Wound Care and Methods of Debridement

Debridement is one of the cornerstones of effective wound care and has been demonstrated to be one of the most important variables in wound healing time. Assessment of tissue types, removal of nonviable tissue, and appropriate wound treatments are all critical for optimal healing.

Wound Bed Tissue

The health of the wound bed is a big determinant of the healing process and treatment plan. The ideal wound bed is covered with granulation tissue. Even exposed bone or tendon will granulate if the healing process is unimpeded.

Necrotic tissue in the wound bed slows healing and increases the risk of infection; non-viable tissue is typically heavily colonized with bacteria. Most necrotic wounds should be debrided in some way to reduce infectious risk to the patient.

It is easy to see why large amounts of necrotic tissue should be removed, but what about wounds with small amounts of necrosis? Even small amounts of necrotic tissue impact wound healing. While there is a much smaller increased risk of infection, the wound risk often has more to do with the health and inflammatory state of the wound bed than overt infection.

Presence of dead cells results in increased inflammation in the wound bed. Necrotic cells can release tumor necrosis factor, which increases the rate of adjacent viable cell death. This inflammatory milieu also diminishes macrophage and fibroblast function critical for healing. Damage-associated molecular patterns (DAMPs) are intracellular materials released from the cells of necrotic tissue that also increase inflammation. These DAMPs cause nearby cells to release pro-inflammatory cytokines, chemokines, and adhesion molecules, which contribute to the exaggerated inflammatory response. All of these processes interfere with wound healing.

Methods of Debridement

These are six methods of wound debridement.

Autolytic

Autolytic is the slowest method of debridement, using the body’s own lytic enzymes to break down proteins, fibrin and collagen. Almost any dressing that maintains a moist wound bed facilitates autolytic debridement. Some advantages of autolytic debridement over other options are its low expense and ubiquitous availability, as well as lack of patient discomfort. It is, however, a very slow method of debriding a wound. Typically, physicians rely on autolytic debridement as an adjunct to other debridement techniques rather than the sole method of removing necrosis.

Enzymatic

Enzymatic debriding agents use enzymes to remove nonviable tissue over a period of days or weeks. The only enzymatic agent available in the USA today is collagenase, or Santyl. Collagenase works by cleaving denatured collagen strands in necrotic tissue. The collagen byproducts aid in healing by stimulating fibroblast, keratinocyte and endothelial cell migration to the wound bed. Many physicians use enzymatic debridement in conjunction with sharp tissue removal.

Enzymatic debridement is quite easy to use, typically painless, and does not damage healthy tissue. The factors limiting its use are primarily expense and speed. A wound with necrotic tissue that must be removed quickly requires more active debridement than waiting for the collagenase to loosen and remove the tissue. Good stewardship of limited financial resources may limit the use of more expensive treatment options such as collagenast.

Surgical or Sharp

Surgical or sharp debridement involves use of a scalpel or other sharp instrument to remove necrotic tissue. Although some complex wounds or complicated medical comorbidities may require debridement under anesthesia in an operating room, most wounds may be safely debridered under local anesthetic in a clinic or other bedside environment. This is the fastest way to remove necrotic tissue and is typically indicated for a wide range of wound types. When performed by a skilled clinician, sharp debridement creates a favorable environment for healing, helps prevent infection, and can help reduce costs. Sometimes not all necrotic material can be removed in a single procedure, necessitating serial procedures in conjunction with other debridement methods (autolytic, enzymatic). Sharp procedures are very effective at removing biofilm, as well. Factors limiting use of sharp debridement include patient discomfort, possible bleeding or damage to intact tissue, and the need for practitioner licensure, training, and supplies.

