Ch 78 - Local or Subdermal Plexus Flaps Flashcards

1
Q

What do subdermal plexus flaps rely on for survival?

A

Collateral circulation from the remaining cutaneous attachment and its vasculature

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2
Q

What range of thickness is hairy skin?

A

0.5 - 5mm

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3
Q

What are the three vascular plexus’ of the skin?

A
  • Superficial subpapillary plexus
  • Middle cutaneous plexus
  • Deep subcutaneous plexus
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4
Q

What substances within skin supply it with its strength and compliance?

A

Collagen and elastin fibers (collagen accounts for 90% fiber content)

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5
Q

What is the delay phenomenon?

A

A group of mechanisms by which flap survival is enhanced through staged flap development.
- physiologically trained to rely on vasculature support from pedicle
- Ischaemic preconditioning
- Decreased production of PGF2alpha (vasoconstruction) with elevated PGE2 (vasodilation)
- Norepiphedrine depletion with delay causing vasodilation
- Number and size of vessels increase and their orientation change to favour vessels parallel to long axis of flap

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6
Q

How has delayed development of single pedicle and bipedical flaps effected perfusion?

A
  • Perfusion drops to 10% and 40% after initial elevation of single and double pedicle flaps respectively
  • Circulation than rises to 120 - 150% of normal after approx 3wk
  • Re-elevation of the flap after 3wk delay then causes a much smaller decrease in perfusion to 90% of normal, resulting in improved survival
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7
Q

What growth factor may be important for neovascularisation?

A

VEGF - Local autologous PRP enhanced tissue perfusion and improved survival of subdermal plexus flaps due to vasodilation

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8
Q

What is a composite flap?

A

Includes underlying muscle, oral mucosa or both

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9
Q

Define advancement flap, rotation flap, transposition flap and interpolation flap

A
  • Advancement flap: Shifts skin without rotation
  • Rotation flap: Semicircular flap that cover a triangular defect along one border of the flap
  • Transposition flaps also share a common border with the defect. It’s created within 90 degrees of the long axis of the defect.
  • Interpolation flap: Lack a common border with the recipient bed. Must be tubed or incorporated via a bridging incision.
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10
Q

List some types of advancement flap

A
  • Single pedicle advancement
  • Bipedical advancement
  • H-plasty (double single pedicle advancement flaps)
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11
Q

How is a rotation flap made?

A

For triangular wounds, a curved incision is begun at a point adjacent to the shortest side of the wound so that the leading edge of the flap shares a border with the long side of the wound

For rectangular wounds, bilateral rotation flaps can be made

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12
Q

How do you develop a transposition flap?

A

A rectangular flap is created within 90 degrees of the long axis of the defect. Should be as wide as the defect and length equivalent to the distance between the pivot point and the most distant point of the defect

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13
Q

What is an example of a direct distant flap?

A

A pouch/hinge flap

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14
Q

What vessels are closely associated with the skin fold flaps allowing them to function as an axial pattern flap if included

A
  • Elbow fold: Lateral thoracic artery
  • Flank fold: Deep circumflex iliac artery
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15
Q

List some examples of subdermal plexus flaps

A
  • Skin fold flaps
  • Scrotal flap
  • Perivulvar flap
  • Preputial reconstructions (bipedical flap with free buccal mucosal graft)
  • Phalangeal fillet
  • Labial flaps
  • Lip-to-Lid
  • Distant direct
  • Tubed flaps
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16
Q

What is the recommened width-to-length ratio for a lip-to-lid flap?

A

No more than 1:2

17
Q

What options are there if corneal abrasion is considered likely due to swelling after a lip-to-lid flap?

A
  • Place a contact lens! Allows temporary protection until swelling and spastic entropion subsides
18
Q

When can a distant direct pouch flap be let down?

A
  • Once the skin has healed (approx 2 weeks) one half of each pedicle is divided
  • Remaining halves divided 2-3 days later and the flap is fully sutured to the remaining wound edges
19
Q

When can a developed tube flap be rotated?

A
  • After 18d, one half of the pedicle base farthest from the wound is severed and then resutured
  • Other half is severed on day 21 and is rotated to the wound
  • Tubed section left in place for at least 3-4 more weeks after which time is can be gradually divided and excised
20
Q

Why is adherence of flaps to the underlying SQ important?

A
  • Reduces dead space
  • Encourages neovascularisation
  • Decreases tension along the flap edge
21
Q

How does radiation therapy effect flap survival/complications?

A

High complications associated with radiation therapy
- 62% dehiscense
- 35% necrosis
- 27% infection

Risk for complications is highest when radiation is performed before flap procedures because of damage to local fibroblasts and blood vessels

22
Q

How does hyperbaric oxygen therapy effect subdermal plexus flaps?

A
  • Small but consistent improvement in survival of random flaps: increases oxygenation of the flap.