Severe burns

A severe burn is a thermal, chemical, electrical or radiation injury with a risk to life, airway, limb or function. It combines airway compromise, burn shock, fluid loss and rapid onset of a systemic inflammatory response, then infection, hypermetabolism and scarring.

Depth.

Extent. Percentage of total body surface area (TBSA) burned, excluding superficial burns. Use a Lund and Browder chart (best, especially in children) or the rule of nines (adult head 9%, each arm 9%, each leg 18%, front trunk 18%, back trunk 18%, perineum 1%). The patient's palm with fingers is about 1% TBSA.

Burn severity (refer to a burns service).

• Partial or full thickness burns over 10% TBSA in adults, over 5% in children.
• Any full thickness burn over 5%.
• Burns of the face, hands, feet, perineum, genitalia or over major joints.
• Circumferential burns, inhalation injury, electrical, chemical or high pressure injury.
• Burns with trauma or major comorbidity, extremes of age, suspected non-accidental injury.

Pathophysiology. Coagulation, stasis and hyperaemia zones surround the burn. Capillary leak peaks over 8 to 12 hours and causes burn shock, and a hypermetabolic state with catabolism lasts for months.

Key distinctions. Depth evolves over 48 to 72 hours, and size is overestimated by inexperienced assessors. Inhalation injury, carbon monoxide and cyanide poisoning, and associated trauma, can kill earlier than the burn itself.

Primary survey. Stop the burning process, remove clothing and jewellery, and apply trauma care with cervical spine protection when there was an explosion, fall or road collision.

History.

• Mechanism (flame, scald, contact, electrical, chemical), enclosed space, duration, temperature, voltage, chemical name and concentration, time of injury, first aid given.
• Loss of consciousness, other injuries, intent (self harm, assault) and consistency of the account (non-accidental injury in children).
• Medical history, medicines, allergies, tetanus status, pregnancy, smoking, alcohol and drug use.

Examination.

• Airway: singed nasal hair, facial burns, soot in the mouth or sputum, hoarseness, stridor, drooling, wheeze, tongue swelling.
• Breathing: respiratory rate, saturation (falsely normal with carbon monoxide), chest expansion, restriction from circumferential chest burns.
• Circulation: pulse, blood pressure, capillary refill, distal perfusion in burned limbs, urine colour and output.
• Burn: depth, size, circumferential extent, associated injury, signs of electrical entry and exit.
• Eyes (fluorescein staining for corneal burns), ears, mouth and perineum.

Red flags.

• Stridor, hoarseness, soot in the airway, facial burns, hypoxia, or Glasgow Coma Scale under 15.
• Carbon monoxide: headache, confusion, carboxyhaemoglobin over 10%.
• Cyanide: smoke inhalation in an enclosed space with coma, seizures, cardiovascular collapse or lactate over 8 mmol/L.
• Circumferential limb or chest burns with poor perfusion or ventilation.
• Pain, pallor, paraesthesia or tense swelling (compartment syndrome).
• High voltage electrical injury with arrhythmia or dark urine.
• Suspected abuse.

Special groups. Children lose heat and fluid faster, are prone to hypoglycaemia and need weight based fluids and analgesia. Older adults have worse survival for the same burn size. Pregnancy needs left lateral tilt after 20 weeks and obstetric review. Region specific: scalds from boiling liquids and open fires are common causes in children, and kerosene stove and bonfire burns are common in adults.

By mechanism and complication.

• Thermal burns (flame, scald, contact), flash burns, friction burns.
• Electrical injury (low voltage, high voltage, lightning), with cardiac arrhythmia, rhabdomyolysis and compartment syndrome.
• Chemical burns: acid burns, alkali burns, hydrofluoric acid burns, phenol burns, cement burns.
• Inhalation injury, carbon monoxide poisoning, cyanide poisoning, upper airway thermal injury.
• Associated trauma and blast injury.

Mimics of burns.

• Toxic epidermal necrolysis and Stevens-Johnson syndrome, staphylococcal scalded skin syndrome.
• Bullous pemphigoid, pemphigus, bullous impetigo, extensive contact dermatitis, cold injury and frostbite.
• Non-accidental injury (cigarette burns, immersion scalds), and dermatological conditions mistaken for scalds.

