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Burns are injuries to tissue that result from heat, electricity, radiation, or chemicals.

• Burns cause varying degrees of pain, blisters, swelling, and skin loss.
• Deep, extensive burns can cause serious complications, such as shock and severe infections.
• Small, shallow burns may need only to be kept clean and to have an antibiotic cream applied.
• People with deep or extensive burns may require intravenous fluids, surgery, and rehabilitation, often at a burn center.

Burns are usually caused by heat (thermal burns), such as fire, steam, tar, or hot liquids. Burns caused by chemicals are similar to thermal burns, whereas burns caused by radiation (see Radiation Injury), sunlight (see Sunlight and Skin Damage: Introduction), and electricity (see Electrical and Lightning Injuries: Electrical Injuries) differ significantly. Events associated with a burn, such as jumping from a burning building, being struck by debris, or being in a motor vehicle crash, may cause other injuries.

Thermal and chemical burns usually occur because heat or chemicals contact part of the body's surface, most often the skin. Thus, the skin usually sustains most of the damage. However, severe surface burns may penetrate to deeper body structures, such as fat, muscle, or bone.

When tissues are burned, fluid leaks into them from the blood vessels, causing swelling. In addition, damaged skin and other body surfaces are easily infected because they can no longer act as a barrier against invading microorganisms.

More than 2 million people in the United States require treatment for burns each year, and between 3,000 and 4,000 die of severe burns. Older people and young children are particularly vulnerable. In those age groups, abuse must be considered.

When Chemicals Burn the Skin Chemical burns are caused by caustic substances that contact the skin. Caustic substances are sometimes present in household products, including those containing lye (in drain cleaners and paint removers), phenols (in deodorizers, sanitizers, and disinfectants), sodium hypochlorite (in disinfectants and bleaches), and sulfuric acid (in toilet bowl cleaners). Many chemicals used in industry and during armed conflicts can cause burns. Wet cement left on the skin can cause severe burns as well. The steps in stopping chemical burns are Remove contaminated clothing Brush away any dry powders or particles Rinse the area with large amounts of water. Because chemicals can continue to inflict damage long after first contacting the skin, rinsing should continue for at least 30 minutes. In rare cases involving certain industrial chemicals (for example, metal sodium), water should not be used because it can actually worsen the burn. In addition, some chemicals have specific treatments that can further reduce skin damage. Further treatment of chemical burns is the same as that for thermal burns. If more information is needed concerning treatment of a burn caused by a specific chemical, the local Poison Control Center can be contacted.

Classification

Doctors classify burns according to strict, widely accepted definitions. The definitions classify the burn's depth and the extent of tissue damage.

Burn Depth: The depth of injury from a burn is described as first, second, or third degree:

• First-degree burns are the most shallow (superficial). They affect only the top layer of skin (epidermis).
• Second-degree burns (also called partial-thickness burns) extend into the middle layer of skin (dermis). Second-degree burns are sometimes further described as superficial (involving the more superficial part of the dermis) or deep (involving both the superficial and the deep parts of the dermis).
• Third-degree burns (also called full-thickness) involve all three layers of skin (epidermis, dermis, and fat layer). Usually, the sweat glands, hair follicles, and nerve endings are destroyed as well.

Estimating the Extent of a Burn To determine the severity of a burn, doctors estimate what percentage of the body's surface has second- or third-degree burns. For adults, doctors use the rule of nines. This method divides almost all of the body into sections of 9% or of 2 times 9% (18%). For children, doctors use charts that adjust these percentages according to the child's age (Lund-Browder charts). Adjustment is needed because different areas of the body grow at different rates.

Burn Severity: Burns are classified as minor, moderate, or severe. These classifications may not correspond to a person's understanding of those terms. For example, doctors may classify a burn as minor even though it can cause the person significant pain and interfere with normal activities. The severity determines how they are predicted to heal and whether complications are likely. Doctors determine the severity of the burn by its depth and by the percentage of the body surface that has second- or third-degree burns. Special charts are used to show what percentage of the body surface various body parts comprise. For example, in an adult, the arm constitutes about 9% of the body. Separate charts are used for children because their body proportions are different.

• Minor burns: All first-degree burns as well as second-degree burns that involve less than 10% of the body surface usually are classified as minor.
• Moderate and severe burns: Burns involving the hands, feet, face, or genitals, second-degree burns involving more than 10% of the body surface area, and all third-degree burns involving more than 1% of the body are classified as moderate or, more often, as severe.

First-Degree Burn

Second-Degree Burn

Third-Degree Burn

Symptoms and Diagnosis

Symptoms of the burn wound vary with the burn's depth:

• First-degree burns are red, swollen, and painful. The burned area whitens (blanches) when lightly touched but does not develop blisters.
• Second-degree burns are pink or red, swollen, and painful, and they develop blisters that may ooze a clear fluid. The burned area may blanch when touched.
• Third-degree burns usually are not painful because the nerves have been destroyed. The skin becomes leathery and may be white, black, or bright red. The burned area does not blanch when touched, and hairs can easily be pulled from their roots without pain.

