Microsurgery principles

Question 1

A 54-year-old woman undergoes breast reconstruction using a deep inferior epigastric artery perforator (DIEP) flap. Arterial thrombosis is noted after performing the microanastomosis. Which of the following is more likely to occur with local administration of tissue plasminogen activator (tPA) as an adjunct to revision microanastomosis as compared with revision microanastomosis alone (without tPA)?

A) Decreased flap salvage rate
B) Decreased incidence of fat necrosis
C) Increased flap salvage rate
D) Increased incidence of fat necrosis
E) Increased incidence of operative hematoma

Answer 1

The correct response is Option B.

Administration of tissue plasminogen activator (tPA) during revision of a microanastomosis has a decreased rate of subsequent fat necrosis. The suspected mechanism of action is thrombolysis of distant “shower” emboli in the microvasculature.

The administration of tPA as an adjunct to microanastomotic revision has no effect on flap salvage rates. In addition, there is no change in hematoma risk since the dose is low (2 mg) and is usually injected directly into the flap artery, which is maintained locally in the flap. Only if larger doses of tPA were given systemically would there be a risk of operative hematoma.

Question 2

When harvesting the profunda artery perforator flap for breast reconstruction, which of the following structures does the perforating vessel travel through in the majority of patients?

A) Adductor longus muscle
B) Adductor magnus muscle
C) Gracilis muscle
D) Septum between the adductor longus and sartorius muscles
E) Septum between the adductor magnus and semimembranosus muscles

Answer 2

The correct response is Option B.

Proximal thigh profunda artery perforators most commonly course through the adductor magnus muscle not the adductor longus muscle. In these cases where musculocutaneous proximal perforators are used, fibers of the adductor magnus muscle will be divided for PAP flap harvest.
* The profunda artery perforator (PAP) flap is a fasciocutaneous flap frequently employed for breast reconstruction as an alternative to the deep inferior epigastric artery perforator flap. The PAP flap has also been described for lower extremity resurfacing and burn scar contracture release, as well as pedicled for perineal reconstruction. The PAP flap skin paddle is harvested as either a transverse skin paddle beneath the gluteal and groin crease or with a vertical skin paddle harvested in the frog leg position. The most common donor site skin paddle orientation for breast reconstruction is a transverse ellipse of skin inferior to the gluteal crease to camouflage the donor site scar.
* The profunda artery perforators emerge from the profunda vessels longitudinally down the postero-medial aspect of the thigh. Most patients have a proximal perforator that supplies the transverse ellipse of skin and adipose tissue most commonly employed for breast reconstruction. However, enough variability exists in perforator location, that preoperative CT angiography is recommended to confirm the presence of a proximal perforator.
* The PAP flap perforating vessel may travel in a septocutaneous plane between the gracilis and adductor magnus at the level of the deep investing fascia and between the adductor longus and magnus closer to its origin but not between the muscles listed as alternate septocutaneous choices.
* The transverse upper gracilis (TUG) flap perforator travels through the gracilis muscle before perfusing the medial thigh skin.

Question 3

An otherwise-healthy 50-year-old man undergoes resection and immediate reconstruction with an anterolateral thigh free flap for recurrent squamous cell carcinoma of the oral cavity. Medical history includes resection, primary closure, and radiation. Intraoperatively, the patient is receiving low-dose phenylephrine infusion for blood pressure maintenance. Which of the following strategies is most likely to decrease the risk for pedicle thrombosis in this patient?

A) Administration of intravenous fluid boluses to wean off phenylephrine
B) Anastomosis to nonradiated recipient neck vessels
C) End-to-end anastomosis instead of end-to-side anastomosis
D) Intravenous heparin bolus 10 minutes before pedicle ligation
E) Venous anastomosis to internal jugular vein instead of the external jugular vein

Answer 3

The correct response is Option B.

Anastomoses performed in radiated fields have higher rates of flap loss as compared with nonradiated recipient neck vessels in head and neck reconstruction.
* Systemic heparin has not been shown to decrease pedicle thrombosis. However, vessel irrigation with topical heparin has been shown to decrease thrombosis at the anastomosis site in animal models, and therefore, most microsurgeons perform this practice.
* Vasopressors do not increase the risk for pedicle thrombosis. A recent meta-analysis showed a decreased rate of pedicle thrombosis with perioperative vasopressor administration in head and neck reconstruction, likely due to improved hemodynamics and decreased detrimental effects of fluid overload.
* There is no difference in pedicle thrombosis rate between end-to-end and end-to-side arterial or venous anastomosis, as shown in a recent meta-analysis.
* There is no proven difference in vessel patency rates between the internal jugular and external jugular systems.

Question 4

A 55-year-old man with a history of squamous cell carcinoma undergoes glossectomy and reconstruction with a free radial forearm flap. Intraoperatively, the patient experiences hypotension, and norepinephrine is administered. Which of the following is the most likely effect of this treatment on the outcome of the free flap?

A) Delayed wound healing
B) Microvascular thrombosis
C) Partial flap loss
D) Total flap loss
E) No effect

Answer 4

The correct response is Option E.

In patients undergoing free flap reconstruction, the use of vasopressors is typically avoided when possible because of concerns that vasoconstriction of the anastomoses will result in microvascular thrombosis. When feasible, intravenous fluid administration should be attempted first to address hypotension. However, numerous studies have examined the effect of intraoperative vasopressors on free flap reconstructions and have generally not found an increased risk of postoperative complications.

Question 5

An 18-year-old man is brought to the emergency department for thumb replantation. After an uneventful microsurgical anastomosis of the digital arteries and veins, papaverine is applied to the vessels. This medication works as a vasodilator through which of the following mechanisms?

A) Blocking calcium channels
B) Decreasing platelet aggregation
C) Inactivating thrombin and factor Xa
D) Inhibiting glycoprotein IIb/IIIa
E) Inhibiting phosphodiesterase

Answer 5

The correct response is Option E.

Papaverine is a phosphodiesterase inhibitor and is a commonly used vasodilating agent in microsurgery. It is administered as a liquid, directly to the adventitia of blood arteries, leading to vasodilation. The proposed mechanism of action of papaverine is by induced increase in cyclic adenosine monophosphate (AMP) levels, causing smooth muscle relaxation in the vessels. It is this mechanism of papaverine that has also led to its use for treatment of cardiac and neurovascular vasospasm.

Nifedipine is another common topical vasodilator, which is a calcium channel blocker. The remaining choices are all used to prevent clotting. Glycoprotein IIb/IIIa inhibitors are antiplatelet agents along with aspirin. Heparin inactivates thrombin and factor Xa through an antithrombin dependent mechanism.

Question 6

A 51-year-old woman is undergoing free flap breast reconstruction. Following anastomosis, the patient sustains a venous thrombotic event, and the decision is made to flush the flap with tissue plasminogen activator (tPA). Which of the following is the primary mechanism of action of tPA as used in this scenario?

A) Antithrombin III activation
B) Fibrinolysis
C) Inhibition of platelet aggregation
D) Protein C activation
E) Prothrombin cleavage

Answer 6

The correct response is Option B.

During microsurgical procedures, the normal clotting mechanism may disrupt flow at the anastomosis. Multiple medications are available to limit clotting following the failure of an anastomosis. However, only certain medications are fibrinolytic and actively break down clots, whereas others limit the formation of further clots. Tissue plasminogen activator (tPA) is one such fibrinolytic agent, which increases the cleavage of the zymogen, plasminogen, to its active form, plasmin. Plasmin is directly fibrinolytic.

Prothrombin cleavage, to form activated thrombin, is primarily facilitated by factor X and results in increased thrombogenesis. Aspirin is a common drug that inhibits platelet aggregation, but this does not have a fibrinolytic effect and is not the mechanism by which tPA functions. Antithrombin III activation is the main mechanism of action of heparin, which limits multiple points in the thrombosis pathway. This medication is not fibrinolytic. Activated protein C is a powerful anticoagulant that inhibits both factors V and VIII in the coagulation cascade. Use of a recombinant protein C has been used in septic shock, but its benefits remain controversial. tPA does not function by protein C activation.

Question 7

A 52-year-old man is admitted to the intensive care unit (ICU) for monitoring after debridement and anterolateral thigh free flap coverage of a traumatic lower extremity wound. He has a history of smoking and type 2 diabetes mellitus. Which of the following methods of free flap monitoring is associated with the highest salvage rate following microvascular compromise?

A) Clinical examination
B) Fluorescent angiography
C) Hand-held Doppler
D) Hyperspectral imaging
E) Near-infrared spectroscopy

Answer 7

Correct answer is option E

Question 8

A 48-year-old woman underwent delayed right breast reconstruction with a DIEP flap in which the internal mammary vessels were used as the recipient vessels. One day after surgery, the skin paddle of the free flap appears congested and Doppler examination of the perforator shows diminished arterial signal. Emergent operative exploration shows that the venous pedicle is thrombosed. Local infusion of which of the following agents is most effective in reestablishing circulation?

A ) Dextran

B ) Heparin

C ) Lidocaine

D ) Milrinone

E ) Tissue plasminogen activator

Answer 8

The correct response is Option E.

