WOUND HEALING
• Wound: Any disruption of cells, be it
tissue or skin
• Wound Healing: Restoration of that
disruption
Types of Wounds
• Surgical Wounds (intentional)
• Traumatic Wounds (accidental)
• Chronic Wounds (persistent) - result of
underlying condition
Surgical Wounds
• Patient sustains this type of wound any time a surgeon
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cuts into the skin to perform a surgical procedure
Are classified according to the CDC:
Class 1 (clean)
- Carries low risk of infection <5%
- Conditions are ideal (aseptic without prior break in
skin)
- Primary closure
- Drains placed in wound are closed systems
-No respiratory, alimentary, oropharyngeal, or
genitourinary system entry
-Does include blunt trauma that is non-penetrating
Surgical Wounds Continued
Class 2 (clean-contaminated)
- infection risk 8-11%
- respiratory, alimentary, or
genitourinary tracts are entered
under aseptic, controlled conditions
- no infection or break in aseptic technique
- drains placed in wound are closed systems
- examples: biliary, appendix (prior to
rupture), vagina, oropharynx.
Surgical Wounds Continued
Class 3 (contaminated)
- infection risk 15-20%
- traumatic, fresh, open wounds < 4 hours
old
- inflammation may be present
- injury could have resulted in spilling of
organ contents
-Includes spillage of GI tract content or
break in sterile technique intra-operatively
Surgical Wounds Continued
Class 4 (dirty/infected)
- infection risk 27-40%
- infection was present before the
surgical procedure
- includes traumatic wounds > 4 hours old
- can be a ruptured or perforated organ (ex.
ruptured appendix)
- tissue may appear necrotic, (dead),
have a purulent (pus) drainage, and foul
odor
Traumatic Wounds
• Chemical, thermal, physical, or outside
force that has caused injury to the body
tissue
• Types of traumatic wounds:
abrasion
laceration
avulsion
perforation
chemical
puncture
contusion
thermal
crushed
Incised Wound Cont.
Chemical
Wound/Burn
The chemical burn is a
part or an entire
destruction of the
molecules, the cells or
the structure of the
skin due to an irritant
or corrosive chemical
product. The
importance of the
tissue modification will
characterize the
degree of the burn.
Thermal Burn
This patient received a
thermal burn to the
buttocks, and there
was complete
destruction of the skin
and some of the
underlying fat. This
shows the exposed fat
after the MD debrided
the necrotic skin.
Normal fat appears
yellow.
Traumatic Wounds Continued
• Classifications of:
Closed - outside skin intact, tissue
under skin is not
Open – outside skin broken
Simple
Complicated
Clean
Contaminated
Closed Wounds
• Simple fractures
• Torn ligaments
• Blisters
Open Wounds
• Simple
• Skin interruption without loss or
destruction of the underlying tissue
• Lacerations
Open Wounds
• Complicated
• Skin and underlying tissue injury or
destroyed
• Burns
• Crushing injury
• Foreign object (bullet or foreign object
that is present such as knife or nail)
Complicated Wound
Complicated
Wound cont.
Pt. from Nigeria.
Machete wound to
the scalp.
Patient survived
wound and
surgery.
Open Wounds
• Clean
• Object or conditions surrounding injury
were clean
• Wound cared for within 6 hours of injury
• Heals by primary intention
• Cut that happens when loading a
dishwasher
Open Wounds
• Contaminated
• Conditions surrounding injury not clean or
care given 6 hours after injury
• Heals by 2° or 3° intention
• Injury occurs when handling feces from an
animal or person
Chronic Wounds
• An underlying condition of the patient is causing
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their wound to not heal
Delayed healing results from persistent infection
or disease processes:
Diabetes (gangrenous ulcer)
PVD
MRSA/VRSA
Pressure sores
Immuno-compromised
(Cancer/chemotherapy/AIDS/steroid therapy)
Wound Healing/Closure
• Types of:
Primary Intention/First Intention
- Surgical wound
- Edges are closely approximated
- Closed by suture, staples, or
adhesive tapes/gels
- No tissue lost
Healing by First or Primary
Intention
Healing by First or Primary
Intention? Maybe not!