Mechanical

Mechanical debridement is rarely used in modern wound care. It is a nonselective type of debridement, meaning that it will remove both devitalized tissue and debris and viable tissue. It is usually carried out using mechanical force: wet-to-dry dressings, pulse lavage irrigation, or whirlpool treatment. In addition to removing both healthy wound tissue as well as necrotic debris, it is typically uncomfortable for the patient. This limits its use in most clinical situations, especially since there are more selective, less traumatic, and less uncomfortable treatments available.

Biologic Debridement

Biologic debridement is the use of green-bottle fly maggots to remove nonviable tissue. While rarely used in modern medicine, maggots are extremely effective and efficient at removing necrosis while not damaging viable tissue.

Biofilm

Biofilm is an often-invisible tissue layer that stalls wound healing. A biofilm is a consortium of bacteria living in extracellular polymeric substances, or EPS. EPS are polysaccharides, proteins, extracellular DNA (eDNA), and lipids. Bacteria in the biofilm are protected from adverse environmental factors and immune response by the EPS, making them virtually impervious to most wound treatments and antibiotics. While there are many cleansing solutions and topical wound products that help manage biofilm, the best way to remove it is to superficially debride the wound bed. Use of some dressing materials can be very helpful in minimizing or slowing reaccumulation, such as silver products, surfactant wound care gel, cadexomeric iodine gel, and sodium hypochlorite products. (Not an exhaustive list.)

Wound Treatment Options

The most important consideration in dressing selection for a noninfected wound is moisture balance. Dressing materials may be divided loosely into two categories: moisture donating and moisture removing. Once the physician characterizes the moisture in the wound, ie, heavy exudate or light/dry exudate, the dressing selection becomes straightforward. Wet wounds require moisture removing dressings while drier wounds typically require moisture donating dressings. There are many other considerations for final dressing selection, including periwound condition, infection, vascular status, and patient compliance, but the “wet vs dry” decision is an important first step to narrow down the list of options.

Adjunctive Treatment Options

There are ancillary treatments that can help with wound healing as well.

Electronic stimulation, or E-stim, involves the use of mild electrical pulses that mimic neuronal impulses. This stimulates blood flow and angiogenesis, thereby increasing capillary density and perfusion, improving wound oxygenation, and encouraging granulation and fibroblast activity.
Diathermy (or pulsed, short-wave diathermy) is the application of shortwave (10 to 100 MHz frequency) electromagnetic energy to the wound tissue. The energy is applied at nonthermal levels and is thought to primarily impact the cellular manufacture of ATP and proteins. It also impacts growth factor activation in fibroblasts and nerve cells, macrophage activation and changes in myosin phosphorylation.
Ultrasound therapy is administration of a high frequency ultrasound to the wound to promote healing. The ultrasonic energy has a vibratory effect on cells and is thought to reduce inflammation and increase tissue perfusion. Although therapeutic ultrasound has been used to aid in the healing of chronic wounds, no consensus exists regarding its effectiveness.

Conclusion

Maintaining a healthy wound bed free of nonviable tissue is an integral part of wound management. Most necrotic tissue should be debrided. There are several different ways to remove nonviable tissue from a wound, each with its own benefits and limitations. Biofilm is another type of nonviable surface material that precludes healing. Wound care practitioners should be mindful of the potential for biofilm when wounds fail to progress. Dressings and ancillary treatments should be determined by the appearance and moisture balance of the wound itself.

Resources and References

Mil Med Res. 2015; 2: 12.

Published online 2015 May 19. doi: 10.1186/s40779-015-0039-0

PMCID: PMC4455968

PMID: 26045969

Programmed cell death and its role in inflammation

Yong Yang, Gening Jiang, Peng Zhang, and Jie Fan

Annu Rev Pathol. 2008; 3: 99–126.

doi: 10.1146/annurev.pathmechdis.3.121806.151456

PMCID: PMC3094097

NIHMSID: NIHMS141099

PMID: 18039143

The inflammatory response to cell death

Kenneth L. Rock and Hajime Kono

March 1, 2003

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Wound Care and Methods of Debridement

Wound Bed Tissue