. Although four plus decades have passed since this historical work documenting the benefits of moist wound healing and managing exudate, too often topical wound care still falls under the premise of “a priori,” based on how one was previously taught, on previous concepts, or on the way it has always been done.

Maintaining a moist wound bed is the evidence-based standard of care for the management of open wounds; however, the “wet-to-dry” dressing (ie, packing a wound space with moist gauze and removing it after it has adhered to the wound bed) is still one of the most common treatments used today. In a retrospective descriptive study⁵ exploring the prevalence of wet-to-dry dressings ordered for care of open wounds healing by secondary intention, a chart review examined admission orders for 202 randomly selected Florida home care and health maintenance organization patients from 2002 to 2004. All subjects in the study had open wounds healing by secondary intention (42 partial-thickness and 160 full-thickness wounds). Wet-to-dry dressings accounted for 42% of wound care orders, followed by enzymatic (7.43%) and dry gauze (6.93%). Most wounds treated with wet-to-dry dressings were surgical (69%), followed by neuropathic ulcers (10%) and pressure ulcers (5.9%). Surgical specialists preferred wet-to-dry dressings (73%). Mechanical debridement was not clinically indicated in more than 78% of the wounds treated with wet-to-dry dressings. Therefore, wet-to-dry dressings were inappropriately ordered in these cases.⁵

In the often cited article from 2002, “Hanging Wet to Dry Dressings Out to Dry,”⁶ Ovington provides evidence that gauze dressings (whether dry or moistened with saline) are substandard for optimal wound care for several reasons, including increasing patient’s discomfort, impeding wound healing, and increasing the risk of infection.

Wet-to-dry debridement is not selective (see Chapter 12, Wound Debridement) and often also removes healthy tissues, thereby causing further tissue trauma and potentially significant pain upon removal (FIGURE 13-1).

The concept of using a wet-to-moist dressing to avoid this trauma may still cause injury. The dressing is prepared in the same manner as a wet-to-dry dressing except the gauze is applied with more moisture with the intent that it will remain moist until removal. Nevertheless, it may become a wet-to-dry dressing in practice. A study of the mechanism of action of saline dressings suggests that they function as an osmotic dressing. Normal saline is isotonic. As water evaporates from the saline dressing, it becomes hypertonic and fluid from the wound tissues is drawn into the dressing in an attempt to reestablish isotonicity. However, wound fluid is not merely water; it contains blood and proteins that may begin to form an impermeable layer on the dressing’s surface. At this point, fluid from the wound is unable to replace the fluid lost from the dressing by evaporation and the dressing dries out completely. Consequently, unless the dressing is changed frequently, or remoistened between dressing changes, it will still function as a wet-to-dry dressing.

Additionally, cooling of the tissues at dressing changes may impede healing. Evaporation of water from a surface results in a reduction of temperature at that surface. Reduction in tissue temperature has multiple physiologic effects, including local reflex vasoconstriction and hypoxia, impairment of leukocyte mobility and phagocytic efficiency, and increased affinity of hemoglobin for oxygen—all of which not only impede healing but increase susceptibility to infection.⁶

Gauze dressings do not present a physical barrier to the entry of exogenous bacteria. An in vitro study showed that bacteria were capable of penetrating up to 64 layers of dry gauze, and moistened gauze provides even less of a barrier to bacterial penetration, again increasing the risk of infection. In a literature review of 3047 wounds, the overall infection rate for wounds dressed with moisture-retentive dressings was 2.6%, whereas the infection rate for gauze-dressed wounds was 7.1%.⁶

Wet-to-dry dressings may incur more labor for the clinician or caregiver and more costs for the health care system. In order for gauze to remain continuously moist to support optimal healing, it must be either changed frequently or remoistened with additional saline. This requires additional labor on the part of the clinician or the lay caregiver. Dressing changes two or three times a day used to be common. In today’s reimbursement climate, this practice is no longer feasible, not only from a reimbursement perspective, but also from the standpoint of best patient outcomes. In home health care, multiple dressing changes a day require the expense of extra travel, home visits, and post-visit time for documentation. Even without the expense of travel in acute or long-term care settings, frequent dressing changes still require time that could be used for other patient care tasks.

