Pathophysiology
- Burn = Coagulative destruction of the skin or mucous membrane
- Caused by heat, chemical or irradiation
- Thermal damage occurs above 48 șC
- Extent of necrosis is related to temperature and duration of contact
- Burns can result in:
- Increased capillary permeability and fluid loss
- Hypovolaemia and shock
- Increased plasma viscosity and microthrombosis formation
- Haemoglobinuria and renal damage
- Increased metabolic rate and energy metabolism
Assessment
- Initial assessment should be by ATLS principles
- Good early management is required to prevent morbidity or mortality
Airway
- Look for signs of inhalation injury
- Facial burns, soot in nostrils or sputum
Breathing
- Be aware of carbon monoxide poisoning
- Patient may appear 'pink' with a normal pulse oximeter reading
Circulation
- The fluid loss from a burn is significant
- It can result in hypovolaemic shock and acute renal failure
Assessment of extent
Body surface area (BSA) involved can be estimated from
- Lund & Browder chart
- Wallace rule of nine
| Area |
% BSA |
| Head |
9 |
| Each upper limb |
9 |
| Each lower limb |
18 |
| Front of trunk |
18 |
| Back of trunk |
18 |
| Perineum |
1 |
- Palm of hand approximates to 1% BSA
Burn depth
- Ability of skin to repair depends on depth of burn
- Burns can be classified as:
- Superficial burns
- Partial thickness burns
- Full-thickness burns
Superficial burns
- Needs to be differentiated from erythema
- Epidermis and papillae only are involved
- Results in red serum0filled blisters
- Skin blanches on pressure
- Burn is painful and sensitive
- Healing occurs in 10 days with no scarring
Partial-thickness burns
- Epidermis is lost with varying degrees of dermis
- Burn is usually coloured pink and white
- May or may not blanche on pressure
- Variable degrees of reduced sensation may be present
- Epithelial cells are present in hair follicles and sweat glands
- Results in regeneration and spread
- Healing occurs in 14 days
- Some depigmentation of scar may occur
- May require skin grafting
Full-thickness burns
- Both epidermis and dermis are destroyed
- Burn appears white and does not blanche
- Sensation is absent
- Without grafting healing occurs from edge of wound
Fluid replacement
To assess fluid requirement need to identify
- Time of injury
- Patient weight
- Percent BSA involved
Intravenous fluid replacement needed for burns
- >10% BSA in child
- >15% BSA in adult
Fluid replacement formulae
Muir & Barclay formula
- = weight (Kg) x BSA / 2 per period
- Provide volume requirement in colloid to be given in first 4 hours
- This volume should be repeated
- Every 4 hours for the first 12 hours
- Every 6 hours between 12 and 24 hours
- Every 12 hours between 24 and 36 hours
ATLS formula
- = weight (kg) x %BSA x (2-4)
- Gives total volume (in ml) to be infused in first 24 hours
Criteria for referral to burns unit
- > 10% BSA in child
- > 15% BSA in adult
- Inhalation injuries
- Burns involving the airway
- Electrical burns
- Chemical burns
- Special areas - eyes, face, hands
Picture provided by Vitoon Chinswangwatanakul, Siriraj Hospital, Bangkok, Thailand
Escharotomy
- Deep circumferential burns of torso can impair respiration
- In a limb can reduce distal vasculature
- In both situations escharotomies should be considered
- No anaesthetic is required
- Burn should be incised into subcutaneous fat
- Release of underlying soft tissue should be ensured
- On chest should be performed bilaterally in anterior axillary line
- Bleeding may be significant and transfusion may be required
Picture provided by Russell George, Texas Women's Hospital, USA
Special situations
Respiratory burns
- Smoke inhalations should be suspected if:
- Explosion in enclosed environment
- Flame burns to the face
- Soot in mouth or nostrils
- Hoarseness or stridor
- Intubation may be required
- Blood carboxyhaemoglobin levels can give indication of extent of lung injury
Electrical burns
- Most electrical burns are flash burns and are superficial
- Do not occur by electrical conduction
- Flash from an electrical burn can reach 4000 șC
- Low-tension burns are usually small but full thickness
- High-tension burns usually have an entry and exit wound
- Current passes along path of least resistance (e.g. blood vessels, fascia, muscle)
- Extent of tissue destruction can often be underestimated
- High-tension burns can be associated with cardiac arrhythmias
- Myonecrosis and myoglobinuria can also occur
Chemical burns
- Commonest acids involved are hydrochloric, hydrofluoric and sulphuric
- Acid burns may penetrate deeply down to bone
- First aid treatment involves liberal irrigation with running water
- Calcium gluconate may be useful in hydrofluoric acid burns
- Commonest alkalis are sodium hydroxide and cement
- Again can cause deep-dermal or full-thickness burns
Picture provided by Michael McFarlane, University of West Indies, Kingston, Jamaica
Bibliography
Clarke J. Burns. Brit Med Bull 1999; 55: 885-894.
Gueugniaud P Y, Carsin H, Bertin-Maghit M, Petit P. Current advances in the initial
management of major thermal burns. Intensive Care Med 2000; 26: 848-856.
Judkins K. Burns resuscitation: what place albumin? Hosp Med 2000: 61:
116-119.
Koumbourlis A C. Electric injuries. Crit Care Med 2003; 30 (Suppl 11):
S424-430.
Rabinowitz P M, Siegel M D. Acute inhalational injury. Clin Chest Med 2002;
23: 707-715.
Sheridan R L. Burns. Crit Care Med 2003; 30 (Suppl 11): S500-514.
Treharne L J, Kay A R. The initial management of acute burns. J R Army Med Corp
2001; 147: 198-205
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