A fourth-degree burn, also known as a full-thickness burn, is the most severe type of burn injury. Fourth-degree burns go through every layer of the skin and underlying connective tissue, damaging nerves, muscles, and bones. Because of the extensive damage, fourth-degree burns are always serious and potentially life-threatening. However, with prompt and proper treatment, many patients can recover from even extensive deep burns.
What is a 4th degree burn?
Burns are classified by severity into first, second, third, and fourth degrees. First-degree burns only affect the outer layer of skin. Second-degree burns go deeper into the skin, causing blistering. Third-degree burns destroy the entire epidermis and dermis, leaving behind a charred appearance. Fourth-degree burns go beyond the skin, through subcutaneous fat, muscles, tendons, and bone.
On visual inspection, fourth-degree burns often look similar to third-degree burns – with charred, blackened skin. However, fourth-degree burns cause even more extensive damage beneath the skin’s surface. They destroy nerves, blood vessels, and muscle down to the bone. This causes the burned area to lose sensation and blood supply.
Layers of skin damaged
Human skin is made up of three layers:
- Epidermis: The outermost layer of skin.
- Dermis: Contains blood vessels, hair follicles, sweat glands, and connective tissue.
- Subcutaneous tissue: The innermost layer made up of fat and connective tissue.
A fourth-degree burn goes through all three layers of skin. It also damages the underlying muscle and bone.
What causes 4th degree burns?
Fourth-degree burns are caused by the same sources as other burn injuries, but to a more severe degree. Common causes include:
- Fire or flames
- Scalding from hot liquids like boiling water
- Chemical burns from strong acids or bases
- Electrical burns from high voltage electricity
- Contact with extremely hot objects like stoves or metal
In many cases, fourth-degree burns result from being unable to get away from the source of the burn, such as being trapped in a fire. They can also occur after prolonged contact with a heat source.
Signs and symptoms
Fourth-degree burns cause the following signs and symptoms:
- Charred, blackened skin: The burned skin loses its usual color and takes on a charred black or white appearance.
- Loss of sensation: The nerves are damaged so there is no pain or feeling in the area.
- Hard eschar: A thick, leathery covering forms over the wound as it heals.
- Swelling: Fluid accumulates under the skin, causing swelling.
- Infection: The large open wound is prone to bacterial infection.
- Shock: Massive fluid loss can lead to shock.
- Disfiguration: Extensive scarring typically occurs after healing.
Are 4th degree burns fatal?
Fourth-degree burns can certainly be fatal. However, the prognosis depends on several factors:
Percent of body surface area (BSA) burned
Larger burns are more dangerous than smaller ones. The percent of total body surface area (BSA) burned is used to classify burn size:
| Burn Classification | % of BSA Burned |
|---|---|
| Minor | |
| Moderate | 25-50% BSA |
| Major | > 50% BSA |
In general, the larger the percentage burned, the higher the risk of complications and death. Over 60% BSA burned is usually fatal without rapid medical treatment.
Location of the burn
Burns to the face, hands, feet, and genitals are considered critical burns because they can cause loss of function. Inhalation injuries that burn internal airways are also extremely dangerous.
Age of patient
Younger children and elderly patients have weaker immune systems and are less able to recover from significant burns. Younger children also have a larger body surface area to weight ratio.
Pre-existing medical conditions
Those with conditions like diabetes, heart disease, and chronic illnesses are less able to survive severe burns due to their weakened state.
Treatment
Fourth-degree burns always require emergency medical care. Treatment focuses on:
- Fluid resuscitation
- Infection control
- Wound care
- Skin grafting
- Scar management
- Physical therapy
With proper treatment, survival is possible even with very severe burns. However, fourth-degree burns often leave significant long-term effects like disability and disfigurement.
Fluid resuscitation
Burn injuries cause massive fluid loss through leaking from the damaged vessels. IV fluids are given as soon as possible to stabilize blood pressure and prevent shock. The Parkland formula is used to calculate the required fluid rate based on the patient’s weight and percent surface area burned.
Infection prevention
Open burn wounds are prone to bacterial infection. Topical antibiotics are applied. Patients may also receive intravenous antibiotics and antifungal medications. Tetanus immunization is also needed if not up to date.
Wound care
Dead, damaged tissue must be debrided to remove devitalized areas that can become infected. Clean dressings are needed to protect the wound. Topical agents may be applied to promote healing.
Skin grafting
Once the wound bed is healthy, skin grafting is used to permanently replace damaged skin. Skin from an unaffected area of the patient’s body is transplanted to the wound. Artificial skin substitutes may also be used.
Scar treatment
Hypertrophic scarring often occurs with deep burns. Compression garments, silicone sheets, steroid injections, and other therapies help minimize scarring.
Rehabilitation
Physical and occupational therapy helps preserve range of motion and function. Hand splints, pressure garments, and exercises are important during healing.
Mortality rate
It is difficult to determine an overall mortality rate for fourth-degree burns, as the prognosis depends greatly on the individual circumstances of the injury. However, some general estimates include:
- Over 60% TBSA burned: Fatality rate over 90%
- 40-60% TBSA burned: Fatality rate over 50%
- 20-40% TBSA burned: Fatality rate 10-20%
- Less than 20% TBSA burned: Fatality rate less than 5%
Young, healthy patients who receive prompt emergency care can survive burns covering over 90% of the body surface area. But for vulnerable populations, even small burns can be fatal if not treated quickly.
Long term consequences
Fourth-degree burns that do not result in fatality still cause severe long-term consequences, including:
- Scarring and contractures: Hypertrophic scarring can limit mobility.
- Amputation: Extensively damaged limbs may require amputation.
- Loss of function: Nerve damage causes paralysis and loss of function.
- Chronic pain: Nerve damage also causes severe chronic neuropathic pain.
- Infections: Open wounds are prone to recurrent infections.
- Cancer risk: Severe burns increase risk of squamous cell carcinoma.
Reconstructive surgeries, rehabilitation, specialized garments, and long-term medical care are needed to achieve the best possible recovery.
Prevention
Fourth-degree burns can be prevented by:
- Practicing fire safety in the home by having fire alarms, extinguishers, and escape plans.
- Setting hot water heaters below 120°F.
- Keeping children away from cooking areas, heaters, and fireplaces.
- Wearing protective gear when handling hazardous chemicals.
- Exercising caution around electrical sources – not overloading outlets or using damaged cords.
- Wearing sunscreen to prevent sunburns.
Those working in occupations at high risk for burns, like firefighters, welders, and factory workers should wear appropriate protective equipment and clothing.
Conclusion
Fourth-degree burns are life-threatening injuries that require emergency medical treatment. However, even severe deep burn wounds covering over half the body can often be survived if the patient receives prompt fluid resuscitation, infection control, wound care, and skin grafting surgeries. Extensive burns leave devastating cosmetic and functional consequences. But with specialized rehabilitation and treatment, positive long-term outcomes are possible. Advances in burn care have allowed many patients to survive and thrive after catastrophic injuries. However, prevention through safety practices remains vital.