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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_612_Библиотеки_им_академика_М_И_Перельмана
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The flap should then be flushed with warm heparinized solution
(5000 IU in 200 mL of normal saline). The single-vessel clamp on the
internal mammary artery can be temporarily opened for flushing to
assess inflow.
Direct Thrombectomy
If the above measures are unsuccessful, direct mechanical
thrombectomy with a 3-F Fogarty unicameral balloon at the proximal
pedicle stump adjacent to the anastomosis may be effective. Prior to
inserting the catheter, the surgeon should test inflation of the balloon
to reinforce the limit relative to the vessel diameter. The Fogarty
balloon is advanced proximal and then distal to the anastomosis.
Care should be taken to ensure that the tip of the catheter remains
intraluminal and the balloon withdrawn slightly if any resistance is
met. The balloon is then inflated with up to 0.2 mL of saline before
withdrawing slowly and carefully, and an existing clot can be
removed in this manner. Of course, more distal thrombi within the
flap are difficult to extract. If the above is successful, the
anastomosis can be redone and the flap reassessed after a short
period of reperfusion. If venous outflow is insufficient despite
successful thrombectomy, chemical thrombolysis may be used as an
additional salvage measure to lyse downstream clot.
Thrombolysis
Thrombolysis with recombinant tissue plasminogen activator (rt-PA),
urokinase, or streptokinase is oftentimes used as an adjunct with
anastomotic revision at the time of free flap salvage. Rt-PA is a direct
activator of plasminogen and like urokinase, is produce by vascular
endothelial cells. It has a theoretical advantage of reducing systemic
bleeding compared with streptokinase and urokinase.37 Infusion of
the thrombolytic agent is confined to the flap circulation and
therefore an atraumatic clamp can be applied to the proximal
outflow. A 2.5-mg dose of rt-PA is injected into the arterial side of the
flap circulation, and the dose can be repeated after 15 minutes if flow
is not restored. Despite the uncertain impact on improving the
likelihood of flap salvage, chemical thrombolysis may prevent fat
necrosis through the dissolution of thrombi in the microvasculature.
38
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Leeches
Medicinal leeches, Hirudo medicinalis, should only be used to aid
venous egress when all other potential technical issues have been
excluded. Leeches are more commonly used in H&N reconstructive
surgery and digit replantation when successful venous outflow
cannot be established. Antibiotic prophylaxis against Aeromonas
hydrophila is necessary, and the majority of patients treated with
leeches will require several blood transfusions.39 When medicinal
leeches are used for uncorrectable venous congestion, partial or
total flap salvage has been reported in patients undergoing H&N
microvascular surgery.40 However, such efforts may be futile in
patients after free flap breast reconstruction and total flap removal
may be a better option.
39
Flap Failure
When flap circulation cannot be restored using the above
mechanisms, the pedicle should be ligated and flap should be
promptly removed to reduce further inflammation or blood loss.
Unless a discussion was had with the family to pursue a
second/alternate flap at the time of the take back, the wound can be
temporized with a vacuum-assisted therapy closure device, other
dressing, or skin graft until definitive soft-tissue coverage is
achieved.
CONCLUSION
Since its inception, the field of microsurgery continues to grow
rapidly with major advances in instrumentation and microscope
technology and enhanced understanding of vascular anatomy, bone
biology, nerve regeneration, and transplantation immunology. The
ever-expanding armamentarium of flaps offers reconstructive
microsurgeons options to improve esthetics and function. Despite
the innumerable advances, there will be failures and how those are
overcome and the learning that results will help expand the field
further. The untold future potential of microsurgery, including
robotics, is inspiring.
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QUESTIONS
1. A 53-year-old patient is recovering in the postanesthesia care
unit 4 hours after bilateral breast reconstruction using deep
inferior epigastric perforator (DIEP) flaps. The on-call resident
is called to assess the left breast flap given a new concern for
swelling and purple/mottled discoloration, but the right breast
exam is unremarkable. An arterial signal is present on both
skin paddles. What is the next best step in definitive
management?
a. Systemic heparin
b. Application of leeches
c. Observation
d. Immediate return to the operating room
e. Application of bear hugger and warming blankets
2. A 64-year-old man is undergoing limb salvage procedures to
his left lower extremity for a diabetic wound and long-standing
peripheral vascular disease. A computed tomography
angiogram (CTA) demonstrates anterior tibial (AT) artery
runoff and the posterior tibial (PT) artery has a small segment
site of occlusion with reconstitution distally. The patient would
benefit free tissue transfer for his wound. What is the next
best step in management?
a. Free tissue transfer, end-to-side arterial anastomosis to
AT
b. Free tissue transfer, end-to-end arterial anastomosis to
PT
c. Vascular surgery consultation to evaluate for optimization
of distal flow
d. Free tissue transfer, end-to-end arterial anastomosis to
AT
e. Alternative reconstructive method given tenuous
extremity perfusion
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3. Which of the following best characterizes loupes microsurgery
when compared to the operating microscope when used by
an experienced microsurgeon?
