- Clinical science
Burns are injuries to tissue caused by heat, chemicals, and/or radiation. The two factors that influence the severity of a burn are its depth and the surface area involved. Accordingly, burns are classified into four grades based on the depth of tissue involvement. Lund-Browder charts are used to calculate the surface area involved. Massive tissue necrosis, which occurs with severe burns, results in sepsis, shock, and sequential organ failure (see for details). In the case of severe burns, patients should be intubated, given supplemental oxygen and resuscitated with IV fluids. Parkland's formula is commonly used to calculate initial fluid requirement, but fluids should be adjusted to maintain clinical stability and appropriate urine output. Pulse oximetry, blood gas analysis, and measurement of electrolyte and creatinine levels are important diagnostic procedures for patients with severe burns. In the case of circumferential burns around limbs, peripheral pulses and capillary refill can be used to detect perfusion. Escharotomy should be performed in order to treat compartment syndrome and prevent acute limb ischemia. First and second-degree burns can be treated with antiseptic ointment and dressings. Treatment of third and fourth-degree burns involves debridement of necrotic tissue followed by skin graft or a tissue transfer via flap. Burn wounds tend to become infected and large, severe burns tend to be fatal injuries. The most common causes of death following burns are shock, sepsis, and respiratory failure.
- Thermal injury (e.g., scalding, contact with a hot surface, fires)
- Non-thermal injury: radiation, chemical burns, electrical burns
Although most cases of burns are the result of accidental injury, non-accidental injury must always be suspected in vulnerable populations, including children and the elderly!References:
Local changes at the burn site (Jacobson's model of the burn wound)
- Zone of coagulation: a central zone of irreversible, coagulative necrosis
- Zone of stasis: surrounds the central zone of coagulation and is comprised of damaged but viable tissue with decreased perfusion
- Zone of hyperemia: surrounds the zone of stasis and is characterized by inflammation and increased blood flow
A burn wound is a dynamic wound. If resuscitation and/or wound care are not adequate, the zone of stasis becomes irreversibly damaged and the depth of the burn increases!
- Almost all burns are colonized by bacteria.
- Eschars can cause constrictive effects.
- Large (> 30% of the body surface area) and/or deep burns → extensive tissue damage →
- Release of cytokines and other inflammatory mediators () →
- Evaporative fluid loss → ,
- Hemolysis, muscle damage → hemoglobinuria and/or myoglobinuria →
- Hypermetabolic state with increased nutritional requirements
Inhalation of hot smoke and/or noxious gases → inhalation injury
- → airway obstruction
The two factors that influence the severity of a burn are its depth and the surface area involved.
Burns are classified into four grades based on their depth, the degree of pain associated with them, and other clinical features (redness, blister formation).
In cases of severe, deep burns, pain may be absent as a result of damage to sensory nerve endings!
Degree of burns
|Depth of tissue damage|| |
1st degree (superficial burn)
| || |
|2a (superficial partial-thickness burn)|| |
|2b (deep partial-thickness burn)|| || |
3rd degree (full thickness burn)
| || || |
Extent of burns (surface area involved)
- Age-specific charts are used to calculate the surface area covered by a burn.
- Most accurate method for both adults and children
Wallace's rule of nines
- A quick but reliable method for estimating the surface area covered by burns in the case of adults.
- The rule of nines is unreliable among children.
|Body surface area|
|Trunk||36% (4 x 9%)|
|Arms||18% (2 x 9%)|
|Thighs||18% (2 x 9%)||14.5%||13.5%|
|Lower legs and feet||18% (2 x 9%)||14.5%||13.5%|
- The palm accounts for 1% of the total body area.
- It is the least reliable method.
- Clinical features of (e.g., hypotension, poor urine output)
- Clinical features of (e.g., dyspnea)
- Inhalation injury should be suspected when any of the following are present:
- In case of circumferential burns around limbs → : clinical features of (e.g., weak/absent pulse, paresthesia, pallor in the affected limb)
- In case of circumferential burns around abdomen → abdominal compartment syndrome: impaired function of nearly every organ system (e.g., oliguria, acute pulmonary decompensation, hypoperfusion) and signs of increased intraabdominal pressure (jugular venous distension, hypotension, tachycardia)
In the case of adults, shock sets in when burns involve > 15% of the body surface. Burns that involve 50–70% of the body surface are usually lethal. In children, signs of shock appear with > 10% involvement of the body surface and 60–80% body surface involvement is lethal! References:
Burn severity is based upon clinical history and physical examination, but further testing is conducted to monitor for complications and guide therapy.
- : monitor for hypoxemia
- : monitor for hypoxemia, metabolic, and/or respiratory acidosis
- Serum electrolytes: and occurs in the acute phase following burns; may occur later.
