Wounds and Wound healing

1. BY MULINDWA EMMANUEL
MBCHB III

2.  Skin can be divided into an outer layer, the epidermis and an inner layer, the dermis. Deep to
the dermis is the hypodermis, which is composed of subcutaneous fat.
 EPIDERMIS
 The epidermis is composed of keratinised, stratified, squamous epithelium and can be
subdivided further into five layers: the stratum basale (deepest), the stratum spinosum, the
stratum granulosum, the stratum lucidum and the stratum corneum (superificial).
 The layers of the epidermis contain
 Melanocytes which produce melanin that gives the skin its colour and protects the skin from
ultraviolet radiation.
 Keratinocytes which produce keratin that forms a protectictive layer on the outside of the skin.

3. DERMIS
Is structurally divided into two layers. The superficial papillary layer is
composed of delicate collagen and elastin fibres in ground substance, into
which a capillary and lymphatic network ramifies. The deeper reticular layer
is composed of coarse branching collagen, layered parallel to the skin surface.
HYPODERMIS SUBCTANEOUS TISSUE
It is composed of areolar and adipose tissue.it is the area of fat storage and
blood vessels

5. DEFINITION
 A wound is a break in the integrity of the skin or tissues often,
which may be associated with disruption of the structure and
function.
CLASSIFICATION
a. According to Rank and Wakefield
b. According to severity
c. According to degree of contamination
d. According to morphological character
e. According to wound depth

6. A. According to Rank and Wakefield
 Tidy wounds
These are wounds inflicted by sharp instruments and contain no devitalized
tissue. . Healing is by primary intention.
They are usually single with clean cut. associate fractures are uncommon in
tidy wounds.
Examples include: cuts from glass and knife wounds and surgical incisions.
 Untidy wounds
Wounds resulting from crushing, tearing avulsion, vascular injury or burns and
contain devitalized tissue. they are usually multiple and irregular.
Commonly associated with fractures. Such wounds can not be closed primarily
and therefore should be allowed to heal by second intention.

7. B. According to severity
 Simple wounds
The integrity of the skin is traumatized without loss or destruction of the tissue and
without the presence of a foreign body in the wound.
 Complex wounds
Tissue is lost or destructed by means of burn or foreign body in the wound.
C. According to morphological character
 Closed wounds
1. Bruises and contusions
Caused by blunt trauma that damages the tissue under the skin without breaking the
skin

8. Characterized by skin dislocation due to bleeding into the tissues.
Blows to the chest, abdomen can cause contusions.
2. Hematoma
may be subcutaneous/intramuscular/subfascial/intraarticular. Small
haematoma will get absorbed. Large hematoma once get infected forms
an abscess and so it should be drained under general/regional anaesthesia
adequately. Often hematoma contains only reddish plasmatic fluid which
can be aspirated with wide bore needle.
3. Abrasions
It is superficial and is due to shearing of skin where the surface is rubbed
off. It heals by epithelialisation.

9.  Open wounds
1.Lacerated wounds
Caused by tearing of tissues wounds have irregular borders.
Loss of tissue is limited to skin and subcutaneous tissue.
2. Penetrating wounds
commonly due to stab injuries. Common example is stab injury to the abdomen.
Stab wound may be small on body surface but damage to the deeper organs like
liver and spleen.
3.Perforating wound
Have to openings one of entrance and the exit e.g gunshot wounds
.

10. D. according to degree of contamination
a. Clean wound
Incision made under sterile conditioned
No inflammation is encountered.
Primary closure and no drain .e.g Herniorrhaphy
B clean contaminated wounds
Operative wounds in which the respiratory, alimentary, genital or urinary tract is
entered under controlled condition and without unsual contamination.
C. Contaminated wounds
Open, fresh or accidental wounds: operations with major breaks sterile technique
from the GIT and incisions in which acute ,non purulent inflammation is
encountered.

11. D. Dirty wounds
Old traumatized wounds with retained devitalized tissue and those that involve
clinical infection
E. According to wound depth
a. Superficial wounds
Only the epidermis is affected and has to be replaced. Superficial wounds do
not bleed nd heals within a few days examples include: abrasions and blisters.
b. Partial thickness wounds
The epidermis and part of the dermis is affected.
A partial thickness wound bleeds and if left uncovered , a blood clot covers the
wound ad a scar will form .the missing tissue is then replaced followed by
regeneration of the epidermis.

12. C. Full thickness wounds
This involves the epidermis and the dermis. The underlying fatty
tissue ,bones ,muscles or tendons may be damaged. Full
thickness wounds cannot be sutured the healing process creates
new tissue to fill the wound followed by regeneration of the
epidermis.

