Management of facial burns

21 Management of facial burns






Introduction


Our face is our window to the world, and its reflection our self-image. The goal remains very straightforward and simple on paper: restore normal facial appearance, aesthetically acceptable anatomical symmetry, and the ability to express emotion through facial animation. However, the attainment of this goal presents a very significant challenge to those caring for the patient. Assessing and treating facial burns continues to be complex and controversial. Management of the acute burns is as relevant as the operations to correct deformity and dysfunction suffered from the initial injury.


Annually, there are more than 500 000 burns treated in the US. A total of 40 000 patients are hospitalized and 25 000 are hospitalized in specialized burn centers. There are 4000 fire and burn deaths per year in the US. The most common causes of burn injury are fire/flame (46%) and scald (32%), with scald burns being a particular problem in children.1


An estimated over 50% of burn injuries involve the head and neck region. This most likely is related to the exposed facial skin and, when one’s clothes are burning, the hot gases travel upward. In the presence of fire, one instinctively protects one’s face. As a result, when one sustains a severe facial burn, it frequently is associated with extensive total body burns. During the acute burn period, this means that the patient is frequently critically ill with extensive burns elsewhere on the body. During the rehabilitation and reconstruction phase, extensive burns reduce normal skin for reconstruction donor sites.


Everyone’s face is exceedingly distinctive, consisting physically of shapes, contours and skin characteristics that provide an identity for each person. This is threatened and frequently destroyed by a severe burn injury. As the face provides one’s identity and is the medium through which everyone interacts socially, it becomes exceedingly important to the individual. Even relatively minor deformity can have a major psychological and social impact.



History


From topical dressings to free tissue transfer, the history of the management of facial burns and facial burn reconstructive surgery spans a widely diverse and interesting history of development.


The history of facial burn wound treatment parallels that of burns elsewhere on the body, with patient appearance being a relatively modern concern. Burn injuries were first described in the Ebers papyrus (1500 bc), which describes a delicate mixture of cattle dung and black mud for a burn dressing. Through the centuries that followed, any physician worthy of note had a favorite remedy for the relief of burn pain and suffering.


In the 20th century, before the advent of topical antibiotics, facial burns were occluded with either dry or saline moistened dressings, or they were exposed and allowed to dry. Frequently, the eschar was allowed to gradually slough by the action of bacterial fibrinolysins exposing granulation tissue that was skin grafted. Debridement was very conservative, and the sub-eschar colonization was acceptable in the face given its excellent blood supply. Development of topical antibiotics in the latter half of the 20th century resulted in delayed eschar slough, and coincided with the popularity of early excision and skin grafting. This led to more emphasis on diagnosis of burn depth and direct excision of facial burn wounds when the diagnosis indicated.


Currently, the acute treatment of facial burns emphasizes the diagnosis of depth of burn trying to get an early diagnosis using diagnostic aids such as the scanning laser Doppler, or, at least, making a diagnosis based on the appearance of the wound within 2 weeks after injury. Surgical treatment emphasizes the importance of the plastic surgical principles that have evolved from facial reconstruction and can involve new devices such as dermal substitutes.


Reconstruction of the burn-scarred face has quite naturally followed the development of plastic surgery. Some of the earliest procedures are based on the transplantation of flaps from adjacent tissue or by successive migration from more distant sites. Originally illustrated in the Sushruta Samhita around the 6th century bc, the first such procedure made popular was for nasal reconstruction. Originally attributed in Europe to Antonio Branca (Sicily) and illustrated by Heinrich von Pfolspeundt in his 1460 work Buch der Bundth-Ertznei; Gasparo Taglicozzi (Bologna) studied this work and in the 1500s wrote his decisive work De Curtorum Chirurgia per Insitionem Libri Duo. This brought the idea to European surgeons. However, it was not until 1794, when the procedure known as the ‘Indian Method’ was published in the Gentleman’s Magazine of Calcutta, that the ancient writings of the ‘Sushruta Samhita’ techniques were brought to academic knowledge. With it came the recognition of the importance of the leaf-shaped axial-based forehead flap to reconstruct the nose. This and other pedicled flaps were invented and used in facial reconstruction during the first half of the 19th century.