Assessment of the patient with an open wound involves a holistic approach and there are many facets of the evaluation that go beyond purely the physical makeup of the wound, for example, the appropriate diagnosis of the wound etiology, patient comorbidities, nutrition, and tissue oxygenation. Open wounds are dynamic and are continuously changing; therefore, dressing selection for optimal healing must also change. It is rare that a singular treatment plan for any given wound will remain the same throughout the healing process. Decision making relative to treatment is based on a thorough assessment of the patient and the wound at regular intervals so that timely changes in the care plan can be made. Specific wound and patient characteristics to be assessed that will drive treatment decisions are illustrated in TABLE 13-1.

Location

The location of the wound on the patient has less to do with the primary dressing (the dressing that is in contact with the wound bed) and more to do with how the dressing may be secured. Wounds located on the torso will require a dressing that is self-adhering, has an incorporated adhesive border, or is secured with additional tape. Wounds on the extremities can be secured with self-adhering dressings, gauze rolls, tubular bandages, or stretch net. The skin condition, patient activity level, potential trauma, possible contamination, and the desire to bathe or shower are also factors to be considered when selecting the secondary dressing. CLINICAL CONSIDERATION

The non-woven, hypoallergenic, adhesive Cover-Roll^® (BSN Medical, Danbury, CT) is a good tape for “picture-framing” a dressing to maintain the peripheral seal.

Size

The size of the wound determines the size of the dressing required to adequately fill any cavity and to cover the wound surface. Undermining or sinus tracts need to be loosely packed or filled, usually with the same primary dressing. All categories of dressings are available in a variety of sizes and shapes to accommodate the dimensions of most wounds. The outlier in the size consideration is the very large wound requiring frequent dressing changes (eg, a large surgical wound) in which case negative pressure wound therapy (NPWT) may accomplish more rapid reduction in wound size and allow more patient activity. (See Chapter 15, Negative Pressure Wound Therapy.) If wound healing is not the immediate or long-term goal, a better dressing selection is one that is cost-effective; requires less frequent changes; and manages exudate, odor, and pain.

Tissue Type

The predominant tissue type and the exposure of vital structures such as bone, tendon, and muscle are key determinants of dressing selection. Healthy granulating wound beds and exposed viable structures need to be kept moist and protected from trauma. The presence of necrotic tissue requires a decision about appropriateness and type of debridement.

Exudate

The amount and type of exudate are fundamental considerations in dressing selection. The optimal dressing material adequately manages wound drainage by wicking the exudate into a secondary dressing. This prevents pooling of exudate on the wound surface, which can become a nidus for bacterial growth as well as a source of leakage and maceration of the surrounding skin. A dry tissue bed requires hydration, a moist bed needs to be maintained, and a wet surface with large amount of exudate requires absorption. The exudate levels will also determine frequency of the dressing change.

Periwound Condition

A key goal of any dressing is to maintain the periwound skin and prevent maceration (ie, over-wetting), stripping/mechanical trauma, prevention and treatment of rashes, and prevention of tape irritation. A dressing that adequately manages exudate is the primary strategy for maintaining intact skin. The use of a barrier wipe or ointment also protects the skin from moisture as well as from trauma during tape removal. Silicone-backed dressings help prevent pain and trauma at dressing change and facilitate remodeling of the wound areas that have re-epithelialized. A rash or blistering of the periwound area may be an indication of an allergic reaction to a particular dressing or tape; the location and distribution of the rash or blisters are a clue to the etiology. A true allergic reaction usually results in the presence of rash or blistering where the tape or irritating agent was in contact with the skin.

Blistering, especially on one side of the dressing edge, is usually indicative of tape being applied with tension, thus resulting in a separation of the epidermis and dermis that subsequently fills with fluid, hence the blister.⁸ Applying tape without tension by anchoring in the middle and smoothing outward can prevent this.

Bacterial Burden

All wounds are contaminated. As bacterial levels rise, the potential for infection in the deeper tissue increases. Even in the absence of gross infection, wound healing can be affected by the increase of proteases, toxins, and other consequences of bacteria. The use of topical agents and dressings to reduce local bioburden can reduce the number of bacteria before they rise to a critical level and negatively influence wound healing. Multiple dressing options exist to address bacteria while still meeting the environmental needs of the wound. (See the section “Antimicrobial Dressings” at the end of this chapter.) CLINICAL CONSIDERATION

The following guidelines for pain medications to take effect are helpful in minimizing pain during dressing changes:

• 
  

  Oral medications—30 minutes before treatment

  
  
