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Wounds: definition and classification

Una Adderley
RGN DN BSc BA
District Nurse Scarborough and NE Yorks NHS Trust, and Research Nurse Department of Health Studies University of York

E Andrea Nelson
BSc RGN
Research Fellow Department of Health Studies University of York and Cochrane Wounds Group Coordinator

A "wound" can be defined as "a break in an epithelial surface that may be surgical or accidental".(1) Wounds can be classified in various ways:

  • Cause of wounding, for example a burn or pressure sore.
  • Mode of healing. For primary intention (eg, a surgical incision), the edges of the wound are held together and new tissue is formed without tissue loss. For secondary intention (eg, a leg ulcer), wounds heal through the formation of granulation tissue and subsequent epithelialisation.
  • Amount of tissue loss. For example, superficial (loss of the epidermis only), partial thickness (loss of epidermis and some dermis) to full thickness (loss of dermis).
  • Stage of healing reached. Wound healing can be divided into four phases (inflammation, destructive, proliferative, maturative), which may overlap and not follow an orderly sequence.
  • Duration of the wound. For example, acute wounds such as traumatic injuries or chronic wounds (wounds that fail to heal in six weeks), such as diabetic foot ulcers and fungating wounds.

Community nurses are likely to manage a wide range of wounds. The vast majority heal within days, but those with large amounts of tissue loss or underlying disease may have delayed healing.

Principles of wound care

Assessment
An initial, detailed, full assessment is essential and should include assessment of the cause of the wound, the wound itself and surrounding tissue.
Accurate and detailed documentation will enable careful monitoring at subsequent assessments.

Treatment
The first line of treatment should aim to correct any underlying clinical condition that is impeding wound healing, such as ischaemia.
Secondly, the wound should be cleaned, if necessary, and covered with an appropriate wound contact layer.

Using research to devise guidelines for clinical decision-making
When assessing research findings it is essential to appraise the quality of the evidence. Systematic reviews summarise results from numerous sources in order to improve the reliability and accuracy of estimates of effectiveness. Where possible we have based the following guidance on systematic reviews.

Burns and scalds
Assess the position and depth of burn and calculate the area using Lund and Browder's assessment chart. Dress with simple non-adherent dressings and consider applying antimicrobial cream. A systematic review on the use of dressings or topical agents in the treatment of burns is currently being prepared for publication.
Consider referral to secondary care when the patient is a child or the burn is large, full thickness or over the joints, face or hands.

Diabetic foot ulcers
Assess the cause of the ulceration (such as neuropathic, ischaemic, neuroischaemic). There is evidence that screening and referral to foot care clinics of people with diabetes who are at a high risk of developing foot ulcers reduces the risk of foot ulcers and major amputation.(2) At present there is no evidence to indicate which interventions are most effective. Growth factors and skin replacements(3) show promise but need further evaluation. Aim for good control of blood sugar, relieve pressure from ulcerated areas and dress wounds with absorbent non-adherent dressings such as foams or alginate dressings. Refer for chiropody for continuing care of feet and debridement of callus.
Consider referral to secondary care urgently in the case of advancing wound infection. Also refer for specialist orthotics. There is limited evidence that total contact casting and topical growth factors improve the healing of chronic, non-infected diabetic ulcers(3) and that therapeutic footwear decreases the recurrence of foot ulceration.(2)

Fungating wounds
Gentle debridement using a hydrogel (for eschar) or calcium alginate (on soft tissue) will reduce the problems associated with exudate and malodour; alginate dressings can be used for haemostasis. Malodour can be reduced through treating the source of the problem with systemic antibiotics or topical metronidazole gel and using charcoal dressings under an intact dressing.
Consider referral to secondary care for palliative treatment such as radiotherapy, surgery or chemotherapy.

Leg ulcers
The first step is to distinguish between leg ulcers with a primarily venous aetiology as opposed to a primarily arterial aetiology. Assessment of the arterial supply to establish the cause of ulceration should include using Doppler ultrasound to calculate the ankle brachial pressure index (ABPI).(4)
Venous leg ulcers benefit from multilayer compression bandaging,(5) but there is no firm evidence on the effects of occlusive and non-occlusive dressings, topical agents or antimicrobial agents compared with simple primary dressings such as knitted viscose dressings (such as N/A or Tricotex). Limited evidence suggests that oral oxpentifylline or flavonoids may accelerate healing, but there is insufficient evidence regarding therapeutic ultrasound or intermittent pneumatic compression.(6)
Consider referral to secondary care for full venous assessment for young mobile patients, for venous leg ulcers that fail to improve despite compression therapy or if diagnosis is (or becomes) uncertain.
For arterial leg ulcers, a systematic review of the effectiveness of topical agents is currently being prepared. Consider referral to secondary care if a patient is found to have an ABPI of 0.8 or less.