Immediate. Capillary glucose (children), arterial blood gas with lactate and co-oximetry for carboxyhaemoglobin (normal under 3% in non-smokers, under 10% in smokers), full blood count, urea, creatinine, electrolytes, liver tests, creatine kinase, coagulation, group and save, ECG, troponin in electrical injury, pregnancy test, and blood alcohol.

Imaging and procedures. Chest radiograph (often normal early), trauma imaging as indicated, flexible bronchoscopy for suspected inhalation injury (grading of airway injury), and fluorescein eye examination.

Interpretation.

• Carboxyhaemoglobin falls with a half life of about 5 hours on room air and about 1 hour on 100% oxygen, so early samples matter.
• Lactate over 8 mmol/L with smoke exposure strongly suggests cyanide poisoning, and treatment is not delayed for the test.
• Base deficit, urine output, and haemoglobin trend direct resuscitation. Urine dipstick positive for blood with no red cells suggests myoglobin.

Limitations. Pulse oximetry overestimates saturation with carbon monoxide. TBSA estimates vary widely. Depth assessment is unreliable in the first 48 hours. Early chest radiographs miss inhalation injury.

Airway and breathing.

• High flow oxygen 15 L/min via reservoir mask for all inhalation injuries and suspected carbon monoxide poisoning, continued until carboxyhaemoglobin is under 3% (under 10% in smokers) and symptoms resolve.
• Intubate early with an experienced operator when there are stridor, hoarseness, facial or neck burns with swelling, soot in the airway, burn over 40% TBSA, or falling consciousness. Swelling peaks at 12 to 24 hours, and later intubation is much harder. Use a large tube (8.0 mm or more) for bronchoscopy. Avoid suxamethonium after the first 24 hours because of hyperkalaemia.
• Escharotomy for circumferential chest burns restricting ventilation and for limb burns with absent pulses or compartment syndrome.

Stop the burning and cool. Cool the burn with cool running water (not ice) for 20 minutes, within 3 hours of injury, for burns under 15% TBSA. Do not apply cooling to large burns in a way that causes hypothermia. Cover with cling film or clean dry dressings, keep the patient warm (room over 28 °C, warmed fluids), and avoid wet dressings in large burns.

Chemical burns. Remove dry chemical powders by brushing, then irrigate with copious water for 30 minutes or more (longer for alkali, and until the pH of the skin is neutral). For hydrofluoric acid, irrigate then apply calcium gluconate 2.5% gel, give IV calcium for systemic symptoms or large burns with ECG and calcium monitoring, and seek poison centre advice. Eye burns: irrigate with isotonic saline or water for at least 30 minutes until the pH is 7.0 to 7.4.

Electrical injury. Switch off the source safely, ECG, and continuous monitoring for 24 hours when there is loss of consciousness, arrhythmia, abnormal ECG, high voltage injury or cardiac symptoms. Fluids to maintain urine output at 1 to 1.5 mL/kg/hour (about 100 mL/hour in adults) while urine is pigmented, creatine kinase monitoring, and early fasciotomy when compartment syndrome occurs.

Fluid resuscitation (adults with over 15% TBSA, children with over 10%).

• Balanced crystalloid (compound sodium lactate). Starting volume for adults: 2 mL x weight (kg) x %TBSA over the first 24 hours from injury, with half given in the first 8 hours. The older 4 mL x weight x %TBSA formula is also used but tends to over-resuscitate. High voltage electrical burns and inhalation injury often need more.
• Children under 30 kg: 3 mL x weight x %TBSA over 24 hours, plus maintenance fluid containing glucose (hypoglycaemia is common in young children).
• Titrate every hour to urine output: adults 0.5 mL/kg/hour (30 to 50 mL/hour), children under 30 kg 1 mL/kg/hour. Reduce the rate by 10 to 20% if output is over target for 2 consecutive hours, and increase by 20 to 33% if under target. Avoid over-resuscitation, which causes compartment syndromes, pulmonary oedema and prolonged ventilation.
• Consider albumin 5% after 8 to 12 hours when fluid needs are escalating (evidence is limited). Start vasopressors only after fluid status and cause of hypotension are reviewed.
• Do not give resuscitation fluid for burns under 15% TBSA other than oral rehydration, apart from maintenance in those who cannot drink.

