80.Skin grafts Flashcards
difference btwn skin flaps and skin grafts
flaps–vascular, living tissue at the time of implantationgrafts–separated from all vascular and nervous supply when implanted
classification of skin grafts
SOURCE1. autografts (same animal)2. allograft (same species)3. xenografts (different species)4. isografts (identical twins)THICKNESS1. full (epidermis and full dermis)2. split thickness (epidermis and partial variable dermis)SIZE OF COVERAGE1. island or seed grafts (rely on keratinocytes)2. sheet grafts
3 most common causes of graft failure
- separation of the graft from bed2. infection3. movement
how does infection contribute to graft failure
exudate accumulation (may separate graft from bed)bacT enzymes (plasmin, proteolytic enzymes, elastase) break down fibrin attachments Beta hemolytic Strep and Pseudomonas
process of engraftment (“graft take”)
for a graft to survive regenerative must exceed degeneration by the 7-8th post op day1. adherence(fibrin strands link btwn collagen and elastin)2. plasmatic imbibition (nutrient exchange and fluid buildup)3. inosculation (connecting of native blood flow)4. revascularization (ingrowth of new vessels)
rate of new capillary ingrowth into graft
0.5 mm/daycytokine control—vascular endothelial growth factors
T/Fsplit thickness grafts are not recommended in cats
TRUEbecause the skin of cats is so thin, split thickness grafts are not indicated
types of graft knives
- weck graft knife2. humby and watson graft knives3. dermatomes (power drive–Brown dermatome)(or just do it free hand with scalpel)
ideal thickness for partial thickness skin grafts in dogs
0.35-0.38 mm
if overlapping graft to recipient bed, how much should they overlap
1-2 cm
bandage post op graft placement
to immobilizenonadherent dressingsmay use triple Ab on graft edges or 0.1% gentamicin sulfate+/- VACbandage change 48 hr (the longer the better)
advantages of partial or split thickness grafts
–better viability (89% vs 58% for full thickness)–greater capillary density (more vessels available)–less distance for ingrowing vessels, nutrients to travel –result in greater expansion after healing
disadvantages of split thickness grafts
—less durable–more subject to trauma–less hair growth–scaly appearance, lack sebaceous glands–expensive equipment (dermatomes, knives)
full thickness mesh grafts
slits–parallel staggered rowsprovides: drainage, flexibility, conformity, expansion
3 indications for mesh graft
- to allow drainage2. to cover large skin defects3. reconstruct irregular surfaces