Tissue plasminogen activator (TPA) catalyzes the conversion of plasminogen to plasmin. Unlike the other previously used thrombolytic agents, urokinase and streptokinase, TPA is more specific because its efficacy is enhanced by the presence of fibrin. In theory, this results in fewer bleeding complications than the less specific thrombolytic agents, which are no longer available in many hospital pharmacies.

Most large free flap series report that venous thrombosis is more commonly encountered than arterial compromise. Free flap monitoring is the most important aspect of free flap care with a low threshold for reexploration critical to the success of free flap salvage. Once thrombosis of a vascular pedicle is observed and the anastomosis taken down, thrombectomy followed by thrombolysis can often result in flap salvage.

Intravenous dextran and heparin have been used for platelet inhibition and anticoagulation to improve free flap patency rates. Heparin irrigation locally is used to prepare vessels for anastomosis. Lidocaine and papaverine are used locally to vasodilate vessels. Milrinone is a systemic vasodilator but has not been shown to improve free flap patency.

Question 9

A 43-year-old woman is evaluated 6 hours after undergoing delayed breast reconstruction with deep inferior epigastric artery perforator flaps. On Doppler examination, arterial signals are present. Capillary refill time is 3 seconds on the right and 1 second on the left. A photograph is shown. Which of the following is the most appropriate management of the left breast?

A) Administration of systemic heparin
B) Administration of systemic tissue plasminogen activator
C) Application of leeches
D) Return to the operating room
E) Observation

Answer 9

The correct response is Option D.

The most appropriate management is exploration of the left flap to assess anastomotic patency and pedicle orientation. This flap is hyperemic with brisk capillary refill and present arterial signals. These are all signs of venous insufficiency, and emergent exploration is indicated to assess the vascular pedicle for kinking or thrombosis. Application of leeches will drain excess blood from the flap but will not address the underlying problem. Observation is unacceptable because there are signs of venous insufficiency, and this requires urgent intervention. Systemic heparin will prevent further clot formation but will not dissolve an acute clot or resolve pedicle kinking. Systemic tissue plasminogen activator would greatly increase this patient’s risk of bleeding. This agent should only be used within a flap.

Question 10

Question: A 62-year-old woman undergoes autologous breast reconstruction with a deep inferior epigastric perforator (DIEP) flap. On postoperative day 1, the flap shows signs of venous congestion with rapid capillary refill, darkening color, and increased turgor. She is taken emergently back to the operating room for exploration. Thrombus is identified at the venous anastomosis, which is revised. Despite re-establishing venous outflow, the flap remains congested with no improvement in capillary refill or color after 30 minutes. Which of the following pharmacologic agents is most appropriate to administer at this time to improve flap salvage?

a) Intravenous heparin
b) Topical papaverine
c) Intra-arterial alteplase
d) Oral apixaban
e) Subcutaneous argatroban

Answer 10

The correct answer is option C.

Rationale: In the scenario of a free flap with persistent congestion despite surgical revision of the anastomosis, the most likely cause is microvascular thrombosis within the flap’s distal vasculature. Alteplase, a recombinant tissue plasminogen activator, is the most appropriate thrombolytic agent for this situation. It works by converting plasminogen to plasmin, which lyses fibrin clots, thereby directly addressing the underlying microthrombi that surgical revision cannot reach. Heparin (option A) is an anticoagulant that prevents new clot formation but does not lyse existing thrombi. Papaverine (option B) is a vasodilator but does not address thrombosis. Apixaban (option D) and argatroban (option E) are anticoagulants that inhibit specific coagulation factors but lack the direct fibrinolytic action required to dissolve established microthrombi in a compromised flap.

References:
1. Barhoum F, Tschaikowsky K, Koch M, et al. Successful free flap salvage surgery with off-label use of alteplase: a case report, review of the literature and our free flap salvage algorithm. Int J Surg Case Rep. 2020;75:398-402. doi:10.1016/j.ijscr.2020.09.035
2. Wimbauer JM, Heinrich KM, Schwaiger K, et al. Anterograde injection of alteplase salvages deep inferior epigastric perforator flap in reconstructive breast surgery. Plast Reconstr Surg Glob Open. 2022;10(6):e4415. doi:10.1097/GOX.0000000000004415
3. Chang EI, Mehrara BJ, Festekjian JH, Da Lio AL, Crisera CA. Vascular complications and microvascular free flap salvage: the role of thrombolytic agents. Microsurgery. 2011;31(7):505-509. doi:10.1002/micr.20905

Question 11

A 64-year-old man presents with biopsy-proven squamous cell carcinoma of the tongue. Excision and reconstruction are planned. Allen tests on both sides show complete radial dominance, which is confirmed with non-invasive ultrasound. The plan is to proceed with an ulnar artery perforator flap from the non-dominant hand. When comparing the ulnar artery perforator flap to the radial forearm flap, which of the following is a major benefit of the ulnar artery flap?

A) It has a larger pedicle artery diameter
B) It has a longer pedicle length
C) It has a lower flap thrombosis rate
D) It is a better choice to incorporate bone as an osteocutaneous flap
E) It is less likely to result in tendon exposure at the donor site

Answer 11

The correct response is Option E.

On the basis of the more proximal location of the ulnar artery perforator flap, the donor site is able to be closed primarily more commonly than a radial forearm flap. When it is not closed primarily, typically the exposed deeper structures are muscle bellies rather than peritenon or tendon in the more distally located and radially positioned radial forearm flap. Another benefit is that the ulnar side of the arm is less hair-bearing and therefore may serve as better choice for intraoral reconstruction.

The other options are incorrect:
* The radial forearm flap has a longer pedicle.
* The ability to incorporate bone into the flap is better reported in an osteocutaneous radial forearm.
* The flap thrombosis rates have been shown to be equivalent
* The arterial diameter is similar or larger in the radial artery depending on the publication.

Question 12

During surgical exploration for a failing free flap, a surgeon revises the anastomosis, performs mechanical thrombectomy with a Fogarty catheter, and injects the flap with tissue plasminogen activator (tPA). Which of the following is the mechanism of action of tPA in fibrinolysis to increase flap survival and decrease fat necrosis?

A) Activates plasmin binding to fibrin
B) Converts plasminogen to plasmin
C) Forms a complex with plasminogen
D) Inhibits plasminogen activator inhibitor type-1

Answer 12

The correct response is Option B.

Tissue plasminogen activator (tPA) is a protease that cleaves a peptide bond in plasminogen, converting it to plasmin. tPA and urokinase have similar mechanisms in converting plasminogen to plasmin through cleavage. Plasmin is an enzyme that lyses the cross-linking between fibrin molecules and therefore breaks up clot formation. Streptokinase, which is derived from Streptococcus and is no longer commercially available in the United States, forms a complex with plasminogen, which then converts to plasmin. Plasminogen activator inhibitor type-1 (PAI-1) binds to tPA and inactivates it by forming a complex. An inhibitor of PAI-1 would facilitate the pathway of fibrinolysis, but tPA does not act in this manner.

Question 13

A 64-year-old man is evaluated 2 days after undergoing soft-tissue coverage of an open distal tibia fracture with a free rectus abdominis flap. On examination, the flap appears dark and swollen. Doppler signals are not present. The patient is brought to the operating room for reexploration, and thrombus is noted within the artery and vein. In addition to thrombectomy, which of the following is the most appropriate treatment to salvage this flap?

A) Aspirin
B) Intra-flap heparin
C) Intra-flap tissue plasminogen activator
D) Systemic dextran
E) Systemic urokinase

Answer 13

The correct response is Option C.

The most appropriate treatment in this patient is thrombectomy to restore flow within the artery and vein and administration of intra-flap tissue plasminogen activator (tPA) to dissolve clot formed within the flap.

Systemic urokinase will carry a high risk of bleeding from all surgical sites and is unlikely to dissolve clot in both the arterial and venous systems of the flap. Administration of intra-flap heparin will prevent further clot formation but will not dissolve the clot in the flap pedicle. Systemic dextran following thrombectomy might prevent clot formation and has mild thrombolytic properties, but it is not nearly as effective as tPA in lysing clot within the flap. Aspirin will potentially prevent further clot formation but has no thrombolytic properties and a slow onset of action.

Question 14

A 58-year-old man requires free tissue transfer for soft-tissue reconstruction of a head and neck defect. Which of the following surgical interventions is most likely to improve flap survival?

a. End-to-end anastomosis
b, Multiple perforators
c. Muscle flap only
d. Supercharging
e. Venous coupler

Answer 14

The correct response is Option E.

In a recent study of 2296 head and neck free tissue transfers, Chang et al demonstrated that the use of a venous coupler had a significantly decreased complication rate compared with performing a hand-sewn anastomosis. Other authors have demonstrated the benefits of venous couplers in head and neck free tissue reconstruction as well.
* Further analysis yielded no significance in survival rates with supercharging, use of multiple perforators, or orientation of anastomosis.
* They noted an increased risk for failure with muscle-only flaps compared with fasciocutaneous or osteocutaneous flaps.

