The Skin and Wound Healing

Question 1

Describe the basic anatomy and physiology of the skin

Answer 1

• it is the largest organ of the body
• it receives 1/3 of all circulating blood volume
• it makes up about 10% of total body weight
• it varies in thickness

Question 2

Describe the structure of the skin

Answer 2

• epidermis
  - -> outermost layer
  - -> avascular
  - -> regenerates every 4-6 weeks
  - -> functions as a protective barrier preventing environmental damage and microorganism invasion
  - -> thickness varies, thicker on palms of hands and soles of feet
• dermis
  - -> provides support and transport of nutrients to epidermis
  - -> contains blood and lymphatic vessels, swear and oil glands and hair follicles
  - -> it is made up of collagen, fibroblasts, elastin and other extra cellular proteins
  - -> the connective tissue within the dermis is highly elastic and its strength helps maintain the skins integrity
• hypodermis
  - -> subcutaneous adipose fatty tissue

Question 3

What are the functions of the skin?

Answer 3

• outer boundary for the body and helps preserve the balance within
• protection barrier against microorganisms, radiation, chemicals, mechanical impacts and pressure
• thermoregulation
  - -> it is sensitive to fluctuations in temperate, perspiration, shivering and peripheral circulation
• metabolism
• synthesis of vitamin D from sunlight
• secretion
• excretion
• cosmetic
• non-verbal communication

Question 4

What is the definition of a wound?

Answer 4

• an injury to living tissue
• a discount intuit in epithelium - may also involve connective tissue
• a breakdown in protective function

Question 5

What are the causes of wounds?

Answer 5

• contusion (bruise)
• abrasion (graze/friction)
• laceration (tear)
• incision (cut/surgical insult)
• puncture (stab)
• burn (heat, cold, chemical)
• pressure
• disease

Question 6

List the common wounds that occur in perinatal women

Answer 6

• abrasions to nipples
• tears to genital tract
• episiotomy
• LSCS wound site

Question 7

What is wound healing?

Answer 7

• it is a physiological process by which the body replaces and restores function to damaged tissue
• it is a cellular and biochemical process which relies on the inflammatory process

Question 8

What are the objectives of wound healing?

Answer 8

• to control bleeding
• to prevent infection
• regeneration and repair
• to replace devitalised and missing cellular structures and tissue layers

Question 9

What are the objectives of wound management?

Answer 9

• to heal the wound in the shortest time possible with minimal pain, discomfort and scarring
• form a flexible and fine scar with high tensile strength

Question 10

Describe the phases of healing (Haemostasis)

Answer 10

• its aim is to have minimal blood loss and no haemotoma formation
• constriction of blood supply (vasoconstriction) in wound bed within a few seconds of injury
• platelets begin clotting
  
  • -> they adhere to vessel walls in the wound site
  • -> and change to an amorphous shape suitable for clotting
  • -> they have the ability to aggregate and release chemical messengers that stimulate a clotting cascade when in contact with exposed collagen
• scab formation
  
  • -> activated fibrin and fibronectin form a plug
  • -> it also acts a structural support matrix for the wound until collagen is deposited
  • -> bleeding ceases when the blood vessels thrombolise (5-10 mins).
  • -> assisted by ligation, alignment optimises healing

Question 11

Describe the phases of wound healing (inflammatory phase)

Answer 11

• occurs between 1 and 5 days
• the normal inflammatory response isolates the damaged tissue decreasing the risk of infection
• the clot and wound tissue releases pro-inflammatory cytokines and growth factors
• with the activation of clotting factors comes the release of histamine
  - -> vasodilation begins
• due to increased permeability of the capillary walls - plasma, proteins, leucocytes, antibodies and electrolytes exude into the surrounding tissues
• the wound appears red, swollen and hot which can be mistaken for infection
• an open blood supply cleanses the wound
  
  • -> chemicals attract essential cells (WBC, macrophages, antibodies, enzymes, growth factors and nutrients) to reach wounded area
  • -> leucocytes maintain host response by destroying bacteria and pathogens
  • -> macrophages engulf and ingest invading bacteria, cleanse the wound of devitalised necrotic tissue, damaged cells and cellular debris
  • -> platelet derived growth factors are released which intimate proliferative phase
• signs (erythema, heat, oedema, pain and functional disturbance)

Question 12

Describe the phases of healing (proliferation and reconstructive)

Answer 12

• 4-24 days, growth of new tissue
• growth factors induce cellular migration, division and proliferation
• fibroblasts enlarge and migrate
• fibronectin and collagen form provisional matrix
• new collagen is laid down
• granulation tissue, formation, rebuilds viable tissue (granules, uneven, pink/red, doesn’t bleed)
• myofibroblasts grip matrix edges and contract wound
• epithelial cells proliferate over moist surface, climbing over one another to migrate, resurfacing the wound site and providing cover for new tissue

