wound

Debridement of Heel Ulcer and Partial Calcanectomy with Graf

NPWT Simplace Dressing Application

Negative Presure Wound Therapy

 NPWT

Negative-pressure wound therapy  is a therapeutic technique using a vacuum dressing to promote healing in acute or chronic wounds and enhance healing of first and second degree burns. The therapy involves the controlled application of sub-atmospheric pressure to the local wound environment,[1] using a sealed wound dressing connected to a vacuum pump. The use of this technique in wound management increased dramatically over the 1990s and 2000s and a large number of studies have been published examining NPWT. NPWT appears to be useful for diabetic ulcers and management of the open abdomen (laparostomy)  but further research is required for other wound types.

General technique for NPWT is as follows: a dressing is fitted to the contours of a wound and sealed with a transparent film. A drainage tube is connected to the dressing through an opening of the transparent film. The drainage tube is also connected to a vacuum source, turning an open wound into a controlled, closed wound while removing excess fluid from the wound bed to enhance circulation and remove wound fluids. This creates a moist healing environment and reduces edema.The technique is usually used with chronic wounds or wounds that are expected to present difficulties while healing (such as those associated with diabetes).

Dresings

Apligraf™ artificial skin in culture

Alloderm™ dermal matrix

Activon™ tulle wound dressing

Medihoney™ wound dressing

Active UMF10+ Manuka honey

Sorbsan™ alginate dressing

Opsite™ film dressing

Duoderm™ hydrocolloid dressing

Curasol™ hydrogel wound dressing

Allevyn™ foam dressing

Dressings for chronic wounds

The principles outlined for acute wounds remain true for chronic wounds including leg ulcers or surgical wounds healing by secondary intention.

In a full-thickness wound, the dermis must be recreated before re-epithelialization can begin. These wounds heal from the base as well as from the edges so the development of some fibrinous exudate in the wound bed is a positive sign.

Occlusive options
Occlusion of chronic wounds:

    Allows macrophages and fibroblasts to enter the wound
    Promotes autolysis mediated by enzymes released from leukocytes.
    Favours cell proliferation because of low pH and hypoxia.
    Enhances growth factors and cytokines within wound fluid.

The occlusive dressings may be divided into five categories:

    Hydrogels
    Hydrocolloid
    Foams
    Films
    Alginates.

Hydrogels are composed primarily of water, fixed in a cross-linked polymer (sodium carboxymethylcellullose, or starch). They may be hydrated or in a dehydrated state requiring moistening with water or saline. They are used to rehydrate dried-out necrotic eschar. Hydrogels are also useful for exudative wounds because they have high absorptive capacity and are nonadherent. They cool the wound and can provide excellent pain relief. They are also useful for partial thickness wounds from resurfacing procedures and skin graft donor sites.

The hydrogel should be covered by an absorbent layer, made of gauze or cotton, and an outer layer of tape, netting or roll bandage.

Hydrocolloid dressings are a mixture of a hydrophilic base and adhesive, often with an outer covering of polyurethane. They adhere directly to the wound and do not usually require a secondary dressing to keep them in place. In addition, they absorb mild to moderate wound exudate so they can be worn for three to seven days without changing.

Hydrophilic foam dressings are permeable to oxygen and water vapour. They usually have a hydrophobic backing that provides occlusion and some have an adhesive surface, which makes application easier. They can absorb only limited amounts of wound exudate so may need to be changed every two to three days or even more frequently during early wound healing when exudation is greatest.

Foam dressings are ideally suited for superficial and dry wounds eg after ablative resurfacing procedures and chronic ulcers since they provide padding that can relieve pressure over bony prominences.

Thin transparent film dressings are not very absorptive, so they are not useful for wounds with significant exudate. They can be used to keep other dressings in place, including as top layer of an acute surgical wound dressing. They are often used to cover sites of IV insertion, superficial abrasions and as temporary dressings e.g. over local anaesthetic cream prior to venepuncture.

