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 (persistant) - result

of underlying condition

Surgical Wounds

• Patient sustains this type of wound any time a surgeon 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/Bur

n

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 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

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 ConsequencesOf 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 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 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 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

• Adhesions• Debridement • Dehiscence• Evisceration• Fistula • Gangrene • Granulation • Hematoma• Hemorrhage

• Herniation• Infection • Ischemia• Keloid• Necrosis • Proud Flesh• Sinus • Suture

breakdown or sensitivity

Other Wound Terms

• Cicatrix• Collagen• Serous - thin, watery liquid, usually

clear• Sero-sanguinous -A serum-like exudate

which is blood-stained (i.e. Pink fluid) Sanguinous – fluid containing mostly blood (i.e. Red fluid)

• Tensile strength

Patient’s Physical Condition

• Smoking• Circulation• Age• Nutritional

status• Obesity• Immunologic

status

• Pre-existing disease 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

• 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