Critical to further development of plastic surgery was the introduction of free skin grafts into surgical repair. Based on the classic experiments of Baronio, published in 1805, Reverdin first described the successful autotransplantation of small epidermal grafts in 1869. Ollier would improve on Reverdin’s small grafts by using continuous sheets of skin in 1872. These were enthusiastically adapted to eye surgery, where Wolfe soon found that full-thickness free skin grafts provided more reproducibly long-lasting ectropion repair.


Thus, by the beginning of the 20th century, two fundamental principles formed the basis of plastic surgery: (1) the transplantation of pedicled flaps; and (2) free transplantation of tissue from distant sites.


The further development of plastic surgery was hugely stimulated by the challenges presented by injuries, largely facial, in the great wars of the 20th century. In the First World War, facial injuries were most commonly related to missile trauma with a few major burns. The parachute had not been invented, so a burn injury in the air meant almost certain death.


Sir Harold Gillies, an otolaryngologist now considered to be the father of modern plastic surgery, was in charge of the facial injuries unit at the Queen Mary’s Hospital in Sidcup, England during and after the First World War. Gillies and his colleagues had ample opportunity to use and further refine established techniques, as well as invent and elaborate on many more. These included treatment with ‘waltzing’ or tubed pedicled flaps. Walter Yeo, a sailor injured at the Battle of Jutland, is assumed to be the first person with severe facial burns to benefit from tubed pedicle facial reconstruction in 1917. Subsequently, many others with facial burn scars were treated using these new techniques.


The development of the parachute subsequently led to an increasing number of airmen who parachuted to safety after sustaining severe burn injuries in their burning planes in the Second World War. These injuries along with burns from other war-related explosions provided the first large experience with facial burn injuries. In 1930, Gillies invited his cousin, Sir Archibald McIndoe to join his practice. McIndoe continued and furthered the work of Gillies and, in 1941, following the Battle of Britain, while the real treatment of burns was still in its infancy, began his pioneering reconstructive operations on facial burn scars elaborating further principles specifically directed to the approach to facial burn scarring.2


Facial burn reconstruction was further developed with the pioneering work of John Marquis Converse and his psychologist colleague, Frances McGregor, who studied and elaborated on the importance of normal appearance with regard to quality of life and positive body image. This emphasis on normal appearance was laid down as the ultimate goal in facial restoration.


Although tissue expansion was first introduced by Neumann in 1957,3 Radovan popularized it with its use for breast reconstruction in the late 1970s and early 1980s.4 In burn reconstruction, expanded advancement flaps began being used for resurfacing after excision of adjacent burn scars. The idea of expanding normal skin to provide more donor site for burn reconstruction was introduced.5 Tissue expanded flaps were found to be more vascularized than normal skin, and flaps were found to survive for greater lengths.6,7 This ultimately led to increased availability of better suited skin for facial reconstruction, expanded free flaps and pre-fabricated flaps.


The 1970s saw the new development of microsurgical techniques allowing further development of autologous tissue transfers (free flaps) from one place on the body to another. Ultimately, this, along with the seminal work of Joseph Murray, a plastic surgeon who performed the first successful human kidney transplant in 1954, which subsequently led to a Nobel Prize in Physiology of Medicine in 1990 for his work on organ and cell transplantation, would lead to the first allotransplantation of the face in 2005.


Currently, new techniques continue to be developed and tested to improve reconstruction after facial burn injury. Stem cell research gives some promise of growing new facial structures.



Basic science


Burn injury primarily consists of damage to the skin and its immediately underlying tissues as a result of physical trauma. The most common physical trauma is thermal in nature. Essentially, the heat energy kills living cells in the tissues and denatures the proteins that make up the tissue that dies. This energy could be from fire and explosions, hot water and steam in the case of scalds, or contact with hot objects. The physical damage can be inflicted through a chemical reaction of some substances such as acids and alkalis with the skin. Electrical energy, converted to heat by the resistance imposed by the skin, and by transmission through the skin can damage the skin and the underlying tissues through which the high voltage electricity passes.


