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Flashcards in 66 Regional & Free Flaps Deck (20):
1

What is the difference between a regional flap and microvascular free tissue transfer?

What is the difference between a regional flap and microvascular free tissue transfer?

Regional flaps are based on a main blood vessel known as the pedicle, which nourishes the muscle and skin in the distribution of the flap. Regional flaps are elevated and rotated into place with care to preserve attachment to the pedicle and integrity of this vessel. Microvascular free flaps are also based on tissues supplied by a single vascular pedicle known as the donor vessels, which are usually a single artery and vein. The donor vessels are ligated at the donor site and the entire flap is transferred to the recipient site where the donor vessels are anastomosed to recipient vessels in the face or neck using a microvascular technique to restore blood flow.

2

What patient considerations are important when deciding between regional and microvascular reconstruction options?

What patient considerations are important when deciding between regional and microvascular reconstruction options?

Previous radiation treatment causes fibrosis of tissues with decreased blood flow and poor healing, and thus necessitates reconstruction with well-vascularized tissue. Free tissue reconstruction requires longer operative times and may not be ideal for ill patients with multiple medical comorbidities who cannot tolerate a long general anesthetic. It is also important to consider a patient’s comorbidities including vascular, cardiac, renal, and pulmonary issues. A patient’s nutritional status and dependence on tobacco and alcohol need to be investigated. These factors can greatly affect a patient’s recovery and surgical outcome.

3

How is the angiosome concept important to flap design?

How is the angiosome concept important to flap design?

An angiosome is the tissue volume supplied by a single source artery and vein. Arteries that connect neighboring angiosomes are known as “choke” vessels. Two or more neighboring angiosomes can be harvested together on one pedicle by interrupting subsequent pedicles and relying on choke vessels to perfuse the distal angiosomes. More angiosomes connected in a series results in a decreased pressure gradient across the flap and raises the likelihood of distal necrosis.

4

What is delayed elevation of a flap and how does it work to improve flap viability?

What is delayed elevation of a flap and how does it work to improve flap viability?

Delayed harvest of a flap involves elevation of the distal portion of the flap from its underlying vasculature and replacing it into the defect to be utilized later. This allows for dilation of the choke vessels between angiosomes and creates a more favorable pressure gradient for viability of distal angiosomes when the flap is transferred to its recipient site a few weeks later.

Only really utilized during plastics, since Head & Neck Surgery does not afford you the time to spare.

5

What is the difference between fasciocutaneous, myocutaneous, and osteocutaneous flaps?

What is the difference between fasciocutaneous, myocutaneous, and osteocutaneous flaps?

Fasciocutaneous flaps include the skin and underlying superficial fascia and are based on a pedicled vessel perfusing one or more angiosomes. Myocutaneous flaps include muscle and are also based on a singular arterovenous system (pedicle) perfusing the muscle and are harvested with a cutaneous portion. A small branch of the vascular pedicle, which perforates the muscle and travels to the skin to supply an angiosome, perfuses the cutaneous portion of the flap. Given the less robust blood supply to the skin portion of the flap, necrosis of the skin flap can occur while the underlying muscle flap remains well perfused. Osteocutaneous flaps are composite flaps that include bone, skin, and sometimes muscle or tendon, which are based on a singular arteriovenous system.

6

What are the common regional pedicled flaps used in head and neck reconstruction?

What are the common regional pedicled flaps used in head and neck reconstruction?

see table.

7

What flap considerations are important in selecting which microvascular reconstruction option to use?

What flap considerations are important in selecting which microvascular reconstruction option to use?

It is important to consider the surgical defect carefully. Reconstruction should be performed with tissue that replicates the appearance and function of resected tissue, using epithelium for mucosal and skin defects, muscle for bulk, and bone for skeletal reconstruction. The length of the pedicle must be considered as well as the donor vasculature available for anastomosis.

8

What are the vascular pedicles of common free flaps used in head and neck reconstruction?

What are the vascular pedicles of common free flaps used in head and neck reconstruction?

see table

9

What is the Allen test, how is it performed, and why is it important in the preoperative evaluation of a candidate for a radial forearm free flap?

What is the Allen test, how is it performed, and why is it important in the preoperative evaluation of a candidate for a radial forearm free flap?

The most feared complication of a radial forearm free flap is ischemia of the hand. This complication could result if a patient has both an incomplete superficial palmar arch and a lack of communicating vessels between the deep and superficial arch. This test is used prior to procedures that will compromise the radial artery and assesses the adequacy of ulnar collateral circulation of the hand. The Allen test is performed by having the patient clench his or her fist followed by the examiner digitally occluding the radial and ulnar arteries at the wrist. The patient opens the hand to approximately 10 degrees of flexion. The examiner releases the ulnar artery and capillary refill in the thumb and index finger is assessed. If the results are equivocal or show inadequate ulnar collateral flow, the opposite arm or an alternate flap is used.

10

How is the donor site of a radial forearm free flap closed?

How is the donor site of a radial forearm free flap closed?

The cutaneous defect of the forearm requires coverage with a skin graft to provide coverage of the flexor tendons. This is usually performed with a split-thickness skin graft from the thigh. It is important to preserve the paratenon over the flexor tendons so that the skin graft will survive. The hand and forearm are immobilized postoperatively, as movement can lead to shearing forces and graft failure.

11

What is the normal “three vessel” blood flow to the foot and why is this important in patients being considered for fibular free flap?

What is the normal “three vessel” blood flow to the foot and why is this important in patients being considered for fibular free flap?

