Chapter 8 – Burn Injuries




Abstract




The skin functions as a critical external barrier and serves a vital role in protecting against pathogens but also in thermoregulation, management of fluids and electrolytes, and protection from trauma. Small size burns cause relatively minor sequelae while larger burns can trigger a massive inflammatory response, secondary organ dysfunction, and result in death. The depth and extent of a burn will determine the severity of the response to this trauma.





Chapter 8 Burn Injuries


Alexandra Lacey , Andrew Tang , Demetrios Demetriades , and Warren Garner



Introduction


The skin functions as a critical external barrier and serves a vital role in protecting against pathogens but also in thermoregulation, management of fluids and electrolytes, and protection from trauma. Small size burns cause relatively minor sequelae while larger burns can trigger a massive inflammatory response, secondary organ dysfunction, and result in death. The depth and extent of a burn will determine the severity of the response to this trauma.


Critical to decisions about the initial management include accurate assessment of the patient’s burn wounds and associated injuries. Failure to accurately diagnose the type, extent, and depth of a burn will dramatically affect the patient’s outcome. Current burn survival rates have continued to improve over the last several decades due to advances in surgical management and ICU care.



Clinical Examination


The initial assessment of a burn patient is similar to the approach for trauma patients. Use of the current Advanced Burn Life Support (ABLS) guidelines, which are similar to the ATLS guidelines, is strongly recommended. This follows a similar ABCs of the initial survey, followed by a secondary survey with a few special considerations. These are summarized as follows:




  1. A– Airway – Initial management should include observations for possible inhalation injury and any difficulties with breathing. Cervical spine precautions should be maintained if there was concurrent trauma. If there was a significant smoke exposure, voice changes, or the patient is reporting changes in their voice, then laryngoscopy should be performed to assess for airway edema or soot on cords. If there is a positive laryngoscopic examination or clinically determined risk of airway occlusion, the patient should be intubated.



  2. B– Breathing – High flow oxygen via a non-rebreather mask while should be given while the respiratory pattern is assessed. Circumferential burns to the chest or neck can cause restricted breathing and require early escharotomy to release the burn.



  3. C– Circulation – Capillary leak syndrome after injury can result in significant loss of intravascular volume. To respond to this process, burn patients require two large bore peripheral IVs for access. If necessary, any lines can be temporarily placed through burn eschar. Circulation in circumferentially burned extremities requires an assessment of pulses.


    Fluid resuscitation in patients with >20% total body surface area burns (TBSA) should have resuscitation started with lactated ringers at the following rates:




    • <5 years – 125 ml/hr



    • 6–13 years – 250 ml/hr



    • >14 years – 500 ml/hr




  4. D– Disability – Neurologic status and obvious deformities should be assessed. If the mental status is abnormal, this could be due to associated injuries, carbon monoxide poisoning, illicit substances, alcohol, hypoxia, or other medical conditions.



  5. E– Exposure – All clothing, jewelry, and contact lenses should be removed to fully evaluate the burn. If a chemical burn occurred, all contaminated articles should be carefully removed and the wounds copiously irrigated with water. The entire body must be exposed to assess the burns. Cover the patient in clean dry sheets to help maintain core temperature if the provider is not going to manage the wounds. If the provider is going to be managing the wounds then an appropriate dressing can be applied.


Upon completion of the primary survey, a head to toe exam and an accurate assessment of the TBSA is completed. TBSA includes second- and third-degree burns (partial and full thickness). First-degree burns (superficial burns) are not included in the calculation for TBSA. When calculating the TBSA, it can be helpful to use the Lund-Browder chart or use the patient’s hand to estimate the size of 1% TBSA on that patient (Figure 8.1).





Figure 8.1 The “rule of nines” in determining total burn surface area in both adults in and children.



Investigations


The necessary tests and blood work for a burn patient is similar to a trauma patient with a few key additions. These include:




  • Arterial blood gas – Early assessment of hypoxia is important for assessing for possible inhalation injury. Pulse oximetry may not be reliable in burn extremities due to swelling or burn eschar.



