Burns and Smoke Inhalation

Authors: Mark Saks, MD, MPH, Pollianne Ward Bianchi, MD, FAAEM, Crozer-Chester Medical Center, Upland, Pennsylvania

Editor: James Ham, MD, University of Hawaii

Updated March, 2019


Objectives

By the end of this module, the student will able to:

  1. List the basic function of skin
  2. Describe the initial evaluation and assessment of the burned patient
  3. List the different types of burns and their distinguishing characteristics
  4. Name the potential comorbid injuries in inhalational injury
  5. List the basic principles of burn management regarding:
  • Minor burn treatment
  • Fluid resuscitation
  • Infection control
  • Management of inhalation injuries


Case Study

A patient presents to the Emergency Department with burns from a house fire. He was extracted by firefighters, and it has been two hours since the initial call. He is young, approximately 20-30 years old, unconscious, with burns to his face, trunk and extremities, with charred clothing, and covered in soot. How will you evaluate and treat this patient?


Introduction

Each year approximately 500,000 burn patients seek medical care in the US. Burn injury can result from heat (thermal burn), chemicals, cold (frostbite), or electricity (flash or internal). However, the clinical significance of a burn depends more on the depth of the burn, the total body surface area (TBSA) involved, the specific area involved, associated injuries, and the promptness of therapy than on the mechanism. Inhalational injuries may result from heat, carbonaceous particles, or the inhalation of abnormal gases such as smoke, carbon monoxide, or cyanide.

Quickly and accurately evaluating the burned or inhalational injured patient in the Emergency Department is difficult because the extent of injury is not always obvious, often evolves over time, and may mask other, more immediately life-threatening injuries. Therefore, it is very important for the emergency physician to understand the complex pathophysiology and clinical management of these patients.

Skin is the body’s largest organ system and is composed of three layers: the epidermis, dermis, and hypodermis. The epidermis is the outermost layer, does not contain any neurovascular structures, and constantly regenerates mitosis and keratinization. The dermis is the middle layer and contains hair follicles, sweat and sebaceous glands, and lymph and blood vessels. The hypodermis is the deepest layer, is comprised of adipose and larger neurovascular structures, and acts to anchor the skin to underlying muscle, bone, and fascia. For figure see here.

Intact skin has many functions including:

  • Protection
  • Fluid retention
  • Electrolyte homeostasis
  • Thermoregulation
  • Sensory
  • Metabolic (vitamin D synthesis)

All of these functions are potentially disrupted with burns, regardless of the severity of injury, source of damage, or the mechanism of burn. In general, the extent of the burn injury worsens as temperatures that the skin is exposed to increases. For example, with temperatures between 40-44ºC, enzymes begin to malfunction, proteins denature, & cellular pumps fail. With temperatures above 44ºC, this damage occurs faster than the skin cells can heal and injury develops. This injury typically exhibits three zones:

  • Zone of Coagulation: In this area, cell death is complete. This is usually nearest to the energy source and forms the eschar of the burn wound
  • Zone of Stasis: In this area, cells are viable but circulation is impaired. If the injury continues, then increased damage and tissue ischemia may result
  • Zone of Hyperemia: In this area, there is minimal cellular injury but there is increased blood flow due to vasodilatation. This tissue usually recovers without intervention


Initial Actions and Primary Survey

Burns often occur as a result of explosions, building collapse, or motor vehicle accidents. In addition, patients involved in fires will often go to extremes, including jumping out of tall buildings, to get out of harm’s way. Therefore, it is important to remember that ALL burn patients should be thought of as trauma patients and the initial assessment and stabilization should be conducted according to the principles of Advanced Trauma Life Support (ATLS).