The damage to the skin is a function of the amount of heat energy transferred to the skin. An agent of very high temperature (i.e., energy) can cause the same amount of damage as a much lower temperature agent applied for a longer period of time.


The degree of tissue damage is classified by the depth of the damage to the skin and the underlying tissues (Fig. 21.1). Damage to the epidermal layer alone is described as an epidermal burn scientifically, and a first-degree burn in common usage. An example of a first-degree burn is typical sunburn. An epidermal burn heals by sloughing the dead epidermal cells with immediate regrowth of new cells.



With greater energy transfer, not only are the epidermal cells lost, but the underlying dermis is damaged to varying depths. This damage consists of the denaturing of the dermal collagen, and thrombosis and destruction of the blood vessels within the dermis. The denatured collagen stays in place, and changes colors from pink to white to black depending on the number of remaining viable capillaries remaining close to the surface of the dermis. A superficial dermal injury consists of the epidermis coming off as a blister leaving a pink collagen surface due to the persistence of patent blood vessels close to the surface. A mid-dermal injury causes the remaining dermis to become increasingly pale, and a deep dermal injury causes the remaining dermis to be white in color.


Corresponding damage to the nerves within the dermis results in progressively less and less sensibility of the surface of the wound. Very superficial dermal burn wounds are very painful to contact because of the nerves at the exposed dermal wound surface. The dermal wound becomes more anesthetic as the depth of injury is greater. Although the dermal surface becomes anesthetic, the burns are still painful because the nerves are still injured at some level within the dermis.


A dermal injury heals by one of two mechanisms. Superficial injuries leave enough epidermal accessory structures such as hair follicles and sweat glands to provide epidermal cells for re-epithelialization of the dermal surface. Superficial injuries will usually re-epithelialize within 2–3 weeks if enough of the epidermal accessory structures are present. Superficial dermal injuries therefore may heal with some change in pigmentation of the new epithelium, but without burn scarring.


With deeper injuries, there are fewer epidermal accessory structures, and the wound heals by development of scar tissue and contraction mediated by fibroblasts and myofibroblasts, respectively. These cells migrate into the burn wound during the 1st week after injury, and proliferate in the granulation tissue that forms if re-epithelialization does not take place. It is, therefore, the deep dermal and deeper burn injuries that heal with burn scarring and burn scar contracture.


When the amount of energy transferred is so great that the full-thickness of the skin is destroyed, the appearance of the dermis can vary from white to cherry-red from capillary thrombosis to black from charring. Left alone, the dead dermis would separate from the underlying wound and it would go on to heal by scar formation and wound contraction.


Scientifically, ‘second-degree’ burns are all dermal injuries, both superficial and deep, and full-thickness burns are technically ‘third-degree’ burns. However, in common usage, ‘second-degree’ refers to the superficial burns that will heal by re-epithelialization within 2–3 weeks, and ‘third-degree’ refers to those deeper burns that will not. For the burn surgeon, the important diagnosis is whether the burn will heal by re-epithelialization and not require excision and grafting to prevent burn scarring and contracture. Therefore, the most useful terminology in diagnose of a burn is either “superficial” or “deep”, which corresponds most closely to the common usage of second-degree and third-degree.


Without intervention, deep facial burns heal by scarring and contraction. If the wound does not epithelialize in 2–3 weeks, fibroblasts and myofibroblasts migrate into the wound and lay down collagen and cause the wound to contract. The excess collagen becomes hypertrophic burn scar: the erythematous, thick, exuberant scar characteristic of any open wound that heals secondarily.


