Cap.9 Cicatrización Flashcards
Name the 3 phases of wound healing:
- Inflammation (1–6 days)
- proliferation (3 days–3 weeks)
- maturation (3 weeks–1 year)
Name several factors that can inhibit wound healing:
- Diabetes
- infection
- ischemia
- malnutrition
- radiation
- steroids
- neoplasia
- anemia
What are the optimal nutrition parameters?
Albumin >3 g/dL and prealbumin >16 mg/dL
What is primary wound closure (primary intention)?
Immediate closure of a wound with suture or staples
Most important factor in healing closed wounds by primary intention:
Tensile strength
What is the most important layer to close for strength in skin lacerations?
Dermis
How long does it take a surgical incision become “water tight”?
24 to 48 hours
What is secondary wound closure?
Leaving a wound open and allowing it to heal by granulation, contraction, and epithelialization over time
Most important factor in the healing of open wounds by secondary intention:
Epithelial integrity
What causes contraction in wounds healing by secondary intention?
Myofibroblasts
What is delayed primary closure?
Closing a wound several days (3–5 days) after incision
Rate of regeneration of a peripheral nerve:
1 mm/d or 1 in./mo
Rate of epithelialization:
1 to 2 mm/d
The strongest layer of the bowel:
Submucosa
The time period that a small bowel anastomosis is at its weakest:
3 to 5 days
Name the 2 major events in the process of epithelialization:
Migration and mitosis
Name the process by which keratinocytes pile up on top of each other at the leading edge of a migration and tumble forward over the top of the heap:
Epiboly
What cell is the most essential for wound healing?
Macrophage
This cell is responsible for the movement and contraction of wound edges:
Myofibroblast
Name the order of arrival of the different cells involved in wound healing:
- Platelets (not a true cell)
- Neutrophils (predominant cell type from day 0–2)
- Macrophages (predominant cell type from day 3–4)
- Fibroblasts (predominant cell type from day 5 and so on)
- Lymphocytes
Platelet factor 4, β-thrombomodulin, PDGF, and TGF-β are contained in this type of platelet granule:
α granule
Adenosine, serotonin, and calcium are contained in this type of platelet granule:
Dense granule
Name the predominant cell during days 0 to 2 of wound healing:
Neutrophils
Name the predominant cell during days 3 to 4 of wound healing:
Macrophages
Name the predominant cell present after day 5 of wound healing?
Fibroblasts
When does the maturation phase usually begin?
~3 weeks after the injury
What is the maximal tensile strength that a wound can reach?
80% of original tissue strength
Time period for maximum collagen accumulation in a wound:
2 to 3 weeks (mostly type III, then gets converted to type I with maturation)
Time period for a wound to reach its maximal tensile strength:
8 weeks
True or false: Denervation negatively affects epithelialization and wound contraction:
False; denervation has no effect on epithelialization/wound contraction
The number of organisms/cm2 required to retard wound healing:
100,000 organisms/g (105 organisms/g)
What is the generally recommended period of time to wait for scar maturation before considering scar revision?
12 to 18 months
What can be given to combat the inhibitory effects of steroids on wound healing and epithelialization? Dose?
Vitamin A; 25,000 IU daily
Necessary cofactor for hydroxylation and cross-linking of proline and lysine in collagen synt hesis:
Vitamin C (deficiency causes scurvy)
Type of scar that extends beyond the boundaries of the original wound:
Keloid
Type of scar that remains confined to the boundaries of the original wound and contains an overabundance of collagen:
Hypertrophic scar
The most common type of collagen is:
Type I collagen
Type of collagen predominantly synthesized in the first 48 hours of a healing wound:
Type III collagen
Type of collagen located in skin, bone, tendon, and is the primary collagen found in a healed wound:
Type I collagen
Type of collagen found in hyaline cartilage:
Type II collagen
Type of collagen in arteries, dermis, and increased in wound healing:
Type III collagen
Type of collagen that is predominant in the basement membrane:
Type IV collagen (type IV found on floor)
Type of collagen found in the cornea:
Type V collagen
Stage the pressure sore: nonblanchable erythema of intact skin:
Stage I (can be seen after 30 minutes, resolves after 1–2 hours)
Stage the pressure sore: partial-thickness skin loss involving epidermis/dermis:
Stage II (can present as blister, forms after 2–6 hours, erythema lasts >24 hours)
Stage the pressure sore: full-thickness skin loss with involvement of underlying subcutaneous tissue:
Stage III (does not extend through fascia)
Stage the pressure sore: full-thickness skin loss with tissue necrosis or extensive destruction of underlying structures (muscle/bone):
Stage IV
Areas at greatest risk for pressure sores:
- Ischium 28%
- Trochanter 19%
- Sacrum 17%
- Heel 9%
- Occiput of scalp
Rules of operative management for pressure sores (name 4):
- Debride all devitalized tissue
- Excise entire bursa (can use methylene blue to identify entire bursa)
- Identify and remodel bony prominences
- Reliable tissue coverage with appropriate flap without burning bridges for future reconstruction
Name the amino acid that is found in every 3 residues in collagen:
Proline
Name the necessary cofactors for the hydroxylation of proline:
Vitamin C, oxygen, iron, and α-ketoglutarate
What enzyme is the rate-limiting step in collagen synthesis?
Propylhydroxylase
Albumin level that puts a patient at risk for poor wound healing:
<3.0 g/dL
Time period to wait for chemotherapy to have no effect on wound healing:
14 days