• 
  

  IM injections—10 minutes before treatment

  
  
• 
  

  IV injections—immediately before treatment

  
  
• 
  

  Topical anesthetics—15–20 minutes before treatment

  
  
• 
  

  Topical injections—only by MD

  
  
• 
  

  TENS—place proximal to wound during debridement

Pain

Every patient has an acceptable level of pain, and every treatment plan includes strategies to mitigate or eliminate pain to the extent possible, or at least to the patient’s acceptable level. A survey conducted in 2002 in 11 European and North American countries identified the top issues in wound healing as (1) preventing trauma to the wound surface and periwound skin and (2) preventing pain to the patient during dressing changes.⁹ Maintaining a moist wound bed, selecting a non-adherent dressing that is easy to remove, gentle cleansing, administering oral and IV pain medications at the optimal times, and using a topical anesthetic for procedures such as debridement are strategies that reduce the pain associated with both acute and chronic wound care. In some cases, having the patient don gloves and assist in the dressing removal can help minimize pain and reduce anxiety.

Support Needs

Topical care is only a part of the multifaceted approach to achieving wound healing. A thorough patient assessment to determine wound etiology and the appropriate supportive management is an integral part of the treatment plan. To that end, dressing choices are also determined by the supportive care or other medical interventions required to manage the underlying etiology and comorbidities. Examples include but are not limited to the following:

• 
  

  Patients with venous disease requiring compression wraps or patients with diabetic foot ulcers (DFUs) off-loaded with total contact casts require dressings that may be left in place until the compression or casts are removed.

  
  
• 
  

  Patients with suspected or confirmed infection may require frequent observation of the wounds, as well as more frequent dressing changes, depending on the topical antimicrobial being used.

  
  
• 
  

  Patients with periwound dermatitis being treated with topical steroids require dressings changed at the frequency needed for the reapplication of medications.

Quality of Life

Optimal wound management involves a holistic approach that considers patient wishes and lifestyle, work requirements, and activities of daily living. An important first consideration is the overall goal for the wound, for example, can it be healed? In the case of a patient with a terminal illness or a wound of the lower extremity with inadequate circulation, the goal may not be healing but pain and odor control, prevention of infection, prevention of wound deterioration, and maintenance of a dressing that allows family to be with the patient without wound concerns. The patient who desires or requires showering needs a waterproof dressing in a case where showering with the wound exposed is not appropriate. The working patient needs a treatment plan that accommodates the working schedule and environment, as well as a dressing that can be camouflaged, hidden, or at least be presentable. In summary, the patient needs a dressing that will prevent the wound from interrupting daily life as much as possible.

There is no “one size fits all” for dressing selection for open wounds. There are literally thousands of dressings available considering the various categories, shapes, and sizes. Although the form (ie, the ingredients) of the dressing is important, the function, or how it will optimize the wound environment, is more essential in decision making. That being said, there is almost always more than one option available to meet the assessed needs of any wound. TABLE 13-2 describes the desired characteristics of an ideal wound dressing.

A myriad of dressing materials are available to meet the ever-changing needs of the open wound, and the task of selecting the appropriate dressing can at times be daunting. There are numerous specialty dressings that create or enhance the wound environment to promote healing. Some have a singular function while others are combinations or composites possessing attributes of more than one category. Familiarity with the basic categories enables the clinician to understand the combination products.

Skin Protectants

Although they are not dressings per se, skin protectants are formulations designed to protect the skin from the effects of mechanical injury due to tapes and adhesives. Composed of a polymer and a solvent, when applied to the skin, the solvent evaporates and the polymer dries, thereby forming a visible transparent protective coating on the skin. When tapes or adhesives are applied over this coating, upon removal, this protective layer is lifted instead of layers of skin cells, thus avoiding mechanical injury to the epidermis. Skin protectants are available with and without alcohol, an important distinction when considering application to broken or irritated skin that is painful with exposure to alcohol. Skin protectors are available in foam applicators, wipes, and sprays (FIGURES 13-3 and 13-4).

Contact Layer Dressings

Contact layers are single-layer woven net-type dressings that act as a barrier between the wound surface and a secondary dressing. Contact layers protect the wound bed from trauma while allowing wound exudate to pass through into a secondary or negative pressure wound dressing. Alternatively, contact layers may be used over-medicated creams, ointments, or biologics such as growth factors or cell therapy products in order to protect them from the secondary dressing. Contact layers are made from non-adherent fabrics such as polyethylene and can be coated with silicone, oil emulsion, or petrolatum to prevent or minimize adherence (FIGURES 13-5 to 13-8).

