Wound Healing and Wound Care

Author: Julian Man, London, Final Year.

The teaching of wound healing and the use of appropriate dressings is often overlooked in the undergraduate medical curriculum. This article will briefly cover the principles of wound healing, along with the basics of wound care in the clinical setting, focussing on the different types of dressings available.

In the majority of healthy patients, wound healing is relatively straightforward. However, patients with long-term conditions or acute illnesses may experience delayed wound healing. Wound care is especially important in plastic surgery, since aesthetics is a key consideration. Therefore, it is important to understand the principles of wound healing and the different tools available in wound care.

Wound Healing Fundamentals

When the body is injured, complex processes take place to convert a traumatic injury into a stable scar. The intrinsic and extrinsic clotting systems are activated, platelets are recruited to form a platelet plug and scar formation occurs with the deposition of extracellular matrix acting as a scaffold. Wound healing is therefore a balance of two main processes: scar formation and tissue regeneration (1).

Scar formation patches the wound with the use of extracellular matrix, stabilising the area of injury and provides a barrier so pathogens cannot enter the body. Tissue regeneration involves the activation of developmental processes resulting in the formation of the original tissue type.

In order to promote wound healing, the wound site would ideally be warm, well-hydrated in a systemically well, non-smoking patient with adequate glycaemic control (2). Other factors which may affect wound care include: age, ischaemia, infection, diabetes and steroid use (3).

Wound Care Adjuncts

To help with recovery and increase the rate of wound healing, adjuncts such as dressings may be used. However, it is important to note that the most important tool for wound care is debridement of the wound – this involves removal of necrotic or foreign material, including accumulation of eschar (4). Reducing the bioburden will in turn promote healing.

There are many dressings available clinically, with use depending on factors such as wound size, wound depth and the presence of exudate. The main classes of wound dressings will be discussed below:

Gauze

Gauze is a non-adhesive dressing with the ability to hydrate wounds when moistened with normal saline. It is most useful on surgical incisions and other superficial wounds. It can also be impregnated with antimicrobials to reduce infection (e.g. silver). However, gauze can be painful to remove and microfibres can be left behind, increasing risk of infection.

Films

Films (e.g. Tegaderm) are adhesive, non-absorbing dressings used for superficial surface wounds and surgical incision sites. They are impermeable to fluids but allows the passage of gas molecules. Films are useful as it allows visual checks and promotes a moist environment.

Hydrogels

Hydrogel sheets are made from insoluble polymers with up to 96% water content, allowing the wound to be kept moist. They can also absorb moderate amounts of fluid from the wound. Applied on the surface, these dressings can be used for sloughy or necrotic wounds.

Alginates

Alginates are derived from brown seaweed and can absorb around 15 to 20 times their weight in fluids, making them suitable for highly exuding wounds. They can be used to pack cavities, and do not require daily changes. Use of alginates on wounds with no exudate will lead to adherence to the wound surface, pain and damage to healthy tissue.

Foam dressings

Foam dressings are highly absorbable, non-hydrating dressings made of polyurethane or silicone. They are designed with a hydrophilic wound surface side and a hydrophobic backing. They can used for superficial and deep wounds with moderate to heavy exudates.

Negative-pressure wound therapy

These dressings effectively use a vacuum with negative pressure to remove any exudates in the wound. Used in both superficial wounds and deep cavities, these can be used on patients with venous statis wounds, diabetic ulcers and abdominal wounds. An example of this is the VAC dressing (5).

CONCLUSION

The key things to remember are:

1. Remember to assess the wound – what is the size? Where is the wound located? Is the wound visibly unclean? Is there any exudate or foreign bodies?
2. Remember to assess the patient – what co-morbidities does the patient have? Does the patient smoke?
3. Other methods may be more suitable to close a wound, ranging from simple primary closure to complex vascularised free flaps.
4. If unsure – ask! Tissue viability nurses will be able to help assess what is needed, and provide further advice on how to best manage the wound.

REFERENCES

1. Gurtner GC and Wong VW. Wound Healing: Normal and Abnormal. In: Thorne CH, Chung KC, Gosain AK, Gurtner GC, Mehrara BJ, Rubin JP, Spear SL (eds.) Grabb and Smith’s Plastic Surgery. 7^th Edition. Philadelphia: Lippincott Williams & Wilkins. p.13-19.
2. Jones V, Grey JE, Harding KG. Wound dressings. BMJ. 2006;332(7544): 777-780.
3. Anderson K, Hamm RL. Factors that impair wound healing. J Am Coll Clin Wound Spec. 2012;4(4): 84-91.
4. Buck DW and Galiano RD. Wound Care. In: Thorne CH, Chung KC, Gosain AK, Gurtner GC, Mehrara BJ, Rubin JP, Spear SL (eds.) Grabb and Smith’s Plastic Surgery. 7^th Edition. Philadelphia: Lippincott Williams & Wilkins. p. 20-28.
5. Agarwal P, Kukrele R, Sharma D. Vacuum assisted closure (VAC)/negative pressure wound therapy (NPWT) for difficult wounds: a review. J Clin Orthop Trauma. 2019;10(5): 845-848.