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Burns
A skininjury that may be caused
by heat, electricity, chemicals, light, radiation, or friction. Most burns only affect the skin
(epidermal tissue and dermis). In more severe burns, deeper tissues,
such as muscle, bone, and blood vessel can also be injured. Burns are
important because they are common, painful and can result in disfiguring and
disabling scarring.
Burn injuries can be complicated
by shock, infection, multiple organ dysfunction syndrome (MODS), electrolyte imbalance and respiratory distress. Large burns can be fatal, but modern
treatments developed in the last 60 years, have significantly improved the prognosis of such
burns, especially in children and young adults.
Burn Depth
Classification
A number of different
classification systems exist. The traditional system divided burns in first-, second-, or
third-degree. This system is however being replaced by one reflecting the need for surgical
intervention. The burn depths are described as either superficial, superficial partial-thickness,
deep partial-thickness, or full-thickness.
The following are brief
descriptions of these classes:
By degree
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First-degree
burns are usually limited to redness
(erythema), a white plaque and
minor pain at the site of injury.
These burns involve only the epidermis. Most
sunburns can be included as
first-degree burns.
-
Second-degree
burns manifest as erythema with
superficial blistering of the skin, and can
involve more or less pain depending on the level of nerve involvement.
Second-degree burns involve the superficial (papillary) dermis and may also involve
the deep (reticular) dermis layer.
-
T
hird-degree burns occur
when the epidermis is lost with damage to the subcutaneous tissue. Burn victims will
exhibit charring and extreme damage of the epidermis, and sometimes
hard eschar will be present.
Third-degree burns result in scarring and victims will also
exhibit the loss of hair shafts and keratin. These burns may
require grafting.
-
F
ourth-degree
burns damage muscle, tendon, and ligament tissue, thus result
in charring and catastrophic damage of the hypodermis. In some instances the
hypodermis tissue may be partially or completely burned away as well as this may
result in a condition called compartment syndrome, which threatens
both the life and the limb of the patient. Grafting is required if the burn does
not prove to be fatal.
Other Burn Injury Classifications
A newer classification of
"Superficial Thickness", "Partial Thickness" (which is divided into superficial and deep
categories) and "Full Thickness" relates more precisely to the epidermis, dermis and subcutaneous
layers of skin and is used to guide treatment and predict outcome.
An even simpler, more accurate and
more descriptive classification is epidermal, dermal and full thickness. Dermal injuries are
subdivided into superficial, mid and deep.
Burn Surface Area
Burns can also be assessed in terms
of total body surface area (TBSA), which is the percentage affected by partial thickness or full
thickness burns (erythema/superficial thickness burns are not counted).
The rule of nines is used as a quick and useful way to
estimate the affected TBSA. More accurate estimation can be made using Lund & Browder charts
which take into account the different proportions of body parts in adults and children. The size
of the patient's hand print (palm and fingers) is approximately 1% of their
TBSA.
The actual mean surface area is
0.8% so using 1% will slightly over estimate the size. Burns of 10% in children or 15% in
adults (or greater) are potentially life threatening injuries (because of the risk of hypovolaemic
shock) and should have formal fluid resuscitation and monitoring in a burns
unit.
Burn Injury Causes
Burns are caused by a wide variety
of substances and external sources such as exposure to chemicals, friction, electricity, radiation,
and heat.
-
-
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Radiation burns
are caused by protracted exposure to UV light (as from the
sun), tanning booths, radiation therapy (as patients
who are undergoing cancer therapy), sunlamps,
and X-rays. The most common burn
associated with radiation is sun exposure, specifically two wavelengths of
light UVA, and UVB, the latter being more dangerous.
Tanning booths also emit these wavelengths and may cause similar damage to the
skin such as irritation, redness, swelling, and inflammation. More severe cases of sun
burn result in what is known as sun poisoning.
-
Scalding
is caused by hot liquids (water or oil) or gases (steam), most commonly occurring
from exposure to high temperature tap water in baths or showers or
spilled hot drinks. A blister is a "bubble" in the skin filled
with serous fluid as part of the
body's reaction to the heat and nerve damage. The blister "roof" is
dead.
-
Steam is a common
gas that causes scalds. The injury is usually regional and usually does not cause
death. More damage can be caused if hot liquids enter an orifice. However, deaths
have occurred in more unusual circumstances, such as when people have accidentally
broken a steam pipe. The demographics that are of the highest risk to suffering
from scalding are young children, with their delicate skin, and the elderly over 65
years of age.
Management of Severe Burns
If the patient was involved in a
fire accident in an enclosed space, then it must be assumed that he or she has sustained an
inhalation injury until proven otherwise, and treatment should be managed accordingly. At this
stage of management, it is also critical to assess the airway status. Any suspicion of burn injury
to the lungs (e.g.
through smoke inhalation) is considered
a medical emergency.
Burns over 10% in children and 15%
in adults need hospital admission and fluid resuscitation due to the risk of hypovolaemic shock.
Most countries have explicit criteria for the transfer and management of burns
patients.