Contact layers may be cut to fit any wound or allowed to overlap onto the adjacent skin. They are usually removed and reapplied with each dressing change; however, they can be left in place to avoid skin trauma while only changing the secondary dressing in the presence of larger amounts of exudate (eg, with radiation burns). Contact layers can be used for wounds of all types and any amount of exudate. Advantages and disadvantages are listed in TABLES 13-3 and 13-4. CLINICAL CONSIDERATION

Any dressing that is placed in undermining or sinuses needs to have some of the dressing exposed in the wound bed so that it does not get left in the wound and cause embedded dressings or granuloma formation. Documentation of the type of dressing and number of pieces used will alert the next clinician of the materials that need to be removed.

Film Dressings

Film dressings, also referred to as transparent film dressings because of the ability to see through them, are polyurethane self-adhering membranes that are moisture vapor permeable, meaning that they allow gaseous exchange from the wound bed. Transparent films are waterproof and prevent contamination of the wound bed, yet water vapor is able to evaporate from the wound bed and oxygen is able to penetrate from the air. The amount of oxygen available is not in a quantity sufficient to support tissue growth, but enough to possibly mitigate growth of anaerobic bacteria if changed frequently.

Film dressings are transparent, thin, and flexible and therefore allow visualization of the wound and surrounding skin. They are frequently used on intact skin for protection from friction and moisture and to reduce shear. Placing transparent films over early skin changes such as Stage I pressure ulcers or suspected deep tissue injuries allow the clinician to frequently assess the site for progression or changes. Standard film dressings have no ability to absorb exudate, thus they are not indicated for draining wounds. There is, however, a film dressing that incorporates an acrylic polymer pad so that exudate transfers through perforations and into the absorbent pad and away from the wound surface (FIGURES 13-9 to 13-11).

Film dressings create an environment conducive to autolytic debridement by holding the body fluid onto the necrotic tissue. The natural enzymes in the fluid emulsify only the necrotic tissue so that it can be easily removed, usually after only 24 hours (refer to Chapter 12) (FIGURES 13-9 to 13-11).

Care must be taken when removing film dressings from intact fragile skin in order to avoid mechanical stripping. Use of a skin barrier wipe before applying the film helps protect the skin as well as increases the adherence of the dressing. Films are often used as secondary dressings and are the dressing materials used with most NPWT devices. See TABLES 13-5 and 13-6 for advantages and disadvantages of transparent film dressings.

Hydrogels and Hydrogel Dressings

Hydrogels are water- or glycerin-based products that are either amorphous (defined as dispensed from a tube or impregnated into gauze dressings) or cross-linked polymers formed into three-dimensional sheets. Hydrogels are moisture-donating products that enable the most rapid hydration of a wound surface as compared to other categories of wound dressings. They may contain other ingredients such as alginate to increase viscosity or allow for small amounts of absorption, antimicrobial agents to address bioburden, and collagen or growth factors to enhance wound healing (FIGURES 13-12 to 13-15).

Amorphous gels are reapplied daily; sheet forms may offer extended wear time depending on the amount of exudate that collects beneath them. The periwound skin of a wound treated with hydrogels may need protection with a moisture barrier film or ointment to prevent over-hydration or maceration. Hydrogels are used for dry wounds and are contraindicated for wounds that have visible exudate. See TABLES 13-7 and 13-8 for advantages and disadvantages of hydrogels.

Hydrocolloid Dressings

Hydrocolloids are wafer-type dressings composed of three layers: an inner slightly adhesive layer, a middle absorbent layer, and an outer semi-occlusive layer. The middle absorbent layer contains combinations of gelatin, pectin, and carboxymethylcellulose with hydrophilic particles, which interact with wound fluid to form a gel mass over the wound bed and thereby maintain a moist environment, support autolytic debridement, and prevent trauma upon removal. The resulting gel is reported to be acidic, therefore, not conducive to bacterial growth; however, caution is advised in suspected or known wound infection as the resulting gelled dressing becomes occlusive in nature and may support bacterial proliferation. The outer layer of the hydrocolloid dressings is either film- or foam-based and does not allow contamination from the outside environment to reach the wound, nor does it allow exudate to strike through from beneath the dressing. Dressings that become soiled from incontinence may be cleaned but care should be taken to ensure that residual stool or urine does not remain trapped at the edge of the dressing (FIGURES 13-16 to 13-19).

