What are the stages or phases of wound healing? 

1.     Inflammatory phase

2.     Debridement phase

3.     Repair (proliferative) phase

4.     Maturation phase

  What are the major characteristics of the first phase of wound healing?

 Characterized by increased vascular permeability, chemotaxis of cells from the circulation into the wounded area, local release of cytokines and growth factors, and the activation of migrating cells. Hemostasis precedes inflammation. 

Which cells are first drawn to the area of a wound?

Neutrophils, followed by monocytes. 

  What is the origin of the first cells drawn to the area of a wound?

Bone marrow, circulation/vasculature

What substances stimulate the attraction of cells to a wounded area?

Platelet-derived growth factor (PDGF), transforming growth factor, platelet-activating factor (PAF), fibronection, and serotonin (all released by platelets)

PDGF is chemostatic for these cells

  What role do the first cells of wound healing play in the healing of wounded tissue?

Inflammatory cells at the site of injury debride the wound of organisms, foreign matter, and nonviable tissue. Neutrophils remove debris via phagocytosis and by releasing proteolytic enzymes and free radicals. Macrophages secrete proteolytic enzymes, much like neutrophils and can also phagocytosize material and organisms by coalescing to form multinucleated giant cells. 

1What are the major cells of the second phase of wound healing; what is their primary function; what is their origin?

Fibroblasts produce components that make up the extracellular matrix.

Endothelial cells form new capillaries via angiogenesis. 

         What is the main feature of the third phase of wound healing; what cells are responsible for this main function?

Main features: deposition and maturation of collagen.

                        Cells responsible: fine collagen fibrils consolidated into thicker collagen fiber bundles. 

 What is “wound matrix”; what is its’ composition?

Wound matrix: collagen, proteoglycans and glycosaminoglycans along with a fibrin clot matrix.

                        Composition: initially (fibrin and fibronectin); next (GAG’, proteoglycans and other proteins); ultimately, collagen becomes the prominent scar protein. 

What is the process(es) by which wound contraction occurs?

       Is an active process in which an open wound defect is “healed” or “closed” by the inward centripetal movement of the normal bordering skin. 

What is the composition of granulation tissue; when does it first appear in a wound?

Granulation tissue: high density of blood vessels, capillaries, myofibroblasts, macrophages, and loosely organized fine collagen fibrils. 

What is the process of wound epithelialization; what is the origin of the cells in the epithelialization process?

Epithelialization is the mobilization and migration of epithelial cells from the wound margins across the surface of the granulation tissue bed.

            Origin of cells: marginal basal cells from the adjacent skin borders. They proliferate, flatten and migrate. 

·     Prolonged hypoproteinemia = adverse effect on wound healing. Need sufficient nutrition vitamin A (deficiency = retard wound repair and increase incidence of wound infection), and vitamin C (deficiency = lack of collagen cross-linking, and reduction in collagen synthesis)

wound healing includes cells with an increase in rate of cell division so these cells (rapidly dividing cells) are targeted and destroyed by this type of therapy. Dosage dependent. 

·   Theoretically inhibit the processes of wound healing. Only high doses administered for a prolonged period of time will do this. 

Infection prevents the “complete” healing of a wound 

surgically created under aseptic conditions

minimal contamination that can be easily removed

gross contamination with foreign debris

What are the important local factors in a traumatic wound that may impair resistance to infection

Local factors: blood supply to injured area; presence of foreign material; ischemic, contaminated, infected or necrotic tissue in the wound; dead space; excessive tension to close a wound; type of suture material placed in the wound. 

     What are the significant systemic factors that may impair resistance to infection?

    Systemic factors: disease conditions which impair immunocompetence; extreme age or obesity, treatment for other conditions (i.e. radiation, high corticosteroid or cytotoxic agents). 

Primary closure: clean or clean-contaminated wound converted to a clean wound; immediate suture closure of viable tissue without tension.

 clean-contaminated or contaminated wounds; questionable tissue viability; edema, excess tension, anticipated wound discharge; closure in 2-5 days after initial major treatment; lavage and debride while open

contaminated or dirty wounds; closure in 5+ days after initial major treatment; lavage and debridement while open; skin edges undermined, trimmed if necessary and sutured

severe contamination and/or skin loss; wound tissue not suitable for closure; healing (closure) by granulation, contraction, and epithelialization

a.     Wound preparation and protection

b.     Wound lavage

c.     Wound exploration

d.     Debridement

 What is meant by “wound debridement”?

  The removal of devitalized tissue and foreign material from a traumatic wound

What factors must be considered when deciding on the type of closure to apply to a traumatic wound?

