Medicine

منتدى جامعة تبوك - University Of Tabouk

2012-10-28T17:44:00.001-07:00

Rhytides

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Wrinkles (rhytides) are partly due to the contraction of underlying muscles and partly
due to a loss of elasticity, thus paralyzing the muscles with the toxin will reduce wrinkles.
The effect of toxin A on glabellar lines was noted incidentally when it was used
therapeutically for strabismus and torticollis, and it subsequently gained FDA
approval specifically for the treatment of glabellar lines. There is extensive use in cosmetic
surgery for a wide variety of indications, generally in an ‘off label’ manner, as
the indications for which the toxin is specifically licensed are fairly limited. Botulinum
toxin is also used in conditions such as dystonias (blepharospasm and hemifacial
spasm) or hyperhidrosis (excess sweating) in the axilla or face (Frey’s syndrome).
The commonest areas treated with botulinum toxin are shown in Table 1.
Other areas include: lower and upper eyelid wrinkles, circumoral lines (orbicularis
oris), nasal lines (nasalis), marionette folds or drooping labial commissure, chin folds
or cobblestone chin (mentalis), platysmal folds or turkey neck, and decollete folds.
The toxin (about 5U per site for Botox—more is needed in men due to greater
muscle mass) is injected into muscle; some use EMG guidance. The action is delayed
for 1–3 days because the toxin needs to be internalized and cleaved to take effect. The
effects peak at 1–2 weeks and last for 8–12 weeks (if boosted, effects may last up to
9 months and may be due in part to muscle atrophy).

Botulinum toxin

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Clostridium botulinum is a spore-forming, gram-positive, anaerobic rod. A number of
different potent neurotoxins (from A–G) are produced by different strains. The name
is derived from the Latin for sausage, botulus, due to its association with food poisoning
from bad sausages. Botulinum toxin A is the most widely studied; it is the easiest
to obtain from culture and was the first to be commercially prepared as Botox (Allergan).
The toxin, consisting of two subunits (light and heavy chains are connected by a
disulphide bridge), selectively inhibits acetylcholine release at the neuromuscular
junctions in a dose-dependent manner.

Treatment

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Surgical excision is the standard treatment. Randomized trials of excision margins are
lacking, but generally margins of 2 mm (for well-circumscribed lesions, particularly on
the face) to 5 mm (for lesions with indistinct margins) are recommended. Four millimetre
margins give a cure rate of 94–96% according to Zitelli.
Some areas such as the medical canthus, and external auditory alar base meatus
are more prone to incomplete excision as the tumour seems to extend deeper at these
locations; the usual explanation being that these areas are embryological fusion lines.
Note that only one-third of incompletely excised BCCs will show histological evidence
of residual tumour on further resection. Recurrent lesions tend to be more
aggressive in behaviour.
Mohs’ micrographic surgery (MMS)—in which successive layers are exised and the
base of the specimen is mapped out and examined histologically perioperatively—
may be most useful in complex lesions with indistinct borders and where tissue conservation
is important. It has the best reported cure rate of 99%.

Basal cell carcinoma

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Basal cell carcinoma (BCC) is the commonest human malignancy in Caucasians, it is
less common in those with pigmented skin. The incidence varies from over 1500 in
100 000 in Queensland, Australia, to 200–300 per 100 000 in the United Kingdom, and
2–3 per 100 000 in Hong Kong Chinese. There is a male predominance, but the incidence
in females is increasing.
The tumour arises in hair-bearing skin, particularly on the face where sun exposure
is the highest; over three-quarters arise on the face, one-quarter on the nose. The
lesion is generally slow-growing, but is locally destructive, hence the common name of
‘rodent ulcer’.
Despite their name, BCCs probably do not arise from the basal cells of the epidermis
but from the pluripotential cells in the epidermis; this is supported by the occasional
observation of appendigeal differentiation in these tumours. The typical
features are raised pearly edges and telangiectasia (small blood vessels) with or
without a central ulcer. Histologically, there are undifferentiated cells in nodules with
peripheral palisading (‘picket fence pattern’).
There are a number of morphological subtypes of BCC:
• Nodular—less than 5% of BCCs in Caucasians are pigmented (can look very
similar to malignant melanoma), but pigmented carcinomas are more common
in darker-skinned races. (Three-quarters of BCCs in Chinese patients are
pigmented)
• Superficial—commoner on the trunk. Multiple lesions in a patient should raise the
possibility of arsenic poisoning as a cause
• Morpheaform/sclerosing—often a scar-like lesion with ill-defined margins
• Infiltrative.

