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Wound care: the science of healing

Sylvie Hampton
MA BSc(Hons) DpSN RGN
Tissue Viability Consultant
Wound Healing Centre

Wound care is a complex process requiring skill and confidence on the part of the nurse. Sylvie Hampton explains the physiology of healing, and offers some tips for developing an effective approach in practice

Wound healing encompasses a number of overlapping phases, including inflammation, epithelialisation, angiogenesis and matrix deposition. However, this process applies mainly to acute wounds, those that will heal with little intervention and without skilled and specialist involvement.

The skill of healing comes into its own once the wound enters the chronic state and becomes malodorous, wet and often painful. To understand these delays in wound healing and to be confident in treatment of wounds, we need to understand the healing process and the pathophysiology of wounds.

In 1346 cobwebs were used for haemostasis in trauma wounds and in 1510-1590 Surgeon Ambroise Pare rejected boiling oil and used rosewater and egg to reduce the bleeding and heal the wounds.1 This did not work and he began to realise that the non-healing was due to the pathophysiology beneath the wound surface. He stated "Man may dress the wound, but only God can heal" and, even with modern knowledge and resources, this remains the same today. The very best we can achieve is to provide an optimum wound healing environment to enable the wound to heal itself. However, if the pathophysiology of the wound is not addressed, then the most expensive and clever dressings will never promote healing.

The true skill of wound healing comes from experience and education (the Art and Science of nursing) and this can take many years of study and often requires confidence and sometimes a little risk taking, to develop that skill. An example of a true "risk taker" would be Judy Waterlow, who realised there was a problem in pressure ulcer treatment and prevention, and developed a tool that would assess the risk for the patient. This required some risk taking as she developed the tool and applied it in practice. Without nurses such as Judy, there would be little development in the prevention and treatment of wounds, and we would still be treating them with cobwebs, urine, boiling oil, oxygen and egg whites.

Accurate assessment depends on an understanding of the physiology of healing, the factors that delay the process and the optimal conditions.2

Wound healing
Wound healing has many stages with acute inflammation being the first stage. The human adult wound healing process can be divided into three distinct phases: the inflammatory phase, the proliferative phase, and the remodelling phase. Within these three broad phases is a complex and co-ordinated series of events that includes chemotaxis, phagocytosis, neocollagenesis, collagen degradation and collagen
remodelling. In addition, angiogenesis, epithelization.3

Acute inflammation is absolutely necessary for wound healing and this means that acute wounds generally heal without problems and will only become chronic when wound healing has been delayed, usually in the inflammatory stage. Chronic inflammation will certainly delay wound healing due to the production of high matrix metalloproteinases levels (MMPs).

Although MMPs are necessary in the acute wound, they change when the wound becomes chronic and become a hindrance to wound healing. Therefore, chronicity must be dealt with by reverting it to an acute wound through clever use of dressings.
There is a big difference between treating and managing wounds and I find that nurses often "manage" the symptoms of wounds and do not "treat" them by considering and addressing the pathophysiology that causes the chronicity.

There are patients who arrive at the Wound Healing Centre in
Eastbourne with very large Gamgee dressings in place, obviously to soak up the high exudate levels. There are those with malodorous wounds, with carbon dressings that are designed to mask odour and there are those who arrive with untreated wound pain. Within a few days, the tissue viability nurses can reverse these distressing symptoms by treating the pathophysiology (Figure 1). Poor blood supply requires specialist involvement and the patient must be referred to a vascular specialist.

[[Fig 1 science]]

There are also nurses who always use their "favourite" dressings no matter the condition of the wound. Albert Einstein stated that "insanity is doing the same thing over and over again and expecting different results" - and constantly using the same dressing type expecting different results is just simply madness.

Reversing the symptoms
Malodour can be very distressing and probably affects the patient's social life more than other symptoms.4 Addressing the problem is simple. The cause is bacteria that produces the odour and removing the bacteria will remove the odour. This does not mean that the bacteria in the wound is related to clinical infection.

In the skin, the average human being harbours at least 200 species of bacteria, totalling more than 1,012 organisms. Therefore, when the skin is broken by trauma or disease, bacteria will colonise the wound fluid.5 Every chronic wound will contain microorganisms of many types, mainly natural flora that is found on the skin. Most of these are not likely to enter the host to cause clinical infection. Therefore, before deciding the dressing, it is important to distinguish between bacterial colonisation and clinical infection.

