Wound Healing Flashcards
(74 cards)
1
Q
What is the objective of wound healing?
A
To restore epithelial integrity & tensile strength
2
Q
What are the two mechanisms of wound healing?
A
- Primary (clean incised wound with opposed edges)
- Secondary (extensive epithelial loss)
3
Q
What is the first stage of wound healing?
A
Haemorrhage leads to accumulation of fibrinogen, which can then form fibrin polymers.
4
Q
What is angiogenesis in the context of wound healing?
A
Ingrowth of blood vessels due to new endothelial cells budding at edges of the wound, attracted by VEGF, PDGF, TNF.
5
Q
When do endothelial cells appear in the wound healing process?
A
After 5 days and acquire lumen.
6
Q
What initiates cell migration in wound healing?
A
Interactions between keratinocytes, epithelium & fibronectin, and cell adhesion molecules.
7
Q
Which leukocytes are involved in the wound healing process and when do they arrive?
A
- Neutrophils arrive within 24 hours
- Macrophages arrive within 24-48 hours
8
Q
What role do fibroblasts play in wound healing?
A
They are responsible for the deposition of extracellular matrix / collagen production.
9
Q
What are the key growth factors that chemoattract fibroblasts?
A
- PDGF
- IGF-1
- TGF
10
Q
What determines the tensile strength of a wound?
A
The amount & orientation of collagen.
11
Q
When is hydroxyproline formed during wound healing?
A
In less than 24 hours.
12
Q
What is the role of metalloproteinases in wound healing?
A
They degrade collagen in the extracellular matrix, leading to remodelling.
13
Q
What is granulation tissue made up of?
A
- Small new blood vessels (vascularised gel)
- Inflammatory cells
- Fibroblasts
14
Q
What are the roles of growth factors in wound healing?
A
They stimulate cells and induce mitosis.
15
Q
What is the function of cytokines in wound healing?
A
They regulate via autocrine & paracrine actions.
16
Q
What are some systemic factors that influence wound healing?
A
- Nutrition
- Immunosuppressive conditions
- Steroids
- Chronic disease
- Sepsis
17
Q
Which nutrients are important for wound healing?
A
- Protein for immune function
- Vitamin C for collagen production
- Vitamin A for cell proliferation & differentiation
- Zinc increases wound healing
18
Q
What are local factors that affect wound healing?
A
- Foreign body & infection
- Excess mobility
- Poor arterial perfusion and/or venous drainage
- Diabetes
- Radiation damage
19
Q
What percentage of wound strength is achieved after 1 week?
A
10% of wound strength.
20
Q
What percentage of wound strength is achieved after 3 months?
A
70-80% of wound strength.
21
Q
A
22
Q
A
23
Q
What are hypertrophic scars?
A
An overreactive healing process resulting in a raised and thickened scar that usually matures and improves over time.
Excess fibrous tissue is confined to the scar, located between the skin edges.
24
Q
How do keloid scars differ from hypertrophic scars?
A
Keloid scars are true tumors of atypical fibroblasts that grow beyond the margins of the original injury or scar and usually do not mature or improve spontaneously.
Keloids may also cause pain symptoms or itch.
25
What is the mainstay of management for keloid scars?
Steroid injections.
26
What does a VAC dressing apply?
Topical negative pressure, also known as subatmospheric pressure.
## Footnote
This is used to deliver negative pressure wound therapy.
27
What were the findings of the RCT comparing skin graft alone vs graft + VAC?
Fewer patients required a second graft procedure with VAC: 5 out of 30 (17%) with graft plus VAC compared to 12 out of 30 (48%) with graft alone.
## Footnote
There is also less graft loss when using VAC dressings.
28
What is the average hospital stay with negative pressure wound therapy compared to without?
13.5 days vs 17 days.
29
In what types of wounds are VACs also useful?
* Diabetic foot amputation wounds
* Infected external wounds after cardiac surgery.
30
31
What are the two types of skin grafts?
Split thickness and full thickness grafts
## Footnote
Split-thickness grafts are better for transplant survival but less aesthetically pleasing than full thickness grafts.
32
Where can full thickness grafts be harvested from?
Postauricular, supraclavicular, inguinal, inner arm regions
## Footnote
These regions are commonly used for harvesting skin grafts.
33
What tools are used to harvest skin grafts?
A knife or manual dermatome
## Footnote
A dermatome is a specialized surgical instrument used for cutting skin grafts.
34
What are the advantages of meshed grafts?
* Increased area of coverage
* Can be used if wound bed is contaminated
* Decreased complications of homeostasis
## Footnote
Meshed grafts can expand to cover larger areas and are useful in contaminated wounds.
35
What is the most useful graft to mesh ratio when using a meshed graft?
1:3 graft vs mesh
## Footnote
This ratio helps optimize the effectiveness of the graft.
36
What types of surfaces will not accept grafts?
* Chronically scarred ulcer beds
* Bone or cartilage denuded of periosteum / perichondrium
* Tendon or nerve without their paratenon / perineurium
## Footnote
Avascular surfaces are not conducive to graft acceptance.
37
What intraoperative factor decreases the risk of graft failure?
Intra-op antibiotics
## Footnote
Administering antibiotics during the operation can improve graft survival.
38
What is the effect of aspirin on graft failure?
Confers a non-significant trend to decrease failure
## Footnote
While aspirin may help, its effect is not statistically significant.
39
What trend is observed in smokers regarding graft failure?
Non-significant trend to increased graft failure
## Footnote
Smoking may negatively impact graft survival, although the trend is not significant.
40
What should be done to scrub wounds within 24 hours?
Remove loose dirt
## Footnote
Failing to do this may result in tattooing of the skin.
41
How should traumatic wounds be irrigated?
