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Seminar - Free Flaps in Reconstruction of Defects after Cancer Surgery Definition A flap is a unit of tissue that is transferred from one site (donor site) to another (recipient site) while maintaining its own blood supply. The ability to transplant living tissue from one region of the body to another greatly has facilitated the reconstruction of complex defects. Although the technique of free tissue transfer is complex and time consuming, the numerous advantages include stable wound coverage, improved aesthetic and functional outcome, and minimal donor site morbidity. Since the introduction of free tissue transfer in the 1960s, the success rate has improved substantially and currently is 95-99% among experienced surgeons. Flaps come in many different shapes and forms. They range from simple advancements of skin to composites of many different types of tissue. These composites need not consist only of soft tissue. They may include skin, muscle, bone, fat, or fascia. History of flap surgery The term "flap" originated in the 16th century from the Dutch word "flappe," meaning something that hung broad and loose, fastened only by one side. The history of flap surgery dates as far back as 600 BC, when Sushruta Samhita described nasal reconstruction using a cheek flap. The origins of forehead rhinoplasty may be traced back to approximately 1440 AD in India. Some reports suggest flap surgeries were being performed before the birth of Christ.

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Seminar - Free Flaps in Reconstruction of Defects after Cancer Surgery

Definition

A flap is a unit of tissue that is transferred from one site (donor site) to another (recipient site) while maintaining its own blood supply.

The ability to transplant living tissue from one region of the body to another greatly has facilitated the reconstruction of complex defects. Although the technique of free tissue transfer is complex and time consuming, the numerous advantages include stable wound coverage, improved aesthetic and functional outcome, and minimal donor site morbidity. Since the introduction of free tissue transfer in the 1960s, the success rate has improved substantially and currently is 95-99% among experienced surgeons.

Flaps come in many different shapes and forms. They range from simple advancements of skin to composites of many different types of tissue. These composites need not consist only of soft tissue. They may include skin, muscle, bone, fat, or fascia.

History of flap surgery

The term "flap" originated in the 16th century from the Dutch word "flappe," meaning something that hung broad and loose, fastened only by one side. The history of flap surgery dates as far back as 600 BC, when Sushruta Samhita described nasal reconstruction using a cheek flap. The origins of forehead rhinoplasty may be traced back to approximately 1440 AD in India. Some reports suggest flap surgeries were being performed before the birth of Christ.

The surgical procedures described during the early years involved the use of pivotal flaps, which transport skin to an adjacent area while rotating the skin about its pedicle (blood supply). The French were the first to describe advancement flaps, which transfer skin from an adjacent area without rotation. Distant pedicle flaps, which transfer tissue to a remote site, also were reported in Italian literature during the Renaissance period.

Subsequent surgical flap evolution occurred in phases. During the First and Second World Wars, pedicled flaps were used extensively. The next period occurred in the 1950s and 1960s, when surgeons reported using axial pattern flaps (flaps with named blood supplies). In the 1970s a distinction was made between axial and

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random flaps (unnamed blood supply) and muscle and musculocutaneous (muscle and skin) flaps. This was a breakthrough in the understanding of flap surgery that eventually led to the birth of free tissue transfer.

In the 1980s the number of different tissues types used increased significantly with the development of fasciocutaneous (fascia and skin) flaps, osseous (bone), and osseocutaneous (bone and skin) flaps.

A brief summary of events in the evolution of flap surgery through the recent years

Over the past three decades, many advances have been made in the treatment of head and neck cancer. These include the combination of radiation therapy and chemotherapy with surgery, conservation laryngeal surgery, and modifications of the classic radical neck dissection. The desire to improve postoperative outcomes by focusing on preservation of tissue and function led to these advances and resulted in more rapid recovery and decreased cosmetic deformities while maintaining equal cure rates to prior techniques. Despite the fact that these changes have decreased morbidity, overall survival rates for patients with head and neck cancer have reached a plateau over the past several decades. Because of this, the focus of many head and neck surgeons in the past 20 years has been directed at further decreasing morbidity from surgery and improving functional and reconstructive outcomes.

The use of free tissue transfer and microvascular re-anastomosis for the reconstruction of head and neck defects from extirpative oncologic surgery is a relatively recent practice. Prior to the past 3 decades, the majority of head and neck defects were closed with either local tissue or random skin flaps that were pedicled and “walked” up to the head and neck region from other sites such as the trunk. Very rarely were large soft tissue and bony defects replaced with anything other than skin. In 1963 McGregor first introduced his forehead flap for reconstruction of oral defects. This was an axial pattern skin flap and was much more reliable than random flaps. In addition it did not require the tedious relocation from distant sites. The problem with this flap was that it left a large skin defect on the forehead and scalp requiring a skin graft, which was rather deforming. Subsequently in 1965, Bakamjian introduced the deltopectoral flap based on the perforators of the internal mammary artery. The donor site was the shoulder and chest, which was much more cosmetically acceptable. The shortcomings of the flap, however, were that its reach was limited by its pedicle. McGregor’s forehead flap and Bakamjian’s deltopectoral flaps were the standard flaps available for head and neck reconstruction during the 1960s and 70s.

Although microvascular transfer of free tissue grafts did not gain favor until the mid 1970s it was performed as early as 1959 when Seidenberg used revascularized free jejunum segments to repair pharyngoesophageal defects. McLean and Buncke used omentum pedicled on the gastroepiploic vessels to cover a cranial defect in 1972. In 1973, Daniel and Taylor described the first free

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cutaneous flap and in 1976, Baker and Panje was the first to publish the use of free cutaneous flaps for the reconstruction of head and neck defects. He followed this in 1977 with a free groin flap based on the superficial circumflex iliac artery to reconstruct an intraoral defect. This flap was met with some favor during this time and was performed by other surgeons, however it was a bulky flap and its vascular pedicle was inconsistent and the vessels were very small in diameter.

