LA Wound Healing & Surgical Inflammation (11)

Question 1

What are the phases of wound healing?

Answer 1

inflammation (4-6 days)
proliferation (4-24 days)
remodeling (21 days - 2 years)

Question 2

What is the goal of hemostasis?

Answer 2

to stop bleeding while maintaining perfusion

Question 3

What happens with endothelial cell disruption in hemostasis?

Answer 3

immediate vasoconstriction —> exposure of vWF —> platelet activation and aggregation —> coagulation cascade

Question 4

Hemostasis leads to inflammation. How?

Answer 4

• endothelial cells release vasodilators mediated by histamine, etc
• post-capillary venue leakiness
• protein leakage

Question 5

What is the purpose of edema?

Answer 5

facilitates delivery of soluble factors and cells

Question 6

What are the two phases of inflammation (the debridement phase)?

Answer 6

early: neutrophil recruitment
late: monocyte transformation

Question 7

How do leukocytes respond to inflammation?

Answer 7

are recruited from circulation by chemoattractants (from coagulation)

rolling, activation, tight adhesion, transmigration of cells through microvascular endothelium

Question 8

What is diapedesis?

Answer 8

the passage of blood cells through intact capillary walls

Question 9

What is neutrophil diapedesis encouraged by and how long does it take?

Answer 9

encouraged by capillary permeability, minutes and peaks 1-2 days after injury

Question 10

What are the functions of macrophages?

Answer 10

• pro-inflammatory functions
• stimulate proliferation of firm, endodermal, and epithelial tissues
• helps with remodeling phase

Question 11

What is the resolution of inflammation?

Answer 11

each of the pathways needs to be halted or reversed - apoptosis of cells

Question 12

Why is the inflammatory phase most easily modulated by clinicians?

Answer 12

1. good surgical debridement
2. good hemostasis
3. adequate drainage
4. NSAIDs and steroids

Question 13

What do steroids do?

Answer 13

inhibit phospholipases

Question 14

What happens in the proliferation phase of wound healing?

Answer 14

• fibroplasia
• angiogenesis
• epithelialization

Question 15

What is fibroplasia?

Answer 15

formulation of granulation tissue by fibroblasts
- scaffold
- temporary barrier of infection

Question 16

What is granulation tissue made of?

Answer 16

• macrophages
• fibroblasts
• blood vessels

Question 17

When do you start to see granulation tissue?

Answer 17

around day 5

Question 18

What are fibroblasts directed by? What do they produce?

Answer 18

directed by macrophages via cytokines and growth factors

• produce extracellular matrix - initially more type III immature collagen, later more type I collagen

Question 19

What is the time of increasing wound strength?

Answer 19

rapid gain 7-14 days (corresponds to time of suture removal)

Question 20

How does angiogenesis occur?

Answer 20

regulated by macrophages and endothelium (vascular endothelial growth factor)

Question 21

What is epithelialization? Which direction does it cover?

Answer 21

• epithelium covers wound

centripetally

Question 22

What happens to fibroblasts regarding maturation?

Answer 22

wound contraction - fibroblasts differentiate into myofibroblasts under influence of growth factors and cytokines

Question 23

What is involved in remodeling?

Answer 23

conversion of granulation tissue into scar tissue

matrix metalloproteinases (collagenases, gelatinases, stromelysins) - demolition team

Question 24

How long can remodeling take?

Answer 24

up to 1-2 years, depending on size of wound

Question 25

When does healing stop?

Answer 25

wound edges meet (good) - tension surrounding skin > force of myofibroblasts (not ideal) - reduced #s of myofibroblasts (not ideal) - granulation tissue is proliferative

Question 26

What is shock? What can it lead to?

Answer 26

cascade of events that begins when cells/tissue are oxygen deprived from inadequate perfusion can lead to systemic inflammatory response syndrome and multiple organ dysfunction

Question 27

What is systemic inflammatory response syndrome?

Answer 27

generally considered excessive response - cytokine storm, leukocyte dysfunction, delayed resolution of inflammation

Question 28

When do you classify something as SIRS?

Answer 28

must meet any **2** with underlying pathologic cause - hyper or hypothermia - tachycardia - tachypnea - leukocytosis or leukopenia - depression - DIC

Question 29

What happens with hyperthermia?

Answer 29

pro inflammatory cytokines act on hypothalamus

Question 30

What happens with hypothermia?

Answer 30

hypoperfusion, central blood sequestration

Question 31

What happens with tachycardia?

Answer 31

dehydration —> hypotension or pain increases heart rate shift fluid between spaces

Question 32

What happens with tachypnea?

Answer 32

**PAIN** leads to metabolic acidosis

Question 33

What are the CBC alterations for shock?

Answer 33

primarily from change in neutrophils 1. leukopenia - increased use 2. leukocytosis - released from sequestered areas 3. left shift

Question 34

What happens with depression and SIRS?

Answer 34

cytokines, eicosanoids

Question 35

What effect do corticosteroids (stress) have on surgical healing?

Answer 35

**reduce** healing - anti-inflammatory, reduce activity/production of growth factors

Question 36

What is multiple organ dysfunction syndrome?

Answer 36

progression or sequelae of SIRS presence of altered organ function in an acutely ill patient such that homeostasis cannot be maintained without interruption