As the middle layer of the dressing gels, the contained moisture is observable from the top of the dressing, thus enabling the clinician to assess the amount of exudate and determine the need for a dressing change. The gel will ultimately migrate toward the edge of the dressing and may leak out from the edge unless it has an adhesive border. The gelatinized exudate is fairly tenacious and sticky, thus can tear fragile skin during removal and cleansing. Hydrocolloids tend to have an odor upon removal, and is not to be taken as a sign of infection unless the odor remains after the wound has been thoroughly cleansed.

Hydrocolloid dressings are available in various shapes and sizes designed to fit and adhere on almost any anatomic location such as the sacrum, elbows, and heels. Hydrocolloid material is also available in pastes, rings, strips, and powders to fill cavities and creases, as well as for use under pectin ostomy appliances. Frequency of dressing changes is dependent on the particular manufacturers’ instructions for use, but is generally between 3 and 7 days. Shearing forces over areas such as the sacrum and coccyx may cause dressing edges to roll and require more frequent changes, although many newer versions have thin borders that adhere better without rolling. In addition, the dressing can be picture framed with tape (FIGURE 13-20). Hydrocolloid dressings can be used as protection from friction and trauma; however, they are not recommended to use over suspected deep tissue injury (SDTI) because the opaqueness prevents visualization of the skin beneath the dressings. Consequently, the evolution of the SDTI cannot be observed frequently. TABLES 13-9 and 13-10 list the advantages and disadvantages of hydrocolloid dressings. CLINICAL CONSIDERATION

Hydrocolloids are effective in protecting periwound skin when other dressings are likely to cause maceration, for example, in conjunction with NPWT systems or when using moist dressings to fill large cavity wounds.

Foam Dressings

Foam dressings, generally made from polyurethane with or without a film outer layer, are very absorbent and prevent “strike-through” or leakage of exudate. There are many differences between the various foam dressings, including thickness, fluid-handling capability, and ability to hydrate or absorb moisture. Foams are available with or without adhesive borders, as well as with standard adhesive or silicone as the adhesion material. The frequently used silicone backing facilitates painless and atraumatic removal. Foam dressings are semi-occlusive, thus allowing for gas and vapor exchange (FIGURES 13-21 to 13-23).

Foam dressings may be used for all wound types, both as a filler and as a secondary dressing, and while indicated for wounds with moderate to large amounts of exudate, they are also suitable for wounds with little to no exudate, especially when used as a secondary dressing. The frequency of dressing change is 3–7 days depending on the amount of exudate or the frequency change required for the primary dressing when the foam is being used as the secondary. The moist environment created under the foam dressing can facilitate autolytic debridement. Foams may be used on infected wounds; however, they should be changed daily or according to manufacturer recommendations, especially if the foam contains an antimicrobial.

Foam dressings are available in anatomical shapes appropriate for problematic areas such as the sacrum, heels, and elbows. Bordered sacral foam dressings, specifically multilayered silicone-backed dressings, have been used successfully for prevention of sacral pressure ulcers and there is ongoing research addressing the mechanism of action for this purpose. See TABLES 13-11 and 13-12 for the advantages and disadvantages of foam dressings.

Absorbent Dressings

Calcium Alginates

Calcium alginate dressings are absorbent, biodegradable, non-woven fibers that are derived from brown seaweed and composed of calcium/sodium salts of alginic acid and mannuronic and guluronic acids. Alginate dressings are available in fiber sheets or packing ribbon/strips and reportedly absorb 15–20 times their weight in wound fluid. When applied to a wound with adequate ambient wound exudate, the sodium ions in the exudate are exchanged for the calcium ions in the dressings, thereby forming a sodium alginate gel. This soft gel mass conforms intimately to the wound surface and creates a moist wound environment while continuing to absorb exudate until the dressing is saturated. As long as they remain moist, alginate dressings are atraumatically and painlessly removed from the wound bed. Occasionally fibers from the alginate will adhere to the wound bed and require removal with soft debridement or sterile forceps, in which case another dressing may be more appropriate.