Wound Healing/Closure
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Secondary Intention/Second Intention
Trauma or Chronic wounds
Wound is not closed
A. Wounds that cannot be re-approximated
B. Infection risk too high to close by 1° intention
Must remove dead or necrotic tissue by process of
debridement prior to allowing healing by this means
Healing occurs from the inside out and is prolonged as a
result
Tissue is lost
Wound Healing/Closure
Tertiary Intention/Third Intention
• Surgical, Trauma, or Chronic wound
• Closure by primary intention must be
delayed due to swelling, inflammation,
contamination, or patient’s condition
(unstable)
• May require debridement before closure
• Closure delayed 4 to 6 days
Physiological Consequences
Of A Wound
• Sympathetic Nervous System Response (Fight or Flight):
↑ HR
hyperventilation
↑ BP
↑ mental status
↑ clotting
↑ muscle tension
* Results in vasoconstriction and decrease in blood being
delivered to the abdominal organs as bleeding is
attempted to be minimized by the body and delivered to
vital organs
Wound Healing
• Natural and Spontaneous Phenomenon
• If cannot occur naturally, must remove
dead tissue or foreign bodies, treat for
infection, and re-approximate the tissue
until healing can take place
• May occur with sutures, stapling devices,
clips, steri-strips, or topical adhesive
(Derma-bond)
Tissue
• Collection of cells that are similar as well
as the intercellular substance around them
• Four Tissues of the Body:
• Epithelium
• Connective tissue (blood vessels, bone,
and cartilage)
• Muscle
• Nerve
Stages of Normal Wound
Healing
• Lag (Inflammatory) Phase
• Healing (Proliferative) Phase
• Maturation (Remodeling) Phase
Lag/Inflammatory Phase
• Lasts 1 to 4 days
• Fluid called exudate, containing blood, fibrin, and lymph
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accumulates in wound
Clotting begins as the exudate binds the wound edges
together
Inflammation, a vascular and cellular reaction gets rid of
bacteria, foreign matter, and dead tissue
Inflammation causes site to be red, swollen, warm, and
painful
Scab (dry, protective layer) forms
Wound strength limited at this time
Healing/Proliferative Phase
• Begins day 5, lasts two weeks
• Epithelialization, new cell formation
• Strength of wound increases due to
collagen fibers that are produced
• Directly related to tensile strength of the
wound
• Edges of wound continue to be brought
closer together
Tensile Strength
• Affects ability of tissue to withstand injury not
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how long it takes the wound to heal
This is the term referring to the pull strength of
a wound or the ability to resist rupture.
As collagen forms, tissue strength rapidly
increases, but it may take months for a plateau
to be reached
Until that plateau is reached, wound tissue
requires extrinsic support, usually sutures to
bring it back together
Remodeling/Maturation Phase
• Begins after 2nd week of wound and lasts about
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4 weeks and can last over a year if the wound is
extensive
Scar tissue forms (collagen formation becomes
dense)
Scars have limited vascularization, hence they
are pale in color
Ultimate strength of wound is 80% of the
nonwounded tissue
Physiological Consequences
Of A Wound Continued
• Contamination/Potential Infection
• Hemorrhage and Excessive Clot Formation
• Complete or total loss of organ function
• Cell or Tissue Death
Factors Influencing Wound Healing
• Wound Type
• Patient’s Physical Condition
• Type of Operation
Wound Complications
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Adhesions – abnormal attachments
Debridement – the process of removing devitalized tissue
Dehiscence – the breakdown of suture lines
Evisceration – the spillage of bowel from the abdominal cavity.
Fistula – pathway between two normally separate surfaces
Gangrene - Localized death and decomposition of body tissue, resulting
from either obstructed circulation or bacterial infection.
• Granulation - new connective tissue and tiny blood vessels that
form on the surfaces of a wound during the healing process
• Hematoma - A solid swelling of clotted blood within the tissues
• Hemorrhage – MASSIVE blood loss (((regular)) blood loss comes
from a paper cut)
Wound
Complications
• Herniation - the protrusion of an organ or the fascia of an organ
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through the wall of the cavity that normally contains it.
Infection
Ischemia – loss of blood flow to an area
Keloid – abnormal scar formation
Necrosis – tissue death
Proud Flesh - the swollen tissue around a healing wound or ulcer
Sinus – cavity with only an exit
Other Wound Terms
• Cicatrix – normal scar formation
• Collagen - The main structural protein found in animal connective
tissue.
• Serous - thin, watery liquid, usually clear
• Sero-sanguinous -A serum-like exudate which is bloodstained (i.e. Pink fluid)
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Sanguinous – fluid containing mostly blood (i.e. Red fluid)
Tensile strength – the pull-strength of tissue or suture.
Patient’s Physical Condition
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Smoking
Circulation
Age
Nutritional status
Obesity
Immunologic status
• Pre-existing disease
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processes:
Respiratory
Diabetes
Drug therapies
Cancer
Anemia
Cardiovascular
Type of Operation
• Aseptic technique
• Handling of tissue involved
• Methods of achieving hemostasis
• Security of the wound
• How the wound was approximated
• Where the wound is anatomically
Surgical Site Infections
• Incisional- at the site of incision
• Deep Wound- within the tissue or in the
cavity where the operation occurred
• Nosocomial- acquired while in the
hospital
Wound Care
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Aseptic Technique
Prophyllactic antibiotics
Antiseptics/antimicrobials used for skin prep
Adequate oxygenation of tissues by
maintaining patient oxygenation
Closed wound drain systems when drains
are used
Sterile technique/supplies with dressing
changes
Dressings secured with clean tape or sterile
packaged dressings (tegaderm/primapore)
Summary
• Definitions
• Physiological Consequences of a Wound
• Wound Types
• Mechanisms of Wound Healing
• Stages of Wound Healing
• Factors Influencing Wound Healing
• Surgical Site Infections
• Wound Care