Burns

• Overview:

  • Burn injuries occur when the skin is damaged by heat sources, electricity, or chemical agents
  • It taken 10 seconds of skin exposure to 60 degree heat for a full-thickness burn to occur
  • Burns can be life-threatening so require prompt referral and treatment
• Risk factors:

  • Young children - often from spilling scalding drinks or touching oven hobs
  • Elderly people
  • Occupation with increased exposure to fire
  • Underlying medical conditions - epilepsy, peripheral neuropathy, cerebral palsy, cognitive disabilities
  • Alcohol and drug use
  • Smoking
  • Poverty and overcrowding
• Patients with burn injuries should undergo a systematic ABCDE assessment
• Airway and C-spine:

  • Look for signs of inhalation injury - can lead to swelling and airway obstruction
  • Signs suggesting inhalation injury - burn in enclosed space, burns to face or oropharynx, signed nasal or facial hairs, hoarse voice, respiratory distress/stridor
  • May be another cause of airway obstruction that is not directly related to the burn e.g. facial trauma, vomit
  • If inhalation injury - sit patient upright and urgent senior anaesthetic review. Early intubation may protect patients airway
• Breathing:

  • Compromised gas exchange may occur secondary to:
  • CO poisoning
  • Direct damage from an inhalation injury to lower airways
  • Burn tissue on the chest or neck creating a constrictive eschar and reducing chest expansion
  • Other traumatic chest injuries - tension pneumothorax, haemothorax, flail chest
• Eschar:

  • Collection of tight and leathery dead tissue caused by deep partial or full-thickness burns
  • When constrictive eschar forms around the circumference of a limb it may constrict distal circulation causing limb ischaemia
  • If eschar forms around the chest it may prevent adequate chest expansion and cause respiratory distress
• Breathing assessment:

  • Expose the chest to assess the adequacy of ventilation and look for further injuries
  • Monitor oxygen sats - administer 100% high flow humidified oxygen through NRB
  • ABG - assess oxygenation and carboxyhaemoglobin levels (CO poisoning)
• Humidified oxygen is used in patients with burn injuries to prevent any airway secretions from thickening and further compromising the airway
• Circulation:

  • Severe burns may cause circulatory shock secondary to large fluid losses and systemic inflammatory response
  • Assess BP before inserting 2 large bore cannulas through unburnt skin - immediately correct any hypotensive shock
  • Bloods - FBC, U&Es, LFTs, blood glucose, group and save, coagulation screen and CK levels
  • Insert catheter
  • Evaluate any areas where there are circumferential limb burns - regularly check pulses and CRT, doppler USS can be used to assess blood flow
• Disability:

  • Regularly check core temperature
  • Use AVPCU or GCS to assess consciousness level
• Exposure:

  • Estimate the percentage of total body surface area (%TBSA) burned and depth of the burns
  • Give a tetanus booster is required (priming course of tetanus vaccine more than 10 years ago)
• Accurate estimation of the percentage of the body burnt is important to allow appropriate fluid resuscitation. The morbidity and mortality of the injury are also closely related to the surface area injured
• Jackson's burn wound model (local response of burns)

  1. Zone of coagulative necrosis - area nearest to heat source - immediate coagulation of proteins leading to irreversible cellular death
  2. Zone of stasis - damage is less severe but there is compromised circulation - untreated, this area undergoes necrosis - potentially salvageable
  3. Zone of hyperthermia - inflammatory mediators cause widespread dilation of blood vessels - tissues will recover
• Systemic response:

  • In a burn more than 25-30% of TBSA there is a widespread release of inflammatory mediators
  • Cardiovascular - increased vascular permeability, large fluid and protein loss = systemic hypotension and reduced end organ perfusion
  • Respiratory - inflammatory induced bronchoconstriction. Severe burns can cause ARDS
  • Metabolic - basal metabolic rate increases = hyper-metabolism, breakdown in muscle protein
  • Immunological - release of stress hormones (e.g. cortisol) suppress immunity. Loss of normal gut barrier can permit bacterial translocation resulting in sepsis
• Three common methods estimating burn surface area:

  • Wallace 'rule of nines'
  • Palmar rule
  • Lund & Browder chart - most accurate
• Wallace rule of nines:

  • Typically used in pre-hospital and emergency departments to quickly estimate the percentage of the body burnt
  • Divides body into section
  • Head and neck = 9%
  • One arm = 9%
  • One leg = 18%
  • Trunk = 36%
  • Genitalia = 1%
  • Can be inaccurate in children
• Palmar surface method:

  • Useful to estimate the size of smaller burns or to estimate the size of unburnt areas in patients with very large burn injuries
  • Surface areas of the patient's entire hand = 0.8% of the patients TBSA
  • Have to use patients hand not your own hand
• Lund and Browder chart:

  • Most accurate method - considers different body shapes
  • Also suitable for paediatric patients
• Assessing depth:

  • Initial fluid resus is not guided by burn depth but further treatment is
  • The British Burn Association has a classification system that splits depth into 4 categories - superficial, superficial partial, deep partial, full thickness
• Superficial (1st degree)

  • Only epidermis damaged
  • Dry and erythematous
  • Blanches
  • Brisk bleeding and CRT
  • Painful
  • Heals in 5-10 days without scarring
• Superficial partial (2nd degree)

