Burns are a type of injury to the skin or other tissues caused by heat, electricity, chemicals, friction, or radiation. They are classified by severity, based on how deep and widespread the burn is.
1st degree burns
First degree, or superficial burns, affect only the outer layer of the skin, the epidermis. These burns cause redness and pain. The skin may swell slightly. Sunburn is a classic example of a 1st degree burn.
2nd degree burns
Second degree, or partial thickness burns, extend through the epidermis and into the dermis, the layer of skin beneath the epidermis that contains blood capillaries, nerve endings, hair follicles, and sweat glands. Second degree burns cause deep reddening, pain, swelling, and blistering of the skin.
3rd degree burns
Third degree, or full thickness burns, destroy the epidermis and dermis, extending into the deeper tissues beneath. They may appear white, black, brown, or red. There may be some swelling. Third degree burns do not produce sensation or pain as the nerves have been damaged. Blood vessels, sweat glands, and hair follicles are all destroyed.
4th degree burns
Fourth degree burns are the most severe type of burn, though there is some debate over whether they truly constitute a distinct category. Also known as full thickness burns, fourth degree burns extend past the skin and through the underlying muscle and bone. They destroy nerves, blood vessels, and bone.
While first, second, and third degree burns are universally recognized, some sources do not differentiate fourth degree burns from third degree burns. Other sources contend that fourth degree burns extend deeper than third degree burns and that the distinction is meaningful in terms of prognosis and treatment.
Characteristics of 4th degree burns
According to sources that recognize fourth degree burns, their characteristics include:
- Destruction of skin, fat, muscle, and bone
- Injury to deeper structures like tendons, joints, blood vessels, and nerves
- Wounds have a white/gray color as tissue is destroyed
- Very little to no sensation in the area as nerves are damaged
- No pain, as pain receptors are destroyed
- Requires extensive debridement and skin grafting
- High risk of infection
- Scarring and contractures likely
- Requires long hospitalization and rehabilitation
Causes
Fourth degree burns may be caused by:
- Prolonged direct contact with flames or extremely hot objects like stoves or metal
- Chemical burns from strong acids or bases
- Severe electrical burns with extensive internal damage
- Friction from dragging on asphalt or other rough surfaces at high speeds, like after being ejected from a vehicle
They usually result from more severe and extended versions of the causes of lesser degree burns like scalding, chemical spills, and fires.
Diagnosis
Diagnosis of a fourth degree burn depends on clinical evaluation of the depth and extent of tissue damage. Doctors look for the destruction of skin, fat, muscle, and bone. Imaging tests like MRI or CT scans may also be done to evaluate which structures are damaged and how deep the injury extends.
Treatment
As with burns of all degrees, initial treatment focuses on stabilizing the patient, stopping the burning process, infection control, and pain management. Specific treatment for fourth degree burns includes:
- Intravenous fluids and treatment for shock
- Debridement of dead tissue
- Application of dressings with antibiotic ointments
- Skin grafting once wounds are healed enough
- Physical therapy to maintain range of motion and prevent contractures as burns heal
- Treatment of infection if it develops
- Nutritional support
- Long term rehabilitation
Skin grafts are required to close fourth degree burn wounds once damaged tissue has been debrided. Healing is very slow, often requiring months. Scarring and loss of function are common even after the burn area has fully closed.
Complications
Possible complications of fourth degree burns include:
- Infection
- Tetanus
- Loss of fluids, electrolytes, proteins
- Shock
- Scarring and contractures limiting movement
- Require amputation in severe cases
- Kidney failure
- Lung injury from inhaling smoke or hot gases
Prognosis
Fourth degree burns have a poorer prognosis than lesser degree burns. Healing is slow and often incomplete, especially in elderly patients. Scarring and loss of function are very common due to the extensive destruction of tissue and bone. Patients require intensive medical and rehabilitative treatment for months to years.
Mortality is high, especially if the burn covers a large percentage of the body’s surface area. Infection risk is elevated due to the destruction of skin barrier. With aggressive treatment, some functional recovery is possible over an extended timeframe.
Prevention
Prevention of severe burns, including potential fourth degree burns, includes:
- Having working smoke detectors in the home
- Avoid smoking in bed
- Keep children away from hot drinks, food, or irons
- Check water heater temperature is not set too high
- Handle flammable materials like gasoline carefully
- Follow safety procedures if working with electrical equipment
- Wear proper safety and insulating gear if handling live power lines
- Follow appropriate chemical handling procedures when using acids/bases
- Store chemicals properly in sealed, labeled containers
Burn injuries can’t always be prevented, but following basic safety practices can reduce risk.
Conclusion
Fourth degree burns, while not universally recognized, are generally understood to be full thickness burns that destroy skin, fat, muscle, and bone. They result from severe trauma like prolonged exposure to flames, chemicals, or electricity. Treatment is challenging, and scarring, loss of function, and complications are common. Prevention through safety practices is key to avoiding such extreme burns.
| Burn Degree | Depth of Skin Damage | Appearance | Sensation |
|---|---|---|---|
| 1st Degree | Outer layer of skin (epidermis) | Redness, swelling, pain | Painful |
| 2nd Degree | Into deeper layer of skin (dermis) | Blistering, wet appearance, red/white | Painful |
| 3rd Degree | Full thickness of skin, fat, glands, hair | White, leathery, charred, dry | Numb |
| 4th Degree | Through skin, fat, muscle, bone | White/gray, wounds exposed | Numb |
This table summarizes the depth of tissue damage, appearance, and sensation for each burn degree from first to fourth degree.
FAQs
Are 4th degree burns the most severe type of burn?
Yes, 4th degree burns are considered the most severe type of burn injury. They extend beyond skin and fat to damage muscle, bone, and deeper structures.
What is the survival rate for 4th degree burns?
Survival rate depends greatly on the extent of the burns and health of the patient. In general, survival rates are lower for 4th degree burns compared to lesser burns due to their severity. Mortality can exceed 50% in those with very extensive 4th degree burns.
How long does it take 4th degree burns to heal?
Healing of 4th degree burns is a very long process, often taking months. The wounds require debridement followed by skin grafting. Physical therapy during healing is also essential to prevent contractures and loss of function.
Do 4th degree burns require amputation?
In severe cases where the limb is extensively damaged, amputation may be required. However, the goal is limb salvage if possible. So amputation is a last resort if salvage is deemed impossible.
What’s the difference between a 3rd and 4th degree burn?
A 3rd degree burn goes through the full thickness of the skin. A 4th degree burn extends beyond the skin to damage underlying fat, muscle, tendons, and bone.
Can you tell how severe a burn is just by looking at it?
Not always. While more severe burns tend to have characteristic appearances, it’s difficult to determine definitively the degree of a burn just by visual examination. A doctor will examine the depth of tissue damage and perform tests if needed.
Do 4th degree burns bleed or ooze fluid?
No, because 4th degree burns destroy local blood vessels, bleeding does not usually occur. There may be some ooze from damaged tissue, but not significant blood loss or fluid oozing.
What is the fastest way to heal burns?
For minor burns, fast healing comes from proper first aid like cooling the burn and keeping it clean to prevent infection. For major burns, medical treatment like debridement, dressings, grafting, fluid/nutrition management, and physical therapy help optimize healing speed.
Can you donate skin to a 4th degree burn victim?
Yes, donated skin may be used in skin grafts to close wounds for patients with extensive 4th degree burns, typically from a cadaver donor, not live donation.
