Necrotic wounds are characterized by devitalized, or dead, tissue. Necrosis may be caused by malignancy, infection, trauma, ischemia, inflammation, or exposure to toxins. It may also be caused by improper care of an existing wound site. Devitalized tissue has no blood supply, and its presence prevents wound healing. It is necessary for necrotic tissue to be removed to allow wound healing to occur.

Understanding Necrotic Tissue

There are two main types of necrotic tissue: eschar and slough. Eschar is dry, black tissue with a leathery texture. Eschar may cover a wound bed in a thick layer, like a scab. However, unlike a scab, eschar is not a part of the wound healing process and must be removed to support healing. Slough is a soft, moist tissue composed of non-viable tissue and bacteria. It can be firmly or loosely attached and may be yellow, green, tan, or brown. In addition to forming a physical barrier to wound healing, necrotic tissue also presents an opportunity for microbial colonization and infection. When cells die as a result of necrosis, the phagocytes responsible for cellular cleanup are not notified, and dead tissue and debris accumulate.

Necrotic Tissue Managment

The first priority in necrotic wound treatment is to address the underlying cause of necrosis, and the second is to remove the necrosis by debridement to allow new tissue to grow. The methods for removal vary based on the type and location of the wound. Each of the four primary types of debridement has advantages and drawbacks. Amputation is an emergency treatment used in cases where it is deemed necessary or urgent.

Types of Debridement

Autolytic Debridement

By keeping wound fluids in constant contact with the wound, autolytic debridement uses the body's natural processes to break down necrotic tissue. This method can be used in partial- or full-thickness wounds, as well as in stage 2 or 3 pressure ulcer wounds with low to moderate exudate. Semiocclusive or occlusive dressings such as alginates, honey-impregnated dressings, hydrocolloids, hydrogels, and hydrofibers can be used to support autolysis. The advantages of autolytic debridement include that it does not require a high level of skill on the part of the clinician, it can be used in conjunction with other methods of debridement, and it can be used on painful wounds in any care setting. The disadvantages are that it is a slow process that can cause maceration of the surrounding skin, and it can increase the risk of infection.

Mechanical Debridement

This is the oldest form of debridement, administered by irrigation, hydrotherapy, an abrasion technique, or wet-to-dry dressings. With the wet-to-dry method, necrotic tissue that has adhered to moist wound dressings as it dries is removed along with the dressing. The advantages of mechanical debridement are its low cost and quick results. However, the drawbacks include the need for frequent dressing changes, the potential for the removal of healthy tissue, and the possibility that it may be painful for the patient. Other forms of mechanical debridement include pulse lavage and wound irrigation.

Sharp Debridement or Surgical Debridement

Often performed in conjunction with autolytic debridement, this form of debridement promotes wound healing by expeditiously removing necrotic tissue and biofilm. Sharp debridement is performed by a skilled clinician using a curette, scalpel, scissors, or forceps to remove devitalized tissue to a viable tissue level. Surgical debridement is a more aggressive form of debridement and may require an anesthetic. The amount of devitalized tissue present will determine the level of debridement required.¹ The advantages of sharp debridement are that it is selective, rapid, and repeatable, and it can be performed on large areas. The drawbacks are the level of skill required, the higher cost, the risk of bleeding, and the potential need for an anesthetic.²

Enzymatic Debridement

This method involves the application of a topical agent that chemically liquefies necrotic tissue with enzymes. This method is often used in conjunction with surgical or sharp debridement and is generally used in the long-term care setting as it is less painful than other methods of debridement.

Larval Therapy

Green bottle fly larvae (maggots) raised in a sterile environment are used to remove moist, devitalized tissue. This is a very selective, rapid method that can be performed on infected wounds and requires minimal clinical training. It is not suitable for dry wounds with hard eschar or for patients with clotting issues or in highly exuding wounds.³

Amputation

Debridement is typically performed in a serial fashion⁴, with the exception of surgical debridement. The removal of bioburden coupled with the use of antibiotics has been shown to reduce infections and promote healing⁵ in necrotic wounds. However, in the case of patients in poor health with coexisting medical conditions, it is sometimes necessary to amputate the area affected by the necrotic wound. Patients with diabetes or vascular disease are at higher risk of requiring a lower extremity amputation for a non-healing necrotic wound.⁶ One potential reason for amputation is necrotizing fasciitis, a rare, life-threatening soft tissue infection of underlying muscle and fat tissue that can spread quickly.⁷ Amputation is a treatment of last resort that can usually be avoided through stringent wound management.

References

1. Moore Z. The important role of debridement in wound bed preparation. Wounds Int. 2012;3(2):19-23.

2. Leaper D. Sharp technique for wound debridement. World Wide Wounds. 2002. http://www.worldwidewounds.com/2002/december/Leaper/Sharp- Debridement.html. Accessed April 15, 2018.

3. Gilead L, Mumcuoglu KY, Ingber A. The use of maggot debridement therapy in the treatment of chronic wounds in hospitalised and ambulatory patients. J Wound Care. 2012;21(2):78, 80, 82-85.

4. Wolcott RD, Kennedy JP, Dowd SE. Regular debridement is the main tool for maintaining a healthy wound bed in most chronic wounds. J Wound Care. 2009;18(2):54-56.

5. Penn-Barwell JG, Murray CK, Wenke JC. Early antibiotics and débridement independently reduce infection in an open fracture model. J Bone Joint Surg Br. 2012;94:107-112.

6. Lipsky BA, Berendt AR, Deery HG, et al. Diagnosis and treatment of diabetic foot infections. Clin Infect Dis. 2004;39:885-910. doi: 10.1086/424846.

7. Tang W, Ho P, Fung K, Yuen K, Leong J. Necrotising fasciitis of a limb. J Bone Joint Surg Br. 2001;83(5):709-714.