Reference(s)

1. Chang EI. Zhang H, Liu J, Yu P, Skoracki RJ, Hanasono MM. Analysis of risk factors for flap loss and salvage in free flap head and neck reconstruction. Head Neck. 2016;38(suppl 1): E771-E775.
2. Kruse AL, Luebbers HT, Grätz KW, Obwegeser JA. Factors influencing survival of free‐flap in reconstruction for cancer of the head and neck: a literature review. Microsurgery. 2010;30(3):242-248.
3. Zhang T, Lubek J, Salama A, et al. Venous anastomoses using microvascular coupler in free flap head and neck reconstruction. J Oral Maxillofac Surg. 2012;70(4):992-996.

Question 15

A 16-year-old boy develops a severe left first web space contracture 8 months after undergoing skin grafting for a soft-tissue avulsion injury. At the time of contracture release, a pedicled fasciocutaneous flap is planned for coverage of the soft-tissue defect. On the basis of the preoperative markings for the flap in the photographs shown, the flap pedicle is located between which of the following muscles?

A) Brachioradialis and extensor carpi radialis longus
B) Brachioradialis and flexor carpi radialis
C) Extensor digiti minimi and extensor carpi ulnaris
D) Extensor digiti minimi and the extensor digitorum communis
E) Extensor digitorum communis and extensor carpi radialis brevis

Answer 15

The correct response is Option C.

The photograph illustrates the markings for a reverse posterior interosseous artery (PIA) flap. The reverse PIA flap is a thin, pliable fasciocutaneous flap that can provide reliable coverage of soft-tissue defects involving the dorsal hand, metacarpophalangeal joints, and first web space.
* Some surgeons report success using this flap for coverage of palmar wounds and soft-tissue injuries of the thumb as well.
* Perfusion of the flap is based on retrograde flow through the posterior interosseous artery, which sends septocutaneous perforators to the overlying skin.
* The axis of the flap can be marked corresponding to a line between the lateral epicondyle and the radial aspect of the ulnar styloid.
* The location of the posterior interosseous artery pedicle is between the extensor digiti minimi and the extensor carpi ulnaris.
* Retrograde perfusion through the flap relies on an intact communication of the PIA with the dorsal branch of the anterior interosseous artery, which is present in nearly all cases.
* This anastomosis is located 2 cm proximal to the radial aspect of the ulnar styloid; therefore, it corresponds to the pivot point of the flap.
* One of the advantages of this flap is that it does not require sacrifice of a major arterial source of blood to the hand.

The other responses do not correctly describe the location of the PIA. Of note, the interval between the brachioradialis and the flexor carpi radialis represents the location of the radial artery fasciocutaneous flap pedicle.

Question 16

A 154-lb (70-kg), 54-year-old man is evaluated because of oliguria and malaise 2 days after he underwent subtotal glossectomy with reconstruction with a free radial forearm flap. History includes chronic renal insufficiency (baseline creatinine concentration was 1.8 mg/dL and is now 3.3 mg/dL). After the procedure, administration of aspirin 81 mg by mouth daily and dextran 40 at 20 mL/hr was initiated. Temperature is 99.9°F (37.7°C), heart rate is 88 bpm, respiratory rate is 20/min, and blood pressure is 110/60 mmHg. On examination, the flap is pink and soft. Urine output is 15 mL/hr. Which of the following is the most appropriate management?

A) Administer a 500-mL bolus of Ringer’s lactate
B) Administer a diuretic
C) Administer dopamine
D) Discontinue dextran
E) Return to the operating room for neck exploration

Answer 16

The correct response is Option D.

This patient is presenting with an uncommon but major complication of dextran administration, specifically acute renal failure, thought to be caused by either direct toxic effect on the tubules and glomeruli or intraluminal hyperviscosity. Surgeons who employ its use must be aware of this potential side effect as well as other serious side effects such as anaphylaxis, volume overload, pulmonary edema, cerebral edema, and platelet dysfunction. At-risk patients include those with a history of diabetes, renal insufficiency, or vascular disorders. It is recommended to avoid dextran in patients with chronic renal insufficiency for this reason.

This head and neck cancer patient also was on aspirin for anticoagulation. It should be noted that a prospective randomized study of dextran- and aspirin-related complications in 100 patients undergoing microsurgical flap reconstruction for head and neck malignancy demonstrated that aspirin and dextran were actually equally efficacious in preventing flap failure. However, despite this, it was demonstrated that patients on dextran had a 3.9- to 7.2-fold increased relative risk of systemic complications after 48 and 120 hours of dextran infusion, respectively. Given this, aspirin should be used over dextran if anticoagulation is desired.

A 500-mL bolus of Ringer’s lactate would not be warranted because it contains potassium, which would already be elevated in acute-on-chronic renal failure and would exacerbate the hyperkalemia.

Administration of a diuretic would not be warranted in this case because there is no evidence of fluid retention.

Low-dose dopamine is commonly administered to critically ill patients in the belief that it reduces risk of renal failure by increasing renal blood flow. This has never been definitely proven, however, in multiple trials. This patient has chronic renal insufficiency exacerbated by dextran administration. Low-dose dopamine has not been demonstrated to confer any benefit in this clinical scenario.

If a hematoma, arterial insufficiency, or venous congestion were suspected, returning to the operating room would be the next most appropriate step. As this is not the working diagnosis, this would be inappropriate.

Question 17

A 39-year-old woman successfully undergoes immediate bilateral breast reconstruction with coverage with free deep inferior epigastric artery perforator free flaps. Postoperative flap monitoring is planned. Vascular compromise is most likely to occur during which of the following time periods postoperatively?

A) 0–1 days
B) 2–3 days
C) 4–5 days
D) 6–7 days
E) 8–9 days

Answer 17

The correct response is Option A.

Free flaps can be monitored by several different modalities in the postoperative period. The main reason for monitoring free flaps postoperatively is to detect vascular complications in a timely fashion, before permanent injury to the flap occurs, and to maximize the possibility of flap salvage. Reviews of large consecutive series of free flaps indicate that the most likely time period for a vascular compromise is early on, usually within the first 24 hours after successful transfer from the operating room. Therefore, postoperative monitoring protocols should be designed to closely follow flap perfusion during this period of time. Vascular events leading to issues with flap perfusion do occur at later times, but such events are generally infrequent and more difficult to salvage.

Question 18

When compared with liberal fluid administration for pressure support, vasopressors have which of the following effects on the overall success of deep inferior epigastric artery perforator (DIEP) flap breast reconstruction?

A) Delay in postoperative patient mobilization
B) Increase in the risk of total or partial flap loss
C) Increase in the risk of venous congestion
D) No difference in the rate of pedicle thrombosis

Answer 18

The correct response is Option D.

Traditionally, the use of vasopressors in free flap surgery has been avoided due to the presumed risk of pedicle vasospasm leading to flap failure. However, recent studies have indicated that this assumption may not be accurate. Additionally, the fear of vasopressor-associated flap complications has led to the practice of liberal fluid administration, which has failed to demonstrate any benefits when compared with a fluid-restrictive vasopressor strategy. Multiple prospective interventional trials and meta-analyses have reported that the use of vasopressors results in no detectable negative impact on flap survival or overall patient outcome. Specifically, intraoperative use of phenylephrine, ephedrine, or calcium chloride as an intravenous bolus does not increase in the risk of total or partial flap loss, delay postoperative patient mobilization or increase the risk of venous congestion. The use of vasopressors in free flap surgery is not contraindicated.

Question 19

A 45-year-old woman with a history of systemic lupus erythematosus requires a free flap reconstruction of her right lower extremity. She has never had a thrombotic event. She is on corticosteroids for collagen vascular disease. Which of the following perioperative measures is most appropriate?

A) Intraoperative and postoperative anticoagulation
B) Intraoperative anticoagulation alone
C) Preoperative and postoperative aspirin therapy
D) Preoperative hypercoagulability workup
E) Preoperative vitamin A therapy

Answer 19

The correct response is Option D.

The most appropriate management would be to get a formal hematology consult and anticoagulation workup prior to surgery. Collagen vascular diseases target connective tissues and have multiorgan manifestations secondary to deposition of antigen-antibody complexes. Affected patients are intrinsically prone to thrombosis from the inflammation of the connective tissue disorder itself and the synergistic effect of having increased chances of having concurrent hypercoagulability risk factors such as anticardiolipin or lupus anticoagulant.

Therefore, in this patient population with the threat of vascular compromise, it is most prudent to perform preoperative hematologic evaluation, especially if they exhibit a history of previous clotting and flap failure. As a more prudent measure, all of these patients should have a detailed hypercoagulability evaluation, including a detailed history and hematology consultation with a laboratory panel looking for hypercoagulability factors. If positive, steps should be taken perioperatively to decrease the risk of thrombotic complications, and chemical anticoagulation should be considered, but if negative with no history of previous thrombotic complications, then no added chemical anticoagulation is needed. Studies have not shown an increase in thrombotic flap failures in such patients, despite their intrinsic risk of thrombosis.

Aspirin therapy has not been shown to decrease flap loss rates. Vitamin A is indicated in this patient, not to decrease thrombotic flap loss rates, but rather to counteract the immunosuppressive medications.

Question 20

A 38-year-old woman undergoes bilateral breast reconstruction using microvascular free tissue transfer from the abdomen. The patient is evaluated 8 hours later because the right breast flap appears mottled and engorged. Administration of which of the following is CONTRAINDICATED in this patient?

