Burns

Medically Reviewed on 12/5/2023

What are burns? What are the 3 layers of the skin?

Burn treatment depends upon the location, body surface area, and degree of burn.
Burn treatment depends upon the location, body surface area, and degree of the burn.

Burn injuries occur from the contact of excessive heat over the skin, causing tissue damage and often resulting in scarring.

The skin has an important role to play in the fluid and temperature regulation of the body. If enough skin area is injured, the ability to maintain that control can be lost. The skin also acts as a protective barrier against the bacteria and viruses that inhabit the world outside the body.

The anatomy of the skin is complex, and there are many structures within the layers of the skin. There are three layers of skin:

  1. Epidermis: the outer layer of the skin
  2. Dermis: made up of collagen and elastic fibers and where nerves, blood vessels, sweat glands, and hair follicles reside
  3. Hypodermis or subcutaneous tissue: where larger blood vessels and nerves are located. This is the layer of tissue that is most important in temperature regulation.

The amount of damage that a burn can cause depends upon the type of burn, its location, its depth, and how much body surface area it involves.

What causes burn injuries?

A burn is a type of injury caused by any of the below factors:

  • Heat (such as hot objects, boiling liquids, steam, fire)
  • Chemicals (such as strong acids)
  • Electricity
  • Sunlight
  • Radiation

Burns from hot liquids, steam, and fire are the most common causes of burns.

What are electrical burns?

Electrical burns may cause serious injury that is not readily apparent. Often the entry and exit points for the electrical shock may not be easily identified.

Electricity flows more easily through tissues in the body that are designed to deal with electricity. Nerves and muscles are wired for this task and often are damaged. If significant muscle damage occurs, muscle fibers break down and chemicals can be released into the bloodstream causing electrolyte disturbances and kidney failure.

What are chemical burns?

Burns can also occur when chemicals are spilled onto the body and generate a reaction that creates heat.

Chemical burns may be classified by their pH or acidity.

  • Acids are those with a pH less than 7 and include common household compounds like acetic acid, hydrochloric acid, or sulfuric acid.
  • Bases or alkali compounds have a pH greater than 7. Ammonia is a common alkali found in the home.

SLIDESHOW

First Aid: Wound Care for Cuts and Scrapes See Slideshow

How are burns classified?

Burns are classified based on their depth.

  1. First-degree burns are superficial and cause local inflammation of the skin. Sunburns often are categorized as first-degree burns. The inflammation is characterized by pain, redness, and a mild amount of swelling. The skin may be very tender to the touch.
  2. Second-degree burns are deeper and, in addition to the pain, redness, and inflammation, blistering of the skin also occurs.
  3. Third-degree burns are deeper still, involving all layers of the skin, in effect killing that area of skin. Because the nerves and blood vessels are damaged, third-degree burns appear white and leathery and tend to be relatively painless.
  4. Fourth-degree burns are the most severe burns with the maximum amount of damage to tissue by heat where all the layers of the epidermis, dermis, and subcutaneous tissue, along with the underlying bones and muscles, are affected. This type of burn is painless because all the nerve fibers are destroyed; thus, they are not able to carry pain.

Burns are not static and may mature. Over a few hours, a first-degree burn may involve deeper structures and become second-degree. Think of a sunburn that blisters the next day. Similarly, second-degree burns may evolve into third-degree burns.

Regardless of the type of burn, inflammation and fluid accumulation in and around the wound occur. Moreover, the skin is the body's first defense against infection by microorganisms. A burn is also a break in the skin, and the risk of infection exists both at the site of the injury and potentially throughout the body.

Only the epidermis can regenerate itself. Burns that extend deeper may cause permanent injury and scarring and not allow the skin in that area to return to normal function.

What is the significance of the amount of body surface area burned?

Picture of the Rule of Nines -- Burns on an Adult
Picture of the rule of nines

In addition to the depth of the burn, the total surface area of the burn is significant. Burns are measured as a percentage of the total body area affected. The "rule of nines" is often used and adjusted for infants and children. This calculation is based upon the fact that the surface area of the following parts of an adult body each corresponds to approximately 9% of the total (and the total body area of 100% is achieved):

  • Head = 9%
  • Chest (front) = 9%
  • Abdomen (front) = 9%
  • Upper/mid/low back and buttocks = 18%
  • Each arm = 9%
  • Each palm = 1%
  • Groin = 1%
  • Each leg = 18% total (front = 9%, back = 9%)

As an example, if both legs (18% x 2 = 36%), the groin (1%), and the front chest and abdomen were burned, this would involve 55% of the body.