a. Greater magnifying ability
b. Decreased efficiency
c. Improved patency rates
d. Equivalent outcomes
e. Higher rate of flap thrombosis
4. A 46-year-old woman presents to your office 2 weeks
following bilateral breast free flap reconstruction using deep
inferior epigastric perforator (DIEP) flaps. The patient has
significant bilateral mastectomy skin flap necrosis and
necrosis of the midpoint of her abdominal incision. Which of
the following is a risk factor for mastectomy and donor site
skin necrosis?
a. Diabetes mellitus
b. Obesity
c. Smoking
d. Age greater than 65 years
e. Clotting disorder
5. A 54-year-old man is recording in the intensive care unit
following free vascularized fibula reconstruction of his
mandible. Despite adequate fluid resuscitation attempts, he
remains hypotensive. Perioperative fluid administration has
been adequate and urine output has been monitored
appropriately. Labs including hemoglobin/hematocrit are
unremarkable. Clinical exam is benign with no facial/neck or
extremity swelling, and the intraoral skin paddle is warm and
well perfused, although the doppler signal is faint. An
additional bolus of fluid and an increase in maintenance fluid
fails to improve the blood pressure. What is the next best step
in management?
a. Computed tomography scan to assess for bleeding
b. Immediate return to the operating room to control source
of bleeding
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c. Vasopressor support
d. Albumin
e. Trendelenburg positioning of the patient
ANSWERS AND EXPLANATIONS
1. Answer: d. Thrombosis is most common in the first 24
hours and the most likely cause is technical in nature. An early
and concerning change in flap monitoring should be managed
by immediate return to the operating room for exploration and
possible revision of the anastomoses. In this case, the flap is
mottled, which indicates likely venous thrombosis, while the
arterial signal is still present. Reduced time from detection of
flap compromise to return to the operating room improves flap
salvage outcomes.
2. Answer: c. Many patients who require reconstruction for
lower extremity wounds have underlying vascular disease.
Impaired vascular flow also inhibits the healing of small defects
secondary to trauma, surgical incisions, infection, or vascular
ulcers. CTA or formal angiogram detects sites of vascular
disease that should be intervened upon prior to microvascular
reconstruction and free tissue transfer. While end-to-side arterial
anastomosis is the correct technique to preserve distal limb
perfusion, the next best step in management is vascular
consultation to determine if an endovascular or bypass
procedure is necessary to optimize extremity blood flow.
3. Answer: d. Regardless of whether the surgeon prefers
loupes versus microscope for an anastomosis, it is highly
recommended to always have a microscope on standby in the
event that its use becomes necessary during a repair of an
injured vessel or if the vessels used in the anastomosis are
smaller than typical. Microsurgical outcomes are less dependent
on the method of magnification used (ie, loupes vs microscope)
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and more so related to surgeon experience and comfort with
their choice. When using loupes for microsurgery, most
surgeons use 3.5× to 4.5× magnification, with up to 6× to 8×
being used for smaller-than-typical vessel and nerve work.
Loupes provide an advantage when operating at an angle or in
a deep field. Expanded field options prove helpful when
performing the flap dissection and harvest. A head light proves
useful particularly when using loupes for microsurgery, and this
can be mounted onto the loupes or used as a separate head
piece. The dual-surgeon operating microscope magnification
typically ranges from 6× to over 40×. A benefit of the
microscope is the ability to adjust the magnification with the
press of a button. The xenon or halogen light tends to be bright
and completely illuminates the field of focus, and the light
brightness may also be adjusted.
4. Answer: c. Given the duration of these complex cases
under general anesthesia and the oftentimes prolonged
recovery, comorbidities should be optimized prior to
microvascular reconstruction. Smokers should be counseled to
quit smoking well in advance of surgery given its negative
effects on surgical outcomes in general, although its harmful
effects on microsurgical outcomes remain debated. In breast
free flap reconstruction, smoking has been associated with an
increased risk of mastectomy/abdominal wall skin necrosis and
hernia formation, and cessation beyond 4 weeks reduces the
risk of complications.
5. Answer: c. Fluid underresuscitation intraoperatively may
place the patient at an increased risk of postoperative flap
thrombosis, and urine output should be used to guide
management. After ensuring adequate fluid resuscitation, if a
patient remains hypotensive, vasopressors may be used with
likely no impact on thrombotic events or flap loss. Ultimately,
adequate blood pressure, even if vasoactive support is
necessary, ensures patient and flap perfusion. In the presented
scenario, the patient has unremarkable labs and clinical exam,
therefore there is no concern for bleeding or flap compromise.
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Vasopressor support in this case is necessary to ensure
adequate patient and flap perfusion.
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