The latter two subtypes are more aggressive in behaviour. The overall
rate of metastasis is extremely low but there have been several reports in the
literature.
Sun exposure (ultraviolet B)—the strongest association is repeated sunburn
in childhood with a lag time of 20–50 years; the field effect is demonstrated
by the almost 50% risk of developing a further BCC in the subsequent 5
years. Psoralen ultraviolet A (PUVA) treatment for psoriasis is another risk
factor.
Other risk factors include:
• immunosuppression
• exposure to carcinogens such as hydrocarbons/arsenic (occupational, medicinal
or environmental—contaminated water supplies are often implicated)
• irradiation
• genetic conditions such as xeroderma pigmentosa or syndromes such as
Gorlin’s syndrome. It has a multitude of alternative names, including BCC
syndrome which is inherited in an autosomal dominant manner. Patients
have a predisposition to developing carcinomas from puberty onward,
particularly BCCs. Other associated feature include jaw cysts, bifid ribs, pits
in the palms and soles, prominent brow with hypertelorism, partial agenesis
of the corpus callosum with learning difficulties.
• pre-existing sebaceous naevus.

Infection

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Burn patients are at risk of infection, but prophylactic antibiotics are generally not
given.
There is a decrease in both cellular and humoral immunity:
• decreased total lymphocyte numbers
• prolonged survival of allografts
• reduction of immunoglobulin levels
• serum from burn patients is immunosuppressive in vitro.
Dressings with physical cleansing of the wound and the use of tropical antimicrobials
are the mainstay of reducing infection. Tetanus prophylaxis is given depending on the
patient’s immunization status.

Pain relief

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Adequate pain relief is important. Keeping the patient comfortable will reduce catabolic
requirements. Opiates are best given intravenously as absorption from intramuscular
administration is unpredictable. Additional analgesia should be given before
dressing changes.

Nutrition

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Adequate feeding is important for healing and resistance to infection. When a burn is
large, the daily calorific requirement can increase 1.5–1.75 times above normal. In
more severe burns, a feeding tube should be inserted to decompress the gut and commence
feeding, preferably within 8 h. Many formulae are available to calculate the
increased calorific requirement, e.g. Harris-Benedict and Curreri. The use of vitamin
supplements is advocated by some, but the role of such supplements in those who
were previously healthy is unproven.
Total parenteral nutrition (TPN) is not indicated in acute burns and is in fact associated
with a higher mortality rate; enteral feeding is preferred as it preserves gut
integrity, reduces bacterial translocation and is safer with fewer complications.

Other factors

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Decompression
Fluid shifts cause tissue oedema, which, combined with loss of soft tissue elasticity
after deep circumferential burns, may lead to raised compartment pressures. This is a
surgical emergency.
• airway obstruction with neck burns
• breathing problems with thoracic burns
• compartment syndrome with limb burns.
Decompression is required: incision of the burn (escharotomy) may be adequate, but
a deeper decompression in the form of fasciotomy is occasionally required. These

procedures are best performed under controlled conditions in the operating room,
with general anaesthesia and diathermy. There are guidelines for the preferred lines
of incision, with particular care taken to avoid nerve damage.

Resuscitation

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Inflammation increases the capillary protein permeability, leading to fluid shifts that
decrease the circulating volume. Intravenous resuscitation is commenced when the
body surface area burnt exceeds 15% in adults and 10% in children; these thresholds
are rather arbitrary, but correspond to the dividing line between minor and moderately
severe burns. Below the threshold, oral fluids would be expected to be adequate.
The Parklands formula
Resuscitation volume V (ml) 4 BSA (%) body weight (kg)
The calculated volume is given over 24 h: half over 8h and the remainder over
16h. (BSA percentage body surface area burnt)
Maintenance fluids are needed for children.
Most modern formulae are equally effective. They serve only as guides and require
adjustment according to the patient’s response. The single best measure in uncomplicated
burns is the urine output (aim for more than 0.5 ml of urine per hour per kg).
Typically, more fluids are needed with inhalational injuries, electrical burns or for
those with concomitant crush injuries—osmotic diuresis may need to be encouraged
using mannitol. No colloid is necessary in the first 24 h when the capillary permeability
to macromolecules is highest.
Patient monitoring should include blood pressure (insensitive), pulse rate (nonspecific)
and temperature (the core–peripheral gradient can be used to gauge the peripheral
perfusion). If required, the central venous pressure (CVP) and pulmonary capillary
wedge pressure (PCWP) may be measured, but this necessitates invasive monitoring.