Alginates are highly absorbent and are indicated when a wound is very exudative. They release calcium ions, which help haemostasis so are useful applied to a surgical wound in a patient with excessive bleeding. In chronic wounds, the exudate combines with the alginate gel to form green or yellowish goo. The alginates are nonadherent unless the wound dries out. They can be soaked off to avoid unnecessarily debriding the wound.

Curasol™ hydrogel wound dressing    
Duoderm™ hydrocolloid dressing    
Allevyn™ foam dressing

Opsite™ film dressing    
Sorbsan™ alginate dressing    
Dressings for chronic wounds

Honey
Honey has been used as a traditional remedy for burns and wounds, and more recently several studies have demonstrated that it has antibacterial activity. Honey can clear infection from cutaneous wounds and improve healing. Honey from New Zealand manuka (Leptospermum spp) has enhanced antibacterial activity. It is available in a jar (also for oral consumption), a tube, or impregnated on a wound dressing. The antibacterial effect is labelled with its UMF (Unique Manuka Factor) according to Waikato University's honey research unit tests.

Proposed mechanisms include:

    Physicochemical properties (eg, osmotic effects and pH)
    Antiinflammatory activity stimulates immune responses
    Hydrogen peroxide concentration.


Active UMF10+ Manuka honey    
Medihoney™ wound dressing    
Activon™ tulle wound dressing
Honey for wounds
Choice of dressing

The most suitable dressing depends on the type of wound.

    Necrotic wounds have a dry black eschar composed of dead epidermis
    Sloughy wounds contain yellow viscous adherent slough
    Granulating wounds contain deep red vascularised granulation tissue
    Epithelialising wounds have a pink margin to the wound or isolated pink islands on the surface
    Infected wounds.

It also depends on the location and size of the wound. Some dressings are easier to use and remove than others. Modern dressings are relatively hypoallergenic and non-adherent but sensitisation may occur to iodine, antibiotics, rubber, adhesives and preservatives. Tape cannot be applied if the skin is treated with emollient or topical steroid creams. Cost and availability must also be considered.

Necrotic wounds
The aim is to rehydrate the dry scab so that it will separate off. Options are: Wet dressings using saline or hypochlorite (Eusol). Hydrogel covered by perforated plastic film absorbent dressing (Melolin or Telfa) or vapour permeable film. Hydrocolloid dressing.

Sloughy wounds
These need debriding to remove the abnormal matrix of fibrin, exudate, inflammatory cells and bacteria. This can be done by surgical debridement or by an agent that soaks up debris and forms a moist gel. Options are:

    Polysaccharide dressing as beads or paste.
    Hydrocolloid dressing if wound less exudative.
    Alginate dressing.
    Enzymes.

Granulating wounds
Granulation tissue is a highly vascular matrix collagen and proteoglycans.

    Cavity wounds are packed with alginate fibre ribbon, silicone foam dressing or foam chips
    Shallow but heavily exuding ulcers are dressed with alginate dressings or hydrophilic foam product
    Less exudative ulcers are dressed with hydrocolloid or thin foam dressing

Epithelialising wounds
Superficial wounds that exude fluid (burns and donor sites):

    Paraffin gauze covered with gauze and cotton tissue (Gamgee)
    Alginate
    Hydrocolloid.

Dry superficial wounds:

    Hydrocolloid
    Film dressing
    Perforated plastic film dressing
    Knitted viscose non-adherent dressings.

Infected wounds
Infected wounds need to be covered because they may have an unpleasant odour, and to prevent the spread of the organisms, particularly if they are resistant to standard antibiotics. Several dressings include antibacterial agents. Their use is controversial.