  • Carboxyhemoglobin levels – Closed space fires can release large amounts of carbon monoxide (CO). CO has an affinity for hemoglobin forty times greater than oxygen and will falsely elevate pulse oximetry readings while causing tissue hypoxia.



  • Trauma imaging – Up to 10% of burn patients will have concurrent traumatic injuries so it is important to assess for these.



General Management


Management of burn patients can take place over weeks to years, depending on the nature and long-term sequelae of the injuries. In this section, we will aim to focus on the first 24 hours of burn care, when the most important tasks are the burn resuscitation, wound management, airway/pulmonary management, and assessing if the patient requires transfer to a higher level of care.


In patients with a TBSA over 20%, there will be a significant total body inflammatory response to the insult resulting in massive vasodilation and capillary leak. Given this, large volumes of fluids are required to maintain intravascular volume and therefore tissue perfusion. This fluid is to be given in a sustained manner, and there should be a major focus on avoiding fluid boluses as these will increase peripheral and intra-abdominal edema. The American Burn Association recommends a total volume of fluids in the first 24 hours as follows:




  • Adults and children >14 years – 2 ml lactated ringers × kg × % TBSA



  • Children <14 years – 3 ml lactated ringers × kg × % TBSA



  • Children <30 kg – 3 ml lactated rings × kg × % TBSA, plus D5LR at maintenance



  • Electrical injury – 4 ml lactated ringers × kg × % TBSA


The fluid is to be given with half the volume over the first 8 hours after burn injury and the other half in the subsequent 16 hours after. This is a guideline, however; the most important facet of resuscitation is to adjust the fluids based on hourly urine output. In adults, the goal urine output is 0.5–1.0 ml/kg/hr, and in children (<14 years), the goal is 1–1.5 ml/kg/hr. If the urine output is under or over goal, then the fluids should be titrated by 10% each hour to meet the goal urine output.


Initial wound management includes cleaning the area of the burn with soapy water. In patients with large blisters (>1 cm), these blisters should be sharply debrided of the devitalized skin. The depth and size of the injury will determine the best dressing for the wound. Silver-based dressings, including silver sulfadiazine and other silver impregnated wound coverings, are very common due to their antimicrobial activity. Every medical center will have access to different dressings, and clinicians should make themselves comfortable with the dressings that they will have available for burn care.


In patients with circumferential full-thickness burns, there is a risk for developing a compartment syndrome. While edema progresses in the tissues adjacent to the burn and the rest of the body, the full-thickness burn does not stretch as normal skin would and instead acts like a tourniquet. The result is venous hypertension, then arterial occlusion, and finally tissue necrosis. In any patient undergoing resuscitation who also has circumferential full-thickness extremity burns, it is prudent to consider early escharotomy to avoid complications, as they are likely to develop compartment syndrome if not managed in a timely manner.


Pulmonary support of critically burned patients or patients with inhalation injury is critical in the initial 24 hours of their care. Inhalation injury can be caused by either superheated air or smoke causing thermal damage to the upper or lower airways and can also cause injury via the toxic products of combustion. A supraglottic injury will cause voice changes and difficulty breathing early in the patient’s course as upper airway edema narrows their airway. This can be assessed with direct laryngoscopy. Any evidence of soot or airway edema necessitates early intubation to prevent an airway disaster as the swelling progresses. A subglottic injury will cause impaired ciliary action, sloughing of respiratory epithelium, severe inflammation, and significant ventilation-perfusion mismatch in the coming hours to days after injury. This injury should be treated with aggressive suctioning, aerosolized N-acetylcysteine, heparin, and albuterol along with advanced ventilatory strategies, which will be discussed further in this chapter.


When seeing patients with massive burns, it is important to consider if the burn wound is survivable. Using the modified Baux score, a rough approximation of survivability can be assessed. This method adds the TBSA of the burn plus the patient’s age, plus an extra 17 points if inhalation injury is present. A score of 160 has been shown to have a 100% death rate, and numbers approaching this have increasingly low chances of survival. A clinician must also include the patient’s existing comorbidities, as there presently is no good model to include significant conditions such as renal failure, cirrhosis, heart failure, or COPD that will dramatically worsen outcomes. This model also has limitations in the extremes of age.


