1. Burns

2. Thermal burns
• Significant thermal burns occur in 0.5% of the population every year.
• Thermal burns tend to occur in:
• The young
• The old
• The unlucky

3. Zones of injury
Jackson has classified thermal burns into three zones of injury.
1 An inner zone of coagulative necrosis
2 An intermediate zone of stasis
3 An outer zone of hyperaemia.

4. Pathophysiology of burn injury
Local effects
• Inflammatory mediators are released from:
• The capillary wall
• White blood cells
• Platelets.
• These inflammatory mediators result in vasodilatation and increased vessel
permeability.
• This leads to fluid loss from the circulation into the interstitial space.

5. Systemic effects
• Systemic effects occur if the burn covers more than 20% of the total body surface
area (TBSA).
• The systemic effects of a burn include:
• Hypovolaemia
• Immunosuppression
• Catabolism
• Loss of the protective function of the gut
• Pulmonary oedema.

6. Inhalational injury Factors suggestive of inhalational injury
Inhalational injury is suggested by the following.
• The history of the incident
• A fire in an enclosed space
• The patient lying unconscious in a fire
• Symptoms:
• A hoarse or weak voice
• Increasing stridor
• A brassy cough
• Restlessness
• Respiratory difficulty
• Signs:
• Soot around the mouth and nose
• Singed facial and nasal hair
• A swollen upper airway
• Hypoxia
• Pulmonary oedema
• The development of adult respiratory distress syndrome (ARDS).

7. Types of inhalational injury
Supraglottic
• This is caused by heat.
• If this injury is suspected, it is imperative to secure the airway before further
swelling develops.
• A tracheostomy should be considered in severe cases.

8. Subglottic
• This is caused by the products of combustion.
• Patients with this injury may require respiratory support, which may consist of:
• Humidified oxygen
• Intubation to allow bronchial toilet
• Intermittent positive pressure ventilation (IPPV).

9. Systemic
• This may result from the inhalation of carbon monoxide (CO) or cyanide.
• These patients may require respiratory support.

10. Carbon monoxide poisoning
• CO has 250 times the affinity for haemoglobin as oxygen.
• The half life of CO in patients breathing room air is 250 min.
• The half life of CO in patients breathing 100% oxygen is 40 min.
• CO binds to the intracellular cytochrome system, producing sick cell syndrome.
• CO levels of 0–15% may be present in smokers or truck drivers.
• CO levels of 15–20% result in headache and confusion.
• CO levels of 20–40% result in hallucinations and ataxia.
• CO levels of 60% are fatal.

11. Treatment
• CO poisoning should be treated with 100% humidified oxygen, delivered at
8 L/min through a non-rebreathing mask with a reservoir.
• It important to continue 100% oxygen treatment for 48 h following injury, as a
secondary release of CO occurs from the cytochrome system.