  • Primary Assessment: Airway, Breathing, Circulation, Disability, Exposure
  • Secondary Assessment: Detailed head to toe examination, AMPLE history

The burn-specific assessment occurs during both the Primary and Secondary Assessments and is focused on the following areas (in addition to the ATLS survey):

  • Airway: Is there carbonaceous sputum? Soot? Hair singed? Stridor? Airway edema? If noted, a patient may require prophylactic intubation or laryngoscopy/bronchoscopy.
  • Breathing: Are there burns to the lung or chest wall? Gas/toxin inhalation? Check pulse oximetry. If noted, a patient may require a variety of interventions, including an ABG to check pH, a carbon monoxide level, or an escharotomy, a procedure to release tension due to scar formation.
  • Circulation: Are there signs of decreased perfusion or circulatory collapse? Check pulses and perfusion in affected extremities. Monitor vital signs and volume input/output. All significant burns require IV access – obtain intraosseous access if indicated. The patient may require central line access for volume resuscitation, hemodynamic monitoring, etc. 
  • Disability/Exposure: Carefully examine all skin areas to determine wound location & depth, remove all jewelry and clothing. This may require detailed drawings to document the injuries and to calculate the extent of burned tissue (discussed below in more detail). Decontaminate if the burn is from a chemical source.


Presentation

The classic presentation of a burn patient usually depends on the extent and depth of injury. The diagnosis is made based on a careful clinical evaluation, rather than specific laboratory or radiologic studies.

If possible, a burn history should be elicited regarding:

  • The circumstances & mechanism of injury
  • Type(s) of material burning and length of exposure to them
  • Exact time of injury
  • Actions taken prior to arrival
  • Associated signs and symptoms

Classification of Burns

Superficial Burns

Minor burn injury; may involve epidermis and parts of the dermis

Superficial injury

Formerly called “First degree.” Superficial burns are limited to the epidermis. Wound is red, painful, and well-demarcated.

Superficial Partial Thickness

Formerly called “Second degree, superficial partial thickness.” Superficial partial thickness burns involve the epidermis and part of the dermis. May involve hair & glands. Wounds are painful, blister, & blanch with pressure. Tends to be wet & slippery to touch.

Deep Burns

Significant burn injury involving multiple skin layers

Deep Partial Thickness

Formerly called “Second degree, deep partial thickness.” Deep partial thickness burns involve deeper parts of the dermis, but not all. May involve hair and glands. Wounds are painful, blister, and blanch with pressure. Tends to be wet and slippery to touch. 

Full Thickness

Formerly “Third Degree.”

Full thickness burns involve all epithelial and dermal elements. Specific wound is painless (but will often be surrounded by painful tissue so patients may report pain). It is depressed, non-edematous, and leathery. May be white, brown, or black, often with a “charred appearance.”

Burns involving fascia and muscle

Formerly “Fourth Degree.”

Deep tissue burns that extend through all layers of skin and involves underlying fascia, muscle and/or bone. Wound is painless but injury is extensive and often requires amputation.

Electrical burns

Electrical energy is converted to heat which causes thermal injury and burns. However, unlike conventional thermal burns, the electricity may flow in unpredictable pattern and significant injury may not be evident at site of entry. Therefore, a detailed skin exam, including evaluation of the palms and soles is essential. Cardiac arrhythmias are common in electrical burns if the flow of electricity crosses through the thorax and across the heart. Extent of injury is determined by voltage type, voltage strength, the resistance of tissue, and the duration of contact.

Rule of Nines

Burns are classified according to the percentage of the total body surface area (%TBSA) that they involve. This area can be estimated by either the “palm estimate” or the “rule of 9s.” The burned patient’s palm (ventral surface of the hand excluding the fingers) is estimated to be equal to 1% of the TBSA and then used to measure the size of the burn. The entire head and each arm are estimated at 9% of the TBSA while each entire leg, the anterior thorax plus abdomen & back is each estimated at 18% of the TBSA. The perineum is estimated at 1% of the TBSA. In children, due to their relatively larger head size, the head is estimated at 18% with the other areas adjusted for this change.

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Figure 4. Estimation of Total Body Area.  Dibildox M., Jeschke M.G., Herndon D.N. (2012) Burn Injury, Rule of Nines. In: Vincent JL., Hall J.B. (eds) Encyclopedia of Intensive Care Medicine. Springer, Berlin, Heidelberg Accessed https://link.springer.com/referenceworkentry/10.1007%2F978-3-642-00418-6_380


Classic Presentation of Inhalational Injury

The evaluation of inhalational injury is difficult since patients will often have few external signs of injury. Therefore, in addition to the detailed history and physical exam described above, a chest x-ray, detailed oropharyngeal exam, nasopharyngeal laryngoscopy, or bronchoscopy should also be considered in order to fully assess the extent of inhalational injury. Complete vital signs including continuous pulse oximetry are essential. Laboratory tests such as an ABG, carboxyhemoglobin level, or methemoglobin level may also be useful at detecting poisonings or metabolic disturbances. More specifically, inhalational injuries may be grouped as temperature-related, smoke-related, or gas-related.