Major burns should be managed using
the principles of Advanced Trauma Life Support (ATLS). This consists of a primary
survey to identify and treat immediately life threatening conditions and then a secondary
survey. The primary survey in burns patients should follow the ABCDE guidlelines (Airway &
axial spine control, Breathing & ventilation, Circulation and arrest of haemorrhage,
neurological Disability, Exposure to allow accurate assessment and Estimation of burn surface
area and Fluid resuscitation).
First
Aid
Regardless of the cause, the first
step in managing a person with a burn is to stop the burning process at the source, and cool the
burn wound (but not the patient. It is essential to avoid the "lethal triad"
of hypothermia, acidosis and coagulopathy).
For instance, with dry powder
burns, the powder should be brushed off first. With other burns the affected area should be rinsed
thoroughly with a large amount of clean water. Cold water should not be applied to a person with
extensive burns for a prolonged period (greater than 20 minutes), however, as it may result
in hypothermia. Do not directly apply ice to a burn wound
as it may compound the injury.
To help ease pain people may be
placed in a special burn recovery bed which evenly distributes body weight
and helps to prevent painful pressure points and bed sores. Survival and outcome of severe burn
injuries is remarkably improved if the patient is treated in a specialized burn center/unit
rather than a hospital.
Intravenous fluids
Children with TBSA >10% and
adults with TBSA > 15% need formal fluid resuscitation and monitoring (blood pressure, pulse
rate, temperature and urine output). Once the burning process has been stopped, the patient should
be volume resuscitated according to the Parkland formula . This formula is
4 ml lactated ringers x TBSA (total body surface area) % burned x patient weight in
kg for first 24 hours, with half this volume given in the first 8 hours. Children also
require the addition of maintenance fluid volume. Such injuries can disturb a
person's osmotic balance.
This formula dictates the amount
of Lactated Ringer's solution or Hartmann's Solution to deliver in the first twenty four
hours after time of injury. This formula excludes first degree burns, so erythema alone is
discounted. Half of the fluid should be given in the first eight hours post injury and the rest
in the subsequent sixteen hours. Inhalation injuries in conjunction with thermal burns initially
require up to 40–50% more fluid.
The formula is a guide only and
infusions must be tailored to the urine output
and central venous pressure . Inadequate fluid resuscitation
causes renal failure and death but over-resuscitation also
causes morbidity and mortality. All resuscitation formulae should be delivered as a goal
directed therapy to prevent the complications of hypovolaemic shock or
over-hydration.
Dressings
In the management of first and
second degree burns little quality evidence exist to determine which type of dressing should be
used. In light of this silver sulfadiazine however is not recommended as it
potentially prolongs healing time and biosynthetic dressings may speed
healing.
Pain management
A number of different options are
used for pain management. These include simple analgesics ( such as ibuprofen and acetaminophen )
and narcotics. A local anesthetic may help in managing pain of minor
first-degree and second-degree burns.
Other treatments
Hyperbaric oxygenation uses pure oxygen in an enclosed
chamber to promote healing.
Honey has been used since ancient
times to aid wound healing and may be beneficial in first and second degree
burns.
What does the future
hold?
The outcome of any injury or
disease depends on three things: the nature of the injury, the nature of the patient and the
treatment available.
In terms of injury factors in burns
the prognosis depends primarily on the burn surface area (% TBSA) and the age of the patient. The
presence of smoke inhalation injury, other significant injuries such as log bone fractures and
serious co-morbidities (heart disease, diabetes, psychiatric illness, suicidal intent etc) will
also adversely influence prognosis. Advances in resuscitation, surgical management, control of
infection, control of the hyper-metabolic response and rehabilitation have resulted in dramatic
improvements in burn mortality and morbidity in the last 60 years.
Following a major burn injury,
heart rate and peripheral vascular resistance increase. This is due to the release
of catecholamines from injured tissues, and the
relative hypovolemia that occurs from fluid volume
shifts. Initially cardiac output decreases. At approximately 24 hours
after burn injuries (for patients receiving fluid resuscitation) cardiac output returns to normal, then increases to
meet the hypermetabolic needs of the body.
Infection is a major complication of burns.
Infection is linked to impaired resistance from disruption of the skin's mechanical integrity
and generalized immune suppression. The skin barrier is replaced by eschar. This moist, protein rich avascular
environment encourages microbial growth. Migration of immune cells is hampered, and there is
a release of intermediaries that impede the immune response. Eschar also restricts distribution of
systemically administered antibiotics because of its
avascularity.
Risk factors of burn wound
infection include:
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Burn > 30%
TBS
-
full-thickness
burn
-
Extremes in age
(very young, very old)
-
-
virulence and
antibiotic resistance of colonizing organism
-
-
Improper initial
burn wound care
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Prolonged open burn
wound
Burn wounds are prone
to tetanus. A tetanus booster shot is required if
individual has not been immunized within the last 5 years.
Circumferential burns of
extremities may compromise circulation. Elevation of limb may help to prevent dependent edema.
An Escharotomy may be
required.
Acute Tubular Necrosis of the
kidneys can be caused by myoglobin and hemoglobin released from damaged muscles and
red blood cells. This is common in electrical burns or crush injuries where adequate fluid
resuscitation has not been achieved.
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