- If inhalational injury is suspected, the following additional tests should be performed:
- BUN/creatinine: monitor for acute renal injury
- Hemoglobin, hematocrit : monitor for hemolysis
- Serum protein and albumin levels
- If wound infection or sepsis is suspected: wound swab and blood cultures
- In circumferential limb wounds at risk for distal ischemia/compartment syndrome, assess perfusion with pulse oximetry (> 90% indicates adequate perfusion) and assessment of capillary refill and peripheral pulses
Immediate measures in case of severe burns: Think “ABCs”– Airway, Breathing, Circulation
- Airway management: intubation and high flow oxygen therapy is indicated if an inhalation injury is suspected or if burns involve more than 30–40% of the body surface; . Don't delay intubation if needed, as fluid resuscitation can increase laryngeal swelling, which will complicate intubation
Begin initial with crystalloids, usually lactated Ringer's solution (RL)
- Parkland formula is used to guide initial fluid therapy: the volume of lactated Ringer's solution to be administered within a period of 24 h = 4 mL x % of total body surface involved in burn x body weight (in kg)
- Half of this volume should be administered within the first 8 hours and the remaining half within the next 16 hours
- Modified Brooke's formula may be used as an alternative to Parkland's formula: volume of lactated Ringer's solution to be administered within a period of 24 h = 2 mL x % of body surface involved in burn x body weight (in kg)
- In children: : initial fluid therapy for a 24 hour period is the Parkland formula + 24 h maintenance fluid requirements
- Note that this is an INITIAL estimate for fluid requirements: fluid therapy should be modified to achieve a urine output of > 0.5 mL/kg/hr in adults and > 1 mL/kg/hr in children.
- In adults
Because of studies demonstrating serious complications from over-resuscitation (e.g., pleural effusions and compartment syndrome), the ATLS and American Burn Association now recommend only giving half of the fluid resuscitation volume that is calculated by the Parkland formula; i.e., 2 mL x %TBSA x weight (kg) instead of 4 mL). The volume is still given over 24 hours, with one half given in the first 8 hours and the remaining half over the next 16 hours.
- Remove any burnt clothing
- Cool the burnt area with cool running water or saline-soaked gauzes. Do NOT use ice or ice water! Cover the wound with a sterile dressing.
- Tetanus prophylaxis
- Analgesia (opiates often necessary)
- Proton pump inhibitors or H2 antagonists: prophylaxis against Curling's ulcers (see and )
- Following resuscitation, the patient should be transported to a special burn unit in the following situations:
- 2nd-degree burns involving > 10% of the body surface or 3rd-degree burns involving > 5% of the body surface
- Inhalation injury
- Burns involving specific regions (hands, feet, face, genitalia, joints)
- Electrical burns and chemical burns
- Prophylactic systemic antibiotic therapy is NOT routinely recommended.
Management based on degree
1st and 2nd-degree burns
- Topical moisturizers (e.g., calamine lotion) or aloe vera-based gels: relieve symptoms of 1st-degree burns
- Consider antiseptic ointments (e.g., silver sulfadiazine, mafenide) or topical antibiotics (bacitractin; triple antiobitic ointments are a combination of bactracin neomycin, polymyxin B)
- Deroofing bullae/vesicles
- Dressing is indicated in partial thickness (2nd-degree) burns.
3rd and 4th-degree burns
- Early debridement of burnt, necrotic tissue
- Method of tissue coverage varies depending on the specific burn characteristics. Options include:
- Topical antibiotics (e.g., silver sulfadiazine, bacitracin, neomycin)
Burn eschars: specific measures
- For circumferential burn
- Perform a doppler test, as well as check the capillary refill time, peripheral pulses, sensations, and pulse oximetry in the limb hourly for 24–48 hours
- If NO impending vascular/respiratory compromise or compartment syndrome:
- Elevate the lower limb or torso
- Perform range of motion exercises as tolerated
If vascular/respiratory compromise or compartment syndrome is impending or has occurred:
- If develops: fasciotomy
- For chest/neck eschars:
- If respiratory compromise impending or has occured → escharotomy
Chemical burns: specific measures
Immediate, copious irrigation of all areas of exposure with water, prior to or on the way to the hospital.
- Once in the hospital, irrigation should be continued until the pH normalizes
- Shock, sepsis, and respiratory failure are the most common causes of death following burns (see “Pathophysiology” above).
- Curling's ulcers (see )
- Keloid formation, contractures
- Complications of chemical burns
- Complications of electrical burns: arrhythmias, trauma
We list the most important complications. The selection is not exhaustive.