Why a Moist Wound Environment is Critical for Wound Healing
Modern wound care practice stands in stark contrast with the common wound management approach in the 1960s. Healthcare professionals are now convinced – through extensive clinical research – that moist wound healing is the best approach to wound management. Moisture promotes re-epithelialization thus accelerating the healing process of acute and chronic wounds. But there’s more to moist wound healing than meets the eye, so let’s get right to the details.
Wound Management Approach Before the 1960s
There has been a significant evolution in the wound care approach over the years. Before the 1960s, healthcare professionals swore by dry wound healing – the approach of managing wounds by creating a dry wound environment. They did this by leaving the wound uncovered to let it dry, or covering it with a dry gauze dressing.
Soon, Dr. George Winter, a British researcher, discovered that superficial acute wounds healed slower under a dry scab than in a moist environment. Wounds that were managed in a dry environment also healed poorly. This was a monumental finding as it laid the foundation for moist wound healing.
Impact of Moisture on Wound Healing
Subsequent studies have now proven that moisture is a key component in wound healing. The normal wound repair process progresses through four phases that are temporarily sequential and overlapping: hemostasis, inflammation, proliferation, and maturation (remodeling).
The proliferation phase is characterized by processes such as cellular infiltration, angiogenesis, and re-epithelialization. During this phase, wounds rebuild through the development of new tissue consisting of collagen and extracellular matrix. But what is the role of moisture in all these processes and phases?
Easier Cell Movement or Migration
The basis of wound healing is the formation of new tissue and the movement of epidermal cells across the wound surface. During the inflammatory phase, fluid engorgement facilitates the movement of healing and repair cells such as keratinocytes to the wound site.
The exudate from blood vessels is also vital in removing damaged cells, bacteria, and pathogens from the wound area. What’s more, a moist environment (due to the exudate) means an extended presence and activity of enzymes, growth factors, and proteinases. This, in turn, results in increased repair tissue synthesis and autolytic debridement.
Enhances Collagen Synthesis and Angiogenesis
Produced by fibroblasts, collagen is a fibrous structural protein – the most plentiful protein in the human body. It is abundant in ligaments, tendons, bones, and the skin. Collagen is responsible for inducing platelet activation and aggregation after an injury. That way, a fibrin clot is deposited at the injury site.
During the inflammatory phase of wound healing, the activation of immune cells results in the secretion of proinflammatory cytokines. These, in turn, impact the migration of fibroblasts, endothelial, and epithelial cells. Fibroblasts at the wound site mean that collagen is continually deposited as the phase progresses.
The creation of new blood vessels through angiogenesis has always been considered essential to wound healing. Moisture enhances the rapid and robust growth of capillaries, creating a vascular bed with more capillaries than normal tissues. New capillaries at the wound site are necessary for bringing nutrients, oxygen, and immune cells, which are critical for healing.
Modulation of the Wound Microenvironment
Treatment of chronic wounds, which are defined as those which don’t heal optimally in six weeks, often involves the use of antimicrobials, growth factors, and even micrografts. The application of topical antimicrobial agents and analgesics is aimed at eradicating contamination and also preventing colonization.
The moisture in the wound area acts as a reservoir and a sustained release system of the added growth factors and antimicrobials. This presents the likelihood of creating a regenerative wound microenvironment, thus aiding healing. It also helps prevent excessive scar formation.
Reduced Scarring and Pain
The healing of open skin wounds is characterized by a varying degree of scar formation. While the degree of scarring can be attributed to the remodeling of collagen from type III to type I during the maturation phase, it can also be correlated with the duration and intensity of the inflammation stage.
A study done on porcine wounds compared the number of inflammatory cells when these wounds were treated in a wound chamber or with dry gauze. Inflammation was significantly reduced in wounds treated in a wound chamber.
Further, there was a strong correlation between the number of inflammatory cells in the initial stage of wound healing and the degree of scarring after four weeks.
Wounds that were treated in moist and sterile conditions and a low concentration of antibiotics showed a smaller macroscopic scar surface area compared to dry wounds. The relatively low degree of scarring also reduces pain during the healing process.
How Much Moisture is Sufficient for Wound Repair?
There is no one definite answer to this question. Rather, wound care experts rely on clinical observations to tell whether the moisture around the wound is sufficient for proper healing. Dry wound dressings often indicate too little moisture, which might cause excessive pain on removal.
A relatively slow rate of wound closure may also indicate insufficient moisture levels. On the other hand, excess moisture will be indicated by signs such as tissue edema, moisture-related skin damage, maceration, and a slower resolution rate of the wound.
Moisture is a critical component of wound healing. Optimizing the moisture level of a healing wound has been associated with various benefits, including faster healing rates, better modulation of the wound microenvironment, stimulation of collagen synthesis, and reduced scar formation.