Burns

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.

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.

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.

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.

Burns are caused by a wide variety of substances and external sources such as exposure to chemicals, friction, electricity, radiation, and heat.

Chemical burn - Most chemicals that cause severe chemical burns are strong acids or bases. Chemical burns are usually caused by caustic chemical compounds, such as sodium hydroxide, silver nitrate, and more serious compounds (such as sulphuric acid and Nitric acid). Hydrofluoric acid can cause damage down to the bone and its burns are sometimes not immediately evident.
Electrical burns are caused by an exogenous electric shock. Common causes of electrical burns include workplace injuries or being defibrillated or cardioverted without a conductive gel. The internal injuries sustained may be disproportionate to the size of the burns seen, and the extent of the damage is not always obvious. Such injuries may lead to cardiac arrhythmias, cardiac arrest, and unexpected falls with resultant fractures.
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.

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).

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.

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.

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.

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.

Honey has been used since ancient times to aid wound healing and may be beneficial in first and second degree burns.

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.

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.