A) Heparin irrigation to the flap vessels
B) Papaverine to the flap vessels
C) Systemic heparin
D) Systemic thrombolytics
E) Thrombolytics to the flap vessels

Answer 20

The correct response is Option D.

Heparin may be used locally or systemically during flap salvage attempts in an effort to encourage further propagation of clot and irrigate existing thrombus. Papaverine and thrombolytic agents are used locally on or within the flap vessels, but not systemically due to concern for systemic complications.

Question 21

A 68-year-old woman undergoes partial glossectomy, resection of the anterior floor of the mouth, and bilateral modified radical neck dissection to treat squamous cell carcinoma of the ventral tongue and anterior floor of the mouth. The resulting defect is reconstructed with a 5 × 6 cm radial forearm free flap. The free flap is anastomosed to the left facial artery and left internal jugular vein. The forearm donor site is reconstructed with a split-thickness skin graft from the thigh. In addition to Current Procedural Terminology (CPT) code 15758 (free fascial flap with microvascular anastomosis), which of the following is most appropriate?

(A) 13152: Complex repair, mouth, 2.6–7.5 cm

(B) 15100: Split-thickness skin graft, arm; less than 100 cm²

(C) 35761: Exploration of vessels without repair

(D) 40840: Anterior vestibuloplasty

(E) 69990: Use of operating microscope

Answer 21

The correct response is Option B.

Free flap procedure codes are global and include the following:

• Elevation of the flap
• Isolation of donor flap vessels used for microvascular anastomosis
• Transfer of the flap to the recipient site
• Isolation of the recipient vessels used for microvascular anastomosis
• Microvascular anastomosis of one artery
• Microvascular anastomosis of one or two veins
• Inset of the flap at the recipient site
• Primary closure of the donor site

If a free flap procedure involves components beyond these global elements, it is appropriate to report them as additional codes, as they are considered over and above the standard procedure. These may include:

• Vein grafts
• Neurorrhaphy
• Nerve grafts
• Skin grafts (donor site or recipient site)
• Closure of the donor site that is more extensive than primary closure
• Wound preparation of the recipient site

Additionally, CPT 69990 (use of the operating microscope) is included within the free flap codes and should not be reported separately.

Question 22

A 48-year-old woman undergoes delayed reconstruction of the right breast with a deep inferior epigastric artery perforator (DIEP) flap. Medical history includes failed tissue expander–based right breast reconstruction because of infection 5 months ago. On postoperative day 5, the patient comes to the emergency department with a swollen, purple flap, which she noticed after showering. The venous anastomosis is revised and flap thrombolysis is performed with tissue plasminogen activator, successfully restoring flap perfusion. Which of the following clinical factors is LEAST likely to increase this patient’s risk of thrombotic flap complications?

A) Antiphospholipid syndrome
B) Antithrombin deficiency
C) BRCA1 or BRCA2 genetic mutation
D) Factor V Leiden mutation
E) Perioperative tamoxifen therapy

Answer 22

The correct response is Option C.

This patient has developed a late venous thrombosis and may be predisposed to a hypercoagulable state. The BRCA1 and BRCA2 genes are tumor suppressor genes involved in DNA repair. Mutations in these genes dramatically increase a woman’s risk of developing breast and ovarian cancer over her lifetime, and are the most common cause of hereditary forms of breast and ovarian cancer. But BRCA genetic mutations do not appear to increase the risk of blood clots over baseline and would be unlikely to contribute to this patient’s condition.

The other options are incorrect because each carries higher than average risk of blood clots. Perioperative tamoxifen therapy increases the risk of thromboembolic events in general and for flap complications and flap loss during microvascular breast reconstruction in particular. Tamoxifen is an estrogen receptor antagonist and is used both to treat and prevent breast cancer. Some authors recommend cessation of tamoxifen at least 14 days prior to microvascular breast reconstruction to minimize thrombosis risk.

Factor V is a protein involved in the coagulation cascade. Factor V Leiden mutation is an inherited condition that confers a hypercoagulable state, increasing the risk of thrombotic complications.

Antithrombin III is a protein similarly involved in anticoagulation. Deficiency may be either inherited or acquired, and it confers an increased risk of venous thrombotic events.

Antiphospholipid syndrome is an acquired autoimmune disorder which also confers a hypercoagulable state. Venous or arterial thrombosis, as well as fetal loss, are characteristic of this disorder. Some patients will have an associated autoimmune disease, such as systemic lupus erythematosus.

Question 23

A healthy 55-year-old woman underwent bilateral breast reconstruction with free deep inferior epigastric perforator (DIEP) flaps. Tissue oximetry-based flap monitoring is used. Which of the following is the main advantage of this technique over a hand-held Doppler with clinical assessment?

A) Direct blood flow measurement
B) Ease of use
C) Improved flap salvage rate
D) Less expensive modality
E) Operator must be bedside

Answer 23

The correct response is Option C.

The main advantage of using tissue oximetry-based monitoring is that it improves flap salvage rates. Tissue oximetry, or near-infrared spectroscopy, is increasing in popularity among microsurgeons and has been shown to be the third most commonly used technique after clinical examination and hand-held Doppler. Rather than directly monitoring flow, tissue oximetry uses infrared light to measure the relative concentrations of oxygenated and deoxygenated hemoglobin. By measuring oxygenation rather than flow, the probe is relatively unaffected by movement artifacts. Recent studies emphasize its value in identifying flap compromise before clinical signs of arterial or venous thrombosis. In a 2011 study, Lin et al. reported an increased flap salvage rate at their institution with the use of near-infrared spectroscopy, from 57.7 to 93.8% (p = 0.015), despite no significant increase in their rate of reexploration, attributing this improvement to earlier recognition of vascular compromise. In a recent small prospective cohort study, Lohman et al. followed 38 free flaps with physical examination and five technologies, including handheld Doppler, implantable Doppler, and tissue oximetry. Although primarily a descriptive study, they concluded that tissue oximetry was the first technology to record signs of flap compromise.

Though tissue oximetry-based flap monitoring is easy to use, so is a hand-held Doppler, so that is not the main advantage. It does have a higher financial investment to buy the system, but over time it could be argued it more than pays for itself given the improved flap salvage rates. Unlike the hand-held Doppler, this modality has a continuous read on the monitor, the examiner need not be in the presence of the patient, and, in fact, can visualize the readings on a smart phone through an app.

Question 24

A 53-year-old woman is evaluated in the recovery room during the first hour after microsurgical breast reconstruction with a free flap. On examination, the skin paddle appears bluish with a rapid capillary refill. There is a strong cutaneous arterial Doppler signal. Which of the following actions is most appropriate to increase the likelihood of flap salvage in this patient?

A ) Administration of systemic heparin
B ) Administration of systemic tissue plasminogen activator
C ) Application of a body warmer
D ) Application of leeches
E ) Emergent exploration

Answer 24

The correct response is Option E.

The patient has a venous thrombosis. The success of free tissue transfer is greater than 90% at most major microsurgical centers. Between 5 to 25% of free flaps require reexploration due to vessel compromise, as venous congestion is more common than arterial compromise. The flap salvage rate is influenced by the timing of reexploration across multiple studies. In one study, flaps that were reexplored within 5 hours had a higher flap salvage rate.

All studies point to early recognition of flap compromise as important and rapid reexploration as the most important factor to improve flap salvage. Administration of heparin, use of thrombolytics, and application of leeches will not increase the salvage rate in the scenario described. Increasing the patient’s temperature also does not improve flap salvage.

Question 25

A 16-year-old boy has right hemifacial hypoplasia secondary to radiation therapy of an orbital sarcoma when he was an infant. Right hemifacial soft-tissue augmentation with a partially buried omental free flap is performed. Photographs are shown. Which of the following is the most sensitive method of monitoring perfusion of this flap and detecting early anastomotic thrombosis? (A) Clinical observation of the flap (B) Bedside duplex ultrasonography of the gastroepiploic vessels (C) Quantitative fluorometry of the flap with Wood’s lamp (D) External Doppler probe monitoring of the gastroepiploic vessels (E) Implantable Doppler monitoring of the gastroepiploic vein

Answer 25

The correct response is Option E. Buried free flaps and flaps without a cutaneous component can be difficult to monitor regarding postoperative flap perfusion. Early detection of anastomotic thrombosis is critical in successful salvage and revision of the failing free flap. Although color, temperature, and turgor can be used to monitor free flap perfusion, the omentum does not contain a skin paddle to help with clinical examination. An external handheld Doppler probe can identify arterial and venous signals, but correlation with the actual pedicle can be difficult to determine. Duplex ultrasound examination of the neck provides a great deal of information, such as direction of flow, alterations in flap resistance, and increased pedicle turbulence, but such imaging is not immediately available and requires the expertise of a vascular technologist. Injection with fluorescein and observation with a Wood=s lamp can assist with the qualitative assessment of flap perfusion if a skin paddle exists and can be monitored. Implantable venous Doppler monitoring will identify problems with both the arterial and venous pedicle. A recent clinical report of 260 vascular microanastomoses with an implantable Doppler probe yielded six false-positive results and eight true-positive results. The overall free flap success rate was 99%; the reexploration rate was 8% and the salvage rate was 83%, partly due to the early detection of anastomotic thrombosis. Doppler ultrasonography has been used to document changes in arterial blood flow after free tissue reconstruction in reconstruction of the head and neck. This modality can be helpful as an adjunctive tool in assessing flap perfusion but currently does not provide cost-efficient, continuous monitoring necessary to detect early anastomotic changes. The photograph below shows the patient after successful reconstruction of hemifacial hypoplasia and after free tissue transfer of the omentum and secondary facelift and browlift, with intact facial nerve function.