Other flaps such as the axillary free flap and dorsalis pedis flap were also described but had short-comings such as an inconsistent pedicle and significant donor site morbidity respectively. In 1976, Harii and colleagues developed the latissimus dorsi musculocutaneous flap. This was a very reliable flap based on the thoracodorsal artery and vein. It has remained a favorable flap for certain head and neck defects to this date.

During the 70s limited numbers of surgeons were performing free flaps for a number of reasons. First, there were only a few to choose from. In addition they did not always provide all the tissue needed to reconstruct head and neck defects requiring combinations of bone, skin, and muscle. Most importantly, the majority of flaps at this time had inconsistent small pedicles making them technically difficult to perform.Towards the end of the 1970s free flaps grew out of favor and an old technique was revisited. In 1896, Tansini had described the pedicled latissimus dorsi flap. In 1976, Olivari brought this back into favor. Subsequently other pedicled cutaneous and myocutaneous flaps arose such as the pectoralis and trapezius flaps. The pectoralis myocutaneous flap was considered the "work Horse" flap of head and neck reconstruction during this time. In 1979, Ariyan used the pectoralis flap in combination with rib and in the same year Demergasso and Piazza described harvest of the spine of the scapula with the trapezius musculocutaneous flap. These pedicled flaps became the choice of most head and neck surgeons over the next decade. They were reliable, quick, and easy to harvest. They also required only one stage, had minimal donor site morbidity, and provided more bulk than the free flaps available at that time. They required only one surgical team, were technically easier, and provided nonirradiated tissue (Chepeha and Teknos, 2001).

In the past fifteen years, limitations of pedicled flaps and desire by surgeons for new and better donor sites has lead to a resurgence of free tissue transfer. Pedicled flaps were not well suited for reconstruction of defects requiring very large bulk or those needing thin pliable tissue. In addition their reach was constrained by the length of their pedicle. As further investigations continued new donor sites for free flaps emerged that possessed longer and larger vascular pedicles and were made up of various tissues including skin, muscle, bone, and nerve. This allowed for much more refined tailoring of harvested tissue to the recipient site. Free flaps can provide a much wider range of skin characteristics that can match the host site well. In addition microvascular transfer makes much more efficient use of harvested tissue as nearly all is used directly in the reconstruction. Pedicled flaps require less efficient use of tissue as entire muscles are defunctionalized in order to safely transfer enough tissue to fill a defect. Because free flap donor sites are often located at a distant location from the extirpative site, a two-team approach can be used to decrease operating room

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time. The excellent perfusion of free flaps significantly improves wound healing and serves to protect against wound breakdown and osteoradionecrosis when postoperative radiotherapy or brachytherapy is utilized. Free flap reconstruction also affords the ability for watertight closures in skull base defects to prevent CSF leaks. Because revascularized tissue transfers maintain their independent blood supply, they are not as subject to resorption, providing for greater long-term stability and cosmesis to the reconstruction. Resorption, which plagued non-viable bony transfers in the past, is virtually eliminated with free flap reconstruction. Finally, many of free flaps have the potential for functional neurosensory and motor innervation from recipient nerves as well as the ability for primary placement of osseointegrated implants for improve oromandibular function

In 1979, Taylor and colleagues described the iliac crest composite flap based on the deep circumflex iliac artery. This was followed by the radial forearm fasciocutaneous flap (Yang, 1981), the scapular skin flap (dos Santos, 1980), the parascapular skin flap (Nassif, 1982), the lateral arm fasciocutaneous flap (Song, 1982), the scapular osseocutaneous flap (Swartz 1986), the lateral cutaneous thigh flap (Baek 1983), and the rectus abdominis myocutaneous flap (Drever, 1985).

Today microvascular free-tissue transfer to the head and neck has become an accepted method of reconstruction. This is due primarily to increased success rates for free-flap surgery (93 to 94%, Schusterman, 1993 and Urken, 1994 respectively) and superior aesthetic and functional results. Increasing numbers of surgeons have become adept at this surgical subspecialty for a number of reasons: (1) widespread application of microvascular techniques by a variety of different surgical disciplines; (2) Advances in technique and instrumentation; and (3) expanding number of dedicated training fellowships.

Classification of flaps

Most classification systems have been designed for the sole purpose of aiding communication with peers. It is simply a matter of being familiar with the correct vocabulary to use. However, the crucial point for any physician to remember is that communication with the patient is of foremost importance. The patient must be able to picture, with the surgeon's guidance, what he or she is planning.

Many different methods have been used to classify flaps. Furthermore, these classification systems are often complex and varied in principle.

To improve understanding of flap classification, it can be summarized into three simplified categories:

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(1) Type of blood supply

(2) Type of tissue to be transferred

(3) Location of donor site.

1. Type of Blood supply

To survive, flaps like any living tissue, must receive adequate blood flow. There are essentially two main ways a flap can maintain its blood supply.

o If the blood supply is not derived from a recognized artery but rather comes from many little unnamed vessels, the flap is referred to as a random flap. Many local cutaneous (skin) flaps fall into this category. If the blood supply comes from a recognized artery or group of arteries, it is referred to as an axial flap. Most muscle flaps have axial blood supplies.