    Framycetin
    Fusidic acid
    Chlorhexidine
    Povidone iodine

Bioengineered skin substitutes

Skin autografts are commonly used to cover acute surgical wounds and chronic ulcers. However, harvesting skin grafts creates another wound that must heal, and suitable skin is unavailable in some cases such as extensive thermal burns. Sterilised cadaver allografts provide temporary wound dressings but eventually slough off. There has been intensive research and development in recent years to provide a satisfactory substitute for healthy skin. Replacement of dermal matrix and epidermis is required.

Cultured keratinocyte autografts can provide permanent coverage of large area from a skin biopsy. However, 3 weeks are needed for graft cultivation.

Keratinocyte allografts cultured from neonatal foreskins are available immediately. They can be cryopreserved and banked, but are not currently commercially available.

Applying a substitute dermal matrix has been shown to improve the likelihood that cultured epidermal cells (or an autologous split skin graft) will take. Several immunologically inert systems are now under investigation for management of refractory venous and diabetic ulcers.

Alloderm™ dermal matrix    
Apligraf™ artificial skin in culture

Chronic Wound FAQ

Chronic Wound Care FAQ

What are the signs and symptoms of a chronic wound?
·    The wound drains milky, yellow, green, or brown fluid that smells bad.
·    The wound bleeds, and is swollen and painful.
·    You have trouble moving the wounded area.
·    The wound has become large or deep.
·    The skin around the wound is dark or black and feels warm to the touch.
·    You have a fever.
How is a chronic wound diagnosed?
Your caregiver may check your health history, including diseases, medicines you are taking, and past surgeries. He will also need to know when and how your wound occurred. You may need any of the following:
·    Physical exam: Your caregiver will look closely at your wound and the area around it. He will check to see how much skin was broken and how deep the wound is. He will also look for other problems or signs of infection.
·    Blood tests: Blood tests are done to see if you have an infection and what may be causing it.
·    Wound culture: A wound culture is done to help caregivers learn more about your infection and decide the best medicine to treat it.

    

X-ray: This is a picture of your bones and tissues in the wound area. You may need to have an x-ray if the wound is near a joint or bone. Caregivers look for broken bones, or objects such as glass or metal.
How is a chronic wound treated?
Your treatment depends on where your wound is located and how severe it is. If a medical problem such as diabetes is delaying wound healing, it is important to treat this problem. Caregivers may change your treatment over time if your wound still does not heal. You may need any of the following:
·    Medicines: Your caregiver may give you an antibiotic to fight infection. You may take this medicine as a pill, get it through an IV, or apply it to the wound. You may also be given medicines to decrease pain, swelling, and fever.
·    Wound care:
o    Cleansing: Caregivers flush the wound with sterile (germ-free) water. They may use a large syringe with a needle or catheter (tube) tip. They may also use a fluid that kills germs.
o    Debridement: Debridement is done to remove anything from the wound that can delay healing and lead to infection. This includes dead tissue, objects such as small rocks, and dirt. Your caregiver will choose the best method of debridement for your wound. He may cut out the damaged areas in or around the wound. Caregivers may also drain the wound to clean out pus. Moist bandages may be placed inside the wound. or bandages that contain enzymes may be used. Hydrotherapy (whirlpool treatment) uses water to mechanically clean wounds. It may be used to clean and debride burn wounds.
o    Wound dressings: Dressings are used to protect the wound from further injury and infection. They also maintain moisture in the wound area to promote and speed healing. An elastic bandage may be wrapped around the wound area to put light pressure on it. The light pressure helps to decrease swelling in tissues around the wound area. Dressings may be in the form of bandages, gauze, films, gels, or foams. They may contain substances to help you heal faster. Skin taken from another part of your body may be used to close a large wound. Caregivers may instead use artificial skin that contains cells needed to repair damaged tissues.
o    Negative pressure wound therapy: Your caregiver will decide if you need negative pressure wound therapy (NPWT). This therapy is also called wound vacuum, or wound vac therapy. A vacuum device uses suction to remove fluid and waste from your wound and pull the edges closer together. NPWT may also increase blood flow and new tissue growth in the wound.

