the autolytic debridement of venous leg ulcers - Wounds International

Technical Guide 

THE AUTOLYTIC DEBRIDEMENT 

OF VENOUS LEG ULCERS 

Deborah Hofman is Clinical Nurse Specialist in Wound Healing, Department of Dermatology, Churchill Hospital, Oxford 

Wound debridement is part of the wound healing process which may occur without intervention but, 

more often, assistance is needed. It is important to recognise the situations when debridement is not 

appropriate. This article will describe how to recognise dead tissue that should be removed from the 

wound, when debridement should not be attempted and the various methods that can be used. 

Debridement describes any 

method that facilitates the 

removal of dead (necrotic) tissue, 

cell debris or foreign bodies from 

a wound (O’Brien, 2003). It is 

regarded as an essential part 

of wound bed preparation, as 

it enhances the potential for a 

wound to heal. Dead tissue in 

the wound not only physically 

prevents the wound from 

Figure 1. Sloughy tissue in a venous 

leg ulcer. 

Figure 2. A wound containing 

calcium deposits. 

68 Wound Essentials • Volume 2 • 2007 

healing, but also makes the 

wound vulnerable to infection by 

providing a source of attachment 

and nutrients for bacteria. 

Identifying dead tissue 

Recognising necrotic tissue 

can present diffi culties for the 

inexperienced practitioner. 

Devitalised or necrotic tissue 

arises as a result of a loss of 

blood supply to the wound bed 

or as a result of infection. It may 

have a variety of appearances 

from loosely adherent slough to 

tightly adherent leathery black 

eschar. 

Slough is generally described 

as yellow or brown tissue in the 

wound, and its texture may vary 

from slimy to leathery (Figure 

1). Yellow slough is frequently 

present in venous leg ulcers, 

particularly in ulcers behind 

the malleoli. A certain amount 

of yellow slough in a leg ulcer 

will not necessarily impede 

healing and will often resolve 

once compression therapy is 

introduced. If after a couple of 

weeks of optimal compression 

the slough fails to resolve, 

autolytic debridement should be 

attempted. 

Tendon, bone, and fatty tissue is 

also yellow and so care should 

be taken not to mistake these 

structures for slough since 

attempts to debride would be 

inappropriate. 

In some leg ulcers, calcium 

deposits may be present (Figure 

2). These are also yellow and 

can be distinguished from 

slough and other anatomical 

structures as they feel like a 

‘tooth’ when touched with 

forceps. Wounds will not heal 

under these circumstances and 

normally surgical intervention 

is necessary to remove 

calcium deposits. If these are 

observed within the wound, the 

patient should be referred as 

appropriate. 

Necrotic tissue is generally 

described as black or dark 

brown tissue covering the 

wound surface and is not 

normally present in healing 

venous leg ulcers. If black 

necrotic tissue is present in


a leg ulcer, other causes of 

ulceration should be looked 

for, e.g. ischaemia (Figure 3), 

in which case urgent referral 

to a vascular unit should 

be instigated. Pyoderma 

gangrenosum and vasculitis are 

relatively rare conditions which 

cause leg ulceration and often 

cause necrosis. In patients 

with vasculitis, there are usually 

mulitple lesions present (Figure 

4). Pyoderma gangrenosum 

usually presents as a rapidly 

enlarging, very painful lesion 

with necrosis and typically there 

is undermining at the wound 

edges (Figure 5). Patients where 

these conditions are suspected 

should undergo urgent referral 

to a dermatologist. 

Slough which is heavily 

colonised with anaerobic 

bacteria is also often black. 

However, this is usually slimy, 

as opposed to the dry leathery 

texture of necrotic tissue, and 

can be effectively managed 

with topical metronidazole. 

Topical metronidazole can be 

used safely on wounds for 

up to six weeks. There is no 

known risk of resistance or 

contact sensitivity. However, in 

patients who are taking warfarin, 

it should be used with care 

as it affects the international 

normalised ratio (INR). 

Dried blood on the wound 

surface is also black and may 

be difficult to distinguish from 

necrotic tissue. 