All scars, even primarily closed wound scars, contract. Contracted scars that limit mobility of joints or deform mobile structures, particularly of the face, are called contractures. Contractures of the neck are extrinsic to the face, but the face is affected by pulling forces from the neck transmitted to the mobile facial structures just as and frequently in conjunction with the intrinsic contractures represented by the scars adjacent to and deforming the mobile facial structures.



Diagnosis: determination of depth of burn


The most critical determination that the acute burn surgeon makes is whether the burn is superficial or deep because it determines whether the burn injury requires surgical intervention. A superficial burn will heal with minimal scarring, and a deep burn will heal with scarring and burn scar contracture causing significant facial distortion.


Therefore the diagnosis of burn depth is critical to determine what to do to get the best outcome for the patient’s facial burn injury. Generally, this diagnosis can be made by examination of the wound for color, sensitivity to touch, and other such characteristics. The most difficult diagnosis is that of a mid-dermal injury. This injury may or may not have enough epidermal accessory structures to allow the wound to re-epithelialize within 2–3 weeks. These mid-dermal burns are often termed ‘indeterminate.’ The decision to excise and graft these is frequently deferred hoping that the wound will heal within 3 weeks without scarring, knowing that excision and grafting will cause a definite change in facial appearance.


Cole et al. have proposed that the decision to operate on indeterminate facial dermal burns be made at approximately 10 days, and based on the best clinical judgment, excise if indicated and graft with thick split-thickness skin graft.8


Recently the scanning laser Doppler has been shown to help with the diagnosis in indeterminate dermal burns.911 This device determines the relative amount of blood flow in the superficial burn wound by reading the change in frequency of laser light caused by the movement of blood cells within the wound as it scans the surface of the wound. The color and numerical flux readings correspond to the likelihood of the burn wound healing within the 2–3 weeks window consistent with healing by re-epithelialization and minimal or no scarring.



Treatment of acute facial burns


Treatment of the acute facial burn injury is based on the diagnosis of the level of burn injury to both the face and the rest of the patient’s body. Severe facial burn injuries frequently occur in the setting of a critically large burn injury to the rest of the patient, and critical care and saving the patient’s life is often the first priority.


Because of the high degree of vascularization of the facial skin, infection of facial burn wounds is less likely than burns in other anatomic areas. This allows for some delay in making critical decisions regarding excision and grafting of facial burns. For management of the nonfacial burn, the idea of early tangential excision of deep dermal and full-thickness burns was championed by Janzekovic in the 1970s and continues to be the standard of care. Controversy still exists among surgeons regarding the early excision and grafting of facial burns. It is currently recommended to first treat a deep burn nonoperatively for 7–10 days with topical ointments, creams and local debridement.8,12 Some deep burns are obvious and may be excised and grafted earlier, but the vast majority are initially indeterminate.


A superficial burn injury will heal by re-epithelialization within two to three weeks if the wound heals without complication. Therefore the primary task of caring for a superficial facial burn injury is to prevent infection or any other problems that might interfere with normal re-epithelialization. Generally, superficial wounds epithelialize better in a moist environment. After initial cleansing, a mild antibiotic ointment is applied. The wound is gently cleansed twice-daily and the ointment reapplied. Every effort is made to avoid disrupting the migration of epithelial cells from the epidermal accessory structures across the surface of the wound. Although stronger antibiotic preparations are available, the author usually reserves these for evidence of active infection. I believe that treating the face open is safer than covering the face with an opaque dressing that prevents observation of the wound or allows for covert infection. Also any dressing that adheres to the wound through a dry interface reduces the pace of re-epithelialization as the fibrin bond between the dressing and the wound has to be broken down before the epithelial cells can migrate.


