Management of Tissue Types
The wound bed as it passes through the wound healing cycle will be dominated by different types of tissue; necrotic, sloughy, granulating and epithelial. At any one time all four tissue types can be present. Recognition and recording of tissue type and expressing the amount as a percentage is a well known and approved method of wound classification and can help with reassessment and understanding of wound progression. Accurate identification of the tissue types at the wound bed will aid accurate dressing selection and treatment interventions1,2
Necrotic tissue is characteristically brown / black in colour and may be leathery in texture. At times it may completely cover the wound surface or be present in patches at the base or margin of the wound bed. Necrotic tissue needs to liquefy in order to be safely removed. This is known as ‘autolysis’. Necrotic tissue signifies dead tissue due to the reduction in supply of oxygenated blood to the tissues.
As the necrotic tissue breaks down, slough is formed.
Sloughy tissue is characteristically yellow in colour unless infected, when it may present as green / brown.
The presence of necrosis and slough only serves to prolong healing as these tissues can act as a source of infection and therefore must be debrided, using either sharp (scalpel) or autolytic (dressings) means before healing can begin. Sharp debridement is a technical procedure and only those trained should undertake such procedures. Necrotic / sloughy wounds and those which are infected can be characteristically malodorous and produce high levels of exudate.
Once the wound bed has been cleaned, granulation tissue can begin to form. Granulation tissue is red in colour and granular / uneven in appearance. It is critical to differentiate at this stage between healthy and unhealthy granulation tissue. Unhealthy granulation appears dark (deoxygenated) and bleeds easily and can indicate infection within the tissues. These wounds can easily become necrotic and sloughy if not accurately assessed and managed. ‘Hypergranulation’ can sometimes occur when the granulation tissue rises above the height of the surrounding skin. This is caused by an excess of moisture.
Once the wound has healed, epithelial cells migrate across the surface of the wound. These cells are pink in colour and translucent in appearance.
The challenges differ with each presenting tissue type, a dressing should be selected which creates a moist wound environment unless contraindicated and can manage exudate so the wound remains moist not wet. At each reassessment the wound should be monitored for signs of infection and treated accordingly. Care should be taken of the peri-wound area to protect the surrounding skin. Necrotic / sloughy wounds and those which are infected can be characteristically malodorous.
Figure 1: A wound showing necrotic and sloughy tissue
Figure 2: A clean granulating wound
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References:
1 Bale S and Jones V (1997) Wound Care Nursing. Baillière Tindall.
2 Butcher M. (2006) Progression to healing in A Pocket Guide to Clinical Decision Making in Wound Management. Cromwell Press, UK.
Caveat: The information given is a guide only and should not replace clinical judgement.