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Burns. 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. Zones of injury Jackson has classified thermal burns into three zones of injury. 1 An inner zone of coagulative necrosis
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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
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.
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.
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.
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).
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.
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).
Systemic • • This may result from the inhalation of carbon monoxide (CO) or cyanide. • • These patients may require respiratory support.
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.
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.