Because of the complexity and variation observed in axial blood supply, a further subclassification (axial types I-V) was made by Mathes and Nahai and is readily used in plastic and reconstructive surgery literature to describe different types of muscle flap

Flap Classification Based on Blood Supply

Random (no named blood vessel) Axial (named blood vessel)

Mathes and Nahai Classification

I. One vascular pedicle (eg, tensor fascia lata)II. Dominant pedicle(s) and minor pedicle(s) (eg, gracilis)III. Two dominant pedicles (eg, gluteus maximus)IV. Segmental vascular pedicles (eg, sartorius)V. One dominant pedicle and secondary segmental pedicles

(eg, latissimus dorsi)

2. Tissue to be transferred

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In general, flaps may comprise in part or in whole almost any component of the human body as long as an adequate blood supply to the flap can be ensured once the tissue has been transferred.

o Flaps may be composed of just one type of tissue (eg, skin [cutaneous flaps]) or several different types of tissue (eg, skin and fascia [fasciocutaneous] or skin, fascia, and muscle).

o Therefore, another way of classifying flaps is by describing the different types of tissue that are being used in the flap.

Flap Classification Based on Type of Tissue Transfer

1. Skin (cutaneous)

2. Fascia

3. Muscle

4. Bone

5. Visceral (eg, colon, small intestine, omentum)

6. Composite

Fasciocutaneous (eg, radial forearm flap) Myocutaneous (eg, TRAM flap) Osseocutaneous (eg, fibula flap) Tendocutaneous (eg, dorsalis pedis flap) Sensory/innervated flaps (eg, dorsalis pedis flap with deep

peroneal nerve)

1. Location of donor site

Tissue may be transferred from an area adjacent to the defect. This is known as a "local" flap. It may be advanced and/or be described based on its geometric design.

Tissue transferred from an incontiguous anatomic site, in other words from a different part of the body, is referred to as a "distant" flap.

Distant flaps may be either "pedicled" (transferred while still attached to their original blood supply) or "free." Free flaps are physically detached from their native blood supply and then reattached to vessels at the recipient site. This anastomosis typically is performed using a microscope, thus is known as a "microsurgical anastomosis."

Flap Classification Based on Donor Site Location

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1. Local (eg Cutaneous flap)

A. Pivotal (Geometric/ Transposed)i. Rotationii. Transpositioniii. Interpolation

Advancement

iv. Single pediclev. Bipediclevi. V-Y

2. Distant

A. Pedicle (eg, groin flap)B. Free (eg, free TRAM

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Principles of microsurgery

The principles of microsurgery include the following:

Careful patient selection and preoperative planning Use of well-defined workhorse flaps Full patient consent Attention to details intraoperatively Meticulous microsurgical technique Vigilant care postoperatively

By careful attention to these factors, the plastic surgeon can optimize success in these versatile yet technically demanding procedures.

1. Patient selection & pre-op plan

History and physical examination

Obviously, a comprehensive history and physical examination is essential for pre-operative clearance and planning of the operation.

Lab studies

Complete blood count necessary for any major operation; however, a hematocrit around 30 may be favorable postoperatively for optimal blood flow characteristics

Type and screen or type and cross if significant blood loss is anticipated Other labs and tests as necessary depending on the general health of the patient

o Electrocardiogram - A general requirement if the patient has a history of cardiac disease

o Chest radiograph - To rule out pulmonary metastases in cancer reconstruction

o Pulmonary function tests - Patients with severe pulmonary dysfunction may not tolerate a prolonged operation under general anesthesia

o Coagulation studies - This is important to rule out either coagulopathy or a hypercoagulable state

o Electrolytes - Depending on previous medical history o Renal panel - Depending on previous medical history o Liver panel - Depending on previous medical history

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Successful free tissue transfer begins with proper patient selection. There are a number of patient characteristics that can additively increase the likelihood of failure. Diabetes and other systemic illnesses such as hypercholesterolemia can increase the likelihood of microvascular disease and muscular artery atherosclerosis. In addition, poorly controlled diabetes often impairs proper wound healing. Microvascular disease delays healing and neovascularization between the flap and surrounding tissues. It also increases the likelihood of infection with potential flap loss. Atherosclerosis is most problematic when using lower extremity vasculature such as in fibula flaps and the dorsalis pedis flap. Atherosclerotic disease is less problematic with upper extremity, truncal, and visceral vasculature. Within the head and neck, the facial artery is the peripheral branch of the external carotid system, which is most susceptible to atherosclerotic plaques. Still, this vessel is frequently used as a recipient vessel for anastomosis because of its close proximity and good vessel caliber. It should also be taken into account that patients who have had previous radiation therapy are at increased risk of atherosclerosis.

Patients with existing cardiac disease have increased morbidity and mortality with any large operation-requiring anesthesia. This is particularly true in the treatment of head and neck cancer where surgeries run for extended periods of time. Free flaps significantly increase the operating time for these surgeries (4 to 6 hours), although at many institutions this is no longer an issue secondary to the development of an increased number of distant donor sites that allow for a two-team approach. Postoperative cardiac complications pose a major threat to the viability of free-flaps, which are dependent on adequate blood flow. Cardiac and anesthetic specialists should optimize cardiac function in these patients in the perioperative period through invasive monitoring and appropriate medical management.

Decreased flap perfusion, hypercoagulation, and impaired wound healing have been associated with smoking. Thus, smoking should be discontinued for at least one week prior to surgery and forbidden in the postoperative period. Obesity may also decrease the success of free tissue transfer as the increased adipose tissue makes dissection of the vascular pedicle more difficult and interferes with the microvascular anastomosis, insetting, and flap tailoring after transfer.

Collagen vascular diseases are another relative contraindication to free flap transfer. These diseases can compromise the cardiovascular system, particularly in individuals with an active vasculitic process. These individuals have a much higher incidence of anastomotic thrombosis and thus may not be candidates for free tissue transfer.

Coagulopathies are another relative contraindication. Most are secondary to coumadin therapy for those who have a history of cerebrovascular disease, deep vein thrombosis, or mechanical heart valves.

