This article outlines postsurgical wound closure techniques: electrostimulation, ultrasound, hyperbaric oxygen therapy, tissue engineering, growth factors,
negative pressure therapy, UV light therapy and superoxidised water
Specialist in Medicine and Surgery
Surgical Intermediate Care Unit
Hospital S. João EPE
Specialist in Public Health
Intensive Care Unit
C. Hospitalar Vila Nova Gaia
General Surgeon, Upper GI Unit
General Surgery Service
Hospital S. João EPE
Innovation is the key word for scientific development – seeking in the present solutions for the future, without forgetting the past. Based on a literature review, many renowned world investigators have reported in various published articles some of the original and subsequent knowledge on surgical wound management.[1–7]
The most recent different techniques for wound management reveal a wide range of strategies for closure. But there are many difficulties in the pursuit of this objective, because of the many complications that can occur with both acute and chronic wounds.
When reviewing the surgical wound there are many challenges, especially concerning healing by second intention or if infection is present, with all the clinical consequences.
Many new therapies have begun to emerge, especially techniques used for different purposes regarding wound management that are under investigation by the scientific community. They are important in optimising local wound management and in promoting patient comfort, with better
results concerning patient care. Nonetheless, it is necessary to evaluate the cost–benefit of all the different forms of care treatment. This issue is of more and more concern regarding health systems cost control.
Management of the surgical wound
In normal circumstances, the surgical wound healing process is that of an acute wound, without complications, which occurs in a certain period of time, with the majority of such wounds healing by first intent. Healing by first intent involves approximation of the wound margins and closure with the use of sutures or the construction of flaps or grafts, which adhere within 24–48 hours, and normally heal within 8–10 days. Healing by second intent implies leaving the wound open, in order for its closure to occur spontaneously, with growth of granulation tissue, contraction of the wound and epithelialisation. When the wound has to be left open for a certain period of time, due to oedema, infection or the need for a future surgical intervention, and is posteriorly closed by first intent, then the healing process is defined as third intent or deferred first intent.
This article concentrates on wounds that heal by second intent or deferred first intent – situations where the wound cannot be primarily closed. Numerous factors that delay normal healing will contribute to their designation as hard-to-heal wounds.
Various conventional techniques are used for their closure, with the objective of promoting tissue growth, granulation and contraction of the surgical margins. New techniques for healing by second intent have also emerged and are under continuous investigation, to try to improve the efficiency of wound management, reduce the response time and consequently improve patients’ quality of life.
Different approaches to wound closure Wound management products
Based on collaboration between the pharmaceutical industry and scientific research, the number and diversity of wound management products have increased. The main characteristics of these products are related to their antibacterial properties, maintenance of a humid environment and exudate control. They range from
simple to complex, and from active to inactive forms, that promote healing of surgical wounds by second intent, and with no evidence-based significant differences between them.
In this group are included tissue cultures, skin substitutes/biosynthetic tissue platforms and growth factors.
This technique has been progressively improved. It involves the harvest of a portion of skin that is cultured in the lab to create sheets of cells that function as skin grafts once placed on completely granulated wounds that are clean and free of any necrotic tissue.
Skin substitutes/biosynthetic tissue platforms.
These are produced from human dermal fibroblasts that are cultured on a biosynthetic dish. During the proliferation process, they segregate proteins and growth factors, and create a threedimensional human skin that can be used as a graft over the wound bed. Studies demonstrate healing acceleration and greater success of the biosynthetical tissue platforms.[15–18]
These are proteins that exist in the body and function as biomediators that establish signals with specific cellular receptors and promote cellular activity.[19,20] Platelet-derived growth factors (PDGFs) are presently the best known, due to their efficiency in wound management at the granulation phase. Studies demonstrate that, due to their ability to accelerate the healing process, they are particularly useful in hard-to-heal surgical wounds.[17,21]
This therapy is characterised by use of a source of electric current that transfers energy to the wound. The human body has its own bioelectrical system, which is vital for the process of tissue regeneration. A wound alters this balance and diminishes the healing process. The objective of this technique is to accelerate tissue repair with the improvement of perfusion, namely the microcirculation flow. Many different forms of application exist relating to the sources of emission that are used.
