Local or subdermal plexus flaps Flashcards by William Hawker

What vascular supply do subdermal plexus flaps rely on for survival?

Collateral circulation from the remaining cutaneous attachment and the subdermal plexus.

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What are the most critical issues to ensure flap preservation?

Preservation of blood supply, closure with minimal tension, appropriate nutritional status

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What is the delay phenomenon?

A group of mechanisms by which flap survival is enhanced through staged flap development.

May include incision and suture apposition of the the proposed flap borders without subcutaneous elevation, partial division of the pedicle of a flap, temporary occlusion of one pedicle of a bipedicle flap.

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What are the major factors that contribute to the delay phenomenon?

Alterations in sympathetic tone (depletion of norepinephrine), dilation of choke vessels, reorientation of vessels (parallel to the long axis of the flap), early and late changes in tissue metabolism (increased production of prostaglandin E2 that causes vasodilation), and neovascularization (increase in vasculogenesis by day 21).

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How long should flap delay be to allow for optimal vascular recovery in the delayed flap?

At least 2 weeks. Recommendation by Pavletic is a 3-week delay; at 18 days half the pedicle is divided, and the remainder is severed after an additional 3 days.

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How much does perfusion decrease following elevation of a single or bipedicle flap?

Decreases to 10 and 40% of normal, respectively. This increases back to 120-150% of normal by 3 weeks if the flap is delayed. With subsequent elevation of the delayed flap the perfusion only decreases to 90% of normal.

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Should a subdermal plexus flap ideally have a wider apex or base?

Base should be wider to preserve vascular supply

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What are the different types of advancement flaps?

Single pedicle (two single pedicle flaps may be used to create an H-plasty) and bipedicle (same as a simple relaxing incision)

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What is the main disadvantage of an advancement flap?

Elastic recoil and innate tension is transmitted to the wound edge

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What are the three types of rotational flaps?

Rotation flap: covers a defect along a common border.

Transposition flap: share a common border but the flap is rotated across intact skin.

Interpolation flap: do not share a common border. Must be tubed or incorporated into a bridging incision.

See images on page 1450 Tobias.

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What is the effect of increasing angle between a transposition flap and wound?

Greater angles reduce tension on the closure of the donor and primary site (as the donor site becomes orientated 90 degrees to the lines of tension). However increased angles and longer flaps will also lead to bigger dog ears. Normally the flap is developed within 90 degrees of the defect.

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What is the benefit of an H-plasty compared to a single pedicle advancement flap?

It has a wider base to length ratio, improving blood supply

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What is an example of a commonly used interpolation flap?

Lip-to-lid flap

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What are the two classifications of distant flaps?

Direct: skin is transferred directly by bringing the recipient skin into direct proximity with the donor skin (pouch or hinged flap).

Indirect: skin is tubed and walked toward the skin defect by progressive division of its pedicles (rare)

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What is a composite flap?

A flap that incorporates underlying structures with the skin (e.g. myocutaneous flaps [latissimus dorsi] or mucocutaneous subdermal plexus flaps [lip-to-lid])

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How many of the four attachments (lateral and medial upper limb, dorsal and ventral trunk) of the elbow and flank folds have to be maintained to ensure flap viability?

Only one

What arteries are close to the elbow and flank fold flaps and can be included in these flaps to function as axial pattern rather than subdermal plexus flaps?

Elbow fold: lateral thoracic artery.
Flank fold: deep circumflex iliac.

Which arteries supply the subdermal plexus in upper and lower labial flaps?

The superior and inferior labial arteries (these rich vascular plexi allow for mobilization of full-thickness composite flaps)

Which artery is likely responsible for the excellent survival of the lip-to-lid flap?

The angularis oris artery

How wide should the base of a lip-to-lid flap be in relation to its length?

Width should be at least 50% of the length

What are some examples of commonly used subdermal plexus flaps?

Elbow and flank fold, scrotal, perivulvar, phalangeal fillet, labial flaps, lip-to-lid

What are examples of direct distant subdermal plexus flaps?

Hinge (single pedicle) and pouch flaps (double pedicle)

When performing a ‘walking’ tubed pedicle flap how many days after creation can the initial pedicle base be severed?

Should be half severed at 18 days, then completely severed at 21 days to allow rotation into the wound bed. Remaining pedicle can be severed at 3-4 weeks.

What are some common complications associated with subdermal plexus flaps?

Infection, seroma, skin edge dehiscence, and necrosis.

What are some causes of subdermal plexus flap necrosis?

Narrow pedicle, damage to the subdermal plexus during flap creation, thrombosis, decreased peripheral perfusion or oxygenation. Hyperbaric oxygen therapy may aid flap survival in cases of marginal vascularity.

What is the effect of failure of a subdermal plexus to adhere to the underlying wound bed?

Increased reliance on vascular supply from the pedicle due to retarded neovascularization from the wound bed, increased concentration of tension along the flap edges.

Is subdermal plexus flap failure more likely before or after radiation therapy?

After radiation therapy. Dehiscence is reported in 62% of flap procedures associated with radiation therapy (necrosis 35%, infection 27%).

In a study by Hildebrandt 2022 in Vet Surg, what defects was a buccal transposition flap used to repair? What was the blood supply to the flap?

Used to repair maxillary lip defects. The blood supply was from the angularis oris and superior labial arteries (both branches of the facial artery). Most common complications were partial flap dehiscence and oronasal fistula formation.

In a study by Logothetou 2024 in Vet Surg, what was the overall complication rate when performing subdermal plexus flaps? What was a risk factor for increased complications?

54% complication rate. Increased weight was associated with increased risk of complications. 72% of skin closures with skin staples compared to 49% with skin sutures had complications, but not enough dogs for statistical comparison.

In a study by Jones 2019 in JAVMA, what was the complication rate following subdermal plexus skin flap procedures in dogs and cats?

51% (although excellent and good outcomes were achieved in 48% and 36% of procedures, respectively)

In a study by Carroll 2023 in JSAP, what flap was successfully used to close rostral to mid maxillary defects in dogs? What were the 2 main complications? When were complications more likely?

Random mucosal rotating (transposition or interpolation) flaps. Two main complications were dehiscence or flap necrosis. Post-operative complications were more frequent when flaps were used to close mid-maxillary defects.