Temperature-related airway injuries

 

Heat tends to affect the upper airway more than the lower airways. There are two likely explanations for this: Vocal cord spasm protects the lower airway from the heat or the air is cooled and moisturized as it enters through the nose and mouth.

Patients will develop edema, erythema, and ulcerations of lips, tongue, posterior oropharynx, and upper airway. Onset may be delayed for up to 24 hours and resolve in 4-5 days. Early signs include erythema and superficial burns to tongue, lips and pharynx and soot in mouth and nares. Stridor can develop quickly. There is generally a low threshold for early intubation before edema develops, and then tracheostomy if edema continues.


Smoke-related airway injuries

Smoke tends to affect the lower airways more than the upper airways. There are several explanations for this including: injury occurs when particles & soot settle in the medium and distal airways, direct thermal injury occurs when hot particles contact alveolar membranes and smaller airways are at increased risk of occlusion due to debris accumulation.

Smoke-related damage leads to reduced mucociliary function. Early signs and symptoms include wheezing and respiratory distress with increased work of breathing, hypoxia, and coughing or gagging. Patients may develop pneumonia as a complication, in part due to impaired clearance.


Gas-related airway injuries

Oxygen is consumed during combustion. Fires create hypoxic environments and patients may be hypoxic on scene as well as on arrival in the ED. Carbon dioxide (CO2) & carbon monoxide (CO) are produced by combustion. Symptoms of CO toxicity are related to the amount of carboxyhemoglobin present in the blood as well as age and health of the patient. Presentation can range from a slight headache, nausea, or confusion to chest pain and vomiting. Severe or prolonged exposure can cause seizures, coma, and death.

Burning of home furnishings and other synthetic materials release various toxins into the environment such as plastics releasing cyanide. Cyanide toxicity most often presents with depressed mental status or respiratory or cardiac arrest and should be suspected in any burn patient with change in mental status or hemodynamic instability.

Water-soluble chemicals (ammonia, chlorine, etc.) can lead to bronchospasm and airway edema causing wheezing and pneumonitis. Lipid soluble chemicals (phosgene, nitrous oxide, etc.) can cause direct cell damage and impaired ciliary clearance.


Diagnostic Testing

Given that the diagnosis of burns is largely clinical, there may be some testing that is helpful in the Emergency Department. Diagnosis of any traumatic injury may require radiologic imaging such as chest X-ray to assess for pneumothorax or rib fractures and CT scans to assess for intraperitoneal, cervical spine, or traumatic brain injury. 

Laboratory studies should include basic metabolic panel (BMP), creatine kinase (CK), complete blood count (CBC), and coagulation studies (PT and PTT). These may be helpful in diagnosing electrolyte abnormalities, such as hyperkalemia and rhabdomyolysis that can be associated with severe burns or coagulopathies and anemia that may be associated with hemorrhage and trauma. ABG or VBG with  carboxyhemoglobin levels are useful in diagnosing carbon monoxide toxicity and lactate will be significantly elevated in cyanide toxicity and severe burns.


Treatment of Minor Burns

The management of the patient with minor burns (either by extent of TBSA involved or by depth of burn) can be treated with basic local wound care and is focused on the following principles.

First, stop the burning process by removing clothes or other materials and running cool (not cold) water over the area until the skin temperature has normalized. Next, initiate pain control with NSAIDs (anti-inflammatory properties) and/or opioids. Follow this with washing the burned area thoroughly with soap & water before careful drying of the area.

Finally, apply topical ointment and sterile dressing. There are numerous options for this. Generally, bacitracin is used for burns on the face. A combination of bacitracin and petrolatum gauze dressings are used for many areas of the body. Silver sulfadiazine (SSD) used to be the mainstay for burn management for burns that can be easily and thoroughly washed off before reapplication. SSD should not be used on the face and can cause abnormal pigmentation. SSD has recently fallen out of favor for everything less than very deep burns as it can be messy to apply and also impair wound healing. 