·    Hyperbaric oxygen therapy: This is also called HBO. HBO is used to get more oxygen into your body. The oxygen is given under pressure to help it get into your tissues and blood. You may be put into a tube-like chamber called a hyperbaric or pressure chamber. You will be able to see your caregivers and talk with them through a speaker. You may need to have this therapy more than once.
What can I do to take care of my wound and help it heal?
·    Do not stop using the bandage on your wound unless your caregiver says it is okay. Keep the bandage clean and dry.
·    Clean the wound as often as directed by your caregiver.
·    Wash your hands before and after you take care of your wound.
·    Your wound may need to be packed with gauze each time you change the bandages. Write down how many pieces of gauze are placed inside your wound. Be sure the same number comes out each time you replace the packing.
What can I do to help my wound heal?
·    Eat healthy foods and drink more liquids: Healthy foods give your body the nutrients it needs to heal your wound. Liquids prevent dehydration that can decrease the blood supply to your wound. Eat a variety of healthy foods including fruits, vegetables, breads, dairy products, meat, and fish. Protein, calories, vitamin C, and zinc help wounds heal. Ask caregivers for more information on wound healing and healthy foods.
Stop smoking: Smoking delays wound healing. Smoking also increases your risk of infection after surgery. If you smoke, ask caregivers for information about how to stop.
·    Prevent pressure damage: If you have a chronic wound, you may be at risk for pressure damage to your wound and other places on your body. Pressure sores can develop when blood flow to an area is blocked. For example, you sit or lie in the same position without moving and put pressure on your legs. Check your skin daily for signs of pressure sores. Common signs are swelling, open sores, blisters, a rash, or changes in color or temperature. Report these findings to your caregiver. You can help prevent pressure sores. Change your position every 15 minutes you are sitting. Prop your legs on pillows to lift your heels while you are lying down. Ask caregivers for more information on how to prevent pressure damage.
When should I contact my caregiver?
Contact your caregiver if:
·    You have a fever.
·    You have increased or new pain, swelling, redness, or bleeding in or around your wound.
·    You have new or different pus or a foul odor coming from the wound.
·    Your skin itches, swells, or has a rash.
·    You have questions or concerns about your medicines or treatment.
When should I seek immediate help?

·    You have muscle or joint pain, body aches, or sweating, with a fever.
·    You have a headache with diarrhea, nausea or vomiting, or a sore throat.
·    You are confused, or feel dizzy or faint when you stand up.
·    You have trouble breathing or sudden chest pain.
·    You see blood in the NPWT tubing or container, or on your bandages.

Understanding chronic wound healing

Nonhealing, or chronic wounds, are complex wounds that do not progress through the usual phases of healing. This can be caused by intrinsic or extrinsic influences and all age groups or patient types from the healthy to those with multiple comorbidities can be affected. It is not uncommon for NPs to evaluate and treat chronic wounds regardless of their practice specialty. Having a basic understanding of the skin, the phases of acute wound healing, and knowing when to refer to a wound-care clinic are all part of comprehensive patient care.

Types of wounds

Wound healing is a complex and dynamic process of restoring cellular structures and tissue layers. There are two types of wounds: acute and chronic. Acute wounds are either traumatic or surgical and move through the healing process at a predictable rate from insult to closure. Chronic wounds do not progress through the predictable stages of wound healing.

The type of wound repair is classified as either primary, secondary, or tertiary intention. In primary intention, the wound edges are approximated and held together with staples, sutures, or some form of adhesive tape. Healing occurs with epithelialization and connective tissue attachments, usually without complications.

Secondary intention is the treatment of choice for dirty surgical wounds, trauma, or wounds resulting from chronic disease. The wound edges are not approximated and healing occurs with granulation tissue, contraction of the wound edges, and epithelialization. In large wounds, granulation tissue is the only tissue reassembled by the body. Muscle, tendons, and ligaments do not regenerate.