It is important to be able to 

recognise and describe different 

types of tissue and to know 

when to leave well alone. If in 

doubt specialist help should 

always be sought. 


Figure 3. Necrotic tissue in ulcer with significant arterial insufficiency. 

Figure 4. Vasculitis. 

Figure 5. Pyoderma gangrenosum. 

Selecting a method 

of debridement 

The selection of a method 

of debridement depends on 

the availability of product, 

local expertise and patient 

preference. 

There are a number of 

debridement techniques used by

healthcare professionals, and 

they can be categorised into: 

8Active debridement 

8Autolytic debridement (either 

moisture donating or moisture 

absorbing). 

Active debridement 

Surgical debridement 

Surgical debridement involves 

the removal of dead tissue from 

the wound bed. It is carried out 

under surgical conditions and 

results in a bleeding wound bed 

as a result of complete removal of 

necrotic material. This is carried 

out by surgeons, podiatrists and 

specialist nurses who have been 

trained in the procedure, using 

scalpel and forceps. 

Sharp debridement 

Sharp debridement is the removal 

of dead tissue with scissors 

or scalpel. This should only 

be carried out by a healthcare 

professional who has been 

trained in the procedure. 

Larval therapy 

Larvae or maggots have been 

used in the UK to debride 

wounds for at least 10 years 

and are a fast, effective and 

safe method of debridement 

(Thomas, 1998). Maggots are 

now available either as ‘freerange’ 

(and placed directly into 

the wound) or contained in 

bags. The powerful enzymes 

in their saliva dissolve necrotic 

tissue, which the maggots then 

ingest. They do not have to be 

in direct contact with the wound 

bed. However, free-range 

maggots have the advantage 

of being able to penetrate 

crevices and sinuses more 

effectively. The disadvantage is 

that they can escape and cause 

distress to both patient and 

practitioner. A detailed guide to 

larval therapy can be found on 

p.156–9. 

Enzymatic 

There are various enzyme 

preparations which are effective 

at digesting dead tissue, e.g. 

collagenase and papaina, but 

these are not currently available 

in the UK (Bellingeri and Hofman, 

2006). 

Autolytic debridement 

Autolytic debridement is the 

process by which the body 

attempts to shed devitalised 

tissue by the use of moisture. 

Where tissue can be kept moist, 

it will naturally degrade and 

deslough from the underlying 

healthy structures. This process 

is helped by the presence 

of enzymes called matrix 

metalloproteinases (MMPs), 

which are produced by damaged 

tissue and which disrupt the 

proteins that bind the dead tissue 

to the body. This process can 

be enhanced by the application 

of wound management 

products which promote a moist 

environment. These products can 

be divided into two categories: 

those that donate moisture 

to the dead tissue and those 

that absorb excess moisture 

produced by the body. Both are 

designed to facilitate the autolytic 

debridement process (Gray et al, 

2005). 

Moisture donation 

Hydrocolloids and hydrogels 

(amorphous gel in a tube or 

hydrogel sheets), donate moisture 

to the dead tissue to facilitate 

autolytic debridement.These 

dressings are particularly useful 

in wounds that are not heavily 

exuding (Tip 1). 


The use of a second generation 

hydrogel sheet, e.g. Actiform 

Cool ® , will absorb a certain 

amount of moisture while 

donating it so, in many cases, 

will provide a good moisture 

balance at the wound surface. 

If desired the dressing can be 

cut to fit the wound (Tip 2). The 

white backing should be peeled 

off and the dressing laid gel side 

down on to the wound surface. 

Dressings should be changed 

when there is strikethrough, but 

may be left on for up to seven 

days if there is no leakage. A 

second generation hydrogel sheet 

dressing may continue to be used 

after debridement has occurred 

through to healing as it promotes 

granulation tissue and maintains a 

clean wound bed (Figures 6,7,8,9). 