13.  Wound healing is a mechanism whereby the body attempts to
restore the integrity of the injured part. The entire wound healing
process is a complex series of events that begins at the moment
of injury and continues for months or years.
Healing involves two distinct processes:
a) Regeneration: is when healing takes place by proliferation of
parenchyma cells and usually results in complete restoration of
the original tissues.
b) Repair:Is a healing outcome in which tissues do not return to
their normal architecture and functions. Repair typically results
in the formation of scar(fibrosis)
NOTE
 Some tissues heal by regeneration only
 Some tissues heal by regeneration and repair
 Some tissues heal by repair only

14. A. Primary Healing (First intention)
 It occurs in a clean incised wound or surgical wound. Wound edges are approximated with sutures.
There is more epithelial regeneration than fibrosis. Wound heals rapidly with complete closure. Scar
will be linear, smooth, and supple.
 Best choice for wounds in well vascularized areas. Treated within 24hr, prior to development of
granulation tissue
B. Secondary Healing (Second intention)
. It occurs in a wound with extensive soft tissue loss like in major trauma, burns and wound with sepsis. It
heals slowly with fibrosis. It leads into a wide or poor scar, often hypertrophied and contracted.
. Unlike primary wounds, approximation of wound margins occurs via reepithelization and wound
contraction by myofibroblast.
. Wound are often left open, heals by granulation, contraction and epithelialisation and there is
increased inflammation and proliferation of cells
. Commonly used in the management of contaminated or infected wounds.
. Complication: Late wound contracture, hypertrophic scar and disability

15. C. Tertiary intention (also called delayed primary intention)
 Wounds that are too heavily contaminated for primary closure are
initially left open but appear clean and well vascularized after 4-5
days of open observation
 Edges later opposed when healing conditions favourable
 Indications:
1. Infected or unhealthy wounds with high concentration of
bacterial content
2. Wounds with a long time lapse since injury
3. Wounds with a severe crush component with significant tissue
devitalization.
4. Tensile strength develops as with primary closure

16. 1. The inflammatory phase
2. The proliferative phase
3. The remodeling phase

17. 1. The inflammatory phase
2. The proliferative phase
3. The maturation phase

20. A. LOCAL FACTORS:
1. Infection is the most important factor acting locally which delays the process of healing.
2. Poor blood supply to wound slows healing e.g. injuries to face heal quickly due to rich blood
supply while injury to leg with varicose ulcers having poor blood supply heals slowly.
3. Foreign bodies including sutures interfere with healing and cause intense inflammatory reaction
and infection.
4. Movement delays wound healing.
5. Exposure to ionizing radiation delays granulation tissue formation.
6. Exposure to ultraviolet light facilitates healing.
7. Type, size and location of injury determines whether healing takes place by resolution or
organization.
B. SYSTEMIC FACTORS:
1. Age. Wound healing is rapid in young and somewhat slow in aged and debilitated people due to
poor blood supply to the injured area in the latter.
2. Nutrition. Deficiency of constituents like protein, vitamin C (scurvy) and zinc delays the wound
healing.
3. Systemic infection delays wound healing. Administration of glucocorticoids has anti-
inflammatory effect.
4. Uncontrolled diabetics are more prone to develop infections and hence delay in healing.
5. Hematologic abnormalities like defect of neutrophil functions (chemotaxis and phagocytosis),
and neutropenia and bleeding disorders slow the process of wound healing.

21.  Infection of wound due to entry of bacteria delays the healing.
 Implantation (epidermal) cyst formation may occur due to
persistence of epithelial cells in the wound after healing.
 Pigmentation. Healed wounds may at times have rust-like colour due
to staining with haemosiderin. Some coloured particulate material left
in the wound may persist and impart colour to the healed wound.
 4. Deficient scar formation. This may occur due to inadequate
formation of granulation tissue

22. When addressing any wound, the key principles required are:
1. WOUND EVALUATION – WHICH ALSO INCLUDES HISTORY
 A comprehensive assessment of the patient to identify factors that are detrimental to wound healing
should be performed for example mechanism of injury, patient's medical problems(allergies to
medication)/immune status, environment in which wound occurred as there maybe potential
contaminants, time of injury(accelerated growth phase of bacteria starts at 3 hours post wound.
 If identified, causative factors of delayed wound healing should be controlled or eliminated; remember,
dressings don not heal the wounds, the patient does
2. Wound assessment
 Perform a systematic assessment of the wound, a useful mnemonic is TIMES: Tissue involved(such as
viable or non viable), infection or inflammation, moisture levels, edge of the wound and surrounding
skin
 Body location i.e. proximity to joints, nerves, tendons, vasculature. Test integrity of each structure
 Physical examination of the wound location. This is important in assessment of areas at infection risk for
example high endogenous bacterial counts in hairy areas