Question 26

A 57-year-old woman undergoes microsurgical breast reconstruction using a muscle-sparing transverse rectus abdominis musculocutaneous (MS-TRAM) flap. Near-infrared spectroscopy (NIRS) is used to monitor the flap in the postoperative setting. NIRS measures which of the following parameters? A) Arterial oxygen saturation (SaO2) B) Mixed venous oxygen saturation (SvO2) C) Partial pressure of oxygen (PaO2) D) Peripheral oxygen saturation (SpO2) E) Tissue oxygen saturation (StO2)

Answer 26

The correct response is Option E. Near-infrared spectroscopy (NIRS) is a noninvasive modality that allows continuous monitoring of tissue oxygenation and perfusion. It measures relative changes in the concentration of oxygenated and deoxygenated hemoglobin. Tissue oxygen saturation (StO2) is the percentage of hemoglobin in tissue that is oxygenated. Since StO2 measures oxygen saturation in the vascular bed of tissue, it measures both venous and arterial saturation and, thus, reflects both oxygen delivery and consumption. This provides a good surrogate for tissue perfusion. Peripheral capillary oxygen saturation (SpO2), measured by pulse oximetry, measures arterial oxygen saturation, which may not reflect perfusion. Arterial (SaO2) and mixed venous oxygen saturation (SvO2) as well as the partial pressure of oxygen (PaO2) are measured directly from blood and are indicative of systemic rather than local tissue oxygenation.

Question 27

A 69-year-old woman with breast cancer undergoes bilateral breast reconstruction using free deep inferior epigastric perforator (DIEP) flaps. During surgery, she has onset of hypotension that is unresponsive to standard crystalloid and colloid solutions. The anesthesia team elects to administer norepinephrine to correct her blood pressure. Which of the following flap-related outcomes is most likely? A) Flap loss B) Hematoma C) Reoperation D) Wound dehiscence E) No effect

Answer 27

The correct response is Option E. There are no known increased flap complications with use of vasopressive medications. In fact, one study has shown decreased intraoperative flap complications compared with controls with the use of ephedrine. Traditional dogma is that vasopressors should be avoided during free tissue transfer due to concern that vasoconstriction or thrombosis could occur, resulting in compromised flap perfusion and subsequent flap loss. Most authors argue for standard intravenous fluid replacement or adjustment of anesthetic medications when feasible to first address the hypotension. However, numerous articles have suggested the safety of vasopressive medications in the setting of free tissue transfer. In fact, there are studies correlating excess intravenous fluid administration with increasing complication rates in free transverse rectus abdominis musculocutaneous (TRAM) flaps. As such, vasopressive medications should be considered when standard anti-hypotensive remedies have failed. The original concern about vasoconstriction of the flap vessels with systemic vasopressor administration and resultant decreased perfusion or thrombosis has largely been disproven. This occurs likely because of sympathetic denervation due to flap transfer, sympathectomy with adventitial removal, and topical use of vasodilators, such as papaverine or nicardipine. Additionally, any vasoconstrictive effect on the flap vessels is more than overcome by increased flap perfusion caused by an elevated blood pressure.

Question 28

A 58-year-old man requires free tissue transfer for soft-tissue reconstruction of a head and neck defect. Which of the following surgical interventions is most likely to improve flap survival? A) End-to-end anastomosis B) Multiple perforators C) Muscle flap only D) Supercharging E) Venous coupler

Answer 28

The correct response is Option E. In a recent study of 2296 head and neck free tissue transfers, Chang et al demonstrated that the use of a venous coupler had a significantly decreased complication rate compared with performing a hand-sewn anastomosis. Further analysis yielded no significance in survival rates with supercharging, use of multiple perforators, or orientation of anastomosis. They noted an increased risk for failure with muscle-only flaps compared with fasciocutaneous or osteocutaneous flaps. Other authors have demonstrated the benefits of venous couplers in head and neck free tissue reconstruction as well.

Question 29

A 28-year-old woman with a traumatic lower extremity wound undergoes free tissue transfer reconstruction. Venous anastomosis is completed with a 3-mm coupler device. Which of the following is the proven benefit of using a coupler device? A) Decreased anastomosis time B) Decreased thrombosis C) Decreased twisting of vessels D) Ease of use E) Improved kinking

Answer 29

The correct response is Option A. The only reliable information gleaned from available data is that the use of a coupler for venous anastomoses does decrease the operative time in performing the vascular technique. Most studies point to an improved patency rate in venous anastomoses as well, but this remains open to interpretation. All the available published data point to one factor with the greatest influence on patency rates: adherence to sound and well-established microvascular technique principles. There is no proof that end-to end, end-to-side, running or interrupted, eversion or mattress, etc., has any superiority over other techniques in patency rates. At the present time there are no adequate reliable data regarding use of sutureless techniques and their long-term outcomes in a clinical setting. Other options have not been proven as benefits of a coupler device over other techniques.

Question 30

A 50-year-old woman undergoes reconstruction of a postburn neck contracture with a free anterolateral thigh flap. On postoperative day 2, the flap is explored for vascular compromise and is successfully salvaged. On postoperative day 3, the flap suffers vascular compromise and is explored again. During the operation, the anastomoses are revised using vein grafts. Which of the following factors is most strongly associated with unsuccessful flap salvage in this patient? ## Footnote A) Anatomic site B) Multiple reexplorations C) No use of anticoagulants D) No use of thrombolytic agents E) Postoperative day of initial reexploration

Answer 30

The correct response is Option B. ## Footnote The need for multiple reexplorations has been found to be a predictor for unsuccessful free flap salvage. Free flap reconstruction of the breast has been associated with higher flap survival rates than other anatomic areas, such as the head and neck and extremities. Higher free flap survival rates have been observed when vascular compromise occurs earlier in the postoperative period (postoperative days 0 to 2) compared with later. Anticoagulants, such as heparin, are sometimes used during free flap salvage attempts. However, their use has not been found to impact flap survivability. The same has been found with regard to thrombolytic agents, such as tissue plasminogen activator.

Question 31

In the treatment of microsurgical vasospasm, topical papaverine is commonly utilized. What is the primary mechanism of action of papaverine? A. Phosphodiesterase inhibitor B. Calcium channel blocker C. Alpha-adrenergic receptor antagonist D. Unknown E. Prostacyclin analogue

Answer 31

Correct answer is option A. The mechanism of action of papaverine is a phosphodiesterase inhibitor. Papaverine is one of the most commonly used antispasmodic medications during microsurgical cases. It belongs to a class of drugs known as phosphodiesterase inhibitors. The usual concentration used is 30 mg/dL. Phosphodiesterase inhibitors antagonize phosphodiesterase, the function of which is to inactivate cyclic guanosine monophosphate. Increased concentration of this second messenger within vascular smooth muscle cells inhibits the action of myosin light chain kinase, ultimately resulting in relaxation and vasodilation. Calcium channel antagonism may be an additional mechanism of vasodilation. It acts within 1 to 5 minutes. Topical nicardipine (1.5 mg/25 mL) has been used as a spasmolytic agent too. It is a calcium channel blocker. Topical 2% lidocaine (20 mg/mL) is another topical agent used, and though its exact mechanism of action for this activity is unknown as of yet, it is a direct smooth muscle spasmolytic. Other drugs that cause vasodilation, such as phentolamine, act as antagonists on the vascular smooth muscle alpha-adrenergic receptors. A demonstrated no increased microvascular risks in allowing patients to continue their aromatase inhibitors. 1. Vargas CR, Iorio ML, Lee BT. A systematic review of topical vasodilators for the treatment of intraoperative vasospasm in reconstructive microsurgery. Plast Reconstr Surg. 2015;136(2):411-422. doi:10.1097/PRS.0000000000001431 2. Ricci JA, Koolen PG, Shah J, Tobias AM, Lee BT, Lin SJ. Comparing the outcomes of different agents to treat vasospasm at microsurgical anastomosis during the papaverine shortage. Plast Reconstr Surg. 2016;138(3):401e-408e. doi:10.1097/PRS.0000000000002430 3. Rinkinen J, Halvorson EG. Topical vasodilators in microsurgery: what is the evidence? J Reconstr Microsurg. 2017;33(1):1-

Question 32

A 48-year-old woman had delayed microsurgical breast reconstruction. Two hours after surgery, the patient has swelling of the breast and increased drain output. On examination at the bedside, the flap appears purple with capillary refill time of 1 second. Heart rate is 70 bpm, blood pressure is 110/60 mmHg, and most recent hematocrit is 28%. An arterial signal is identified in the skin paddle with a handheld Doppler. Which of the following is the most appropriate next step in management? A) Application of nitroglycerin paste B) Operative reexploration C) Pinprick of the flap D) Placement of leeches E) Streptokinase therapy

Answer 32

The correct response is Option B. The patient described has venous insufficiency after microsurgery and the next step in management is emergent reexploration in the operating room. Multiple studies confirm that earlier reexploration improves flap salvage rates. The rate of reexploration ranges from 6 to 14%; in these cases, the flap salvage rate ranges from 36 to 94%. Time of return to the operating room is associated with flap salvage. The majority of microvascular complications occur in the first 48 hours, and the majority of these complications are due to venous thrombosis. Common presenting signs include a purple or blue skin discoloration, brisk capillary refill, edema, oozing, or hematoma. Release of sutures and pinprick of a flap and application of nitroglycerin paste can improve venous congestion in pedicled flaps, but do not obviate the need for reexploration in a microsurgical flap. Placement of leeches is a salvage option and often used when intraoperative maneuvers are unsuccessful. Streptokinase has been described for use in cases where a clot is found within the vascular system, but this should be reserved for use during reexploration, not before.