·       Is the wound free of necrotic tissue?

·       Is there minimal wound drainage?

·       Is the wound healthy? (i.e. further wound assessment is unnecessary)

An accumulation of serum in the subcutaneous space

What are the differences between an active and a passive wound drain?

·       Active: function by suction through the drain.

·       Passive: function by gravity flow and the surface tension properties between fluid and the drain material. Most are open (i.e. they drain into a bandage and not a collection receptacle)

·       Determining when to remove a drain is subjective and depends on the amount of fluid being drained.

Monofilament polypropylene or nylon is good for highly elastic tissue such as skin. 

Avoid suture that causes tissue reaction or is capillary.

Swaged = immediately available, always sharp, guaranteed sterile and less traumatic (all because always attached to suture material)

Swageless = reusable and less expensive. Can be single or double armed

True

therefore swaged is preferred. 

False

The architecture should not be weakened; therefore use taper in loose tissue and cutting in dense tissue, preferably reverse cutting

False

It should always minimize tissue damage and breakage. 

Absorbable

Strength loss with infections, knots loosen when wet. Degradation by MO and enzymes.

Capillary and multifilament. 

Absorbable

Multifilament

Degradation via MO and enzymes

Very fine for ophthalmic sx

Absorbable

Vicryl

Braided, multifilament

Usually coated, rapid hydrolysis in infected urine and alkaline

Absorbable

Dexon

Braided, multifilament

Tissue drag, cuts friable tissue, infected urine and alkaline

Absorbable

Monofilament

Similar to Maxon, but more $$

May retain kinks, minimal tissue drag

Maxon

Monofilament

Similar to PDS II but cheaper

Poor handling with larger suture

Absorbable

Monocryl

Monofilament

Best handling characteristics

Nonabsorbable 

Twisted or braided multifilament

Best handling, good for ligation, GI ulcers and urine calculi if intraluminal

Nonabsorbable

Mono or twisted multifilament

Best strength & knot security, cuts tissue, breaks w/cyclic bending

Nonabsorb

Ticron Ethibond

Braided multifilament

Coating decreases tissue drag & reduces knot security

Nonabsorb

Ethilon

Monofilament

Degradation products may be bactericidal 

Nonabsorb

Vetafil Supramid

Twisted multifilament

For skin closure only

Nonabsorb

Prolene, Surgile

Monofilament

Very flexible, good in contaminated wounds

Nonabsorb

Novafil

monofilament

stretches easily, properties of polyester & polypropylene

Blood vessel hemostasis

The use of suture material and surgical knots to occlude blood vessels

Secure anatomical closure. Can apply precise tension. Easily applied. Excess tension = eversion.

Used for skin, subcutis, fascia, vessels, nerves, GI tract

Modified simple interrupted. less wicking of bowel contents. Prevents mucosal eversion.

Used for intestinal anastamosis

Simple interrupted with knot buried in subcutis.

Used for skin closure

Stronger than simple interrupted. Resists tension. Prevents eversion. Easiest mattress to place.

Used in skin, especially for amputation stumps of tails and digits.

Saves time and suture. Good apposition. Gives an air-or fluid-tight seal. Good in tissues under low tension. less strength than simple interrupted. Excess tension = puckering and strangulation of skin. 

Uses: Skin, subcutis, fascia, vessels, nerves, GI tract

Modified horizontal mattress. Saves time and suture. Less strength than interrupted

Uses: skin closure

Similar to simple continuous but is more secure if suture line breaks.

Uses: skin, diaphragm

Normal pH

5x fraction of inspired oxygen (FiO2)

5 x 20 = 100 mm Hg

Can be a little bit above and a little bit below

85 - 105 mm Hg

18-28 mmol/L

Vary by species

Cat at lower end

-4 to +4 mEq/L

If negative base excess = more negative number

Positive base excess = more positive of a number

How do you treat hypotension?

1.) Reducing amount of anesthetic administered

2.) Intravenous fluid therapy

3.) Inotropes/vasopressors

FALSE!

Cyanosis is not clinically visible until the hypoxemia is severe! 

1.) Decreased FiO2

2.) Hypoventilation

3.) Diffusion impairment

4.) Ventilation-perfusion mismatches

5.) Intra and extra-pulmonary (right to left) shunting 

1.) Decreased CO

2.) Histiocytic hypoxia (cyanide toxicity)

3.) Hemoglobin abnormalities

"hissing" of excess gas around the endotracheal tube cuff and an over-filled breathing bag.

Also, a decreased amplitude of the QRS complexes on the ECG or Doppler sounds may fade suddenly.