23.  3. WOUND PREPARATION
 Administration of topical, local or regional block anesthesia if necessary
 Hemostasis can be achieved through application of direct pressure, using ligatures,
chemicals such as epinephrine, gel foam
 Foreign body removal. Suspect foreign body with point tenderness. Do imaging
 Cleaning of the wound through high pressure irrigation of normal saline to dislodge foreign
bodies, contaminants and bacteria. Hair removal by clipping hair with scissors as shaving
increases risk of infection x10. Never shave eyebrows(may not regrow)
 Debridement to remove devitalized tissue and create sharp wound edge
4. Wound closure in relation to time
 Primary closure using sutures, adhesive or tape. Performed on recently sustained
lacerations: <12hrs generally and <24 hours on face
 Secondary closure in order to allow granulation
 Tertiary closure. Delayed primary(observed for 3-4 days)

24.  Most wounds can be managed with secondary intention healing or primary
closure. However, wen wounds are large or complex, more complex solutions be
required. Even in these cases, they may initially require management with
dressings prior to definitive reconstruction. The ‘Reconstructive ladder can be
used as a step wise progression of wound management options
1.Secondary intention
2.Primary closure
3.Delayed primary closure
4.Split thickness graft
5.Full thickness skin graft
6.Tissue expansion
7.Random flap
8.Pedicled flap
9.Free flap

25.  No scar formation till early 3rd trimester
 High hyaluronic acid and rapid deposition of collagen is
responsible for no scar formation
 The growth factor profile is reduced in the fetus with low
PDGF and high epidermal GF giving high rate of wound
healing
 Higher type III collagen has also been attributed to lack of
scar in fetus

27.  It is spreading inflammation of subcutaneous and fascial planes.
 Infection may follow a small scratch or wound or incision
CAUSES
 Commonly due to Streptococcus pyogenes and other Gram +ve
organism
 Often gram –ve organisms like Klebsiella, Pseudomonas, E. coli
are also involved (usually Gram –ve organisms cause secondary
infection)

28.  Fever,
 toxicity (tachycardia, hypotension).
 Swelling is diffuse and spreading in nature.
 Pain and tenderness, red, shiny area with stretched warm skin.
 Cellulitis will progress rapidly in diabetic and immunosuppressed
individuals.
 Tender regional lymph nodes may be palpable which signify severity of
the infection.

31.  Deep vein thrombosis
 Gas gangrene
 Insect bite

32.  History collection
 Physical examination
 Complete blood count
 Culture and sensitivity

33.  Cellulitis can progress to lymphangitis, abscess formation, or sepsis
 Infection by additional species of bacteria(superinfection) may occur,
complicating treatment. Infection can also spread to the layer of tissue
enveloping muscles(fascia), causing necrotizing fasciitis. Cellulitis of the scalp
may cause scarring, leading to hair loss(alopecia)
 Infection may spread from the orbit to the brain or tissues lining the brain and
spinal cord(meninges)
 Orbital cellulitis may progress to blindness, cavernous sinus clots(thrombosis),
or inflammation of all tissues of the eye(panophthalmitis)
 Older individuals may develop a blood clot(thrombophlebitis) as a result of
cellulitis in more superficial tissues

34.  Mild cases of cellulitis can be treated on an outpatient basis with oral
antibiotic therapy with Dicloxacillin, amoxicillin, or cephalexin
 If the cellulitis is severe, the patient is hospitalized and treated with
i.v antibiotics for at least 7 to 14 days
 Immobilize the part and elevate the gravity above the level of the
heart
 Provide moist heat to promote wound healing
 Do not underestimate cellulitis as it can spread very quickly and may
progress rapidly to necrotizing fasciitis. It should be treated
aggressively.

35.  It's not always possible to prevent it, but the following measures may
help reduce your risk:
 Use moisturizer if your skin is dry or prone to cracking
 Lose weight if you're overweight – being obese can increase your risk
of cellulitis
 Try to ensure any conditions that can increase your risk of cellulitis –
such as eczema, athlete's foot, leg ulcers and lymphoedema – are well
managed
 Make sure any cuts, grazes or bites are kept clean – wash them under
running tap water and cover them with a plaster or dressing
 Wash your hands regularly – particularly when treating or touching a
wound or skin condition