A newer complement to burn management is the use of new, commercially-available skin-like dressings that are applied to the cleaned burn and remain in place as the burn heals. Each specific brand has its own indications and contraindications. Mepilex is one of the most common and can be impregnated with silver. As the burn heals, dressings should be changed at a minimum of once daily by the patient with the same procedure as above with careful monitoring for cellulitis and wound healing. Arranging for follow up may include returning to the ED for a wound check, with a primary care doctor, or at a regional burn center.

There is debate in the literature about whether to debride intact bullae. In general, intact bullae (blisters) have been considered to be sterile dressings and may be left intact unless they are quite large, painful, or in areas that interfere with functioning. However, recently there has been a trend to debride the bullae and then dress the wound under sterile technique as this also provides a sterile barrier and some evidence suggests that the material within the bullae is cytotoxic.

Tetanus vaccination status should be verified and may need to be administered. There is no need to treat with oral or IV antibiotics on initial presentation for prophylaxis.


Treatment of Significant Burns

The management of the patient with significant burns is focused on accounting for the impaired functioning of the damaged skin, especially regarding the role of skin in fluid retention and as a barrier to infection. Significant burns are considered partial thickness burns involving greater than 20% TBSA.

Fluid Resuscitation: Large, deep burns can lead to the loss of massive amounts of fluids and electrolyte imbalances for several reasons including: increased microvascular permeability that leads to extracellular edema and cell membrane defects that contribute to intracellular swelling. Additionally, burn patients have increased metabolic and respiratory rates that lead to increased evaporation and other insensible losses and often become hypoproteinemic leading to decreased intravascular oncotic pressures. Therefore, adequate fluid resuscitation is of paramount importance. The resuscitative fluid of choice is Lactated Ringer’s (LR) solution, given according to the Parkland formula:

  • %TBSA burn x wt in kg x 4 mL/kg = volume of LR that should be administered over the first 24 hours

Half should be given in the first8 hours following the burn and the remaining half should be given over the next 16 hrs (24hrs total). Remember, this is extra fluid in addition to the patient’s baseline fluid requirements.

There is new evidence to suggest that we do not need to give fluids as aggressively as previously thought. Large amounts of fluids can create complications of their own such as third spacing with massive edema, heart failure, and electrolyte abnormalities. The modified Brook formula is the same as the Parkland formula except is 2 mL/kg instead of the Parkland formula’s 4 mL/kg and is aimed at prevention of over-resuscitation with fluids of burn patients. Clinicians also typically overestimate the size of burns, further leading to over-resuscitation.

Infection Control: Sepsis is the leading cause of death in patients with large burns, accounting for up to 75% of deaths. Although the specific pathogens vary from patient-to-patient and between burn centers, patients with large burns have increased susceptibility to infection for several reasons: the normal skin barrier is lost and they are in a hypermetabolic & catabolic state. Patients develop depleted energy stores and various metabolic deficiencies. The local release of cytokines, breakdown of normal tissues, and circulating cellular components contribute to a global immune system impairment. Burned tissue creates a favorable bacterial environment. Eschar has increased moisture, acidic pH, and little blood flow.

More specifically, the prevention and control of infection in the burned patient takes three main forms:

  • Debridement of devitalized tissue: cut away dead, necrotic tissue and expose underlying viable tissue. A fasciotomy or escharotomy may be necessary in severe, circumferential burns that limit chest mobility or compress vital structures.
  • Wound management: limit bacterial invasion by covering affected areas with antibiotic dressings and through early wound closure with skin grafting and/or commercial products.
  • Preventing the delayed development of pneumonia and sepsis: universal precautions and general infection control practices are of paramount importance. Contact isolation with gown, gloves, and mask. Frequent changing of intravenous lines, etc. Aggressively evaluate fevers by pan-culturing and initiating broad-spectrum antibiotics.

Disposition: Patients with superficial or localized burns are generally treated in the Emergency Department and discharged with close outpatient follow-up with a burn surgeon. Adult patients with >20% TBSA burns are generally transferred or admitted to a regional burn center for evaluation. There are other criteria, usually elucidated by prehospital EMS, to determine transfer such as burns to the hands, face, feet and genitalia, chemical burns, inhalational injury, or the possibility of major trauma associated with the burn. Pediatric patients with >10% TBSA burns are generally transferred to a regional pediatric burn center for evaluation.