Lastly, the American Burn Association has created specific transfer criteria for burn patients. These criteria should be followed by all centers that do not house a burn treatment unit. Patients who qualify for transfer to a burn unit include:




  • Partial-thickness burns that are over 10% TBSA



  • Partial or full-thickness burns that involve sensitive areas including the face, hands, feet, genitalia, perineum, or major joints



  • Full-thickness burns of any size and in any age group



  • Electrical burns including lightening



  • Chemical burns



  • Inhalation burns



  • Burns in a patient with significant comorbidities



  • Burns in children if the center they presented to does not have adequate facilities for the care of children



  • Burns in patients who will require interventions for their social situation, emotional state, or rehabilitation needs



Tips and Pitfalls




  • Missed or delayed diagnosis of inhalation injury. These patients will progressively develop worsening airway edema and what could have been an elective intubation will become an emergency situation.



  • Incorrect estimation of burn size. The entire body must be examined to accurately assess TBSA, and an age-appropriate Lund-Browder chart should be used. If using the “hand” to approximate 1% TBSA, be sure to use the patient’s hand, not the practitioner’s.



  • Missed coexisting trauma. Up to 10% of burn patients will have coexisting trauma, and this may be overlooked in the setting of significant burn. Be sure to complete a standard trauma work-up in these patients.



  • Missed or delayed diagnosis of compartment syndrome. Full-thickness burns that are circumferential are at very high risk of causing a compartment syndrome. These patients should have hourly neurovascular checks if an early escharotomy is not pursued.



  • Inadequate fluid resuscitation. Underestimation of TBSA will result in inadequate resuscitation and lead to hemodynamic instability, kidney injury, and conversion of any partial-thickness wounds to full-thickness wounds.



  • Overresuscitation. The use of fluid boluses and excessive fluid resuscitation not titrated to urine output will result in anasarca, ileus, pulmonary edema, conversion of partial-thickness burns to full-thickness burns, and dramatically increase the patient’s risk of developing abdominal compartment syndrome.



  • Inadequate analgesia and sedation. Burn patients require large volumes of sedation and narcotics to manage their pain adequately especially during dressing changes.



  • Inadequate wound care. Failure to properly debride wounds and provide a moist antimicrobial dressing will result in infection of burns, causing conversion of wounds to deeper injuries and a worsened inflammatory response.



Extent of Burn Injury


Burn wounds are classically described as having three distinct zones of injury. The zone of coagulation is the most central area of the burn, which is irreversibly damaged and has no perfusion or chance of recovery. The adjacent zone of stasis is moderately damaged tissue that is perfused and has the ability to recover. This is the tissue that is most at risk for progressive necrosis, increasing the burn injury burden. The outermost zone of hyperemia is not injured but is inflamed from the release of proinflammatory signals from the zone of stasis. There is significant hyperemia in the area (Figure 8.2 AC).





Figure 8.2 A–C Diagrams showing the normal skin anatomy and varying burn depth. Normal skin layers (A). Zones of injury in a superficial partial-thickness burn (B). The deeper elements of the skin remain uninjured and thus able to regenerate. Deep partial-thickness injury in cross section (C). The zone of necrosis extends deep into the dermis with the zone of stasis extending into the adjacent adipose.



Superficial Burns (First-Degree Burns)


A superficial burn is limited to the epidermis while the dermis and all elements of the dermal appendages remain intact. The burned skin is erythematous, painful, blanches with touch, but does not blister. It is similar to a casual sunburn. Skin regeneration typically happens within a few days as the damaged epidermal layer desiccates and sloughs off. Treatment is aimed at providing comfort with moisturizing lotion to create a supportive environment for healing. Pain control should include non-steroidal anti-inflammatory drugs or acetaminophen (Figure 8.3 A,B).


Apr 22, 2021 | Posted by in EMERGENCY MEDICINE | Comments Off on Chapter 8 – Burn Injuries
Premium Wordpress Themes by UFO Themes