Deep facial burn injuries that will clearly not heal by epithelialization are doomed to heal with hypertrophic scarring and contractures if there is no surgical intervention. The standard surgical intervention is early excision and grafting in facial aesthetic units. This should be done as early as possible to minimize the migration of fibroblasts into the facial burn wound. Engrav recommends that a decision be made to excise and graft by 7–10 days post-injury, and have the face entirely grafted by 21 days. Initial excision of the wound is followed by sheet split-thickness skin allograft for 1 week. After that, the patient is returned to the operating room for closure with thick split-thickness autografts in the range of 0.018–0.021 inches in adults, and 0.008–0.012 inches in children placed in facial aesthetic units (Fig. 21.2).12



Another consideration is to use the acellular dermal matrix applied immediately after facial burn wound excision in aesthetic units, preferably after preparation with sheet allograft for up to 1 week, as above. When successful, the engrafted acellular dermal matrix is covered with split-thickness autograft which can yield facial skin that is superior to thick split-thickness autograft.



Eyes/eyelid


Generally, it is rare for a thermal injury to involve the globe. In the current literature, the reported incidence of ocular, intraocular, intraorbital foreign bodies (especially in explosions) and periorbital injury due to a burn ranges from 8% to 20% of all burn admissions.13 This is most likely due to a significant number of protective mechanisms that include a patient’s reflex protective movements of the head and arms, and more importantly, the blink reflex. It should be noted that one of the most commonly overlooked or missed foreign body is the contact lens.


All facial burns should have an ophthalmological exam on admission, preferably by an ophthalmologist.


Most commonly the problem is globe protection in burns that damage the eyelids. Various ointments, corneal shields, or protective contact lenses help shield the cornea from further injury. A temporary suture tarsorrhaphy may be useful and effective in aiding lid closure, but dehiscence and complications are common, making tarsorrhaphy use controversial.14 Tarsorrhaphy does not prevent wound contraction, and the basic principles of early excision and grafting, and ectropion release and tissue transplantation are primary.


In the very young patient population, eyelid closure for as little as 3 days places an infant at a high risk for blindness in the affected eye. Prolonged occlusion of the eye due to scar contracture leads to decreased retinal stimulation and subsequently poor neuronal development of the corresponding optic cortex.






Wound nonoperative management of facial burn scars


Once facial burn wounds are healed, there are a number of ways that facial scars can be minimized and maturation of the scars can be encouraged. The two primary mainstays of non-operative facial burn scar therapy are compression and contact with silicone gel. The silicone gel is thought to be effective in reducing scarring and in encouraging scar maturation.15,16 Compression tends to keep the hypertrophy of the scars in check.


Modern facial compression masks made with clear plastic with silicone interfaces provide patients with the benefit of both, and allow the patient’s face to be visible. This is an improvement over opaque elastic compression masks. Not only because they allow the patient’s face to be seen, but it allows individual pressure regulation on each of the hypertrophic scars by molding the plastic to the point of blanching of the scars.


Other important modes of nonoperative therapy during the ‘waiting period’ before surgery and in the postoperative period include splints to maintain scars to as optimal length as possible, massage to reduce swelling and help orient new collagen fibers in as normal orientation as possible, and occasionally steroid injections into smaller hypertrophic scars.


The use of pulsed dye laser therapy has been used to reduce the erythema and pruritus, and possibly improve scar remodelling in immature hypertrophic burn scars.17,18 Carbon dioxide fractional ablative laser therapy seems to have a positive effect on remodeling of mature burn scars sometimes many years after forming.19,20



Surgical management of the late effects of face, head and neck burns




General principles











Skin replacement should generally be performed in “aesthetic units” when subtotal or total unit defects are present

This avoids the aesthetically23 unfavorable appearance of a ‘patch.’ Complete excision of the entire aesthetic unit including residual normal skin should, at least, be considered if more than half the aesthetic unit is scar (Fig. 21.5).








An algorithmic approach to facial burn in reconstruction


Based on some of the above general principles, a framework (Fig. 21.7) evolved in the author’s practice allows for analyzing burn-related facial deformity and dysfunction, simplifying often complex problems, and guiding reconstructive surgical decisions.24,25



This algorithm first divides the facial aesthetic units into two broad categories: the peripheral aesthetic units of the forehead and bilateral cheeks, and the central aesthetic units of the eyelids, nose, upper lip, and the lower lip and chin aesthetic units. The peripheral facial aesthetic units are large units with minimal contour definition or structure and with relatively uniform skin characteristics. The central facial aesthetic units are smaller and have a higher degree of contour definition with intricate infrastructure and variations of skin characteristics.