Calcium alginates are indicated for moderate to highly exudating wounds of all types. The frequency of dressing change is dependent on the amount of exudate. Copiously draining wounds may need daily changes while wounds with less drainage may be left in place up to 7 days. Calcium alginate dressings tend to wick fluid laterally; therefore, protection of the skin immediately adjacent to the wound is necessary if the alginate dressing extends beyond the wound edge (FIGURE 13-24). Calcium is known to act as a clotting factor (factor IV); therefore, alginate dressings may be used as a hemostatic agent for minimally bleeding wounds, for example, after debridement or in the case of low platelets. Alginate dressings require a secondary dressing to manage excess drainage, to hold the dressing against the wound bed, and to protect from external contaminants.

Hydrofiber Dressings

Hydrofiber dressings are soft, sterile dressings composed of sodium carboxymethylcellulose. They are able to absorb large amounts of wound exudate, which transforms the dressing into a soft gel, creating a moist wound healing environment and supporting autolytic debridement. Hydrofibers are used in similar wounds as calcium alginates but are technically in a category by themselves due to their composition, features, and mechanism of action. They do tend to wick only vertically so that any excess dressing overlapping onto the periwound skin does not become wet with exudate. The nature of the dressing creates a soft, conformable gel mass that maintains intimate contact with the wound bed. Thus if they adhere to a dry wound bed, they can be rehydrated and easily removed. See TABLES 13-13 and 13-14 for advantages and disadvantages of these absorbent dressings (FIGURES 13-25 to 13-30).

Nanofibrillar Cellulose Dressings

Nanofibrillar cellulose dressings (also referred to as cellulose nanofibrils, microfibrils, or microfibrillar cellulose) are composed of cellulose fibrils of typically about tens of nanometers in diameter and hundreds of nanometers in length, giving it a high specific surface area to absorb fluid and to deliver antimicrobials (eg, silver), antibiotics, and growth factors.^17–19 Just as alginates and hydrofibers, the nanofibrillar cellulose dressing responds to wound exudates by creating a hydrogel and by time-releasing the impregnated agents, thereby facilitating wound healing. Their strength, non-cytotoxicity, and ability to maintain moisture make them a promising addition to the armamentarium of wound dressings.¹⁷

Specialty Absorptive Dressings^10–16

Gauze and gauze products are not covered specifically in this chapter because they are rather generic in nature. One example is the abdominal pad, a larger absorbent dressing used as a secondary wound cover over filler products to absorb exudate and provide padding for the wound. There are similar multilayered dressings that combine a non-adherent layer to mitigate adherence to the wound bed with varying layers of absorbent materials to wick (and often gel) exudate for higher levels of absorbency. A common example of this construction is also seen in most baby diapers. Some are available in larger sizes (eg, 24 in × 36 in) for use with overwhelming tissue loss, incontinence, and burns (FIGURE 13-31).

Collagen Dressings

Collagen is the primary protein in human tissues and is necessary for wound healing and repair. Research about and evidence for the use of collagen dressings in wound healing has proliferated in recent years as the role of topically applied collagen has been better understood. Because of its chemotactic effects, collagen plays an important role in each of the wound healing phases. It attracts cells needed for healing (eg, fibroblasts and keratinocytes) to the wound and then provides temporary scaffolding for these cells. Additionally, chronic wounds are known to have higher levels of matrix metalloproteases (MMPs) and a reduced number of the MMP inhibitors (TIMPs). When MMPs are present in a wound bed at too high a level, for too long a time, and in the wrong places, they begin to degrade proteins that are not their normal substrates. This can result in “off-target” destruction of proteins (eg, growth factors, receptors, and ECM proteins that are essential for healing) and thus impair the healing process.^20,21 Adding topical collagen to a wound provides an alternate collagen source that can be degraded by the high levels of MMPs as a sacrificial substrate, leaving the endogenous native collagen to continue normal wound healing and to protect other proteins such as growth factors (FIGURES 13-32 to 13-34).^20,21

