Chapter 80 Skin Grafts Flashcards
Based on graft source, what are the 4 classes of graft?
- Autograft
- Allograft
- Xenograft
- Isogaft (twin or F1 hybrid)
In experimental beagle study, how did skin on dorsum differ from elsewehere
Thicker dermal and overall thickness, greater density of hair follicles
What are the three most common causes of graft failure?
- Infection
- Movement
- Separation
–> disruption of fibrin bonds.
Which two bacteria types specifically produce large amounts of plasmin and proteolytic enzymes?
Pseudomonas and b-haemolytic Strep
When is first graft dressing change recommended?
48 hours
In rats, when was graft innervation first noted and when complete?
Noted day 13
Complete by day 40
List an instument that can be used for split thickness graft harvest
Dermatome,
most commonly used is called ‘Brown dermatome’
What exam finding can be used as a sign that granulation tissue bed is likely healthy for graft?
Advancement of epithelium from wound edge.
List the 5 stages of graft take = ‘engraftment’. Highlight the three key phases
-
Adherence:
- Phase 1 up to 72h = fibrin attachments.
- Phase 2 fibrin network invaded by fibroblasts etc: Fibrin –> fibrous network
-
Plasmatic imbibition:
- serum like fluid absorbed by capillary action –> oedematous appearance. Venous drainage may lag behind arterial. Peaks day 2-3
-
Inosculation:
- Anastomosed between capillary bed and graft vessels. Day 3-4.
-
Revascularization:
- New vessel ingrowth, 0.5 mm/day
-
Reinnervation:
- takes up to 40d to be complete in rats
Outline the change in healty graft appearance over time
Day 1-3: Congested, oedematous. Breakdown products of Hb
Day 3-4: Becoming reddish
By day 7-8: Graft pink/red if surviving
By day 14: More normal pale pink
Comment on split thickness grafts and cats
Split thickness not indicated in cats as skin is so thin
What is the recommended thickness of split thickness grafts?
0.38mm (n.b. scalpel blade thickness is 0.35mm)
What is the advantage of split thickness grafts and 3 proposed mechanisms behind that
List 3 disadvantages
Thinner so better viability (one study reported 89% survival vs 58% for full thickness.
Proposed mechanisms are:
- Greater density of vessels in dermal plexus (compared with subdermal plexus of full thickness grafts).
- Shorter distance for vascular ingrowth
- Shorter distance for diffusion
Disadvantaged:
- Thinner dermis
- Sparse hairgrowth
- Expensive equipment
List 3 indications for mesh grafts
- Allow drainage of fluid
- Cover large defects
- Reconstruct irregular surfaces
What is the appearance of full thickness graft when sc tissue adequately timmed?
Cobblestone
Briefly outline how mucosal graft for reconstruction of nasal passages is perormed
- Silicone stents sutured into nasal passages for 10d to allow granulation tissue to form.
- Silicone stents removed, mucosal graft sutured as tubes around stents (cut side facing outward). Stay sutures rostrally and caudally (caudal ones fed through tube so that also exiting rostrally.
- Stents slid back into place with graft held taught around stent.
- 3 Mucosa-skin sutures rostrally and 3 stent, mucosa, skin sutures to hold everythingin place. Stay stures cut.
Describe a point of note when performing mucosal graft as a flat sheet e.g. for prepucial recon:
Contraction as they heal i.e. second stage of surgery performed as soon as graft taken to bed (approx 7d as very thin!)
A mucosal graft was previously applied to a wound bed that was created by removing abdominal skin at the cranial aspect of a hypoplastic prepuce. The penis protrudes from the prepuce. After the graft has healed, the lateral and cranial edges of the mucosal graft are incised (A), and the graft is undermined to mobilize it (B). The dissection plane is kept deep to preserve the blood supply. C, The lateral edges of the graft are being sutured together around the penis to form a lining for the preputial extension. D, Completed suturing of the mucosal graft lining. Bilateral single-pedicle advancement skin flaps will be advanced to cover the mucosal graft lining. E, Skin flaps sutured together over the mucosal lining.