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As such, most can be modulated with cessation of the coumadin, and the use of replacement blood products such as fresh frozen plasma. However, patients with a history of ethanol-induced hepatic insufficiency will often have a less easily controlled coagulopathy and the risk for severe intraoperative bleeding, postoperative hematoma, and consequent risks to the vascular anastomosis are greater. The only absolute contraindication for free tissue transfer is a hypercoagulable state. In these persons (i.e. polycythemia, sickle cell disease), the risk of anastomotic thrombosis is too great to justify the use of free tissue transfer.

Imaging studies

In lower extremity reconstruction, angiography is useful to determine the zone of vessel injury and the location of recipient vessels. Newer techniques such as magnetic resonance angiography and CT angiography eventually may be used routinely for evaluation of vessels.

Lower extremity angiography is indicated prior to free fibula harvest in patients who have peripheral vascular disease and/or absent foot pulses.

CT scans of the head and neck may be useful in planning regions of tumor excision prior to definitive free flap reconstruction of cancer.

Final pathology results to determine negative margins in tumor excision is necessary to prevent free flap transfer prior to adequate surgical excision

2. Choice of flap

Once the extent of the defect is accurately defined and characterized, donor sites are evaluated and the most appropriate and reliable flap is selected.

The extent of potential oral cavity defect is assessed by estimating the amount of soft tissue and measuring the amount of bone to be excised.

In case of SCC, soft tissue cover should take precedence over bony restitution because oral cavity function is more dependent on tongue mobility and function.

After total or partial glossectomy, the goal is to achieve adequate bulk yo prevent aspiration and preserve the larynx. in such cases- Rectus abdominus (vertical or transverse) , Latissmus dosi, scapular flap.

Following mandibular segmental resection, composite flaps – Fibula, radia forearm,

3. Patient consent

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Informed consent for these major operations should include the following:

Bleeding and need for transfusions Need for anticoagulation Infection Nerve damage Stiff joints Vascular compromise if extremities are operated on Need for emergency re-operation Partial or total flap loss Scar Need for revision operations Major anesthetic complications including myocardial infarction, stroke,

and death

4. Attention to intraoperative details

Will be dealt with later..

5. Vigilant care postoperatively

Also will be dealt with later..

Techniques of Microvascular surgery - Pre op & Intra op considerations.

Pre op considerations.

1. The operating microscope

The modern microscope with its refined optics and wide range of magnification enable surgeon to carry out techniques that were otherwise impossible to be done with naked eye.

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Structures < 3mm

1921 – Nylen from Sweden first operating microscope for labrythine fistulas and fenestrations in rabbits. 10 to 15 X

A monocular microscope later developed by Nylen in 1954, 1972 with a magnification with 235 X

1n 1921, Holmgren, chief of Nylen introduced Zeiss binocular to otology

In 1946, Peritt in US used microscope in ophthalmology

Jacobson and Saurez in 1960 used microscope in peripheral nerve injury

2. Magnifying loupes

These are more practical than an operating microscope especially for microdissection.

Preliminary dissection is carried out till the stage is reached when only microscope can provide needed resolution and control.

3. Micro-instruments

Adequate miniaturization of instrument and sutures are needed

Micro-instruments – simple, glare free, few in number

Require careful maintenance – silicone or rubber tubes for protection of fine tips

Non toothed forceps should be of good quality and resistant to staining and rusting. Tips – fine, smooth, uniform and jaws meet precisely.

Scissors are spring operated with delicate sharp blades. Westcott scissors with straight or curved blades with sharp or slightly rounded tips are useful to section or trim vessel ends.

Spring loaded needle holders, approximately 6 inches lomg rest on the web b/n thumb & forefinger. It is held like a pencil and slowly rolled b/n index and middle fingers and thumb during motion of inserting sutures. Needle holders do not have locking mechanism as they can be traumatic to the delicate tissues

A 2 or 5 ml syringe with an attached 2-3 cm fine caliber silastic intercath is useful for irrigating the Microvascular field.

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A background of contrasting colour against which a fine suture is more easily seen and is useful for performing small anastomosis is employed

A millimeter ruler for easy measurement of vessel size is included. An ocular micrometer in the eye piece can be more convenient and more accurate.

4. Clamps

Small, light weight atraumatic vascular clamps play an important role in successful Microvascular anastomosis. Many variations in size and design are available.

They are gently applied across the vessel walls to be anastomosed as the surgeon looks through the microscope in order to minimize damage to the intimal lining of the vessel walls. Excessive pressure if applied is known to cause minimal damage as shown histologicallly. These are however not suitable for vessels < 1.5 mm and lymphatics.

5. Bipolar coagulator

It can be an invaluable aid in coagulating the small vessels during micro-dissection. It conducts current through the tips of jeweler’s forceps and can safely coagulate small branches near the main vessel.

6. Doppler monitors

These are instruments with microprobes that detect blood flow in vessels 1mm or less in size, below the skin and to map the course of blood flow in proposed Microvascular free flaps and to monitor microvascular free flaps.

7. Suction

Small amounts of blood in operative field can totally obscure the vision of surgeon. Small Fischer suction tube with a Zollner fine tip can be used. If suction is too powerful, it can damage an anastomosis.

The Weck cell micro-sponge or moist hydrocellulose sponge or gauze can also be used.

Van Beek designed a suction tube through a perforated background plate.

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8. Micro-sutures

The assessment of sutures that are satisfactory for microvascular repair depends on the size and consistency of the vessel to be anastomosed. The ideal needle for micro-suturing should be the same size as the micro suture itself, which is not as yet achieved.