Question 33

A 60-year-old man with a history of smoking requires near total mandibular reconstruction with a free vascularized fibula. During dissection of the flap, the surgeon should encounter which of the following muscles prior to incising the interosseous septum from an anterior approach? A) Extensor hallucis longus B) Flexor hallucis longus C) Soleus D) Tibialis anterior E) Tibialis posterior

Answer 33

The correct response is Option A. Just prior to incising the interosseous septum, the surgeon would be in the anterior compartment of the leg. The muscle lying just anterior to that septum would be the extensor hallucis longus. The tibialis anterior is medial to the plane of dissection for a fibula flap. The flexor hallucis longus and tibialis posterior are located in the deep posterior compartment while the peroneus brevis is found in the lateral compartment. The soleus is located in the superficial posterior compartment.

Question 34

A 59-year-old right-hand–dominant woman with type 2 diabetes and coronary artery disease undergoes a radial forearm adipofascial perforator flap for palmar contracture release and resurfacing to treat a severely contracted burn scar. Which of the following characteristics is a benefit of this flap choice? A) It can be designed as a myofascial flap B) It has a distal pivot point at the radial styloid C) It has robust, 1.5- to 2-mm perforators D) It is a reliably thin, pliable flap E) It is a sensate flap

Answer 34

The correct response is Option D. The radial forearm adipofascial perforator flap is a reliably thin, pliable flap. As such, the flap is a good option for reconstruction of the distal upper extremity when a thin flap is desired, such as for palmar/dorsal hand coverage, revision carpal tunnel/median nerve surgery, and radioulnar synostosis surgery. Other advantages of this flap include avoiding the need to sacrifice the radial artery, shorter operative time compared with free tissue transfer, and low donor morbidity. The vascular supply to the flap is a series of roughly 10 small 0.3- to 0.9-mm septocutaneous radial artery perforators found in the septum between the flexor carpi radialis and the brachioradialis tendons. The most distal perforator arises approximately 1.5 cm proximal to the radial styloid. Therefore, the pivot point for this flap is safely 4 cm proximal to the radial styloid. Since the flap is supplied by the adipofascial perforating vessels superficial to the radial artery, the inclusion of muscle in the flap design is not reliable. During flap elevation, the superficial radial nerve and lateral antebrachial cutaneous nerves are identified and preserved, but are not included into the flap.

Question 35

A 42-year-old woman presents with a Gustilo Type IIIB open tibial fracture with a large area of soft-tissue loss. Rectus abdominis free flap reconstruction is planned. CT angiography shows a patent posterior tibial artery; however, the peroneal and anterior tibial vessels are not suitable for use because they do not traverse past the level of the fracture. Compared with end-to-end anastomosis, which of the following is the main advantage to using end-to-side arterial anastomosis in this scenario? A) Allows anastomosis in zone of injury B) Decreases ischemia time C) Facilitates visualization D) Minimizes kinking of vessels E) Preserves distal blood supply

Answer 35

The correct response is Option E. ## Footnote In this clinical scenario, the patient has a one-vessel runoff in the lower extremity. Preservation of the distal blood supply is critical and that is the main advantage of an end-to-side anastomosis. In general, an end-to-side anastomosis is more technically difficult with longer ischemia time. Kinking of the vessels is still possible with end-to-side anastomosis and therefore is not a major advantage to this technique. There is no added benefit in visualizing the vessel and it is generally more difficult to see the entire vessel compared to an end-to-end anastomosis. This technique does not preferentially allow for an anastomosis in the zone of injury. Finally, it is controversial whether or not the flap survival rate is different between end-to-side and end-to-end anastomosis. An early paper by Godina shows an advantage for end-to-side; however, many subsequent papers have contradicted these results.

Question 36

A 47-year-old woman comes to the office for elective thinning of a free flap to the forearm 6 months after undergoing an uncomplicated sarcoma reconstruction. During the procedure, a vascular clamp retained from the initial procedure is uncovered. The clamp did not adversely affect the patient's outcome or the need for the present operation. Which of the following is the most appropriate course of action? A ) Inform the patient only, as risk management notification is not required because of lack of harm B ) No action is required because there was no injury or deviation from standards C ) Notify the risk management department and inform the patient D ) Notify the risk management department only, as patient notification is not required because of lack of harm

Answer 36

The correct response is Option C. The incidents of retained foreign bodies after surgery are estimated to be between 1/8000 to 1/18,000 operations for a mid- to large-sized hospital that performs 10,000 cases per year. This would amount to approximately one case per year. The most commonly retained foreign body is a surgical sponge or laparotomy pad. The most common risk factors examined are emergency operation, unexpected change in the operation, more than one surgical team involved, change in nursing staff during the procedure, high BMI, volume of blood loss, female gender, and surgical counts. The most significant risk factors are emergency surgery, unplanned change in operation, and increased BMI. Cases of retained foreign bodies after surgical procedures often enter into the legal realm. Proof of negligence is not required when a foreign body is erroneously left in a patient. The doctrine of res ipsa loquitur, or €œthe thing speaks for itself, € applies when a foreign body is encountered that is asymptomatic. The most important aspect is communication with the patient. Often, open lines of communication can prevent these incidents from becoming legal malpractice cases. It is important to have communication with the hospital risk management officials as well.

Question 37

Which of the following is NOT a proposed mechanism of action of dextran used in microsurgery? (A) Decreased factor VIII and von Willebrand factor (B) Increased alpha-2 antiplasmin (C) Increased electronegativity (D) Structural modification of fibrin (E) Volume expansion

Answer 37

The correct response is Option B. Although the benefits of dextran 40 used during microsurgery are controversial, this agent is still used frequently. Dextran decreases factor VIII and von Willebrand factor, resulting in a decrease in platelet function. It is thought to increase the electronegativity of platelets in the endothelium, which prevents platelet aggregation, and is also thought to modify the structure of fibrin, increasing its susceptibility to degradation. It alters the rheologic properties of blood and acts as a volume expander. Dextran inhibits, not increases, alpha-2 antiplasmin, leading to a subsequent activation of plasminogen. Because dextran has the potential for antigenicity, a test dose of 20 mL of 150 mg/mL solution is typically administered one to two minutes before infusion. **Reasons for decreased dextran use in clinical practice**: Although dextran is still FDA-approved, its use in current clinical practice has significantly decreased, largely replaced by safer and more effective alternatives like crystalloids and albumin. Here's why dextran is not currently used as frequently: Risk of severe adverse reactions: Dextran can cause serious allergic and anaphylactic reactions, including fatalities. Even after a negative test dose, individuals may still experience severe or fatal reactions. Interference with blood compatibility testing: Dextran can interfere with blood typing and cross-matching procedures. Potential for kidney damage: Dextran use, particularly in high doses or in patients with pre-existing kidney conditions, has been associated with acute renal failure due to the risk of tubular plugging. Availability of safer and more effective alternatives: Crystalloids and albumin are now the preferred choices for plasma volume expansion due to their improved safety profiles and efficacy.

Question 38

Clinically proven effects of dextran include which of the following? (A) Improved flap survival (B) Increased systemic complications (C) Ischemia reperfusion protection (D) Leukopenia

Answer 38

The correct response is Option B. Low-molecular-weight dextran is a polysaccharide produced by bacteria that is frequently used as an antithrombotic agent in microsurgical procedures. It is believed to have multiple actions, including decreasing platelet aggregation, increasing fibrin degradation, inhibiting alpha-2 plasmin, decreasing factor VII and von Willebrand factor and thereby altering platelet function, as well as acting as a volume expander. Anaphylactic reactions to this substance can occur, and many practitioners recommend administering a test dose of the hapten dextran one hour before starting infusion. However, severe reactions are uncommon and generally are noted early in its administration. Cases of pulmonary edema and acute respiratory distress syndrome have been reported. Some animal experiments and a few retrospective nonrandomized studies have shown improved patency rates of anastomoses in free flaps; however, conflicting data have resulted in a lack of consensus among microsurgeons. An overall increase in systemic complications (pulmonary, cardiac, anaphylactic) has been demonstrated with dextran compared with aspirin only. Improved flap survival, leukopenia, or ischemia reperfusion protection has not been demonstrated with dextran.

