Wound Healing Lecture Notes.

University Degree Medicine and Dentistry

Wound Healing Lecture Notes

Learning outcomes

At the end of the module the student will

Have a basic understanding of the process of wound healing
Recognise the difference between primary and secondary healing
Be aware of factors influencing wound healing and of potential complications
Relate the physiology of the wound healing process to nursing care

Definition of wound healing

‘A cut or abrasion in the continuity of any tissue. It is a visible result of individual cell death or damage, and can be classified by size, depth and cause’

Questions to consider – how big is the wound? How much surface area does it involve? Does this have implications for patient in terms of fluid loss/loss of mobility/pain?

How deep is the wound? Does this have implications for fluid loss/pain/loss of mobility? What types of tissue are affected? Epithelial/muscle/bone etc

What caused the wound? Clean cut/surgical incision/burn/scald/abrasion/clean or dirty?

Wound Healing

It is very important for nurses to understand the process of wound healing so that they can effectively assess the wound and implement wound care towards the goal of promoting healing and preventing delayed healing. The nurse needs to provide the ideal environment for the wound, both locally at the wound site, and systemically (throughout the body, taking a holistic approach)

Patient Factors which affect Wound Healing

Type of wound – clean or dirty, chronic eg leg ulcers or acute eg cut what type of tissue involved
Nutritional status of patient – wounds need protein and energy for healing. Vitamin C has also been shown to aid wound healing. Can the patient eat Vit C with diet or is supplement appropriate? How is the patients appetite? Body weight?
Age – healing takes longer the older a patient is. Older patients have less efficient circulation, blood is necessary for wound healing to bring oxygen and nutrients and take away waste.

This is a preview of the whole essay

Patient Factors which affect Wound Healing

Type of wound – clean or dirty, chronic eg leg ulcers or acute eg cut what type of tissue involved
Nutritional status of patient – wounds need protein and energy for healing. Vitamin C has also been shown to aid wound healing. Can the patient eat Vit C with diet or is supplement appropriate? How is the patients appetite? Body weight?
Age – healing takes longer the older a patient is. Older patients have less efficient circulation, blood is necessary for wound healing to bring oxygen and nutrients and take away waste.
Body build – obese patients have slower rate of wound healing. The layer of adipose (fat) tissue beneath the surface of the skin does not have such a rich blood supply. Very thin patients may possibly be undernourished.
Stress – can cause loss of sleep (a symptom of stress) Growth hormone is released during deep sleep and is necessary to promote cell division and heal a wound. May be lacking in a patient who is stressed. NB the wound itself can cause stress and pain
Medical conditions – need to know patients medical status – anaemia causes reduced oxygen availability, diabetes increases risk of wound infection, malignant disease can cause malnourishment, cardiovascular disease can cause reduced blood supply to peripheries.
Drug therapy – certain medications can affect wound healing eg warfarin can increase bleeding, steroids can suppress immune response, cytotoxic drugs can suppress immune response

Tissue repair and regeneration

When cells are damaged they are deprived on essentials – nutrients, oxygen, waste removal

Two types of healing produce

Regeneration – the same type of tissue is renewed

Fibrosis – the tissue is replaced by fibrous tissue which forms a scar

Note: some wound healing involves both of these things, cell replacement AND fibrous cells

Some cells regenerate more easily than others

Good regeneration – epithelial tissue eg skin, mucous membranes (Score an A!)

Quite good regeneration – connective tissue eg bone, cartilage (Score a B)

Poor regeneration – muscle, cardiac muscle, cartilage (Score a C/D)

Very poor or not at all – nervous tissue (Score a D/E)

Stages of wound healing

These stages are general. If you read text books you might find slightly different words used

Vascular response – this is immediate – the wound bleeds! This dried blood forms a scab over the wound creating a nice healing environment beneath (therefore discourage patients from removing this scab) The broken blood vessel ends and damaged calls also give rise to:-

Inflammatory response – damaged cells release histamine and prostaglandin. These cause the blood vessels to dilate so that a richer blood supply is given to the wound. The red cells bring oxygen, the white cells ingest bacteria and debris, the plasma bring nutrients, waste matter is taken away. This stage lasts 3-7days.

Proliferation – connective tissue is produced which bridges one side of the wound to the other. The bridge then contracts, drawing the sides of the wound together. The wound is healed but is weak – slight pressure to it would cause a break down. This stage lasts 3-24days. The scab will fall off and new epithelial cells or fibrous cells will cover the surface of the wound.

This is primary wound healing (primary wound intention)

If the wound is too large for this, then healing will take place by secondary intention. New tissue will be deposited in the bed of the wound (the bottom of the wound) This will build up in layers until the surface is reached. This is liable to be a much longer process and produce much more scarring. The patient is vulnerable for a much longer time.

Maturation – the healed wound now needs to build in strength and elasticity. Wounds only achieve 80% of their original strength and elasticity (as a maximum – can be much less). This stage lasts 30days to years.

These lecture notes contain no diagrams. Looking in a text book at the stages of wound healing will help understanding and remembering of the stages.