In tertiary intention, the wound is left open for an amount of time determined by the surgeon, usually to decontaminate the wound base and restart the granulation process. Granulation is allowed to continue to a given depth, and then the wound edges are approximated.

A chronic wound is a wound that has not resolved over a reasonable period of time no matter the cause.Changes occur within the molecular environment of a chronic wound that are not conducive to healing, such as high levels of inflammatory cytokines, proteases, and low levels of growth factors.These changes terminate the healing process and increase the potential for septic infections. Addressing the issues that might be responsible for the physiological wound changes may restart healing.

All chronic wounds begin as acute wounds The most common chronic wounds are lower extremity ulcers. Chronic venous insufficiency (CVI) accounts for 80% to 90% of lower extremity ulcers and affects 2% to 5% of the population. The cost of treating CVI ulcers alone is estimated at 1 billion dollars/year in the United States. Other types of nonhealing wounds are surgical, diabetic, arterial, burns, dermatitis, vasculitis, and radiation. With the increase in new cases of diabetes, treatment of neuropathic and pressure ulcers are likely to increase proportionately.

Chronic wounds are encountered in every specialty and the occurrence of nonhealing wounds will continue to rise as the population ages, people continue to live longer with chronic diseases, and the nutritional needs of the body are not met. Approximately 2 to 3 million people suffer from chronic wounds in the United States.

Skin

The skin is the largest organ of the body and is continually adapting to meet the needs of an ever-changing external environment. It is a protective barrier from the outside world, and maintains a homeostatic internal environment. The skin consumes about one-third of the body's blood supply and is the first organ to lose that blood supply when the body is in crisis.

Normal skin is elastic, lubricated, and has a pH of approximately 4 to 6.8. The pH of the skin is acidic due to the sebum secreted by sebaceous glands onto the skin surface.Sebum contains antimicrobial properties and, along with the acid pH, inhibits the growth of microorganisms.

Langerhans cells, antigen presenting cells, are part of the immune system of the skin preventing microorganism invasion (see Langerhans cells). Other cells involved in the skin's immune system can be found in the dermal layer. Macrophages ingest bacteria and mast cells are involved in the inflammatory process caused by the injury. Keeping the skin intact is essential to protect the rest of the body from microbial invasion.

As the skin ages, or with chronic disease, some of the protective properties are lost or diminished. There is a reduction in sebum production and the skin becomes dryer and less elastic. Dryness leads to small cracks in the skin, which will support bacterial invasion. Combined with a chronic disease such as vascular disorders or diabetes, reduction in blood flow to the skin will occur, directly impacting wound healing.

Aging skin is more susceptible to damage due to thinning and increased friability. Other issues are a decrease in the inflammatory response, cell senescence, decrease in cytokines and growth factor production, and a reduction in receptor sites

Healing cascade

Understanding the phases of wound healing will assist the practitioner with evaluating where and when the healing stopped and what might have contributed to the wound stalling. The healing cascade starts with the injury or insult and progresses toward complete closure. The phases of acute wound healing are the inflammatory phase, the proliferative phase, and the remodeling phase.

Inflammatory phase

There are two parts to this phase starting from the initial injury and progressing toward the formation of the clot. Clot formation is a crucial step within the inflammatory phase because the clot itself brings cytokines (polypeptide regulators) to the site of injury. Another important chemical released by the clot is platelet-derived growth factor, which influences cellular growth and development.The formation and degradation of the clot are important aspects of the inflammatory phase.

Hemostasis begins when the injury occurs and lasts only a few hours.The injury creates a vascular response to try to control the bleeding. The exposure of the epithelium of the blood vessels triggers platelet aggregation which generates a temporary barrier to bacteria and controls the bleeding. Vasoconstriction, thromboplastin production and clot formation are the major components of hemostasis.