Moisture absorption 

Alginates, cellulose dressings and 

foams are designed to absorb 

exudate. By absorbing excess 

wound fluid, these products 

avoid damage to the surrounding 

skin from maceration (Tip 3).The 

structure of some foam dressings 

alters under compression so that 

the moisture remains in contact 

with the skin. Care should be 

taken therefore to select an 

appropriate foam. These dressings 

Tip 1 

8A common error is to apply 

a hydrogel to a wet wound 

that contains some slough 

in an attempt to debride the 

wound. It is more important 

to get the moisture balance 

right than to remove the 

sloughy tissue which will 

resolve itself in the right 

environment. 

Wound Essentials • Volume 2 • 2007 71


Figure 6. Slough is present on the wound 

bed before application of dressing. 

Figure 7. Remove the backing from the 

hydrogel sheet and place gel side down 

on the wound. 

Figure 8. A clean wound bed on removal 

of the dressing. 

Figure 9. Once debridement has 

occurred, the dressing can be continued 

to promote granulation. 

should not be used on a dry 

sloughy wound as they will further 

dry out the tissue, making it more 

adherent and painful. 

Dressings which reduce the 

bacterial burden of the wound 

A heavy bacterial burden in 

a wound will encourage tissue 


degradation and slough formation. 

Dressings which reduce bacteria in 

a wound such as honey, silver, or 

cleansing fluid such as Prontosan ® 

(Horrocks, 2006), may help to 

reduce slough and promote healthy 

granulation. 

The process of debridement 

will increase exudate and this in 

turn may damage surrounding 

skin. The frequency of dressing 

change may have to be 

increased and surrounding 

skin protected with a suitable 

barrier such as Cavilon cream/ 

ointment (3M Health Care) or 

zinc paste. Dressings which 

donate moisture (such as 

hydrogels) should not be used 

on a wet wound as the increase 

in moisture will macerate the 

skin. Honey dressings, although 

increasing exudate in the initial 

phase, will, by reducing bacterial 

load, also eventually reduce 

exudate. 

The choice of method of 

debridement depends on wound 

severity and patient preference. 

Many patients like the idea of a 

natural product such as honey. The 

only reason to avoid this dressing 

would be pain as patients often find 

the drawing sensation intolerable. 

Maggot treatment is more rapid 

than autolytic debridement and if 

the wound is very offensive and 

there is a lot of sloughy/necrotic 

tissue the larval therapy should 

be considered. 

If the wound is very painful it is 

unlikely that maggot treatment will 

be tolerated, and some patients 

are repelled by the idea of larval 

therapy. In a painful wound, 

the use of a second generation 

hydrogel sheet should be 

considered. 

Common misconceptions 

8Practitioners are rightly 

taught that debridement is an 

essential part of wound healing. 

However, dressings which are 

marketed as having a debriding 

action, e.g. hydrogels, are often 

applied inappropriately without 

consideration of moisture 

balance. This can result in 

maceration. 

8In an attempt to debride 

wounds on wet leg ulcers, 

the healthcare professional 

often uses a combination of 

dressings which are thereby 

rendered ineffective, e.g. 

hydrogels (moisture donating) 

and alginates (moisture 

absorbing) or hydrogels and 

foams (moisture absorbing). A 

combination of these dressings 

results in a ‘sludge’ which has 

no debriding effect. 

Where the wound is very 

wet the practitioner should 

attempt to identify the 

Tip 2 

8Patients should be warned 

that the constituency of 

the second generation 

hydrogel sheet dressing will 

change and there may be 

an unpleasant odour. This 

is also true of hydrocolloid 

dressings. 

Tip 3 

8Capillary action dressings or 

those with a super absorbent 

capability may be useful in 

the management of very wet 

sloughy wounds.

cause and address moisture 

balance before considering 

debridement. Possible causes 

of wetness include: 

1. Heavy bacterial burden: Does 

the patient need systemic 

antibiotics and/or topical 

antibacterial management (e.g. 

honey, silver, iodine)? 

2. Wet eczema: does the patient 

need referral to a specialist 

nurse or dermatologist? 

Topical steroid therapy may be 

needed. 

2. Oedema: Is the patient 

receiving adequate 

compression? Are they 

elevating their legs sufficiently? 