Ultrasound results from a mechanical vibration that has a frequency that is not perceptible to the human ear, and that is applied by a transducer that uses gel or water as a conducer. The passage of this type of energy stimulates cellular activity and its transformation, by the cells, into thermal and electrical energy. The ultrasound mechanism shortens the inflammatory phase, anticipating the arrival of the proliferative phase. Studies show positive results, with less pain and reduced oedema.
This treatment consists of inhaling 100% oxygen inside a high-pressure atmosphere (hyperbaric chamber). It works in two ways – via hypoxia and on the infected wound – both in a distinct fashion. First, it provides the oxygen necessary to counteract the anaerobic metabolism and, in this way, contributes to the high demand necessary for the healing process. Secondly, it elevates the concentration of nitric oxide, which is vital for regulating microcirculation and endothelial cells.
This is a mechanical non-invasive treatment, with the objective of reducing wound exudate, stimulating the formation of granulation tissue and reducing bacterial colonisation. The pressure used may be continuous or intermittent, even though there is still no consensus as to which form of application is better.
This system creates a hypoxic environment that does not allow survival of aerobic bacteria, and it stimulates blood flow, rich in growth factors and macrophages that accelerate debridement and promote angiogenesis. Other important achievements are reduction of oedema and contraction of the wound margins.
Low-intensity laser therapy
This treatment uses the application of a laser. All that is needed for the light to reach the wound is for the wound to be exposed or to be covered by a transparent dressing.
Different wavelengths, chosen according to the cells to be activated, selectively interact with different types of cells. The laser effect alters cell permeability, stimulating the release of growth factors and accelerating the healing process.
Control of local wound infection
One of the major concerns, in open wounds, is the control of bacterial invasion. According to the literature, the most common ways of preventing this are the use of prophylactic antibiotics (although there is some controversy about this),[27–29] active dressings and topical antiseptics. Nonetheless, the following alternative measures are also of interest to the scientific community.
The application of this UV radiation appears to inhibit bacterial growth by acting on the nucleus and DNA synthesis of the bacteria. Studies have demonstrated that the use of UV light can be of great interest for the treatment of infected wounds, especially in cases where the microorganisms present are multi-resistant.[30–33]
This treatment results from the application of electrochemical processes of solutions of pure water and sodium chloride. Many physical and mechanical properties are referred to as unique: an oxidation–reduction potential (ORP) superior to 1,100 mV, a pH variation between 2.3–2.7, 5.6–6.537 or 9–10, creating hostile conditions in the environment of the wound for bacterial survival. These solutions are, in certain cases, used in association with other therapies (negativepressure therapy and wound bed preparation).
Evidence-based economic aspects
Factors that lead to a prolonged healing process may result in longer hospital stays, which will inevitably increase costs.
Data from European economic studies related to, for example, local wound infection reveal a cost of €19.1 billion per year. Other studies reveal that the average hospital stay increases to 9.8 days, with daily costs of approximately €325.5,41
The use of new therapeutic approaches for surgical wound closure may contribute to a reduction in length of hospital stay, and to control of local wound infection. However, these therapies are expensive, and to generalise their use there is a need to evaluate their cost–benefit.
When economic factors and the availability of materials at different levels of healthcare are compared between different countries, various realities are perceptible.
The lack of knowledge of the professionals treating these wounds and the relatively low investment in prevention and treatment (when expenses of materials and education are included) contribute to this situation. Finance is important, as proper investment is needed to guarantee that all patients have access to the appropriate innovative treatments.
Complicated surgical wounds have led to an extraordinary effort to find alternative solutions to traditional wound closure.
Given the diversity of options, the choice of an adequate treatment plan will continue to be a challenge, and needs to take into account the following factors: the efficiency of the techniques and the materials used; the experience, technical capacity and expertise of the professionals; patients’ quality of life indicators; results regarding the status of wounds; and adequate financing.
The new techniques that have emerged can be used in an isolated form or as a combination of different therapies, revealing, in many cases, positive results. However, the efficiency demonstrated is far from completely satisfactory, warranting the need for more prospective studies to
better define treatment strategies.
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