After the bleeding has been controlled the body focuses on cleaning up the debris generated by the healing process. This phase starts with vasodilation causing the leakage of plasma, neutrophils, and other cytokines into the tissue surrounding the injury site. Usually what will be noted clinically is edema, induration and heat in the periwound skin. This is part of the wound-healing process and does not, alone, signify infection. The practitioner should evaluate lab tests such as a white blood cell count and quantitative wound culture to evaluate for infection.

The mediators of this phase are nitric oxide, neutrophils, and macrophages. Macrophages are responsible for the release of growth factors, enzymes that stimulate angiogenesis, fibroblasts, and the process of connective tissue synthesis.This is the phase of healing where most chronic wounds stop progressing.

Proliferative phase

The proliferative phase usually lasts 2 days to 3 weeks and can be broken down into two phases. The first phase is the foundation of the wound base with granulation tissue. Remember muscle, tendon, fascia cannot regenerate. All the body can produce to fill in the wound base is granulation tissue. Granulation will only begin after the dead tissue has been removed from the wound base.

Macrophages release fibroblasts to create the foundation of the wound base after the debris has been removed. Fibroblasts build the foundation or framework to construct the wound base. Angiocytes create the blood supply to stimulate angiogenesis. The macrophage release many physiologic activators and messengers to stimulate connective tissue formation. The end product of this process is the wound base framework to support the granulation tissue. The major mediators for this phase are the macrophage and the vascular endothelial growth factor responsible for angiogenesis.

After the wound base is completely filled with granulation tissue, the wound edges are stimulated to start epithelialization. The process is similar to the freezing of a pond in winter. Epithelialization starts from the outside edges and progresses toward the center. Keratinocytes start the process of migration across the wound base leading to eventual closure of the wound.

Remodeling phase

After the wound is closed, the body continues to heal the wound. The remodeling phase lasts anywhere from 6 months to 2 to 3 years depending on the patient's health. During this time, the body's cytokines change the wound matrix and strengthen the collagen support structure.This process increases the strength of the scar, known as tensile strength. The highest tensile strength that can be restored is 80% of the original strength of the tissue. Before the completion of this phase the wound is vulnerable to reinjury. (See Cellular view of acute wound healing).

Etiology

There are many reasons for a wound to stall during the healing process (see Pathologic process of chronic wounds). Some factors are unusual and related to the individual such as autoimmune diseases. There are a few factors that cross all age barriers and when understood will help the practitioner with the screening process for impaired wound healing. Aging, as mentioned before, has an impact on healing. A few of those changes are; decrease in blood supply to the skin, alteration in collagen formation, flattening of the basement membrane, and a slower inflammatory response. The elderly seem to have a higher percentage of chronic illnesses that may lead to polypharmacy.

Impaired perfusion influences oxygen transport. Decreased oxygen availability will have an impact on collagen formation, angiogenesis and epithelialization. Neutrophil and macrophage microorganism ingestion consumes an increased amount of oxygen. Impaired perfusion and decreased tissue oxygenation increases the patient's risk of infection.

Proper nutrition is key to continued wound healing. Malnutrition leads to decreased collagen production, impaired fibroblast production, and impaired angiogenesis. Poor eating habits lead to decreased available protein needed for wound repair. Bacteria, usually Gram-negative, in higher concentrations compete with granulation tissue for the nutrients available in the wound bed and their byproducts are toxic.

The age of the wound, in other words how long the wound has been open, also affects healing. As mentioned earlier, "old" wounds seem to have "old" cells that lose the ability to proliferate. The problem is not limited to the elderly. Underlying chronic disease, such as diabetes, can affect the wound chemistry.

Stressors have been implicated in the impaired healing process. An increase in the production of cortisol and vasoconstriction can impair wound healing.Early research findings have shown a correlation between decreased wound healing and psychological stressors, pain, and noise.Further research on how stressors influence wound healing is needed.

The bioburden is the number of bacteria, on the wound base. Chronic wounds are contaminated and the degree of contamination will have an effect on the rate of healing. In other words, the higher the quantity of the bioburden the slower the healing rate.