Have they been taught 

dorsiflexion exercises to reduce 

oedema? 

3. Is the dressing sufficiently 

absorbent? Dressings within 

the same category perform 

differently, e.g. foams. Some 

will remove the exudate 

from the wound, but others 

keep the exudate next to 

the skin causing further 

tissue damage. Many foams 

do not perform well under 

compression. Alginates and 

cellulose (Aquacel ®, ConvaTec) 

dressings can be beneficial. If 

there is heavy pseudomonal 

exudate, which has a 

characteristic bright green 

colour, dressings containing 

silver may be helpful. 

When is debriding a venous leg 

ulcer not appropriate? 

1. Arterial ulcers should not 

normally be debrided (Leaper, 

2002). If there is a poor blood 

supply to the limb, it is best to 

keep a necrotic wound dry until 

seen by a vascular surgeon, as 

wet gangrene can occur. 

2. When diagnosis is in doubt. 

For example, pyoderma 

gangrenosum is characterised 

by rapid ulceration and 

necrosis. Debridement is 

contraindicated as it may 

cause extension of the 

ulceration (Chakrabarty and 

Philips, 2002). 

3. The debridement of malignant 

wounds serves no useful 

purpose and may cause 

bleeding. If diagnosis is in 

doubt, specialist help should 

be sought. 

4. When the patient is 

systemically severely unwell, 

for example, in ITU or terminally 

ill. Local intervention is unlikely 

to help heal the wound and 

patient comfort rather than 

debridement should be 

a priority. 

Conclusions 

There are four questions that 

should be asked before making 

a decision on how to manage a 

sloughy/necrotic wound: 

1. Is the tissue in the wound 

definitely slough? 

2. Is debridement appropriate? 

3. What is causing the slough 

within the wound? Infection? 

Poor blood supply? 

4. Are the causes being 

addressed? 

5. In choosing dressings which 

promote debridement, has 

moisture balance and patient 

preference been considered? 

If in doubt specialist help must be 

sought. WE 

Bellingeri A, Hofman D (2006) 

Debridement of pressure ulcers. In: 

Science and Practice of Pressure 

Ulcer Management. Springer–Verlag, 

London:129–39 

Chakrabarty A, Philips TJ (2002) 

Diagnostic Dilemmas:Pyoderma 

gangrenosum. Wounds 14(8): 302–5 

Glossary 


Autolysis: natural degradation of dead 

tissue in a wound. 

Calcification: calcium deposits which 

may occur in a leg ulcer. 

Debridement: removal of dead tissue 

from a wound. 

Necrotic tissue/necrosis: dead tissue 

which is desiccated usually dark 

brown or black. 

Slough: yellow or grey or brown 

in coulour, wet stringy tissue that 

adheres to the wound bed. 

Eschar: dry necrotic tissue. 

INR: the time taken for blood to clot 

compared to a control. Normal range 

is 0.9–1.2. 

Gray D, White R, Cooper P, 

Kingsley A (2005) Applied Wound 

Management. In: Wound Healing: A 

Systematic Approach to Advanced 

Wound Healing and Management. 

Wounds UK, Aberdeen: 59–96 

Horrocks A (2006) Prontosan wound 

irrigation and gel: management of 

chronic wounds. Br J Nurs 15(22): 

1222–8 

Leaper D (2002) Sharp Techniques 

for Wound Debridement. World Wide 

Wounds, Dec 2002 

Moffatt C, Morison MJ, Pina E (2004) 

Wound bed preparation for venous 

leg ulcers. In: European Wound 

Management Association (EWMA) 

Position Document: Wound Bed 

Preparation in Practice. MEP Ltd, 

London: 12–15 

Thomas S, Jones M, Andrews AM 

(1998) The use of larval therapy in 

wound management. J Wound Care 

7(10): 521–4 

O’Brien M (2003) Exploring methods 

of wound debridement. In: White 

R, ed. Trends in Wound Care. Vol 

2. Quay books, MA Healthcare, 

London: 95–107 

Wound Essentials • Volume 2 • 2007 73

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