Area

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The severity of the injury is usually approximated to the burn surface area (BSA) as a
percentage of the total body surface area, though this does not take into account the
burn depth or any pulmonary injuries. In crude terms, the larger the burn, the more
severe the injury, and the greater the degree of inflammatory response to fluid shift
from the intravascular compartment to the tissues—hence the burn surface area is
used to assess the risk of developing hypovolaemic shock.
• The body is divided into regions of 9% total body surface area (head and neck,
upper limbs) or 18% (lower limbs, front of trunk and back of trunk) and 1%
(perineum).
• Wallace’s rule of nines is easy to remember, but is only an approximation (it tends
to overestimate the size of the burn). It is unsuitable for children (different body
proportions), except when modified.
• Patient’s palm area (the palmar surface of both the anatomical palm and the closed
fingers) is taken as 1% of the total body surface area. This is good for patchy
burns, but is only an approximation (the area is nearer 0.8% of the body area).
This method is not suited for burns larger than 10% of the total body surface area.

• Burns charts, e.g. the Lund and Browder chart, take account of different body proportions
with age and provide a permanent visual record of the area and the depth
of the burn.
Erythema (associated with first-degree burns) is not included in the assessment as it
represents intra-epidermal damage with little irreversible damage or pathological
insult, and heals without scarring.

Secondary survey

2011-06-04T15:47:00.001-07:00

The secondary survey involves a head-to-toe examination to look for other injuries:
• remove clothing
• examine for wounds
• assess area and depth of burn.
The neurological status is assessed by the patient’s responses using the Glasgow coma
scale or the simpler AVPU system (Alert, responsive to Voice, responsive to Pain or
Unconscious). Remember to assess the pupil reflexes.
Temporary dressings for burns are simple; they should be clean (not necessarily
sterile), moist and cool to reduce pain (but keep the patient warm). Clingfilm or
saline-soaked gauze is perfectly adequate as a temporary dressing. No topical antiseptics/
antibiotics are required at this stage.

Secondary survey

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Inhalational injury

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Inhalational injury is a major cause of death in large burns. It may be classified
according to the site of injury:
• Supraglottic—hot gases injure the upper airway directly, causing oedema. The
obstruction may be delayed for up to 1–2 days and can resolve spontaneously after
a few days.
• Subglottic—thermal injury to the distal airway is rare but chemical injury can be
caused by noxious or irritant gases, such as acids or aldehydes.
• Systemic—inhaled gases may cause metabolic upset, e.g. carbon monoxide or cyanide
compounds. Carboxyhaemoglobin levels can be measured (threshold is higher in
smokers, 10% vs 5%), but depends on the time elapsed since the injury (half life
2–6 hours depending on which study you believe) and also on the oxygen delivered.
A high index of suspicion of possibility of an inhalational injury is required; intubating
prophylatically is preferable to performing emergency intubation for overt respiratory

Primary survey ‘ABC’

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Initial treatment should follow standard advanced trauma life support (ATLS) algorithms.
• Airway—cervical spine stability needs to be maintained. Open and maintain the
airway; intubation may be required. Upper-airway oedema may cause obstruction;
circumferential full-thickness burns of the neck may also cause extrinsic compression.
• Breathing—100% O2 is given. Life-threatening injuries such as tension pneumothorax,
massive haemothorax and massive flail chest can result from the initial incident,
e.g. the force of the blast, or from injuries sustained while escaping the scene,
such as jumping from a height. Circumferential full-thickness chest burns may limit
ventilatory movements.
• Circulation—treat any life-threatening haemorrhage. Obtain adequate intravenous
access.
Take an ‘AMPLE’ history: The history is very important:
• Allergies Cause—determines likely depth of the injury.
• Medication Place—particularly if in an enclosed space,
• Past medical history to ascertain risk of smoke inhalation.
• Last meal Enquire about any first aid given. There may
• Event. be associated injuries from the initial event or
from trying to escape.

First aid

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The aim of first aid is to reduce the ongoing damage by shortening the exposure to
heat; this involves:
• Removing the source by extinguishing the flames, e.g. by rolling along the ground
(‘stop, drop and roll’), by using blankets, water or fire extinguishers as appropriate.
Clothing that was burnt or soaked in the hot liquid retains heat and should be
removed immediately.

• Cooling the burnt skin for 10 min or until the pain stops, but being watchful for
hypothermia (‘cool the burn, warm the patient’). Cooling a burn has been shown to
be effective in increasing perfusion and reducing protein denaturation in the
injured area if done within 30 min. After 3 h, this has no value other than reducing
pain. Do not use ice.