Only second and third-degree burn areas are added together to measure the total body burn area. While first-degree burns are painful, the skin integrity is intact and it can do its job with fluid and temperature maintenance.

If more than 15%-20% of the body is involved in a burn, significant fluid may be lost. Shock may occur if inadequate fluid is not provided intravenously. As the percentage of burn surface area increases, the risk of death increases as well. Patients with burns involving less than 20% of their body should do well, but those with burns involving greater than 50% have a significant mortality risk, depending upon a variety of factors, including underlying medical conditions and age.

How important is the location of a burn?

Burn location is an important consideration.

  • If the burn involves the face, nose, mouth, or neck, there is a risk that there will be inhalation injury and enough inflammation and swelling to obstruct the airway and cause breathing problems.
  • If there are circumferential burns to the chest, as the burn progresses, the tissue involved may not allow enough movement of the chest wall to allow adequate breathing to occur. If circumferential burns occur to arms, legs, fingers, or toes, the same constriction may not allow blood flow and put the survival of the extremity at risk. Burns to areas of the body with flexion creases, like the palm, the back of the knee, the face, and the groin may need specialized care. As the burn matures, the skin may scar and shorten, preventing the full range of motion of the body area.

What do burn injuries look like?

It may happen that initially a burn appears superficial but becomes deeper over time.

  • First-degree burns:
    • Painful, dry, and red
    • Turn white when pressed
    • Usually, they heal in 3 to 6 days without scarring
    • An example is a non-blistering skin burn
  • Second-degree burns:
    • Painful to the extent of being sensitive to even air movement or air temperature
    • Red and seep fluid
    • Usually form blisters
    • Turn white when pressed
    • Heal within 7 to 21 days
    • Affected skin becomes permanently dark or light in color
    • Does not lead to scar formation
    • An example is a sunburn that forms blisters after several hours
  • Third-degree burns:
    • Painful with deep pressure
    • Almost always form blisters
    • Do not turn white with pressure
    • Take more than 21 days to heal
    • Usually results in severe scarring
    • An example is a burn that blisters immediately
  • Fourth-degree burns:
    • Usually painless (due to destruction of the nerve endings)
    • Waxy white to leathery gray or charred black color
    • Affected skin looks dry
    • Does not turn white when touched
    • Cannot heal without surgical treatment
    • Usually results in severe scarring

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How do you treat burns?

For major burns (second-and third-degree burns)

  1. Remove the victim from the burning area, remembering not to put the rescuer in danger.
  2. Remove any burning material from the person.
  3. Call 911 or activate the emergency response system in your area if needed.
  4. Once the victim is in a safe place, keep the person warm and still. Try to wrap the injured areas in a clean sheet if available. Do not use cold water on the victim; this may drop the body temperature and cause hypothermia.

Burns of the face, hands, and feet should always be considered a significant injury (although this may exclude sunburn).

For minor burns (first-degree burns or second-degree burns involving a small area of the body)

  • Gently clean the wound with lukewarm water.
  • Though butter has been used as a home remedy, do not use it on any burn.
  • Remove rings, bracelets, and other potentially constricting articles (edema, or swelling from inflammation may occur and the item may cut into the skin).
  • The burn may be dressed with a topical antibiotic ointment like Bacitracin or Neosporin. Silvadene (silver sulfadiazine) topical is the preferred agent for most burns and is available over the counter in many locations.
  • If there is concern that the burn is deeper and could be second or third-degree in nature, seek medical care.
  • Update tetanus immunization if needed.

For electrical burns

Victims of electrical burns should always seek medical care.

For chemical burns

  1. Remove the chemical from contact with the victim.
  2. Identify the chemical that was involved.
  3. Contact the Poison Control Center in your area or your local hospital's emergency department. The United States National Poison Hotline is 1-800-222-1222. You will be automatically linked to the nearest poison control center. Many chemical burns may be treated with local wound care. Some chemicals can cause life- and limb-threatening injuries and need emergent intervention. Store the hotline phone number on your cell phone and post it at home and work.
  4. Victims with chemical burns to their eyes should always seek emergency care.

