Pathophysiology⁶

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  Local tissue damage is classified into three zones from the center out, termed the zone of coagulation, zone of stasis, and zone of hyperemia (Figure 21.1).

  
  
  
  
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    Zone of coagulation is the area of maximal injury containing irreversible tissue coagulation and necrosis.

    
    
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    Zone of stasis has decreased tissue perfusion but is potentially reversible. The tissue is at high risk for irreversible damage if any additional insults occur and is the area most targeted by therapies.

    
    
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    Zone of hyperemia is the outermost zone and has increased perfusion initially. Tissue in this zone should recover.

  
  
  
  
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  Burn injuries cause the release of cytokines and other inflammatory mediators to the site of the injury. However, in large burns, typically >20–30%, this inflammatory response can have systemic effects. Capillaries become more permeable, and fluids are lost to the interstitial space. Vasoconstriction occurs peripherally and in the splanchnic circulation, in addition to decreased overall myocardial contractility causing diffuse hypoperfusion. Bronchoconstriction and acute respiratory distress syndrome may also occur.

Figure 21.1 Layers in normal skin and superficial second-degree burn. (A) Normal skin layers. (B) Zones of injury with a superficial second-degree burn. The central coagulation zone is irreversibly damaged tissue. The zone of stasis may progress to necrosis or may recover, depending on good resuscitation and prevention of infection

(illustrations by Robert Amaral, reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

ED Evaluation and Management

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  As with all trauma evaluations, airway, breathing, circulation, disability, and exposure must be quickly evaluated in a primary survey.

  
  
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  Once the primary survey is completed and the patient has been stabilized, a complete secondary survey should be performed.

  
  
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  Remember to assess for all traumatic injuries, in addition to the burn, as many of these patients have been thrown, fallen, or were even in a motor vehicle accident.

  
  
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  Hypotension is rare in a burn patient. Any patient with hemodynamic instability and burn requires evaluation and resuscitation for the associated type of shock.

Airway Management

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  Always consider an inhalational injury, as airway swelling can occur very quickly.

  
  
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  Indicators for a possible inhalation injury include: burns to the face or neck, singed nasal or facial hairs, hoarse voice, soot in the airway, dyspnea, wheezing, or stridor.^{1, 2, 5}

  
  
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  If any of the above indicators are present and there is concern for inhalational injury, early intubation is recommended.

  
  
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  Other therapies that may be helpful are humidified supplemental oxygen and bronchodilators. However, do not delay intubation to attempt these therapies if there is concern for significant inhalational injury.⁵

  
  
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  Always consider carbon monoxide and cyanide poisoning in patients presenting with burns from fires, especially house fires or any other enclosed space.⁵

Estimating Burn Size and Depth

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  It is important to estimate burn size and depth as it will help guide management in the emergency department (Table 21.1 and Figures 21.2–21.4).

  
  
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  When estimating total body surface area (TBSA) burned, only partial thickness and full thickness burns are included.^{7, 8}

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  The “rule of nines” provides a quick estimation of TBSA burned in adults (Figure 21.5).

  
  
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  For children, the Lund-Browder diagram is available to help estimate TBSA (Figure 21.6).

  
  
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  Another quick estimation is to use the palm of the patient’s hand as approximately 1% TBSA.^{1, 5}

Figure 21.2 Sunburn is a typical first-degree burn. The skin is erythematous and painful, but without blistering

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

(A) Superficial and deep second-degree burn from hot-water scald to the hand.

(B) Deep second-degree burn with central third-degree burn. Notice the classic color differentiation.

(C) Foot scald injury consisting of largely nonblanching pale appearing third-degree burn and erythematous deep second-degree burn over the medial forefoot

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Figure 21.3 Deep second-degree burns.

(A) Third-degree burn with its characteristic leathery appearance and lack of tissue edema.

(B) Third-degree burn of the foot from hot cooking-oil splash.

(C) Fatal 95% TBSA fourth-degree burn from a household fire

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Figure 21.4 Third-degree burns.