Types of thermal burn

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• scald—caused by hot liquids or gases, such as a cup of tea
• flame burn—caused by burning of clothing or a flammable liquid on the skin
• flash burn—caused by explosions, e.g. an ignited gas leak
• contact burn—caused by physical contact with a hot object, e.g. an iron or radiator
• radiation burn—caused by close proximity to a heat source.
The depth of a burn is related to the energy transferred, which is related to the temperature
of the agent and the contact time. This is modified by the thickness of the
skin which is related to the patient’s age as well as the anatomical site.
First

Acute burns

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Definition
A burn is damage caused by pathological excesses of energy within the tissues. This
can occur through a number of mechanisms but for the purposes of this chapter, we
will limit the discussion to thermal burns. Heat causes protein denaturation at 43°C
and cell damage at 45°C. Burn injuries lead to the release of inflammatory mediators
that increase capillary permeability—the fluid shift that then occurs may lead to hypovolaemic
shock and death.
Jackson’s burn model
This theoretical model of burn injury divides the tissue damage into zones depending
on the distance from the contact area and is helpful in appreciating the dynamic and
three-dimensional nature of a burn:
• Zone of coagulation. Tissue at the contact area is dead.
• Zone of stasis. Adjacent tissue is hypoperfused and oedematous and in a precarious
condition; with adequate resuscitation to improve perfusion, it may recover,
but continuing inflammation, superimposed infection or ischaemia can cause irreversible
damage.
• Zone of hyperaemia. Tissue furthest away is minimally injured and will recover
quickly (in 7–10 days).
Effective burns management aims to maximize the survival of tissue in the zone of stasis.

Umbilicus

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The aesthetics of a ‘natural looking’ umbilicus are subjective, changing with time and
fashion, but the general consensus is that a vertically orientated umbilicus with a
superior hood and slight surrounding fullness is most desirable. There are different
types of incision to create the desired shape, e.g. reverse omega or ‘smiley’. De-fatting
of the midline to recreate the effect of a raphe is advocated by some.
The umbilical stalk needs to be positioned through the flap: the normal position of
the umbilicus is level with the top of the iliac crest. Traditionally the umbilicus is
tacked to the anterior rectus sheath. This has been reported to cause discomfort and
consequently some have suggested tacking to the superficial fascia instead.

Complications

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Severe complications (e.g. pulmonary embolism and deep vein thrombosis) are very
rare. Minor complications are more common (12%); these mainly involve:
• haematoma/seroma 6%
• infection/dehiscence/necrosis (including the umbilicus), 5–7%
• scar problems—hypertrophic scarring is common
• decreased sensation, ‘dog ears’.
Contraindications
• smoking
• morbid obesity
• cardiovascular disease
• diabetes
• thromboembolic disease

It was previously thought that supra-umbilical scarring would be a relative contraindication
and such scarring was associated with an increase in complication rates (23%
vs 7%, commonly fat necrosis) in one study. However, recent work suggests that with
carefully selected patients, abdominoplasty may still be performed if the following are
avoided: excessive tension during closure, over-dissecting the flap (especially laterally)
and excessive concomitant liposuction. Pregnancy is not absolutely contraindicated,
but there needs to be careful observation, particularly if plication of the recti
has been performed.

Supplementary procedures

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• Liposuction, particularly suction-assisted liposuction (SAL), can be used to
remove fat in patients without significant excess skin or as an adjunct to surgical
procedures. It is used most often on the flanks; when combined with an abdominoplasty,
it is particularly important to avoid damaging the blood vessels through
excessive liposuction as this would jeopardize the skin flaps.
• Plication of the recti may be required if there is severe divarication. Plication
around the umbilicus itself is avoided to prevent strangulation. Plication of the
external oblique muscle has also been advocated. The procedure has a long lasting
effect as demonstrated by postoperative CT scans (at six months) in some studies.
Pregnancy after plication may cause potential problems.
• A fleur-de-lis-shaped incision (or inverted T) can deal with lower central abdominal
fullness. It can be used to tighten the waist at the expense of an additional vertical
scar.

Procedures

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• Abdominoplasty. With a long suprapubic incision, a large flap of skin and fat is
raised and undermined to the costal margin. The flap is then pulled downward and
the excess tissue is excised. Repositioning of the umbilicus through the flap is
required. There are some variations in placement and design of the scar, but the
incision is generally placed low for cosmesis.
• Mini-abdominoplasty. This can be performed for excess tissue that lies below the
umbilicus. As it involves only modest trimming with a smaller scar and obviates the
need to reposition the umbilicus, it is a less extensive procedure overall but probably
less effective too.

Abdominoplasty

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Abdominoplasty, in general terms, is the surgical removal of excess skin and fat from
the anterior abdominal wall. When patients present (typically after multiple pregnancies),
it is important to assess their individual problem(s) systematically:
• excess fat
• excess skin
• divarication of the muscles of the abdominal wall
• abdominal striae and scars.
The ideal patient would be within the weight limits for their height with only a moderate
abdominal fullness and would not be considering future pregnancies.
Abdominal fat is arranged in layers:
• a superficial layer that is uniformly compact with many dense fibrous septa
• a deep layer that is less organized with fewer septa and is primarily responsible for
the abdominal contour.