Colonisation can mimic clinical infection as it causes odour, can cause pain and discharge and increases exudate. Clinical infection however, goes further as it enters the host and causes systemic reactions such necrosis as spreading cellulitis and pyrexia which are not found in colonisation. If there is spreading cellulitis and pyrexia, with increased wound size and odour, the antibiotics must be considered. In leg ulcers, there should not be any dark necrotic tissue unless there is arterial involvement. Necrotic tissue plus spreading cellulitis is an absolute sign of clinical infection requiring antibiotics. If there is no spreading cellulitis or pyrexia, then consider antimicrobial dressings (Table 1) until the wound is clean and free of odour.
Levels of pain depend on the cause. Arterial pain cannot be addressed through the use of dressings and requires gabapentin, tramadol or amitriptyline to reduce the pain.

[[Tab 1 science]]

Wound pain can be reduced by dressings such as ActiFormCool and Biatain Ibu. Reduction of pain on removal of dressings is helped by the use of silicone dressings such as Silifix and Mepitel.

Treating pressure ulcers
When working as a tissue viability nurse in the local hospital, I would often find patients with a dressing on their sacrum, heels or ischial tuberosity because they had a reddened or slightly broken area but there would not be a pressure reducing mattress and in place. A dressing cannot prevent pressure from damaging the tissues and the area will never recover unless appropriate pressure reducing equipment is in place.4 Once the equipment (appropriate mattress and cushion and possibly Heel-protection devices are provided, then the dressings can be considered:

  • Topical Negative Pressure (TNP) is very often effective as it negates the positive pressure from the chair, floor or bed but should never be used on necrotic tissue that is dry.
  • Maggots can remove dead tissue very successfully and can prepare the wound for healing with TNP or with the next stage of dressing.
  • When the wound is needing debridement, wet dressings are the optimum choice.
  • When the wound is healing, a drier dressing such as a hydrofibre, alginate or foam may be selected.
  • If there is dry eschar on the heels and, particularly, when the patient is moribund, is the one time that wet dressings (such as gels etc) should not be used.6

If the wound is highly colonised (identified by the odour), then review antibacterials, as in Table 1.

Surgical wounds
A surgical wound is expected to heal without complications and, generally, achieves a surface seal within 24 hours. As a result, the potential of infection mainly occurs during surgery and this risk is greatly increased if the surgery is abdominal.4,7,8 The ideal wound dressing applied in theatre should absorb exudate and protect the wound from injury and bacteria until the incision line is sealed.

If a surgical wound becomes chronic, it is often due to the infection and/or the pathophysiology associated with the patient's condition. To treat appropriately, first decide if infection is involved (can be occult if abdominal) and review potential of antibiotics if clinical infection is suspected. Then the dressing may be considered.

If the wound has become a sinus, consider either a capillary dressing (ie, Avadraw spiral, Sumar Spiral) which can be placed in the sinus and will draw fluid out from the base of the wound. A wound bag can be placed over the wound to collect the fluid.

A surgical wound that has fully dehisced can be successfully treated with TNP although care should be taken not to use it directly on wounds that expose body organs or cancer.

Conclusion
In wound healing, it is absolutely vital that the pathophysiology of the wound is considered and dealt with prior to any thought being given to the type of dressing used. Once the problem that has led to chronicity is identified, the appropriate treatment can be provided to reverse the pathophysiology and allow the wound the freedom to reach full closure.

References
Leaper DJ. Traumatic and surgical wounds ABC of wound healing. BMJ 2006;332(7540):532-5.
Flanagan M. American Council on Education Series: Wound Management. London: Churchill Livingstone; 1997.
Mercandetti M, Cohen AJ. Wound Healing, Healing and Repair. http://emedicine.medscape.com/article/1298129-overview
Hampton S, Collins F. Tissue Viability: A comprehensive Guide. London: Whurr Publications; 2003.
Ovington L. Bacterial toxins and wound healing. Ostomy and Wound Management 2003;49(7A Suppl):8-12.
European Pressure Ulcer Advisory Panel (EPUAP) and National Pressure Ulcer Advisory Panel (NPUAP). Prevention of Pressure Ulcers: A Quick Reference Guide. Available from: www.epuap.org/guidelines/Final_Quick_Prevention.pdf
Watret L, White R. Surgical wound management: the role of dressings. Nurs Stand 2001;15(44):59-69.
Harris DR. Healing of the surgical wound: I. Basic considerations. Journal of the American Academy of Dermatology 1979;1(3):197-207.

Your comments (terms and conditions apply):

"I enjoyed reading this article. It was good to reiterate knowledge and to find out of any new developments. Helps to check if ones' practice is up to the current standards. My only question of this article is how the dry eschar on the heel should be treated, as what dressing is to be avoided has been mentioned but what is to be used is not clarified. But over-all it is a good article" - Anne Majumdar, Wilts