Irrigate with forceful ejection
## Footnote
Debridement and irrigation should follow to ensure cleanliness.
42
What is the difference in infection rates when using saline vs tap water for irrigation?
No difference in infection rates
## Footnote
This was reported in a study by Medscape in 2008.
43
When should wounds other than the face and scalp not be closed primarily?
If they occurred more than 12 hours before presentation, unless caused by a very clean agent
## Footnote
This is to prevent infection and complications.
44
What is the management approach for nearly all facial wounds less than 24 hours old?
Can be closed primarily with careful debridement, irrigation & antibiotic cover
## Footnote
Timely intervention is crucial for facial wounds.
45
What is an alternative to immediate closure for wounds?
Delayed primary closure (delay by approximately 5 days)
## Footnote
This allows for management with dressings and antibiotics before closure.
46
What should be done with non-facial puncture wounds or bites?
Should be opened to avoid gas gangrene, tetanus, or severe infection
## Footnote
Proper management is essential to prevent complications.
47
Can bites on the face usually be cleaned and safely closed?
Yes
## Footnote
Facial bites can often be managed effectively.
48
When does maximal scar contracture and improvement in erythema occur?
Approximately 1 year
## Footnote
This is an important timeline for monitoring healing and aesthetic outcomes.
49
50
What is the definition of a pressure sore?
Wound acquired from pressure over bony prominences
## Footnote
Also known as pressure ulcers or decubitus ulcers.
51
What is the approximate incidence of pressure sores in hospitalized patients?
Approx 3-10% have pressure sores; approx 3% develop new pressure sores, mostly in >70yo
## Footnote
This highlights the vulnerability of older patients.
52
What are the stages of pressure sores according to Barczak classification?
* Stage 1: skin intact but reddened for >1hr after relief of pressure
* Stage 2: blister or other break in dermis with/without infection
* Stage 3: subcut destruction into muscle with/without infection
* Stage 4: involvement of bone or joint with/without infection
53
What is a major aetiological factor for pressure sores?
Immobility
## Footnote
This can be due to various conditions affecting movement.
54
What are common causes of immobility that lead to pressure sores?
* Neurological problems: para-/quadra-plegia, spina bifida
* Immobilization in hospital
55
Where do pressure sores commonly occur in recumbent patients?
* Sacrum
* Heels
* Scapula
* Ischium
* Trochanter
* Post iliac spine
56
What type of tissue is often found at the base of pressure ulcers?
Necrotic tissue
## Footnote
Indicates the severity and extent of tissue damage.
57
What is the pathology underlying pressure sores?
Ischaemic necrosis resulting from prolonged pressure against the soft tissue overlying bone
## Footnote
Fat and muscle are more likely to become necrotic than skin.
58
What investigations are typically conducted for pressure ulcers?
* Bloods: WCC, albumin
* +/- x-rays: for assessment
59
What management strategies are recommended for pressure ulcers?
* Bedridden pts should be turned at least Q2H
* Paraplegics should not sit in one position for >2hrs
* Optimise nutrition (e.g., albumin)
* Stage 1 or 2 wounds usually treated conservatively
* Removing pressure aids healing in small wounds
* Infected wounds must be debrided
* Large wounds to bone require surgery, often with flaps
60
What must be treated before considering flap surgery for pressure ulcers?
Infection / osteomyelitis
## Footnote
Essential to ensure successful healing.
61
What is the prognosis for wounds extending down to bone?
Rarely heal without surgery
## Footnote
Indicates the seriousness of such wounds.
62
What potential complication can arise from chronic wounds?
Malignant transformation, known as a Marjolin ulcer
## Footnote
This underscores the importance of timely and effective treatment.
63
64
Define tetanus
An anaerobic infection that causes nervous irritability and tetanic muscular contraction
## Footnote
None
65
What was the incidence of tetanus in the US in 2000?
43 cases per year
## Footnote
None
66
What is the aetiology of tetanus?
Wound infection with anaerobe Clostridium tetani that releases a neurotoxin
## Footnote
None
67
What factors increase the risk of tetanus?
* Wounds more than 6 hours old
* Contused/abraded wounds
* Wounds more than 1cm in depth
* Wounds from high-velocity missiles
* Burns or cole
* Significant contamination (especially burns and wounds with ischaemic tissue)
## Footnote
None
68
What are some clinical presentations of tetanus?
* Pain/tingling in area of injury
* Face/Neck/back muscles affected first
* Limitation of jaw movement (lockjaw)
* Spasms of facial muscles (risus sardonicus)
* Stiffness of neck
* Spasms of back muscles (opisthotonos)
* Dysphagia, laryngospasm
* Chest and diaphragm spasms causing apnoea
## Footnote
None
69
What is the median incubation period of tetanus?
7 days (range 1 day – months)
## Footnote
None
70
How does Clostridium tetani affect the nervous system?
Produces a neurotoxin distributed via lymphatics & vessels to nerves, transported to CNS neurons, particularly affecting GABA neurons, leading to loss of inhibition of motor reflex responses
## Footnote
None
71
What is the bedside test for tetanus?
Spatula test: touch oropharynx with a spatula → reflex spasm of masseters → patient bites the spatula (94% sensitivity & 100% specificity)
## Footnote
None
72
How can tetanus be prevented?
* Tetanus toxoid (0.5mL im) booster every 10 years
* Tetanus toxoid injection if there is a tetanus-prone wound and >5 years since last booster
## Footnote
None
73
What is the treatment for tetanus?
* Tetanus Ig (250u of human tetanus Ig)
* High dose penicillin or metronidazole
* Debride wounds to create an aerobic environment
* Mechanical ventilation required in 67% of patients
## Footnote
None
74
What is the mortality rate in established tetanus?
Approximately 18%
## Footnote
None