Question 13

Describe the phases of wound healing (maturation/remodelling phase)

Answer 13

• 21 days to 1 year
• final phase once wound is closed
• collagen fibres enlarge and re orientate along lines of tension in the wound
• cellular activity is reduced
  
  • -> redundant cells have programmed cell death and removal
• the number of blood vessels in wounded areas regress and decrease
• max tensile strength is reached from approximately 3 months although the scar will only achieve 70-80% of normal skin strength

Question 14

Explain what is meant by healing by primary intention

Answer 14

• surgically incised (aseptic conditions)
• surgically clean margins (uncontaminated, uninfected)
• close approximation by surgical ligatures
• minimal epithelial cell mortality - small gap to bridge
• contraction plays a minor role
• healing occurs with minimal granulation tissue
• rapid in growth of wound healing cell (macrophages, fibroblasts)
• rapid skin regeneration - short healing period
• edges united by 2 weeks
• dense scar tissue by 1 month
• minimal scar tissue, neat hairline scar

Question 15

Explain what is meant by healing by secondary intention

Answer 15

• significant sub-epithelial damage and loss
• dead space
  
  • -> open gaping wound with large blood clot, inability to directly bridge gap between separated edges
• irregular margins (jagged edge)
• unclean, contaminated, infected
• no surgical intervention
• larger scab
• granulates filling area, from bottom to surface of wound site
• protracted healing process
  
  • -> increased potential for infection and other complications
• the wound edges are not brought together, healing occurs by contraction and epithelialization
• large amount of scar tissue

Question 16

Explain what is meant by healing by tertiary intention

Answer 16

• surgical incision
• wound edges not re-approximated initially, they are left open for a few days to permit drainage of oedema, blood, contamination or infection
• wound debrided and devitalised tissue removed
• late surgical closure but within few days
• increased granulation
• wide scar

Question 17

What are some of the local factors that can affect wound healing?

Answer 17

• size of wound
• surgical apposition (poor surgical technique)
• skin tension
• vascular supply
• venous drainage
• chronic excessive exudate (fluid from tissue damage)
• location and mobility
• poorly applied dressing
• presence of foreign body or localised reaction to it
• present of microorganisms or infection
• UV light
• radiation

Question 18

What are some of the systemic factors that can affect wound healing?

Answer 18

• cold (drop in temp delays healing by 4 hours)
• excessive heat over 30 degrees
• age - slower metabolic and circulatory functions
• degree of immobility
• obesity
• stress
• smoking or alcohol
• malnutrition
• deficiencies of vitamins
• diabetes
• cardiovascular compromise
• anaemia
• White cell disorders
• shock
• respiratory compromise
• systemic infections
• malignancy or terminal illness
• radiotherapy, chemotherapy

Question 19

What is the midwife’s role in facilitating healing?

Answer 19

• phases of wound healing need to be supported by controlling the environment as much as possible
• provision of advice in relation to:
  
  • -> nutrition - vitamin A, C and E, zinc
  • -> hydration
  • -> sleep
  • -> cleanliness
  • -> signs of infection
  • -> management of pain
  • -> pelvic floor exercises

Question 20

What are some of the vitamins and minerals that aid wound healing?

Answer 20

• Vitamin A is required for epithelial and bone tissue development, cellular differentiation and immune system function
• vitamin C is an essential co-factor for the synthesis of collagen and other organic components or the intracellular matrix of tissues such as bones, skin, capillary walls and other connective tissue
• vitamin E is popular among consumers for skin care and to prevent scar formation
  
  • -> it functions as the major lipophillic antioxidant, preventing per oxidation of lipids resulting in more stable cell membranes
• zinc is an essential trace mineral for DNA synthesis, cell division, and protein synthesis, all necessary processes for tissue regeneration and repair

Question 21

What should a midwife do at each visit?

Answer 21

• ask about a woman’s wound
• obtain maternal informed consent to visualise it
• note colour and appearance
  
  • -> persistent erythema (reddening)
  • -> non blanching hyperaemia (capillaries do not empty and refill)
  • -> blisters
  • -> alignment of margins
  • -> amount of exudate
• note odour
• localised heat (warm to touch)
• localised oedema (swelling)
• induration (hardness)
• purplish/bluish areas in women with dark skin

Question 22

Describe some of the changes that can occur in the skin during pregnancy

Answer 22

• increase in melanocyte stimulating hormone, progesterone and oestrogen results in skin darkening
  - -> secondary areola
• linea alba is a line that lies over the midline of the rectus muscles from the umbilicus to the symphysis pubis, hyperpigmentation causes it to darken resulting in the linea negra
• pigmentation of the face (chloasma)
• as maternal size increases in pregnancy stretching of the collagen layer of the skin occurs, particularly over the breasts, abdomen and thighs - in some women this results in striae gravidarum caused by thin tears occurring in the dermal collagen
  - -> these appear as red stripes, changing to glistening silvery white lines