High quality atraumatic microsutures of extremely small caliber are ideal. Nylon drawn into round, smooth, monofilament fibers of small caliber and high tensile strength is better than Prolene which has poor contrast and easily breaks down, has less surface tension, softer and adheres less to itself.

Intra op considerations

As part of the planning of the free flap transfer knowledge of the local vascular anatomy is essential with a clear idea of which vessels are likely to be used in the receiving site as well as their probable normality. A healthy vessel wall and an adequate pulse volume must be demonstrably present. In cases of previous irradiation or trauma, this becomes of paramount importance. the presence of infection in the operative area is an absolute contraindication to free tissue transfer

Ischemia time: It is the time which elapses between division of the axial vessels of the flap and the restoration of perfusion. To minimize its adverse effects, the operative sequence should be organized to reduce by maintaining the flow through the vascular pedicle of the flap until the last minute before transfer.

Vessels may be anastomosed by attaching the flap vessel to an opening made in the wall of the donor vessel in the recipient site. end-to-side anastomosis

Alternatively the donor vessel in the recipient site may be divided and anastomosis carried out end-to-end.

End to end anastomosis

It is the easiest, most reliable and widely followed procedure

Interrupted sutures

Carell s trifurcation technique as suggested in his Nobel prize winning paper in 1905

It is important to accurately oppose the vessel walls.

Sutures taken with equal full thickness bites of each vessel wall without picking up the opposing wall

Each suture with 3 throws and after division one end of the suture is left long to facilitate stabilization and manipulation of the vessel. These are regarded as stay sutures

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On the front wall the third suture should be placed equidistant from the first two sutures.

Regarding the back wall, the stay sutures (and vascular clamps) can be used to rotate the vessel to offer up the back wall to allow visualization for suturing. the technique is similar to the one explained already.

End to side anastomosis

The first step is to perform a venotomy / arteriotomy on the recipient vessel.

An opening the size of the donor vessel is made with a curved scissors which produce a round opening. or with a little more dexterity a diamond shaped opening with a straight scissors.

The stay sutures are placed across the opening 180º to each other. first the front wall sutured as described and then the stay sutures used to turn over to the back wall which is sutured likewise.(figs from Langdon )

Always it is important to check the patency of the sutured vessels after suturing. Strip test – 2 jeweller’s forceps (1 & 2) are used to expel the blood distal to the anastomosis. When the no.2 forceps is released blood flows across the anostomic site.

It is considered safe that if successful flow has been achieved in both vessels in the absence of complications such as tension or vascular kinking, it will be successful in the longer run.

But a better way to observe this is by observing for pulsation within the vessel distal to the anastomosis site as well as the venous outflow from the donor vein in case of an arterial anastomosis.

Venous patency can be assessed by removing the venous vascular clamps before removal of arterial clamps and observing engorgement of the donor vein.

With experience, once all clamps are removed, good venous flow can be assessed by observing the color of the vein which should be light blue rather than dark blue.

Final inset and Closure

It is important at the time of closure to ensure that the site of anastomosis or the vessels involved should be free of any drains. soft silicone drains are preferred. The skin overlying site of anastomosis should be marked to prevent inadvertent pressure application of straps, bands and dressings over it can be avoided in the post op nursing period. Also care to be taken while transferring the patient from OT to avoid unnecessary movements of the head which could put unnecessary strain at the site of anastomosis.

Post op Considerations

Maintenance of normal blood pressure and prevent vasopressive drugs.

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Maintain adequate blood volume with use of crystalloid and colloid solutions and a haemoglobin level of approx 10.5 /dl is ideal as at this level oxygen carrying capacity and blood viscosity is appropriately balance.

The patient should be kept warm and the circulation hyperdynamic. Use of an heated-air over blanket is extremely useful in maintaining body temperature.

Pain and cold are powerful stimuli for release of endogenous catecholamines which can cause vascular spasm of either donor or recipient vessels.

Anticoagulants – Antiplatelet agents not necessary. I.V. low dose heparin is routinely used to avoid thrombo-embolic disease and has no adverse effect on the success of reconstruction.

Microvascular monitoring

24 – 72 hours post op monitoring is warranted

post op monitoring of posteriorly placed tissues and in case of free bone transfer where the flap has no cutaneous component. Doppler devices can be used.

visually the flap becomes deathly white in case of failure of arterial supply but becomes dark, engorged, tense and edematous when venous outflow is obstructed

Mechanism and timing of thrombus formation(added later)

Patency of an anastomosis can be tested in various ways. Venous patency is easily evident when the vessel is translucent. Direct observation of expansive pulsation is a reliable indicator of vessel patency, whereas longitudinal pulsation usually indicates a partial or complete obstruction. The Doppler ultrasound can be also used as an indicator of vessel patency. The chances of thrombosis are greatest at the site of anastomosis 15-20 minutes following closure. Therefore, it is customary to observe the anastomosis and test its patency during this period of time. If partial obstruction occurs, gently squeezing the vessel with forceps or massaging the vessel may break up the thrombus. A complete thrombus necessitates resection of the damaged segment and reanastomosis.

Vascular thrombosis is most commonly due to technical error in suture placement or pedicle kinking, or the use of a vessel with a damaged intimal layer. Thrombosis at the venous anastomosis accounts for 9 of 10 thromboses and is more likely due to the slower venous flow and relative stasis of blood at this site. After the first 20 minutes, the next critical period is within the first 3 postoperative days as 90% of vascular thromboses occur during this time. After this time, vascular thrombosis is more often associated with the late development of a hematoma, infection, or fistula. Although neovascularization may be complete in a short period of time in thin flaps, which have a large surface to volume ratio, thicker flaps may take several weeks before they are independent of their anastomosed blood supply.