The appearance and symptoms of deep burns can worsen during the first hours or even days after the burn.

Did You Know... The deepest burns may cause the least pain because the nerves that sense pain are destroyed.

Doctors frequently examine hospitalized people for complications and assess burn wound depth and extent. In people with large burns, blood pressure, heart rate, and urine volume are measured often to help assess the extent of dehydration or shock and the need for intravenous fluids. Doctors do blood tests to monitor the body's electrolytes and blood count. Electrocardiography (ECG) and chest x-ray are also required. Tests of blood and urine are done to detect proteins caused by the destruction of muscle tissue (rhabdomyolysis) that sometimes occurs with deep third-degree burns.

Smoke Inhalation Many people who have been burned in fires have also inhaled smoke. Sometimes people inhale smoke without sustaining skin burns. Smoke inhalation often causes no serious, lasting effects. However, if the smoke contains certain poisonous chemicals, is unusually dense, or inhalation is prolonged, serious problems can develop. Hot smoke sometimes burns the throat, resulting in swelling. As the swelling narrows this area, airflow into the lungs is obstructed. Breathing hot steam can burn the lungs as well as the throat, causing severe breathing problems. Inhalation of chemicals released in the smoke, such as hydrogen chloride, phosgene, sulfur dioxide, and ammonia, can cause swelling and damage to the windpipe (trachea) and even the lungs. Eventually, the small airways leading to the lungs narrow, further obstructing airflow. Smoke can also contain chemicals that poison the body's cells, such as carbon monoxide (see Poisoning: Carbon Monoxide Poisoning) and cyanide. Damage to the trachea or the lungs can cause shortness of breath, which can take up to 24 hours to develop. Obstruction of airflow due to swelling of the airways can produce difficulty breathing air in, wheezing, and shortness of breath. People may have soot in the mouth or nose, singed nasal hairs, or burns around the mouth. Lung damage may cause chest pain, coughing, and wheezing. If the oxygen supply is depleted due to smoke, people may pass out. High levels of carbon monoxide in the blood may cause confusion or disorientation or may even be fatal. To assess the extent of injury due to smoke inhalation, doctors may pass a flexible viewing tube (bronchoscope) into the trachea. Doctors may assess lung damage with a chest x-ray or with a test that determines the level of oxygen in the blood. People who have inhaled smoke are given oxygen through a face mask. If a tracheal burn is suspected, a breathing tube is inserted through the nose or mouth in case the trachea later swells and obstructs airflow. If people begin to wheeze, drugs that open small airways such as albuterol may be given, usually as a mist that is combined with oxygen and inhaled through a face mask. If lung damage causes shortness of breath that persists despite use of a face mask and albuterol , a ventilator may be necessary. Relieving the stress of breathing conserves people's energy and usually allows faster recovery.

Complications

Minor burns are usually superficial and do not cause complications. However, deep second-degree and third-degree burns swell and take more time to heal. In addition, deeper burns can cause scar tissue to form. This scar tissue shrinks (contracts) as it heals. If the scarring occurs in a limb or digit, the resulting contracture may restrict movement of nearby joints.

Severe burns and some moderate burns can cause serious complications due to extensive fluid loss and tissue damage. These complications may take hours or days to develop. The deeper and more extensive the burn, the more severe are the problems it tends to cause. Young children and older adults tend to be more seriously affected by complications than other age groups. The following are some complications of some moderate and severe burns:

• Dehydration eventually develops in people with widespread burns, because fluid seeps from the blood to the burned tissues and, if burns are deep and extensive enough, to the whole body.
• Shock develops if dehydration is severe (see Shock).
• Chemical imbalances can result from extensive burns.
• Destruction of muscle tissue (rhabdomyolysis) sometimes occurs with deep third-degree burns. The muscle tissue releases myoglobin, one of the muscle's proteins, into the blood. If present in high concentrations, myoglobin harms the kidneys.
• Infection can complicate burn wounds. Sometimes the infection can spread throughout the bloodstream and cause severe illness or death.
• Thick, crusty surfaces (eschars) are produced by deep third-degree burns. Eschars can become too tight, cutting off blood supply to healthy tissues or impairing breathing.

Treatment

Before burns are treated, the burning agent must be stopped from inflicting further damage. For example, fires are extinguished. Clothing—especially any that is smoldering (such as melted synthetic shirts), covered with a hot substance (for example, tar), or soaked with chemicals—is immediately removed.

Hospitalization is sometimes necessary for optimal care of burns. For example, elevating a severely burned arm or leg above the level of the heart to prevent swelling is more easily accommodated in a hospital. In addition, burns that prevent people from carrying out essential daily functions, such as walking or eating, make hospitalization necessary. Severe burns, deep second- and third-degree burns, burns occurring in the very young or the very old, and burns involving the hands, feet, face, or genitals are usually best treated at burn centers. Burn centers are hospitals that are specially equipped and staffed to care for burn victims.