Figure 21.5 “Rule of Nines” to estimate adult TBSA burned

(from https://cnx.org/contents/FPtK1zmh@6.27:CHzzQ6Vf@4/Diseases-Disorders-and-Injuries-of-the-Integumentary-System; reproduced here under CC BY 4.0 license https://creativecommons.org/licenses/by/4.0/)

Figure 21.6 Lund-Browder diagram

(image courtesy of the US Department of Health & Human Services, at www.remm.nlm.gov/burns.htm)

Fluid Resuscitation

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  Patients with TBSA >20% will need fluid resuscitation.⁹ The area affected no longer has the normal skin layer which acts as a semipermeable barrier to help avoid fluid loss through evaporation.^{5, 10} Fluid resuscitation is also beneficial to prevent burn shock from the systemic inflammatory reaction and prevent hypoperfusion to end organs and salvageable burn tissue.¹¹ However, burn patients should not be hypotensive. If so, other etiologies of shock need to be investigated, such as cyanide poisoning, sepsis, trauma, hemorrhage, or myocardial infarction.⁹

  
  
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  Intravenous access is ideally placed in an unaffected area but may be placed through burned skin if necessary. Once obtained, the access must be sufficiently secured, which may require suturing if in a burned area.¹⁰

  
  
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  Several different formulas exist to calculate the rate of the fluid resuscitation (Figure 21.7).^11–13

  
  
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  Lactated ringers (LR) is generally preferred over normal saline. LR is more similar to human plasma, while normal saline is less physiologic, with greater risk of metabolic and renal disturbance. Therefore, in large volumes normal saline can induce a hyperchloremic acidosis.^11–13

  
  
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  Patients receiving fluid resuscitation should be monitored for signs of volume overload, especially concerning the development of pulmonary edema or acute respiratory distress syndrome, or in the chronically volume overloaded patient.

  
  
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  A urinary catheter should be placed for adequate input and output monitoring. The goal urine output is 1 mL/kg/hr.⁵

Figure 21.7 Burn resuscitation formulas

Escharotomies

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  Circumferential burns may require an escharotomy in the emergency department (Box 21.1 and Figure 21.8). This can be assessed for by delayed capillary refill, decreased pulse oximetry distal to the burned area (<95% in a non-hypoxic patient), decreased Doppler signals, and absence of a palpable pulse in the affected extremity. If the patient is awake and alert, he/she may also complain of increasing pain, numbness, or tingling. Loss of motor activity and loss of pulses are late signs, but, if present, should prompt immediate escharotomy.¹⁴

  
  
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  Trunk escharotomies may also be required if the patient cannot be adequately ventilated due to chest constriction or if abdominal compartment syndrome develops. It is important to routinely monitor a patient’s ventilation status, including airway pressures, as well as oxygenation, and measure bladder pressures in patients that are at risk.^{2, 5, 14–16}

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  To perform an escharotomy, standard sterile precautions should be used. For extremities, use a scalpel to create an incision on both the lateral and medial aspects from 1 cm proximal to 1 cm distal of the constricted tissue. These incisions may need to cross joints. Be very careful in these areas to avoid damaging underlying blood vessels and nerves. For the trunk, create an incision in the anterior axillary line bilaterally from the clavicle to below the costal margin or to the entire abdomen as needed. Then create a transverse incision to connect the two incisions at the superior chest and subcostal margin.¹⁴

(A) Illustration of the recommended escharotomy incisions.

(B) Truncal and extremity escharotomies in a household fire victim

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition, illustration at (A) by Alexis Demetriades)

Figure 21.8 Escharotomy for circumferential burn.

Transfer to a Burn Center

Small burns can be managed in any emergency department; however, there are several situations when a patient should be transferred to a regional burn center (Box 21.2).^{5, 15}

Wound Care

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  Superficial and partial thickness burns can be very painful, especially during wound care. Ensure adequate analgesia for the patient which may require intravenous narcotics or anxiolytics.

  
  
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  Wounds should be cleaned and debrided if necessary. Most blisters can be left intact, but any large blisters that may restrict movement, such as over a joint, should be debrided.⁵

  
  
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  Tetanus vaccination status should be obtained and updated if last vaccination was >5 years ago.

  
  
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  Either silver sulfadiazine or Bacitracin may be used to cover the affected area. Avoid using silver sulfadiazine on the face or neck and in any patients with a sulfa allergy.^{1, 5}

  
  
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  After applying the ointment, a sterile dressing should be placed.

  
  
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  Minor burns can follow up with a primary care physician, but all others should follow up with a burn specialist.

  
  
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  Patients should be instructed on how to change their dressings daily and to return to the emergency department for any symptoms or signs of infection.⁵