Question 39

A 76-year-old man undergoes radical resection of the floor of the mouth and reconstruction with a free tissue transfer. Which of the following is an absolute contraindication for the use of the microvascular arterial anastomotic coupler? A ) Age of the patient B ) Atherosclerotic calcification C ) History of radiation therapy D ) Vessel-size mismatch

Answer 39

The correct response is Option B. The mechanical device used most commonly in the clinical management of microvascular anastomoses is the coupler. It is used commonly in venous anastomoses, and some centers also use it in arterial anastomoses. The ring-pin technique involves passing each end of the vessels to be anastomosed through a ring that has matching sets of pins and holes. The vessel ends are then everted over the corresponding pins, and a device operated by a thumb nut then pushes the two rings together. Theoretically, this produces a "perfect" anastomosis, with total eversion of the edges and exact intima-to-intima contact. This instrument has been shown to provide rapid microvascular repairs in experienced hands, with published reports of 2 to 3 minutes per anastomosis. Stiff, nonpliable vessels resulting from atherosclerotic calcification should not be anastomosed using the coupler system because the technique requires pliable vessels being draped over the pins. Stiff vessels will not allow for this, and a poor technical outcome will result. There have been reports of successful end-to-end, as well as end-to-side, venous anastomoses performed with the coupler. Age, by itself, has not been proven to be a contraindication to microvascular surgery and, therefore, coupler anastomoses. History of radiation therapy is not a contraindication to microvascular surgery or to the use of the coupler system. However, the vessels should be inspected for radiation-induced fibrosis and stiffness of some vessels. If this is the case, akin to stiffness from atherosclerotic calcification, the coupler should not be used. One of the benefits of the coupler lies in its ability to handle vessel-size mismatches, more so with venous than with arterial anastomoses.

Question 40

A 25-year €‘old man has shortness of breath one day after undergoing radical resection of dermatofibrosarcoma protuberans of the scalp. Surgical margins are clear, and the 15-cm-diameter defect was covered with a free latissimus flap. Heparin 2500 U was administered immediately after completion of microvascular anastomosis. The patient has been receiving Ringer €™s lactate 70 ml/hr, low-molecular-weight dextran 20 ml/hr, and aspirin 81 mg daily since the procedure. Temperature is 38 °C (100.4 °F). Pulse rate is 105 bpm. Respirations are 28/min. Blood pressure is 105/70 mmHg. Crackles are heard on auscultation of the chest. Radiographs of the chest show bilateral diffuse infiltrates. Which of the following is the most likely cause of the respiratory distress in this patient? (A) Atelectasis (B) Bacterial pneumonia (C) Drug reaction (D) Postoperative fluid overload (E) Pulmonary metastasis

Answer 40

The correct response is Option C. Systemic use of dextran, even in a low €‘molecular-weight form, has been shown to result in complications. The most serious of these is adult respiratory distress syndrome. This has been seen even in young patients and appears to be related to dose; however, it may occur even after a test dose. The etiology of this reaction and its specific mechanism are not understood completely, although this specific complication from systemic administration has been shown multiple times in the literature. Atelectasis, despite being prevalent in the immediate postoperative period, usually presents in a bilateral basilar fashion rather than diffusely throughout the lung fields. Bacterial pneumonia usually does not present early or with bilateral diffuse pulmonary infiltrates. Postoperative fluid overload in an otherwise healthy 25-year-old patient receiving 70 ml/hr of intravenous fluids is extremely unlikely. Sarcomas usually do not metastasize.

Question 41

A 34-year-old man is scheduled to undergo soft-tissue coverage with an anterolateral thigh free flap to treat a nonhealing, complex, traumatic wound involving the distal third of the left lower extremity. Which of the following is most likely to have the greatest effect on anastomotic patency? A ) Anastomotic type B ) Anticoagulation C ) Magnification equipment D ) Surgical skill E ) Suture technique

Answer 41

The correct response is Option D. Acland outlined five basic factors that influence anastomotic patency: (1) surgical precision, (2) size of the vessel, (3) blood flow, (4) tension, and (5) use of anticoagulation and antithrombotic medication. Studies have not demonstrated the efficacy of anticoagulation in improving microvascular patency rates and free flap survival. Studies evaluating types of anastomosis, including end-to-end and end-to-side, and those comparing suture techniques, including interrupted or running sutures, have also not demonstrated significant differences in patency rate. Both loupe magnification and an operating microscope can be successfully utilized in microsurgery. The skill and experience of the surgeon in using an atraumatic technique for the dissection and anastomosis of the vessels, assuring good vessel apposition, and avoiding tension, compression, or kinks in the vascular pedicle, remain the most critical factors in microsurgery.

Question 42

A 65-year-old woman undergoes breast reconstruction with a free superficial inferior epigastric artery (SIEA) flap. The vascular pedicle is 1.5 mm diameter, including both the artery and vein. The second/third intercostal perforators on the left chest are prepared as the recipient vessels. The surgeon performs a hand-sewn microvascular arterial anastomosis with 9-0 suture and a 1.5-mm anastomotic coupler for the vein. This patient is at increased risk for which of the following? A) Arterial occlusion B) Interposition vein graft C) Kinking of the vascular pedicle D) Vasospasm E) Venous thrombosis

Answer 42

The correct response is Option E. This patient has a high risk for venous thrombosis given that the 1.5-mm anastomotic coupler was used. In a large retrospective study, Hansen et al, found that based on 5643 reconstructions, the 1.5-mm diameter coupler had an overall thrombosis rate of 6.9%. This is significantly higher than all other coupler sizes. In another study, Jandali et al, found that using the anastomotic coupler in breast reconstruction is safe. In fact, these authors demonstrated a 0.6% flap loss rate in 1000 cases of autologous breast reconstruction. When encountered with a recipient vein that is less than 2.0 mm, the surgeon should either perform a hand-sewn anastomosis or find different recipient vessels.

Question 43

A 64-year-old man undergoes radial forearm free muscle flap reconstruction of a hemiglossectomy defect from resection of a squamous cell carcinoma. The procedure is uneventful. During which of the following periods of time is microvascular thrombosis most likely to occur after reconstruction? A ) Within the first day B ) Between 1 and 2 days C ) Between 3 and 4 days D ) Between 5 and 7 days E ) Between 8 and 14 days

Answer 43

The correct response is Option A. The most common time for a microvascular thrombosis to occur during head and neck reconstruction is within 12 hours of completion of the anastomosis. Often, the thrombosis occurs intraoperatively or upon arrival in the postanesthesia care unit. Nearly 90% of all thromboses occur within 24 hours. Most commonly, thromboses occur as a result of technical issues. Microvascular thrombosis can occur in a delayed manner, even 7 to 14 days postoperatively. However, the rate of these events is much lower than the initial 24 hours.

Question 44

A 73-year-old man undergoes mandible reconstruction for squamous cell cancer. A microvascular thrombosis is most likely to occur within what period of time after the completion of the microvascular anastomosis? A ) 0 to 24 Hours B ) 25 to 36 Hours C ) 37 to 48 Hours D ) 49 to 72 Hours E ) 73 to 96 Hours

Answer 44

The correct response is Option A. During head and neck reconstruction, a microvascular thrombosis is most likely to occur within 12 hours of completion of the anastomosis. The thrombosis often occurs intraoperatively or upon arrival in the postanesthesia care unit. Nearly 90% of all thromboses occur within 24 hours. Most commonly, thromboses occur as a result of technical issues. Microvascular thrombosis can occur in a delayed manner, even 7 to 14 days postoperatively; however, the rate of these events is much lower than during the initial 24 hours.

Question 45

A 48-year-old woman is evaluated for immediate bilateral breast reconstruction using coverage with deep inferior epigastric artery perforator free flaps. Which of the following conditions is most likely to be associated with hypercoagulable state? A) Celiac disease B) Graves disease C) Rheumatoid arthritis D) Systemic lupus erythematosus E) Type 1 diabetes mellitus

Answer 45

The correct response is Option D. In some cases, patients with systemic lupus erythematosus (SLE) can develop antibodies against platelet membrane phospholipids, increasing adhesion and aggregation of platelets, and producing a state of hypercoagulability. Although not all patients with SLE will develop these antibodies, a history of SLE should raise concern when evaluating a patient for a free flap reconstruction. All of the other options are autoimmune diseases, but none are typically associated with coagulopathies.

Question 46

A 43-year-old right-hand–dominant man presents with Volkmann flexion contractures of the right hand after sustaining a severe burn injury to the right volar forearm. Reconstruction with an innervated gracilis free myocutaneous flap is planned. During flap elevation, the vascular pedicle is identified approximately 7 cm distal to the pubic symphysis between which of the following structures? A) Adductor longus and adductor magnus muscles B) Adductor magnus and vastus medialis muscles C) Sartorius and adductor longus muscles D) Semimembranosus and sartorius muscles E) Vastus medialis and semimembranosus muscles

Answer 46

The correct response is Option A. The innervated gracilis muscle flap is a useful functional reconstructive tool. Its tendinous distal third makes this flap an attractive choice for finger flexor or extensor tendon reconstruction. The dominant supply to the vascular pedicle to this flap arises from the *profunda femoris artery*, and the muscle is innervated by the *obturator nerve*. During harvesting of the flap, the nerve and vascular pedicle can be reliably identified between the *adductor longus* and *adductor magnus muscles*, approximately 7 cm distal to the pubic symphysis. When a skin paddle is included, it is recommended to design the skin paddle within the proximal two thirds of the muscle, because skin necrosis is a greater concern over the distal third of the muscle.