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Postoperative medications

Using postoperative medications to inhibit clot formation at the anastomosis is controversial. Studies evaluating the efficacy of heparin, dextran, and aspirin have demonstrated that none is absolutely necessary for an uncomplicated anastomosis. However, the author prefers to run IV dextran-40 at 30 cm3/h for the first 12-24 hours, followed by oral Ecotrin 325 mg daily for 2-4 weeks.

Techniques to monitor the free flap depend on the tissue composition and location of the flap.

Specific monitoring techniques include evaluation of color1. capillary refill 2. turgor 3. surface temperature 4. presence of bleeding 5. skin graft adherence 6. Auditory assessment of blood flow.

Use of these techniques depends on whether the flap has a fasciocutaneous component, is covered with a skin graft, or is buried and inaccessible to visual assessment.

Surface characteristics

For the fasciocutaneous, musculocutaneous, and osteocutaneous flaps, surface characteristics are important.Normal flap color is similar to that of the recipient site. Normal capillary refill is 1-2 seconds. Surface temperature of the flap can be monitored using adhesive strips (for an accurate number) or the back of the hand (to provide a comparative assessment with the surrounding skin). Problems with arterial inflow are suggested when the flap is pale relative to the donor site, cool to the touch, and when capillary refill is slow or absent. Problems with venous outflow are suggested when the flap is congested, edematous, and when capillary refill is brisk and rapid. Color and appearance of congested flaps can vary depending on whether the congestion is mild or severe and ranges from a prominent pinkish hue to a dark bluish purple color. Surface Doppler assessment for flaps with a fasciocutaneous component may yield a false positive result by picking up signals from surrounding or deep blood vessels. Characteristics of blood from the flap following pinprick also can provide clues. Dark venous blood suggests venous occlusion, and absence of bleeding suggests arterial occlusion.

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Muscle flaps with skin grafts

The muscle flap covered with a skin graft often is easier to monitor. Surface temperature and capillary refill generally are not used in these situations; however, color, turgor, skin graft adherence, and Doppler signals are useful. Signs of venous outflow obstruction include flap congestion and edema, dark blood on pinprick, and loss of the venous Doppler signal. Signs of arterial occlusion include a flat and pale flap, poor skin graft adherence to the flap, no bleeding on pinprick, and loss of the arterial signal.

Deep or buried flap

The most difficult flap to monitor is the deep or buried flap (eg, fibula flap without a skin paddle). Surface Doppler signals often are unreliable. In these situations, placing the temporary implantable Doppler probe adjacent to the artery and vein at the time of operation is useful.

Salvage procedures for the failing flap

Monitoring the free flap during the postoperative phase is critical to ensure flap survival. When recognized early and managed promptly (<6 h), compromised flaps have a 75% salvage rate when taken back to the operating room. Studies have demonstrated that venous thrombosis alone is more common than either arterial or combined arterial and venous thrombosis. Thrombosis typically occurs within the first 2 days in 80% of patients. Thus, all personnel responsible for flap monitoring must be knowledgeable of the appearance and evaluation of the healthy and compromised flap.

Following recognition of flap compromise, immediately transport the patient to the operating room for exploration.

Administer intravenous heparin. Inspect the vascular pedicle for kinks and compression and

assess the patency of the anastomosis. Identification of thrombus requires separation of the vessels at

the anastomosis. Perform embolectomy, proximally and distally, using a

number 2 or 3 Fogarty catheter. Administer intraarterial streptokinase or urokinase at a dose of

50,000-100,000 U as necessary. Following restoration of adequate circulation, inset the flap

again and maintain the patient on intravenous heparin or dextran.

Failure to restore adequate circulation requires flap removal. The use of medicinal leeches, Hirudo medicinalis, has

demonstrated value in the treatment of venous congestion. This option is indicated when arterial inflow is adequate but

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venous outflow is poor. The mechanism of action depends on the active agent, hirudin, which is a selective thrombin inhibitor. Apply the leech to the surface of the flap and surround it with a corral of moistened gauze to prevent leech migration. Prophylactic antibiotics are recommended to prevent infection with Aeromonas hydrophila.

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Free flaps

The ability to transplant living tissue from one region of the body to another greatly has facilitated the reconstruction of complex defects. Although the technique of free tissue transfer by anastomosing vessels of small caliber using the operating microscope is complex and time consuming, the numerous advantages include

stable wound coverage, improved aesthetic and functional outcome, and minimal donor site morbidity

Free tissue transfer currently is used for the reconstruction of complex defects and disorders throughout the body. As with all techniques in plastic surgery, adhere to the basic principles and concepts of reconstruction.

The “reconstructive ladder” that all plastic surgeons learn is based on performing the simplest procedure to correct a particular condition. Although these principles are valuable and almost always justified, aesthetic and functional considerations occasionally warrant performing more complicated procedures. These considerations are most evident following ablative procedures for cancer, for restoration of function, and for aesthetic appearance.

Rationale of free flaps

In general, the free vascularized transfer is feasible with all tissues, which are supplied by a defined and reliable arterio-venous system and which do not leave unacceptable functional deficits if removed for reconstruction at a distant site of the body. in this manner, many of the flaps previously used as pedicled flaps, have now been used as vascularized flaps.

Preoperative considerations

Preoperative preparation is an essential component of the successful free tissue transfer. Preoperative evaluation includes analysis of the recipient site, consideration of available donor sites, and the clinical status of the patient.

Analysis of recipient and donor sites

Factors related to the recipient site include the

1. size, depth, and location of the defect2. quality of the surrounding tissue3. exposure of vital structures or hardware

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4. zone of injury5. presence of bacterial colonization or infection 6. previous irradiation7. functional and aesthetic considerations

Factors related to the donor site include

1. appropriate tissue match2. length of the vascular pedicle 3. caliber of recipient vessels 4. surface area, volume, and thickness of the flap 5. donor site morbidities.