There are variations in collagen dressings, including the source from which the collagen is harvested. Collagen is basically the same regardless of the source; it can be derived from any animal source because there is no difference between species. Current collagen dressings are derived primarily from bovine collagen, and fewer from porcine or ovine sources. Most of the other categories of dressings are used to interact with wound fluid and impact moisture balance in some way. Although some collagen dressings are powdered and/or combined with additional material (eg, alginate) to provide some absorption, most collagen dressings are intended to interact with the wound at the cellular level and are biodegradable; therefore, they have a minimal impact on fluid balance. Frequency of dressing change, which varies from 2 to 7 days, is dependent on the formulation of the collagen product and the amount of wound exudate. Collagen products are only placed on clean and/or granulating parts of the wound, not on slough or eschar. The collagen attracts the cells to which it is adjacent, so if epithelial migration is the goal, the dressing needs to connect with the skin at the edge of the wound. Most products are more effective if moistened with normal saline at the time of application, and are covered with a secondary dressing that will prevent desiccation of the material. Manufacturers’ instructions are advised for optimal results with each product. Advantages and disadvantages of collagen dressings are listed in TABLES 13-15 and 13-16.

Miscellaneous Dressings

The previously described dressing categories are the more standard, with multiple sizes, types, and brands within each category. Knowledge of the category functions enables the clinician to understand combination dressings (also referred to as composites), which have attributes of more than one dressing type and serve to be all inclusive. Combination dressings manage exudate as well as provide absorption, coverage, and security. Many of these dressings can be applied by one clinician and are thus less labor intensive. They may be as simple as a transparent film or adhesive sheet with a central pad for coverage and minimal exudate absorption, or as complex as an antimicrobial hydrofiber with a bordered foam covering. These dressings tend to be more expensive, but can be cost-effective if both the frequency of changing the dressing and the time for wound closure are reduced.

Other dressings fall into “stand-alone” categories and are unique in their attributes and mechanism of action. They may be considered niche products by some, yet are mainstays of other practices. Following are a few of these specialty dressings.

Drawtex Hydroconductive Dressings²²

Drawtex (Steadmed Medical, Ft Worth, TX) is a unique primary dressing with a combined mechanism of action. The dressing is composed of a variety of different fibers collectively referred to as LevaFiber technology. This technology is not medicated and has been shown clinically to lift and draw exudate, wound debris, bacteria, and harmful MMPs into the dressing through a combination of capillary, hydroconductive, and electrostatic activities. Exudate is dispersed vertically and horizontally, thereby locking it into the dressing fibers. The exudate then transfers into a secondary dressing. Drawtex is indicated for all types of wounds, especially wounds with moderate to heavy exudate including, but not limited to, burns (superficial and partial thickness), amputations, postoperative wounds, venous leg ulcers (VLUs), pressure ulcers, cavity wounds, DFUs, Buruli ulcers, and complex surgical wounds (FIGURE 13-35 to 13-37).

Procellera²³

Numerous physical modalities have been used in attempts to augment the healing process, including ultrasound, low-energy light therapy, and electrical stimulation. There is good clinical evidence supporting the use of electrical stimulation; it has been shown to benefit tissue repair in a variety of wound types and is used extensively for multiple indications in the practice of physical therapy (see Chapter 14, Electrical Stimulation). Procellera (Vomaris Wound Care, Inc, Chandler, AZ) is a unique antimicrobial wound dressing with wireless microcurrent technology that provides an advanced wound healing solution for the management of wounds. Silver and zinc are applied on the device surface in a dot matrix pattern, creating multiple microbatteries. In the presence of moisture, which may come from wound exudate or exogenously applied saline or hydrogel, low-level microcurrents are generated at the device surface. These reactions occur without an external power source or accessories. Procellera antimicrobial dressing is indicated for partial- and full-thickness wounds such as pressure ulcers, venous ulcers, diabetic ulcers, burns, surgical incisions, donor and/or recipient graft sites, and so forth. The dressing may be left in place for up to 7 days; more frequent dressing changes may be needed with high exudate levels (FIGURES 13-38 and 13-39).

Enluxtra Self-Adaptive Dressing²⁴

The Enluxtra Self-Adaptive Wound Dressing (Osnovative Systems, Inc, Santa Clara, CA) adapts to continuously changing wound conditions and emerging requirements that may have been unknown or unpredictable when the dressing was first applied. The dressing material is designed to change its properties according to the feedback from underlying wound tissues. Thus, the dressing dynamically balances the evolving moist wound environment and provides hydration or absorption depending on the instantaneous needs of wound and periwound skin. Dry areas of the wound stay properly hydrated, fluid from exuding areas is absorbed and locked in, and periwound skin is protected from maceration. The dressing is indicated for all wound types and all exudate levels and is changed based on the amount of exudate; however, it may be left in place for up to 7 days (FIGURE 13-40).