The fluid that is secreted from a wound during the healing process is called  ‘wound exudate’. While it might be unpleasant to look at, wound exudate is an essential component of wound healing. It is secreted during the ‘inflammatory phase’ of wound healing due to vasodilation of blood vessels. Wound exudate helps provide a moist environment for optimum wound healing, and also contains essential nutrients that nourish the tissues on the surface of the wound. In addition, it also helps reduce infection rates and reduces discomfort associated with wounds.1

Types of Wound Exudates

Wound exudate is not simply an inert liquid. It can help provide valuable clinical information to wound care specialists and podiatrists regarding etiology, the progression of a wound, and the presence of infection. The biochemical properties of wound exudate are altered depending on the wound micro environment. Therefore, its composition can help wound care specialists determine whether a wound is acute or chronic. 

Generally speaking, a healthy wound has a small amount of exudate visible on its surface. Wound exudate can be classified into the following types depending on the morphological appearance:

• Serous: it appears thin, watery, and straw-colored. It is normal.
• Fibrinous: it is thin, watery, and cloudy in appearance. It contains fibrin which is a normal finding
• Bloody: it is thin, watery, and bright red
• Serosanguineous: it is thin, watery inconsistency, and pale pink to bright red in appearance
• Purulent: it contains inflammatory cells and debris resulting from an infection2

The causative factor of the wound influences the volume of wound exudate. Patients with venous and infectious etiology have excessive exudate production. The presence of systemic conditions like congestive heart failure can also increase the amount of wound exudate.

Characteristics of Acute And Chronic Wound Exudate

Chronic wounds result from persistent inflammation that fails to promote wound healing. The characteristics of wound exudate can help podiatrists and wound care specialists differentiate between acute and chronic wounds. The exudate in chronic wounds contains high levels of degrading enzymes like neutrophil elastase and matrix metalloproteinases (MMPs). As a result, the wound is not able to heal due to the degradative action on the extracellular matrix and granulation tissue. Chronic wound exudate also contains high levels of glucose, protein, and low albumin.

In contrast to chronic wound exudate, the wound exudate in acute wounds supports fibroblast mitotic activity. It does not cause damage to the skin around the wound and is rich in essential nutrients. This helps promote optimum wound healing.3

Management of Wound Exudate

Excessive wound exudate can considerably impact a patient’s well-being and quality of life. Many patients experience discomfort related to leakage, soiling of clothes, and malodor. The presence of excessive exudate can also have social, economical, and psychological implications for the patient. Patients might find frequent washing and changing of clothes cumbersome. Therefore, management of wound exudate should involve a patient-centered approach to wound care. An effective wound exudate care plan addresses the patient’s concerns and optimizes the wound bed for healing. Following are the main aims of effective exudate management:

• Identification and treatment of the underlying cause e.g infection or congestive heart failure
• Improving patient’s quality of life
• Optimal moisture maintenance through dressing
• Frequent assessment of wound to ensure progress and optimum wound healing
• Prevention of odor and other exudate-related problems
• Prevention of damage to periwound skin4

Selecting A Wound Dressing

While selecting a dressing, it should be kept in mind that the properties of the wound dressing should be favorable towards wound healing. Simply wiping off the excess exudate is not going to optimize wound healing. It is also important for wound care specialists to consider the type of wound exudate when selecting a dressing. 

An ideal dressing absorbs excess exudate and creates a moist environment in the wound bed which promotes wound healing. Moisture is also essential in preventing maceration of the skin. A wound dressing should also prevent leakages as they can be uncomfortable for the patient. The wound dressing should be adherent to the skin, but still able to be easily removed without causing damage to the fragile, peri-wound skin.  As frequent dressing changes require dedicated nursing, a cost-effective solution is to select dressings that require minimal change without compromising on the quality of wound care. Patient comfort can be maximized by selecting a dressing that is not painful on removal.

A variety of dressing types are available that can help effectively manage wound exudate. Alginate dressings cross-react with the exudate to form a gel-like substance that both absorbs and retains the exudate. These dressing types are also effective in providing a moist wound environment. Another type of dressing transmits wound exudate to the surface of the dressing from where it can evaporate into the air.5

Use of Skin Barriers And Ointments

Excess exudate can cause maceration of the surrounding skin. Macerated skin is also at increased risk of infection.6 Therefore, skin barriers and ointments should be considered to avoid additional damage to the fragile peri-wound skin. However, before prescribing skin ointments, allergies to the ointment material should be ruled out. In addition, gentle cleansing of the skin should be recommended to keep the periwound skin healthy.6

Conclusion

Wound exudate provides critical information regarding wound etiology and the health status of the wound. Wound exudate is an essential component of wound healing, but excess can contribute to patient discomfort. In addition, excessive exudate can also be a signal of infection. Effective wound management should always be patient-centered and should address patients’ concerns. Regular assessments should be carried out to evaluate the effectiveness of wound care. 

References

1. Wiechula R (2003) The use of moist wound healing dressing in the management of split-thickness skin graft donor sites: a systematic review. Int J Nurse Pract 9(2 Suppl): 9–17
2. Cutting KF. Wound exudate: composition and functions. British journal of community nursing. 2003 Sep;8(Sup3):S4-9.
3. Katz MH, Alvarez AF, Kirsner RS et al (1991) Human wound fluid from acute wounds stimulates fibroblasts and endothelial cell growth. J Am Acad Dermatol 25: 1054–8
4. Dowsett C. Moisture in wound healing: exudate management. British Journal of Community Nursing. 2011 Jun;16(Sup6):S6-12.
5. Adderley UJ. Managing wound exudate and promoting healing. British journal of community nursing. 2010 Mar;15(Sup1):S15-20.
6. Guest JF, Greener MJ, Vowden K, Vowden P (2011) Clinical and economic evidence supporting a transparent barrier film dressing in incontinence-associated dermatitis and peri-wound skin protection. J Wound Care 20(2): 76–84