Treatment of Inhalational Injury

Patients with suspected inhalation injury should be placed on 100% oxygen by a non-rebreather mask as soon as possible. Patients with any signs of airway burns (soot in nares, burns to oropharynx) or impending edema (swelling of face or oropharynx, stridor, voice changes) should be intubated as soon as possible to avoid loss of airway. 

Non-invasive pulse oximetry is not a reliable method to diagnose CO toxicity, as levels can actually be normal. Carboxyhemoglobin levels greater than 4% in non-smokers and 10% in smokers should be treated for acute CO toxicity. Patients with carboxyhemoglobin levels greater than 25%, children, pregnant patients, older patients or those with significant comorbidities or altered mental status should be considered for hyperbaric oxygen therapy to prevent delayed neurologic sequelae.

Patients with altered mental status, respiratory or cardiac arrest should be considered for treatment of cyanide toxicity. There are two approaches to this. The old “Cyanide Antidote Kit” contained sodium thiosulfate and involved a two-step approach which included inducing methemoglobinemia. This has fallen by the way-side in favor of hydroxocobalamin administration, which is faster acting and safer.


Case Conclusion

You evaluate your burn patient using the burn classification system and rule of nines above after fully undressing him and performing the ATLS survey. Since he is unconscious, with a depressed mental status and signs of inhalation injury, such as soot in the airway and facial burns, you decide to intubate him in the resuscitation bay. A chest X-ray is performed, showing no pneumothorax and appropriate endotracheal tube placement. It is determined that he has 20% TBSA deep partial thickness and full thickness burns. You send laboratory studies including complete blood count, basic metabolic panel, arterial blood gas, carboxyhemoglobin, and coagulopathy studies. While he is in CT scan you calculate his fluid requirement using the Parkland Formula. His weight is 70 kg. 

(70 kg) x (20%) x (4 cc/kg) = 5,600 mL

Remembering that he gets half of this in the first 8 hours and half in the next 16 hours, you calculate he’ll need two boluses, each being 5,600 mL / 2 = 2,800 mL.

Since two hours of the first 8 hours has already passed from the initially injury, he will need to get that first bolus over the next six hours.

2,800 mL / 6 hrs = 467 mL/hr (additional fluid given over the next 6 hours)

The remaining 2,800 mL would have to be administered over the next 16 hours.

2,800 mL / 16 hrs = 175 mL/hr (additional fluid given over the next 16 hrs)

This is in addition to his maintenance fluids, which for a 70 kg man would be 104 mL/kg. So his final fluid orders would be:

467 mL/hr (bolus) + 104 mL/hr (maintenance) = 571 mL/hr (for the first 6 hrs)

175 mL/hr (bolus) + 104 mL/hr (maintenance) = 279 mL/hr (for the following 16 hrs)

Remember, these calculations are just a general guide. You must also monitor urine output to ensure adequate fluid resuscitation and adjust fluids as necessary to achieve a target urine output:

  • Adult urine output: 0.5 mL/kg/hour
  • Pediatric urine output: 1-2 mL/kg/hour


Pearls and Pitfalls

  • Don’t be distracted by the sight and smell of the burns. Burn patients are trauma patients and often have concomitant injuries that must be addressed.
  • Fully undress the patient to expose all skin and remove charred or burning clothing that can further contribute to burn injury.
  • Be liberal with pain medications. Most patients with significant burns will require large doses of pain medications.
  • Most patients may have burned areas with a mix of depths including superficial and deeper areas.
  • Inhalation injuries are common but difficult to assess initially. Don’t forget to carefully assess burn patients for potential delayed airway compromise and have a low threshold for intubation as airway edema can progress within minutes.
  • Altered mental status can be due to trauma injury or inhalational injury. Don’t forget to give oxygen, check carboxyhemoglobin levels and have a low threshold to treat for cyanide toxicity.
  • Do not place moist towels, gauze, or sheets on burned areas as this will contribute to hypothermia. Clean burns cover burns with petrolatum gauze or antibacterial medications and gauze.
  • Children have different total body surface area calculations compared to adults.
  • Significant fluid losses only occur with deeper burns greater than 20% TBSA. Superficial burns do not generally require extra fluid resuscitation beyond maintenance fluids.


References

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  2. American Burn Association. Multiple educational resources and a listing of US burn centers is available on line at http://www.ameriburn.org.
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