Flaps with a short vascular pedicle requiring a vein graft and flaps with a bone component are associated with an increased rate of flap loss in some clinical series.

Clinical status of the patient

The clinical status of the patient depends on a variety of factors that also may impact the free flap. These include

1. advanced age 2. nutritional status 3. tobacco usage 4. presence of underlying comorbidities (eg, diabetes mellitus,

cardiopulmonary disease, peripheral vascular disease).

Although advanced age and tobacco use are not contraindications to free-flap operations, poor nutritional status can impede wound healing and recovery. Patients with poorly controlled diabetes mellitus and peripheral vascular disease require adequate glucose control and may require revascularization procedures prior to free tissue transfer. Surgical clearance by a medical physician is recommended for patients with multiple medical problems.

Donor tissues

Specific donor tissues are variable and are chosen based on recipient site requirements. Available tissues include muscle, musculocutaneous, fasciocutaneous, osteocutaneous, and bone flaps. In general, free muscle flaps are indicated for soft tissue coverage of bone and synthetic materials and to obliterate a large dead space.

Innervated muscle flaps are useful for facial reanimation operations and for upper extremity reconstruction.

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Musculocutaneous free flaps are useful for large defects requiring aesthetic contouring.

Fasciocutaneous flaps permit tendon gliding in the extremities and provide excellent contouring of the head and neck.

Osseous and osteocutaneous free flaps are useful for segmental bone defects involving the mandible and extremities.

For the irradiated wound, free tissue transfer is recommended and has been demonstrated to be safe and well tolerated, with no increased rate of partial or total free flap loss.

Timing

In the trauma patient, the timing of free-flap reconstruction is of prime importance. Free tissue transfer within 3-7 days allows time for adequate debridement, declaration of the zone of injury, and prevention of chronic bacterial colonization. Immediate free-flap reconstruction often is preferred for the acquired operative wound, especially in the presence of vital structures and hardware and for aesthetic and functional considerations. Consider delayed free-flap reconstruction when oncologic concerns are present.

Other considerations

Other factors requiring consideration include choice of anesthesia and patient position for the operation. Anesthetic options include general, spinal, or epidural and depend on the nature and location of the reconstruction. General anesthesia is preferred for most patients and can be administered via oral, nasal, or tracheal routes. Oral intubation is preferred for trunk and extremity reconstructions; however, nasal and tracheal intubations are preferred for most reconstructions involving the head and neck. Spinal anesthesia occasionally is used for lower extremity free flaps and has the advantage of providing a transient sympathectomy that promotes vascular dilation. Epidural anesthesia primarily is used for postoperative pain management. Patient positioning may require an inflatable beanbag, Wilson frame, or Mayfield headrest. The inflatable beanbag is useful in placing the patient in the lateral decubitus position (eg, when harvesting a latissimus dorsi flap). The Wilson frame or chest rolls benefits patients in the prone position, allowing chest expansion during general anesthesia.

Intra operative considerations

The operative portion of the free tissue transfer requires absolute attention to detail. Numerous factors must be considered to predictably obtain a successful outcome. These include use of

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appropriate medications and solutions, properly functioning equipment and instruments, anastomotic issues, and flap insetting.

Intraoperative medications

Required medications include intravenous (IV) antibiotics, antibiotic solution for wound irrigation, IV heparin administered 5 minutes prior to free flap harvest, 4% Xylocaine for topical vasodilatation, and heparin solution (100 U/cm3) for luminal irrigation. Studies evaluating the effects of various intraoperative anticoagulants have demonstrated that the flap loss rate is lower in patients receiving a heparin bolus of 5000 U only or a heparin bolus of 2000-3000 U followed by postoperative infusion. Low-dose heparin does not increase the risk of hematoma or postoperative bleeding.Other medications that may be used include Decadron 4-8 mg to reduce edema and swelling (especially for reconstructions of the head), papaverine as an alternate vasodilator, and streptokinase or urokinase for lysis of intraluminal thrombus.

Anastomoses issues

A variety of issues are related to the anastomoses.

The nursing staff and primary surgeon must inspect the micro-instruments and microscope to ensure proper function.

The diameter of the artery and vein, both for the flap and recipient site, should be 1-3 mm to permit adequate inflow and outflow.

Blood vessels must be free of all loose adventitia, and the vascular approximation must be tension free. Acland clamps should facilitate vascular exposure and manipulation.

Complete the anastomosis using either a vascular coupler or sew it by hand. The author prefers to hand sew; however, the coupler has demonstrated its usefulness, especially for venous anastomoses, in improving patency and decreasing operative time.

Complete the hand-sewn anastomosis using 8-0, 9-0, or 10-0 nylon sutures placed in an interrupted fashion. In general, anastomose larger caliber vessels (2-3 mm) using 8-0 or 9-0 sutures and smaller caliber vessels (1-2 mm) using 9-0 or 10-0 sutures.

Using operative loupes rather than a microscope has been reported; a minimum of 3.5-power magnification is recommended.

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Flap ischemia time does not contribute to flap demise if the ischemia time is less than 3 hours or less than the time for no-reflow to occur.

Following completion of the anastomoses, inset the flap. Inspect the vascular pedicle for kinks, twists, compression, and to ensure that no tension is present across the anastomosis. Inspect the distal aspect of the flap for arterial and venous bleeding. Use a Doppler unit to assess arterial and venous flow through the pedicle and in the flap. Finally, recheck the vascular pedicle to ensure a gentle, nontwisting course of the vessels before completing the final suturing of the flap, especially if the patient's position has been changed.