What is the prognosis for burn injuries?

Minor burns usually heal without further treatment. Minor burns refer to first-degree burns anywhere on the body or second-degree burns smaller than two to three inches in width. Most first-degree burns can be managed at home. However, they may hurt considerably and leave a scar if not properly treated.

Medical help must be sought if the affected area is very big, if the affected person is an infant or an elderly person, or if the burn is severe.

A second-degree burn can take anywhere between five days to three weeks to heal itself. If there are complications, recovery might take longer.

Seek urgent medical help in case of a major burn. If the person is on fire, ask them to stop, drop, and roll. Contact your local emergency number or call 911 immediately.

If you are not certain about the type of burn, you must treat it as a major burn. For all serious burns, urgent medical attention is needed. You must contact the local emergency number or call 911 right away.

What happens if a burn is left untreated?

The most common complications of an untreated burn, depending on its depth, include infections and scarring.

Severe cases of deeper burns that cover an extensive part of the body can lead to dehydration, shock, and even death if left untreated.

Why do burn scars form?

When part of the skin is burnt, all the cells present are charred and destroyed, resulting in newer replacement cells taking over the area.

Scar formation is nothing but a healing mechanism of the body in which to cover the destroyed part, the cells rich in collagen are formed in increased numbers to make a healed and thickened discolored area called a scar.

Three major types of scars

  1. Hypertrophic scars: Raised from the surface and are reddish-purple
  2. Contracture scars: Usually contract and tighten the skin, muscles, and tendons to cover up the area that was damaged
  3. Keloid scars: Form shiny and hairless bumps that are raised from the skin, such as large tumors

Scar tissue formation is usually not seen in first-degree burns but is seen in second and third-degree burns where there has been a significant amount of damage to the tissues. First-degree burns can result in pigmentation that usually fades.

How can you prevent burn injuries?

It is possible to prevent most burns by following certain precautions, such as:

  • Turn down the temperature on your water heater to 125 degrees Fahrenheit.
  • Use sunscreen before you venture out to avoid sunburn and then reapply it every three hours.
  • Placing pots and pans on the back burners while cooking.
  • Installing grounded electrical sockets.
  • Unplugging appliances that are not in use.
  • Install smoke alarms/detectors in your home.
  • Changing the batteries in your smoke detectors twice a year.
  • Keeping a dry chemical fire extinguisher at home. Learn how to use it and teach other family members in your home how to use it as well.
  • Getting the wiring in your home checked by an electrician at least once every 10 years.

How do you prevent burn scars from forming?

Appropriate and prompt burn care of first- and second-degree burns can help prevent large scar tissue formation. Proper scar management by prevention is the best possible way to avoid a scar because once it is formed it's very difficult to treat it.

It is typically difficult to prevent scar formation with third- and fourth-degree burns. Acute treatment of large third and fourth-degree burns usually requires hospitalization and intensive care unit care, as well as surgery.

The following burn care steps can aid in faster recovery and minimize scarring following first and second-degree burn injuries:

  • After the burn injury, rinse the area with cool water as fast as possible to nullify the effect of heat.
  • Apply antibiotic ointment over it to prevent any secondary infection.
  • Cover the burnt area with a clean bandage and stretch it for a few minutes daily to prevent wound contraction.
  • If there is a blister formation, then let it pop on its own, and don't let it be exposed to the sun to prevent excessive pigmentation.
Medically Reviewed on 12/5/2023
References
National Institutes of Health. "First aid and treatment of minor burns."

https://www.asds.net/skin-experts/skin-conditions/burn-scars

https://www.aad.org/public/everyday-care/injured-skin/burns/treat-minor-burns

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3038392/

FamilyDoctor.org https://familydoctor.org/burns-preventing-burns-in-your-home

American Academy of Dermatology Association
https://www.aad.org/public/everyday-care/injured-skin/burns/treat-minor-burns

Initial Evaluation and Management of the Burn Patient. Available at: https://emedicine.medscape.com/article/435402-overview#a3

Patient education: Skin burns (Beyond the Basics). Available at: https://www.uptodate.com/contents/skin-burns-beyond-the-basics