Burns/Inhalational Injury

Types of Burn Injuries

• Scald Burns

  • Account for majority of pediatric burns

  • More likely to be associated with child abuse (glove/stalking, symmetric burns of buttocks/legs/perineum)

• Thermal Burns

  • Secondary to flame or contact with hot objects

  • Generally minor

  • Mortality influenced by size of burn, patient age, +/- inhalational injury

• Electrical Burns

  • Rare but serious. Lack of obvious skin damage can mask serious underlying soft tissue injury

  • AC more dangerous than DC (tetanic contractions from cyclic flow of electricity)

  • "Let go" threshold, max current one an grasp and "let go" lower for children than adults

• Chemical Burns

  • Alkali drain cleaners, hydroflouoric acid, etc

  • DO NOT NEUTRALIZE acid or base as leads to exothermic reaction that can worsen injury

  • Treat with copious irrigation 

Assessment of Burns

Burn Degree

• First degree

  • Superficial, erythematous without blistering. Painful. Blanch easily, spares dermis. heals in 2-3 days. i.e sunburn

• Second degree

  • Partial thickness involving all of epidermis and either superficial dermis or deep dermis 

  • Fluid filled blisters at dermis-epidermis junction

  • Burns that extend to superficial dermis are erythematous underneath the blister and heal in 2 weeks

  • Burns that extend to deep dermis can appear mottled with variable color. Do not blanch easily, less painful as a result of nerve injury. Typically requires excision and grafting as can lead to scarring and contractures

• Third degree burns

  • Full thickness burns requiring definitive surgical management.

  • White, cherry red, brown, black and do not blanch with pressure. Dry/leathery compared to normal skin. Insensate

Zones of Injury

• Zone of coagulation: necrotic tissue closest to site

• Zone of hyperemia: uninjured skin with increased blood flow

• Zone of stasis: located between zones of coagulation and hyperemia and represents area of ongoing inury

Estimating Extent of Burn

• TBSA correlates with LOS and mortality but has been shown to be overestimated by up to 75% by initial care provider

• Rule of nines for adults and modified for children due to relatively larger heads and smaller extremities in children (see diagram below)

• Patient's palm and fingers accounts for ~1% of normal BSA

Treatment

Initial Evaluation

• Wash with tepid water

• Chemical burns should be copiously flushed to remove inciting agent

• Evaluate for other sources of trauma (~10% of all burn patients have additional traumatic injuries)

• Evaluate for signs of inhalational injury (singed nasal hairs, carbonaceous sputum, facial burns, hypoxia)

• IV access in any patient with greater than 10% TBSA

• Assess TBSA. >10% TBSA in infants/children or if suspicion of inhalation injury warrants admission

• Avoid wet dressings as can precipitate hypothermia

Resuscitation

• Parkland or modified Brooke formulas serve as guidelines for resuscitation. (UM has a specific protocol) \

• Parkland formula (4 cc/kg/%TBSA over first 24 hours with half in first 8 hours and half in subsequent 16 hours) tends to overestimate fluid needs leading to overresuscitation although no clinical difference in outcome has been found between the two formulas

• Modified Brooke Formula (2 cc/kg/%TBSA) of crystalloid

• Titrate fluids for clinical endpoints (urine output of 0.5-1cc/kg/hr) and normal hemoydnamic parameters. Little/no role for bolus fluid therapy

• No clear difference with colloid vs. crystalloid. Per UM policies, switch to 5% albumin as part of the difficult fluid resuscitation pathway (projected >6 cc/kg/%TBSA in first 24 hours). 

• Want to balance restoring adequate volume and perfusion vs. over-resuscitation and complications such as compartment syndrome, reperfusion injury, or ARDS

• Eval for compartment syndrome: Can insert 18 gauge needle connected to arterial pressure transducer and place into subcutaneous/subfascial tissue. Compartment pressure >30 mmHg diagnostic, requires escharatomy or fasciotomy (alternatively, some use a delta of less than 30 mmHg between compartment pressure and diastolic blood pressure as an indication for critically impaired perfusion pressure and need for fasciotomy).

• Intraabdominal hypertension seen in up to 70% of those with extensive burns. Bladder pressure measurements crucial (12-20 mmHg consistent with IAH and >20mmHg consistent with ACS in adults)

Inhalational Injury

• Clear link between inhalation injury and mortality- single most important risk factor for mortality1

• Pathophysiology involves inflammatory response, capillary leak, reactive oxygen species, tissue edema, airway casts/obstruction, direct cellular damage

• Pulmonary insufficiency at ~36 hours, pulmonary edema at 48-96 hours, and bronchopneumonia at 3-10 days postburn

• Bronchoscopy gold standard for diagnosis of inhalational injury

• Incomplete oxidation of hydrocarbons leads to formation of CO. Treat with 100% oxygen as half life of carboxyhemoglobin is 240-320 minutes but decreases to 40-80 minutes with 100% oxygen

• Cyanide, produced by combustion of carbon and nitrogen containing substances inhibits oxidative phosphorylation (cytochrome c oxidase) and produces relative tissue anoxia and acidosis. Treat with sodium thiosulfate and sodium nitrite

• Early endotracheal intubation

• O2 therapy at 100% to treat increased carboyhemoglobin levels until <10% and normalization of acidosis

• Arterial blood gases needed initially as pulse oximetry may be inaccurate and cooximetry is needed to measure CO-Hb levels

• Mechanical ventilation, APRV, HFOV all potential options

• Nebulized heparin or tPa, N-acetylcysteine, bronchodilators, iNO

• Corticosteroids not currently recommended

• VV ECMO also an option, even in the setting of external burns

Nutrition

• Minimize catabolism and the hypermetabolic state: metoprolol

• Promote anabolism: oxandrelone 10 mg PO BID

• Prealbumin <15 mg/dl consistent with malnutrition

• Enteral feeding ideal route, initiate upon stabilization. TPN if unable to tolerate

Wound Care

• Wounds colonized within first few hours with GPC's such as staph aureus and staph epidermidis and subsequently colonized with gut flora such as pseudomonas, enterobacter, and E. Coli by 5 days. Topical agents such as silvadene used to control colonization although it delays wound healing. Mepilex, Acticoat, Mepitel sometimes used

• Early debridement crucial. Excision and skin grafting per burn surgeons

References

1) S.E. Wolf, J.K. Rose, M.H. Desai, et al.: Mortality determinants in massive pediatric burns. An analysis of 103 children with > or = 80% TBSA burns (> or = 70% full-thickness). Ann Surg. 225:554-565 1997

2) Pediatric Burn Injury Presentation: Drs. S Tomlinson, D Nguyen, and L Metzler 2016.