The popliteal artery provides branches into the anterior tibial artery, posterior tibial artery, and the peroneal artery. Harvest of the peroneal artery with a fibular free flap can lead to ischemia of the foot if there is inadequate collateral circulation. Preoperative evaluation is critical to ensure adequate blood supply, especially in patients with peripheral vascular disease, heart disease, and history of tobacco use. Commonly used studies include magnetic resonance angiography, standard angiography, or ankle-brachial index screening, and Doppler studies.

12

How does the abdominal wall anatomy above and below the arcuate line affect closure of a rectus abdominis donor site?

How does the abdominal wall anatomy above and below the arcuate line affect closure of a rectus abdominis donor site?

Above the arcuate line the posterior sheath is composed of contributions from the transversus abdominis and internal oblique muscle and closure of just the posterior sheath is necessary, though the anterior sheath is often also closed for additional strength. Below the arcuate line, the posterior sheath is comprised of only transversalis fascia, which is inadequate to prevent an abdominal hernia in itself. Both anterior and posterior abdominal sheaths must be closed below the arcuate line.

13

When would a microvascular free tissue latissimus dorsi flap be used as compared to a pedicled regional latissimus dorsi flap?

When would a microvascular free tissue latissimus dorsi flap be used as compared to a pedicled regional latissimus dorsi flap?

The latissimus dorsi flap can be used as either a pedicled or free flap depending on the location and availability of vessels for anastomosis. In a radical neck dissection, when there are few vessels available for microvascular anastomosis, a pedicled flap would be preferred. In scalp and skull base defects, a free tissue transfer is often preferred as it gives more flexibility in flap positioning and allows for placement over more superior defects, such as the vertex scalp, which is difficult with a pedicled flap.

14

How are microvascular free tissue flaps monitored?

How are microvascular free tissue flaps monitored?

It is essential to closely monitor free tissue flaps for signs of arterial and venous compromise, as these can quickly lead to loss of the flap and require emergent surgical exploration. Clinical examination is the gold standard for monitoring free tissue flaps. The tissue should be examined for color, temperature, and capillary refill. A Doppler probe is used to monitor arterial and venous blood flow through the vascular pedicle. Some surgeons place an implantable Doppler intraoperatively for monitoring. A pinprick can also be used to assess the color of the blood and how quickly it bleeds. Rapid bleeding of dark blood suggests venous congestion. Lack of bleeding or slow bleeding may indicate arterial compromise.

15

What are the signs of a failing flap?

What are the signs of a failing flap?

Venous Congestion

  • Bluish discoloration
  • Increased warmth and swelling
  • Bounding Doppler
  • Rapid bleeding of dark blood on pinprick

Arterial Compromise

  • Pale discoloration
  • Cool temperature
  • Weak or absent Doppler
  • Slow or no bleeding on pinprick

16

What is the most common cause of microvascular free flap failure?

What is the most common cause of microvascular free flap failure?

Studies have shown that venous thrombus alone is more common than either arterial or combined arterial and venous thrombosis. Thrombosis typically occurs in the first two days in 80% of patients. When recognized early and managed promptly (<6 hrs) the salvage success rate is 75%. Thus, good monitoring and evaluation of these flaps is critical to their success.

17

How are leeches used in the salvage of compromised microvascular flaps?

How are leeches used in the salvage of compromised microvascular flaps?

When flap failure occurs, usually due to venous outflow obstruction, and the flap is not otherwise surgically salvageable, leeches may be used as an alternative method to establish venous outflow until inosculation occurs. The effectiveness of leech therapy is due to both the action of the leech extracting congested blood from the flap and coagulation inhibitors in the saliva of the leeches (including hirudin, a factor Xa inhibitor). Patients require close hemodynamic monitoring, frequent hemoglobin evaluations, and often transfusions during leech therapy. Leeches are also colonized with Aeromonas hydrophilia and patients require prophylactic antibiotic coverage during and after leech therapy.

18

How long can a flap survive ischemia?

How long can a flap survive ischemia?

Controversy 

All flaps undergo a period of primary ischemia during excision at the donor site until blood flow is reestablished at the recipient site. Most flaps can tolerate up to 4 hours of ischemia (enteric flaps can tolerate only a maximum of 2 hours). Once a flap has reached its ischemic limit, reperfusion will result in the “no flow” phenomenon where arterovenous shunting prevents perfusion of the flap despite blood flowing through the pedicle. Reperfusion after a period of ischemia can cause “reperfusion injury” due to activation of neutrophils and release of oxygen free radicals.

19

Should patients with microvascular free flaps be placed on anticoagulation?

Should patients with microvascular free flaps be placed on anticoagulation?

Controversy

Flap failures can result from microvascular thrombosis and it has been suggested that anticoagulation may lead to decreased failure rate. This question has been difficult to study as it would require a large number of flap failures, which are overall uncommon. Existing studies have suggested no significant difference in outcomes or complications between the use of aspirin, heparin, and no anticoagulation.

20

What is the cost associated with reconstructing head and neck defects with microvascular free flaps versus regional flaps?

What is the cost associated with reconstructing head and neck defects with microvascular free flaps versus regional flaps?

Controversy

Longer operative time, increased length of hospital stay, increased use of monitoring in the ICU, and increased use of drugs result in a higher cost of free flaps when compared to pedicled flaps. However, some justify the increase costs of free tissue transfer because of the perceived benefit of improved long-term functional and aesthetic outcomes.

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