Pressure sores
Those at risk of developing pressure damage can be identified through using a recognised scale (such as Waterlow). However, a systematic review found that it is uncertain whether pressure sore risk scales are better than clinical judgement or that their use improves outcomes.(7) Relieve pressure areas and encourage mobility. A recent Cochrane review found that contoured foam reduced the incidence of pressure sores compared with standard hospital mattresses.(8)
For treatment, pressure sores should be graded using a recognised scale (such as Stirling). There is limited evidence in favour of hydrocolloid dressings over saline-soaked gauze for dressing pressure sores but no good evidence on the effects of other dressings, nutritional supplementation or ultrasound on healing rates of pressure sores.
Consider referral to secondary care for treatment of invasive infection that has failed to respond to oral antibiotics, surgical debridement and skin grafting or specialist nutrition advice.

Surgical incisions
Assess for evidence of clinical signs of infection or exudate and note any sutures or staples. Usual practice is for uncomplicated wounds to be left clean and dry or covered for protection using a simple, non-adherent island dressing. One systematic review of dressings and topical agents for surgical wounds healing by secondary intention (such as dehisced surgical wounds) found no evidence of benefit in using any particular product.(9)
Consider referral to secondary care if there is deep layer dehiscence, major skin layer dehiscence, major infection (fever or deep abscess formation), abnormal fluid collections deep to the wound (large haemotoma), fistula formation or suspected infection involving any implanted prosthesis.

Traumatic wounds
Establish the cause (animal bite? gunshot wound? stab wound?) and consider the potential for contamination by bacteria, devitalised tissue or foreign bodies. A recent Cochrane review found that antibiotics reduce infection following mammalian bites.(10)
Consider referral to secondary care to exclude possible foreign bodies by X-ray, when major structures are involved (arteries, nerves, tendons, body cavities), for debridement or suturing beyond primary care facilities, and for immunoglobulin in tetanus-prone wounds in previously non-immunised patients.

References

  1. Morison M, et al. A colour guide to the nursing management of chronic wounds. 2nd edn. London: Mosby; 1997.
  2. Hunt D, Gerstein H. Clin Evidence 1999;2:231-6.
  3. O'Meara S, et al. Health Technol Assess 2000;4(21):1-237.
  4. Royal College of Nursing Institute, University of York Centre for Evidence Based Nursing and University of Manchester School of Nursing, Midwifery and Health Visiting. The management of patients with venous leg ulcers. London: RCN; 1998.
  5. Cullum N, et al. Compression for venous leg ulcers [Cochrane Review]. Cochrane Library - 2001/2. Oxford: Update Software.
  6. Nelson EA, et al. Clin Evidence 1999;2:792-801.
  7. Cullum N, et al. Qual Health Care 1995;4(4):289-93.
  8. Cullum N, et al. Beds, mattresses and cushions for pressure sore prevention and treatment [Cochrane Review]. Cochrane Library - 2001/2. Oxford: Update Software.
  9. Bradley M, et al. Health Technol Assess 1999;3(17, pt 2):1-35.
  10. Medeiros I, Saconato H. Antibiotic prophylaxis for mammalian bites [Cochrane Review]. Cochrane Library - 2001/3. Oxford: Update Software.

Resources
European Wound Management Society
W:www.ewmaonline.com

Tissue Viability Society
W:www.tvs.org.uk

Clinical Evidence
W:nelh.nhs.uk

Further reading
Bale S, Jones V. Wound care nursing - a patient-centred approach. London: Baillière Tindall; 1997.

Dealey C. The care of wounds: a guide for nurses. 2nd edn. Oxford: Blackwell; 1999.

Morison MJ, Moffatt CJ, Bridel-Nixon J, Bale S, editors.
A colour guide to the nursing management of chronic wounds. 2nd edn. London: Mosby; 1997.