Place a closed suction drain under the flap away from the anastomoses and suture the flap in position.

Free flaps

Reconstruction after head and neck cancer extirpative surgery frequently requires replacement of bone and soft tissue to provide the most functional and aesthetic result. Microvascular free flaps have the advantage of providing healthy, vascularized, non-irradiated tissue for recipient sites that may have been compromised by surgery, radiation, chemotherapy, or a combination of the three.

Radial forearm free flap.

History of the Procedure: Since its introduction by Yang et al in 1978, the radial forearm free flap (RFFF) has become a workhorse flap in head and neck reconstruction. The RFFF's popularity has stemmed from its superior soft tissue characteristics, which offer a large amount of thin pliable skin that conforms well to the native contours of the recipient site. The flap is relatively easy to harvest and can be dissected at the same time as the extirpative procedure. It has a long vascular pedicle with large-caliber vessels, predictable innervation for reestablishing local sensation, and minimal donor site morbidity. It is particularly useful in the oral cavity. Two issues have been largely to blame for limiting surgeons' consideration of the OCRFFF as an option for single-stage reconstruction of composite defects in the head and neck: inadequacy of available bone and potential for morbidity.

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Various patterns of vascular pedicles for musculocutaneous flaps

Muscle and musculocutaneous flaps are characterized by their vascular patterns. They have a dominant vascular pedicle that supplies the named muscle and the overlying skin secondary to perforating branches of the dominant vessel. The 5 different vascular patterns of the muscle and musculocutaneous flaps are as follows:

I. Single vascular pedicle (eg, tensor fascia lata; see Image 1)

II. Dominant vascular pedicle and minor vascular pedicle (eg, gracilis; see Image 2)

III. Two dominant pedicles (eg, gluteus maximus; see Image 3)

IV. Segmental vascular pedicles (eg, sartorius; see Image 4)

V. Single dominant vascular pedicle and secondary segmental pedicles

Difference b/n flap and graft

Often the concepts of a flap and a graft are confused. In an effort to sort between the two terms, their definitions are listed below.

Flap - A segment of tissue transplanted to a defect while maintaining its own and/or original blood supply

Graft - A segment of tissue transplanted to a defect when the nutrients for graft survival depend on the recipient site blood supply and not the donor blood supply

Pathophysiology of flaps

Flaps work because of eventual vascular connections between the flap with its nutrient vessels and the recipient site. Approximately 4 weeks are required before homeostasis returns after a tissue transfer. Below are chronologic changes of a flap and the recipient site after elevation and transfer.

After 10-24 hours - Decreased arterial supply; congestion and edema; dilation of arterioles and capillaries

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After 1-3 days - Increased number and quality of anastomoses between flap and recipient bed; increased number of small vessels in pedicle

After 3-7 days - Reorientation of vessels along the long axis of the flap; anastomoses created at 1-3 days now functionally significant

After 1 week - Circulation well established between flap and recipient bed

After 2 weeks - Continuous maturation of anastomoses After 3 weeks - Flap achieves 90% of its final circulation After 4 weeks - Vessels at definitive size; few remaining newly

formed vessels

New addition to complications of free flaps

Errors in judgment, technique, and patient treatment foster complication in muscle and musculocutaneous flap survival. Poor flap design is often a source of flap demise. For example, failure to recognize posttransfer tension and failure to recognize compromised flap blood supply after tissue elevation and transfer can risk flap viability. Both tension on a wound and impaired tissue perfusion represent general flap ischemia. With "reverse planning" (ie, preceding operative intervention with a mock transfer using a piece of fabric and rotating it from the donor site to the recipient site as would be done during the procedure), some technical complications can be intercepted.

Improper flap design (eg, failure to factor nutrition, obesity) leads to seroma formation, hematoma formation, superficial skin necrosis, and wound separation with eventual partial and/or complete flap loss. Seromas generally can be treated with a continuous pressure dressing to promote reabsorption. Conversely, dependent on surgeon preference, the fluid pocket can be actively aspirated with a needle or passively aspirated with a closed suction drainage system.

Intraoperative examination of the flap provides an early opportunity to optimize flap survival. At the time of surgery, the presence of a brisk, bright red blood flow from the distal edge of the flap is the only anatomic test helpful in determining flap viability. Again, the flap must provide adequate coverage under no tension. Keeping the skin edges moist to decrease depth of tissue loss and keeping the flap warm to prevent the vasoconstriction of hypothermia are techniques that can increase the chance of flap survival.

The primary cause of flap demise is not inadequate arterial inflow but rather venous insufficiency (ie, compromise of venous outflow). During venous congestion necrosis requires several days for definitive demarcation. Areas of concern are those that are bluish in color and that

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demonstrate a sluggish circulation. Because necrosis is a slow phenomenon, often the elapsed time allows for some revascularization from peripheral tissues at the recipient site. Therefore, instead of complete flap death there will be loss of tissue centrally where the revascularization is most challenged. If the warnings of imminent flap death are identified early, then simple maneuvers like taking out sutures/staples at areas of tension and freeing congestion with periodic needle sticks may curb necrosis. Frequently, partial flap salvage is possible. If there is definitive loss of tissue in an area of the flap, then the affected region requires sharp debridement with subsequent local wound care.

Complications such as hematoma formation and complete flap loss may require second-look operative intervention, particularly if persistent bleeding and signs of infection appear, respectively. Complete flap loss is rare and proper flap design and planning are the keys to successful muscle flap transfer. Korean researchers at the Wonju College of Medicine conclude, based on rodent models, that prostaglandin E1 may increase flap survival. Pending further in vivo success, prostaglandin E1 use could be part of a future musculocutaneous flap protocol.

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