Burns

Thermal (90%) - This is the most common type of burn. The extent of the burn depends on the temperature and duration of application. These type of burns can be caused by:

• Scalds (wet heat) tend to be partial thickness

• Dry heat caused by direct contact, flame, or radiant heat and tend to be deeper

Chemical - These are either:

• Acid burns cause damage by coagulative necrosis – Local and short-lived

• Alkali burns cause progressive liquefactive necrosis – Deep and prolonged e.g. cement burns

  
  

These types of burns are managed by removing the clothing and diluting the chemical.

Electrical - These can either be:

• Low voltage - Caused by domestic electricity

• High voltage - This is a lot more severe as there's an entry and exit point of the burn, therefore anything in between can get damaged. Complications of this are:

  • Extensive tissue damage

  • Arrhythmias and asystole

  • Rhabdomyolysis

  • Compartment syndrome

  • Renal failure

    
    

These types of burns are managed with ECG monitoring and Serum cardiac enzymes.

In a fire, the most serious worry is if the person has an Inhalation Injury (smoke contains noxious products of combustion e.g. soot, CO). Lots of CO is inhaled, which Hb has a much higher affinity compared to O2, therefore will be preferred if present. Those with this injury are managed with High-Flow O2. This is effective because Hb-CO has a half-life of 4 hours in air, but 30 mins in O2, so HF O2 gets rid of the CO much faster.

Local Response to a Burn

• Zone of coagulation – tissue necrosis centrally due to tissue destruction by injury

• Zone of stasis/ischaemia – can progress therefore increasing area of necrosis or depth of injury

• Zone of hyperaemia/inflammation – due to increased vascular permeability, and the inflammatory mediators also cause oedema and thrombosis

Systemic Response to a Burn

In those with larger burns (> 25-30% TBSA), mediators are released into the circulation. The affects of this are:

• Burn oedema = Oedema of burned tissue and non-burned tissue

  • Protein loss peaks at 8-12 hours

• Impaired microvascular integrity

  • Physical gaps between endothelial cells

  • Vasoactive substances released i.e. PG, LT, Histamine, Free rads

    
    

  • Hypovolaemia

  • Myocardial depression

  • Red cell destruction – up to 40% of circulating volume

  • Glucose intolerance

N.B. TBSA = Total Body Surface Area.

Depths of a Burn

Erythema - Epidermal damage, no skin loss, heals within days without scarring

Superficial partial thickness (1st degree) - Loss of superficial (papillary) dermis

• Moist, blistered, blanching, very painful

• Heals within 3 weeks with minimal scarring

Deep partial thickness (2nd degree) - Loss of deep (reticular) dermis

• White/red, no blanching

• Prolonged healing by migration of epidermal cells from burn area

• Scarring, and sometimes/often needs skin grafting

Full thickness (3rd degree) - Loss of entire dermis

• Leathery, no sensation (painless)

• Won’t heal unless very small, will have scarring and contractures and needs skin grafting

4th degree - Loss of entire dermis and extends into subcutaneous fat, muscle and bone

• Dry, painless

• Doesn't heal and requires excision

• Amputuation needed, and the patient is left with significant functional impairment

Early complications

• Impaired renal function

• Haemoglobinuria

• Infection and impaired immune function

• Pulmonary damage

• Burn encephalopathy

• Toxic Shock Syndrome

• Malnutrition