Second, the algorithm analyzes the donor skin available for addition to or replacement of scarred or contracted facial skin. Specifically it asks the question whether there is donor site available locally in the ‘blush’ areas, the skin that is the most well-matched to replace facial skin. If this is not available, another path is taken in the decision tree.


This algorithm also incorporates all available techniques ranging from the simplest scar revision or excision and closure to complete replacement of the skin of the face. When scarred skin replacement is indicated, the algorithm recommends flap replacement of the peripheral aesthetic units as these areas are best reconstructed with broad, relatively featureless normal skin. However, when the replacement of the central facial aesthetic units is indicated, the infrastructure of the various contours needs to be reconstructed first, if necessary, and covered with a thin skin replacement usually in the form of full-thickness skin graft. As described in the literature, the expanded transposition flap26 is central in the algorithm when major facial deformities are addressed, as it provides both relatively thin flaps for the peripheral aesthetic units and full-thickness skin grafts for the central aesthetic units (Fig. 21.8).




Specific techniques



Scar replacement with local skin


The simplest example of scar replacement with local skin is simple scar excision with primary closure. This excises the burn scar and replaces it with a surgical scar that is designed to be better and, optimally, much less noticeable. Basic plastic surgery principles critical to obtaining the best results include: (1) performing the excision within relative adjacent tissue excess where possible; and (2) respecting resting skin tension lines (RSTL) in the planning of the new scar (Fig. 21.9).27 This repositions the new scar in a pre-existent anatomic line or contour such as the nasolabial crease, a hairline, or forehead wrinkles. It also imparts the least tension across the new scar minimizing the negative effects of tension on the scar.



Generally, there should be careful perpendicular incision through the skin to allow the most accurate re-approximation on closure of the new surgical wound. The optimal quality of the new scar is based on very careful anatomic re-approximation of the dermis and epidermis individually. The dermis is carefully re-approximated with absorbable sutures minimizing tension on surface sutures if they are used. It may make the accurate epidermal closure with surgical adhesive possible. Long-term it reduces the spreading of the new surgical scar.


The epidermis is carefully re-approximated with either surgical adhesive if the dermal sutures have brought the epidermal edges into anatomic alignment, or carefully placed sutures, with just enough tension to bring epidermal edges into anatomic alignment. If the epidermal edges overlap or are inverted, less favorable healing and suboptimal scars will form. The failure to close the epidermis results in a small open wound that will lead to increased scar formation and possible scar hypertrophy.



Serial excision


An extension of simple scar replacement by excision and primary closure is the technique of serial excision. When a scar is too large for excision and primary closure, only that portion of the scar that can be excised is, and the wound closed. The tension resulting from the first wound closure results in stretching of the surrounding skin (mechanical creep) and subsequent growth of the skin in response to the additional tension (biologic creep).28 The increase in the amount of surrounding skin that takes place over at least 3 or 4 months allows reoperation to excise the residual scar and close the resulting wound with the expanded normal surrounding skin. With the advent of tissue expansion to develop new skin adjacent to scars, serial excision is used much less, but should be considered if the serial excision is likely to take only two or, at most, three operations.



W-plasty


A W-plasty is the closure of a wound with multiple sawtooth lines that better approximate the resting skin tension lines (RSTL) of the facial skin (Fig. 21.10).29 The resulting lines more in-line with the RSTL become less noticeable. They also break up the linear nature of the unfavorable scar. A similar effect can occur if multiple small Z-plasties are placed in the linear skin closure. Technically, this technique can be exceedingly tedious. For W-plasty closure to be safe and effective, it needs to have limbs that are millimeters in length not to exceed 1 centimeter.



Feb 21, 2016 | Posted by in General Surgery | Comments Off on Management of facial burns
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