Cyanide poisoning. Hydroxocobalamin 5 g IV over 15 minutes (children 70 mg/kg, maximum 5 g), repeated once over 15 minutes to 2 hours if no response; maximum 10 g; use a dedicated line; monitor blood pressure (may rise), expect red discolouration of skin and urine for several weeks, and note interference with co-oximetry and colorimetric laboratory tests (take samples before the dose where possible); no kidney adjustment in an emergency. Give 100% oxygen in addition.

Analgesia.

• Morphine 0.05 to 0.1 mg/kg IV in 2 mg boluses every 5 minutes titrated to effect (maximum 10 mg before reassessment); monitor respiratory rate and sedation with naloxone available; reduce in older adults, shock and kidney impairment (use fentanyl instead).
• Fentanyl 0.5 to 1 microgram/kg IV (25 to 50 micrograms) every 3 to 5 minutes; intranasal fentanyl 1.5 micrograms/kg (maximum 100 micrograms) in children when IV access is difficult.
• Ketamine 0.1 to 0.3 mg/kg IV for procedural analgesia, with monitoring of blood pressure and emergence reactions.
• Paracetamol 1 g IV or orally every 6 hours; maximum 4 g daily (3 g daily if weight under 50 kg, malnutrition, alcohol excess or liver disease); children 15 mg/kg every 6 hours, maximum 60 mg/kg daily. Avoid NSAIDs in major burns because of kidney risk.
• Pain is often undertreated, so reassess every 15 minutes in the first hour.

Wound care.

• Debride blisters that are large, tense or over joints, clean with saline or tap water, and apply a non-adherent dressing. Silver sulphadiazine 1% cream once or twice daily (avoid in sulphonamide allergy, G6PD deficiency, late pregnancy, neonates and over the face) or silver impregnated dressings for 7 days then review; monitor white cell count with prolonged use of cream.
• Early excision and grafting of deep burns within 24 to 72 hours reduces infection and mortality. Superficial partial thickness burns heal with dressings.
• Systemic antibiotics are not given as prophylaxis. Treat cellulitis or sepsis as directed by cultures: for clinical infection, amoxicillin with clavulanic acid 1.2 g IV every 8 hours (maximum 3.6 g daily; reduce frequency for eGFR under 30 mL/min), widened to cover Pseudomonas and resistant organisms under specialist direction.
• Tetanus toxoid 0.5 mL IM when the last dose was over 10 years ago (over 5 years for dirty wounds) or immunisation is unknown, with tetanus immunoglobulin 250 units IM (500 units when over 24 hours since injury or with heavy contamination) for high risk wounds with unknown or incomplete immunisation.

Supportive care.

• Nasogastric feeding within 12 to 24 hours for burns over 20% TBSA. Energy about 30 to 35 kcal/kg daily adjusted by indirect calorimetry (avoid overfeeding), protein 1.5 to 2 g/kg daily (higher in children), and glucose control 7.8 to 10 mmol/L.
• Stress ulcer prophylaxis for ventilated patients and large burns: omeprazole 20 to 40 mg daily orally or IV, reviewed when feeding is established.
• Venous thromboembolism prophylaxis with enoxaparin 40 mg subcutaneously once daily (20 mg daily if CrCl 15 to 30 mL/min; unfractionated heparin 5000 units subcutaneously every 8 to 12 hours if CrCl under 15 mL/min), starting when bleeding risk allows.
• Keep temperature over 36 °C, elevate burned limbs, start early physiotherapy and splinting, and plan psychological support.
• Safeguarding referral when an injury is inconsistent with the history.

Monitoring. Hourly urine output, blood pressure, heart rate, saturation, temperature and neurovascular checks of burned limbs, blood gas, lactate, electrolytes and creatinine every 4 to 6 hours at first, creatine kinase in electrical injury, and wound review at 48 to 72 hours.

Referral and escalation. Burns service by telephone for every burn meeting these criteria, critical care for inhalation injury, ventilation or large burns, plastic surgery, ophthalmology for eye burns, toxicology or a poison centre for chemical injury, and child protection services when abuse is suspected.

Admission criteria. All severe burns and all patients meeting burns service referral criteria are admitted. Small superficial burns with good analgesia and safe follow up may be managed in the community.

Discharge and safety netting. Discharge only with dressing plans, analgesia, follow up in 24 to 48 hours, and scar management. Patients are told to return for fever, spreading redness, offensive discharge, increasing pain, reduced urine or swelling, and to avoid sun on healing burns.