Superficial Minor Burns: Superficial minor burns are immersed immediately in cool water if possible. The burn is carefully cleaned to prevent infection. If dirt is deeply embedded, doctors can give analgesics or numb the area by injecting a local anesthetic and then scrub the burn with a brush.

Often, the only treatment required is application of an antibiotic cream, such as silver sulfadiazine

. The cream prevents infection and forms a seal to prevent further bacteria from entering the wound. A sterile bandage is then applied to protect the burned area from dirt and further injury. A tetanus vaccination is given if needed (see Immunization: Tetanus).

Care at home includes keeping the burn clean to prevent infection. In addition, many people are given analgesics, often opioids for at least a few days. The burn can be covered with a nonstick bandage or with sterile gauze. The gauze can be removed without sticking by first being soaked in water.

Small, Shallow Burns Most people who sustain small burns attempt to treat them at home rather than visit the doctor. Indeed, simple first-aid measures may be all that is necessary to treat small, shallow burns that are clean. In general, a clean burn is one that affects only clean skin and that does not contain any dirt particles or food. Running cold water over the burn can help relieve pain. Covering the burn with an over-the-counter antibiotic ointment and a nonstick, sterile bandage can help prevent infection. Generally, a doctor's examination and treatment are recommended if a tetanus vaccination is needed. Likewise, a doctor should examine a burn if it has any of the following characteristics: Is larger than the size of the person's open hand Contains blisters Darkens or breaks the skin Involves the face, hand, foot, genitals, or skinfolds Is not completely clean Causes pain that is not relieved byacetaminophen Causes pain that does not improve within one day after the burn was sustained.

Deep Minor Burns: As with more superficial burns, deep minor burns are treated with antibiotic cream. Any dead skin and broken blisters should be removed by a health care practitioner before the antibiotic cream is applied. In addition, keeping a deeply burned arm or leg elevated above the heart for the first few days reduces swelling and pain. The burn may require admission to a hospital or frequent re-examination at a hospital or doctor's office, possibly as often as daily for the first few days.

A skin graft may be needed. Some skin grafts replace burned skin that will not heal. Other skin grafts help by temporarily covering and protecting the skin as it heals on its own. In a skin grafting procedure, a piece of healthy skin is taken from an unburned area of the person's body (autograft), or a dead person (allograft) or an animal (xenograft). After any dead tissue is removed and the wound is clean, a surgeon sews the skin graft over the burned area. Artificial skin can also be used. Autografts are permanent. Allografts and xenografts, however, are rejected after 10 to 14 days by the person's immune system and artificial skin is removed. These skin covers help by temporarily covering and protecting the skin as it begins to heal on its own. However, an autograft eventually must be placed. Burned skin can be replaced anytime within several days of the burn.

Physical and occupational therapy usually are needed to prevent immobility caused by scarring around the joints and to help people function if joint motion is limited. Stretching exercises are started within the first few days after the burn. Splints are applied to ensure that joints that are likely to be immobile rest in positions that are least likely to lead to contractures. The splints are left in place except when the joints are moved. If a skin graft has been used, however, therapy is not started for 3 to 5 days after the grafts are attached so that the healing graft is not disturbed. Bulky dressings that put pressure on the burn can prevent large scars from developing.

Severe Burns: Severe, life-threatening burns require immediate care. People who have gone into shock as a result of dehydration are given oxygen through a face mask.

Large amounts of intravenous fluids are given, beginning immediately, for people who have dehydration or shock or burns that cover a large area of the body. Fluids are also given to people who develop destruction of muscle tissue.. The fluids dilute the myoglobin in the blood, preventing extensive damage to the kidneys. Sometimes a chemical, sodium bicarbonate, is given intravenously to help dissolve myoglobin and thus also prevent further damage to the kidneys.

A surgical procedure to cut open eschars that cut off blood supply to a limb or that impair breathing may be needed. This procedure is called escharotomy. Escharotomy usually causes some bleeding, but because the burn causing the eschar has destroyed the nerve endings in the skin, there is little pain.

Skin care is extremely important. Keeping the burned area clean is essential, because the damaged skin is easily infected. Cleaning may be accomplished by gently running water over the burns periodically. Wounds are cleaned and bandages changed 1 to 3 times per day. Skin grafts are needed to cover burns that will not heal.

A proper diet that includes adequate amounts of calories, protein, and nutrients is important for healing. People who cannot consume enough calories may drink nutritional supplements or receive them by way of a tube inserted through the nose into the stomach (a nasogastric tube), or less often nutrition may be given intravenously. Additional vitamins and minerals are usually given.

Physical and occupational therapy are needed.

Depression is treated. Because severe burns take a long time to heal and can cause disfigurement, people can become depressed. Depression often can be relieved with drugs or psychotherapy or both.

Prognosis

First- and some second-degree burns heal in days to weeks without scarring. Deep second-degree and small third-degree burns take weeks to heal and usually cause scarring. Most require skin grafting. Burns that involve more than 90% of the body surface, or more than 60% in an older person, are often fatal.