Burns

Burns may result from a variety of insults:

• thermal injury
• electrical injury
• chemical injury
• inhalational injury

The main early clinical challenges are:

• resuscitation of a patient in burn shock
• management of the airway in patients with inhalational injury
• pain control
• prevention and treatment of sepsis

Later problems include the prevention of scarring and contractures.

Classification of burn severity

• classification of the injury is according to its severity - its depth and size
• superficial (first-degree) burns
  • burns that affect the uppermost layer of the skin (epidermis only)
  • skin becomes red and the pain experienced is limited in duration
• superficial partial-thickness (second-degree) burns (formerly known as 2A burns)
  • are painful, weep, require dressing and wound care, and may scar, but do not require surgery
• deep partial-thickness (second-degree) burns (formerly known as 2B burns)
  • are less painful owing to partial destruction of the pain receptors, drier, require surgery and will scar
• full-thickness (third-degree) burn
  • extends through the full dermis
  • paradoxically, usually present with almost no pain. - not typically painful owing to damage to the nerve endings
  • requires protection from becoming infected and, unless very small, surgical management
• fourth-degree burn
  • involves injury to deeper tissues, such as muscle or bone
  • often blackened
  • frequently leads to loss of the burned part (1)
• although superficial and superficial partial-thickness burns usually heal without surgical intervention, more severe burns need careful management, which includes topical antimicrobial dressings and/or surgery (1)

Burns are classified as either minor or major

• minor burn is usually a burn that encompasses <10% of the total body surface area (TBSA), with superficial burns predominating
• major burn
  • burn size that constitutes a major burn is not commonly well-defined (1)
    • some guidance to classify severe burn injuries are:
      • >10%TBSA in elderly patients,
      • >20%TBSA in adults and
      • >30%TBSA in children

Definition of a small burn

• no clear definition for a small or a large burn (2)
  • burns that are >=10% of the total body surface area (TBSA) in children and >=15% TBSA in adults require fluid resuscitation and expeditious transfer to a specialist burns service
    • burns that are smaller than this can, in theory, be managed in A&E or primary care
    • in practice, however, burns greater than 2% TBSA in children and 3% TBSA in adults benefit from management and follow-up at a burns service

Criteria for referral to a specialist burns service (2)

• infected burns
• an unwell child with a burn
• burns >2% of total body surface area in children or >3% in adults (remember not to include simple erythema)
• circumferential burns
• full thickness burns
• burns involving the face, hands, genitals, or perineum
• chemical, electrical, and friction burns along with cold injuries
• burns with concerns about non-accidental injury or neglect
• burns in patients with complex medical or social issues that could complicate treatment or recovery
• burns that are >= 2 weeks old and have not healed

Alongside injuries to the skin, burns can be accompanied by smoke inhalation or other physical trauma to other organs.

A review with respect to small burns stated (2):

• 1% of total body surface area (TBSA) is roughly equal to the size of the patient’s hand, including digits
• do not include areas of erythema without skin loss when calculating burn size
• small burns <2% TBSA in children and <3% TBSA in adults can be managed in local accident and emergency departments, minor injuries centres, or primary care practices if the patient is clinically stable and there are no complications or associated injuries
• cooling of the burn is effective up to 3 hours after the injury
• flamazine (silver sulphadiazine) cream is avoided except for infected burns as it is absorbed by the burnt skin and makes depth estimation difficult (2)
  • can also delay healing
  • however, the review notes
    • application is still advocated by the American Burn Association
    • silver sulfadiazine forms a 'pseudoeschar' when in contact with a burn-a khaki staining of the wound itself which makes subsequent assessment difficult
    • evidence generally favour silver based dressings compared with silver sulfadiazine with regard to infection rates, pain, wound healing time, and frequency of dressings changes
  • an alternative review states (1)
    • topical antimicrobials have been the mainstay of nonsurgical burn treatment
    • topical agents take a variety of forms: creams, ointments, liquids and impregnated dressings
    • majority of dressing protocols use silver in some form owing to little clinical resistance by microorganisms
    • literature to support one type of dressing over another is of variable quality and, accordingly, no clear consensus favouring one dressing is available

Reference:

• Jeschke MG, van Baar ME, Choudhry MA, Chung KK, Gibran NS, Logsetty S. Burn injury. Nat Rev Dis Primers. 2020 Feb 13;6(1):11
• Antrum J H G, Galloway J E, Anwar M U, Hodson S L. Managing a small burn BMJ 2022; 379 :e068812 doi:10.1136/bmj-2021-068812