Question 47

A 45-year-old woman undergoes reconstruction of the right breast with a deep inferior epigastric artery perforator flap. Postoperatively, the flap shows signs of ischemia and is reexplored. During flap salvage, which of the following agents should be administered to inactivate thromboxane? A) Aspirin B) Dextran C) Heparin D) Hirudin E) Streptokinase

Answer 47

The correct response is Option A. Aspirin, or acetylsalicylic acid, inhibits the enzyme cyclooxygenase. Cyclooxygenase ordinarily functions to form multiple compounds from arachidonic acid, including thromboxane and prostacyclin. Thromboxane is a platelet aggregator and vasoconstrictor. Prostacyclin is also a platelet aggregator. By decreasing formation of these compounds, aspirin acts as an anticoagulant. Dextran is a polysaccharide whose mechanism of action is thought to involve decreasing platelet aggregation by altering the electric charge of platelets, as well as by decreasing blood viscosity. Dextran also acts as a volume expander. Heparin is a glycosaminoglycan that binds to antithrombin III and enhances its ability to inactivate thrombin (which ordinarily converts fibrinogen to fibrin), as well as clotting factors IX, X, XI, and XII. Heparin may also additionally decrease thrombosis by causing nitric oxide-mediated vasodilation. Hirudin is derived from the medicinal leech Hirudo medicinalis and functions by directly inhibiting thrombin, in contrast to heparin, which requires the antithrombin III cofactor. Streptokinase is a thrombolytic agent that functions by activating plasminogen and its conversion to plasmin. In turn, plasmin breaks down fibrin into fibrin degradation products.

Question 48

A 43-year-old woman is evaluated because of lymphedema of the lower extremities. She demonstrates pitting edema, which does not improve with limb elevation. Her skin feels otherwise normal, with no evidence of fibrotic change. Which of the following International Society of Lymphology stages best describes this patient's lymphedema? A) 0 B) 1 C) 2 D) 3

Answer 48

The correct response is Option C. Lymphedema results from congenital or acquired dysfunction of the lymphatic system. It results from changes to the lymphatic vessels, including ectasia and valve dysfunction. This results in reflux of lymphatic fluid into the interstitial space. Lymphatic fluid accumulation leads to chronic inflammation, extracellular matrix remodeling and fibrosis, adipose tissue differentiation, progressive fibrosis/sclerosis, and eventual obliteration of the lymphatic vessel lumen. Over time, accumulation of interstitial lymphatic fluid causes subcutaneous fibroadipose production. Lymphedema is a chronic condition that slowly worsens over time. It progresses through four stages. -*Stage 0* indicates a clinically normal extremity but with abnormal lymph transport (identified via lymphoscintigraphy). -*Stage 1* demonstrates a relative accumulation of fluid high in protein content, which improves with limb elevation. Pitting may occur. -*Stage 2* represents pitting edema that does not resolve with elevation, but no evidence of fibrotic skin changes. Late in Stage 2, the limb may not pit as excess fat and fibrosis begins. -*Stage 3* describes fibroadipose deposition and fibrotic skin changes. The presence of dermal backflow on contrast-enhanced imaging of the lymphatic system is diagnostic for lymphedema, and the severity and distribution of this backflow correlate closely with the pathologic condition of the lymphatic vessels. Indocyanine green fluorescent lymphography enables detailed dynamic functional evaluation of the superficial lymphatic system and can also be used for intraoperative lymph node mapping for vascularized lymph node transplantation.

Question 49

A 72-year-old man undergoes composite mandibular resection followed by fibula osteocutaneous free flap reconstruction. Patient history includes squamous cell carcinoma of the oropharynx. The morning after surgery, ischemic compromise of the flap is noted. Urgent exploration of the microvascular anastomosis is performed. Which of the following causes of flap compromise is most likely to result in failure of salvage attempts? ## Footnote A) Arterial thrombosis B) Hematoma C) Pedicle kinking D) Venous thrombosis

Answer 49

The correct response is Option A. ## Footnote Arterial thrombosis is associated with lower flap salvage rates than venous thrombosis or mechanical causes. Bui et al. demonstrated salvage rates of 40%, 71%, and 90% for arterial thrombosis, venous thrombosis, or hematoma, respectively. Selber et al. demonstrated a similar tendency toward flap failure after arterial thrombosis. They also documented a 92% flap salvage rate for mechanical causes of ischemia, compared with 64.9% for vessel thrombosis. Mechanical or extrinsic causes of flap ischemia are generally easy to correct and are less likely to be associated with vessel injury. It is postulated that arterial thrombosis is more likely to be associated with endothelial injury than venous thrombosis.

Question 50

A 45-year-old male fitness instructor has squamous cell carcinoma of the oral cavity requiring reconstruction with a soft-tissue free flap. The patient is very concerned about maintaining all muscular function at the flap donor site. To address the patient's concern, which of the following fasciocutaneous flaps should be used for reconstruction to minimize muscular donor site morbidity? A) Anterolateral thigh flap B) Deep inferior epigastric artery perforator flap C) Medial sural artery perforator flap D) Parascapular flap E) Profunda artery perforator flap

Answer 50

The correct response is Option D. The benefit of perforator flaps over traditional musculocutaneous flaps is the ability to preserve muscle at the donor site. Depending on perforator anatomy, it can either traverse between surrounding myofascial units requiring no muscle sacrifice, or alternatively pass through the muscle substance requiring division of a small amount of muscle to liberate the flap. The anterolateral thigh (ALT) or deep inferior epigastric artery perforator (DIEP) flaps have variable perforator anatomy containing either septal or muscular perforators, or both within the same flap. The profunda and medial sural artery perforator flaps have vessels that pierce the adductor magnus and gastrocnemius muscles, respectively. Of the options listed, only the parascapular flap consistently has a septal perforator located between the teres major, teres minor, and the triceps.

Question 51

A 20-year-old man undergoes harvest of the lower extremity free flap as shown in the photographs. A long length of bone is required for the reconstruction. With proximal dissection and osteotomy, which of the following nerves is at the highest risk for injury? A) Common peroneal B) Lateral femoral cutaneous C) Saphenous D) Sural E) Tibial

Answer 51

The correct response is Option A. The fibula is a long, thin triangular bone of the lower extremity. The fibula can be harvested as a free osseous or free osteoseptocutaneous flap with primary blood supply from the peroneal artery. Preservation of 4 to 6 cm of length proximally and 6 cm distally is important for the maintenance of stability of the knee and ankle. The peroneal nerve should be identified prior to proximal dissection as it wraps around the fibular neck. At this level, the nerve can be palpated and marked out to avoid injury during proximal dissection. The common peroneal nerve arises from the sciatic nerve, running along the biceps femoris toward the posterior fibular head. It wraps around the proximal fibula at the neck, continuing laterally through a fibrous tunnel comprised of the aponeurosis of the peroneus longus, lateral gastrocnemius, and soleus muscles. Under the peroneus longus, the nerve branches into the superficial and deep branches; the superficial branch runs under the peroneus longus to innervate the peroneus longus and peroneus brevis, and it provides cutaneous sensation for the foot dorsum. The superficial peroneal nerve can be injured during anterior dissection for the skin paddle at the mid lower leg. The deep peroneal nerve can be identified after deep dissection through the interosseus membrane into the anterior lower leg compartment. This nerve can be found between the extensor hallucis longus and extensor digitorum longus muscles. The deep peroneal nerve provides innervation to the muscles of the anterior compartment and sensation to the first web space. The tibial nerve branches from the sciatic nerve, running through the popliteal fossa, sitting lateral to the neurovascular bundle, then proceeds deep to the gastrocnemius and soleus muscles. It then proceeds to run along the medial ankle posterior to the medial malleolus and provides sensory innervation to the plantar foot. Along its path, it provides innervation to the posterior compartments and intrinsic muscles. The sural nerve is a sensory nerve, traditionally a confluence of the medial sural nerve from the tibial nerve and a lateral sural cutaneous nerve from the common peroneal nerve. The nerve is found superficial to the superficial posterior compartment in the posterior calf at the midline, lateral to the Achilles tendon; then it veers laterally in the ankle. This nerve provides sensation to the dorsolateral foot. The saphenous nerve is the terminal sensory nerve of the femoral nerve; it perforates the femoral canal and becomes superficial and descends with the saphenous vein. It descends along the medial lower leg from the medial epicondyle region to the medial malleolus. Sensation is provided for the anteromedial lower leg. This nerve is unlikely to be injured in free fibula harvest given its medial leg location. The lateral femoral cutaneous nerve arises from the posterior divisions of the L2 and L3 spinal nerves. The nerve usually exits from the lateral psoas muscle, heading towards the anterior superior iliac spine. It exits below the inguinal ligament and bifurcates. The sensory distribution is the skin of the anterolateral and lateral thigh. Given the proximal location, this nerve should not be in the region of dissection.