  • Epidermis and upper dermis damaged
  • Wet, blistered and erythematous
  • Blanches
  • Brisk bleeding and CRT
  • Painful
  • Heals in <3 weeks without scarring
• Deep partial (2nd degree)

  • Epidermis, upper and low dermis damaged
  • Dry, yellow, or white
  • DOES NOT blanch
  • Delayed bleeding, sluggish or absent CRT
  • Decreased sensation
  • Heels in 3-8 weeks with scarring if more than 3 weeks to heal
• Full thickness (3rd degree)

  • All skin layers to subcutaneous tissues damaged
  • Dry, leathery or waxy white
  • DOES NOT blanch
  • No bleeding and absent CRT
  • No sensation - painless
  • Heals in >8 weeks with scarring
• Initial wound management:

  • Remove loose clothing and jewellery apart from anything that is adhered to the wound.
  • Cool the wounds with cool tap water for 20 minutes if the wound occurred 3 hours ago or less. Do not use ice packs or other extremely cold products.
  • Clean the wound with normal saline.
  • Cover the wound with clingfilm loosely. Never wrap clingfilm around a limb circumferentially, as this may create a constrictive eschar and can affect distal blood flow.
• Fluid resuscitation:

  • In the first 8-12 hours after a burn, fluid rapid shifts from the intravascular to interstitial fluid compartments = hypovolaemia, may cause reduced organ perfusion and tissue ischaemia
  • A burn percentage of more than 15% TBSA in adults and more than 10% in children typically warrants formal resuscitation
  • Correct any clinical hypovolaemia shock on arrival
  • Then calculate the patient's additional fluid requirement using the Parkland formula
• Parkland formula in adults:

  = 2-4ml x body weight (kg) x %TBSA

  = initial crystalloid fluid requirement for the first 24 hours

  • Only include partial and full thickness burns in the TBSA calculation
  • Hartmann's solution should be used
  • Give the first 50% calculated volume over the first 8 hours since the time of the burn
  • Give remaining 50% over the following 16 hours
  • Titrate fluid requirements by monitoring and maintaining urine output
• Analgesia:

  • Adequate pain relief should be given early
  • Cooling methods - running under cold water and covering with clingfilm
  • Pharmacological - simple, opioids, ketamine
• Refer to specialist burn service if any of the following are present:

  • All burns 2% or more in children, 3% or more in adults
  • All deep partial or full thickness burns
  • All circumferential burns
  • Any chemical, electrical, friction burns or cold injuries
  • Any burn not healed in 2 weeks
  • Any burn with suspicion of non-accidental injury
  • Burns over perineum, face, hands, feet, genitals or major joints
  • Pregnant patients or severe co-morbidities
• Reconstruction:

  • Deep partial and full thickness burns often require early excision of necrotic tissue followed by a skin graft
  • Wound debridement - tangential excision, fascial excision, amputation
  • Grafting - autograft (from patient) is preferred
  • Allograft (another human) or xenograft (typically pig) may be used in extremely large burns which cannot be covered with the patient's donor tissue alone - act as a temporary measure until more autograft tissue becomes available
• Treatment of scars and contractions:

  • Surgical treatment - scar release, local and regional flaps, skin substitutes, tissue expansion
  • Physiotherapy
  • Steroid injections
  • Cryotherapy
  • Laser treatment
• Chemical burns:

  • Can cause continuous tissue destruction until the pH is neutralised
  • Acidic substances cause damage by coagulative necrosis
  • Alkaline chemicals typically result in more extensive burns secondary to liquefactive necrosis
  • Immediately irrigate with WARM water for at least 30 minutes
  • Remove any clothes
• Electrical burns:

  • Lightning strikes and contact with power lines may cause large electrical burns with visible entry and exit wounds
  • Damage is often more serious than it first appears
  • Risk of arrhythmias and myoglobinuria (muscle break down)
  • All patients should have an ECG, U&Es and urine output monitoring
  • CK levels should be checked for rhabdomyolysis from extensive muscle breakdown
  • Burns to a limb can involve a whole compartment and can cause compartment syndrome
• Systemic complications from burns arise secondary to a systemic inflammatory response (SIRS) where an exaggerated and dysregulated inflammatory response develops

  This may progress to multiple organ dysfunction syndrome (MODS) where the inflammatory response causes end-organ failure
• Systemic complications:

  • Acute lung injury - burns and smoke inhalation, may progress to ARDS
  • Rhabdomyolysis - muscle breakdown from full thickness burns
  • Dehydration and shock
  • AKI - SIRS, hypovolaemia and rhabdomyolysis
  • Electrolyte imbalances - third space losses and AKI
  • Paralytic ileus
  • Curling's ulcer
• Curling's ulcer:

  • Significant hypovolaemia from severe burns causes ischaemia of the gastric mucosa
  • Creates a gastric ulcer which may lead to GI bleeding or perforation
  • Starting patients on PPI therapy at admission can reduce risk
• Local complications:

  • Scarring - may be hypertrophic or keloid
  • Contractures
  • Infection
  • Circumferential eschars - escharotomy may be needed - scalpel incision down to the level of the subcutaneous fat but not into the muscle or fascia