Burns

Overview

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Full thickness burns are paradoxically painless - all dermal nerve endings are destroyed. White, waxy, insensate skin = full thickness = needs grafting.

Presentation

•Inhalation injury - hoarse voice, stridor, singed nasal hairs/eyebrows, soot in mouth/nostrils, carbonaceous sputum, facial burns; any feature demands urgent anaesthetic review
•Carbon monoxide poisoning - suspect in all enclosed-space fires; SpO2 falsely normal (COHb absorbs same wavelength as OxyHb); patient may appear flushed
•Circumferential burns - tourniquet effect as oedema develops under inelastic eschar; limb ischaemia or respiratory compromise (chest burns)
•Burn shock - tachycardia, hypotension, reduced urine output; develops over first hours in burns >15% TBSA in adults (>10% in children)
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Inhalation injury is the single biggest determinant of burns mortality. Do not wait for obstruction - call anaesthetics early for consideration of intubation.

Investigations

•TBSA estimation - Rule of Nines (adults) or Lund and Browder chart (gold standard, especially in children)
•ABG with co-oximetry - COHb >10% confirms significant CO poisoning; standard SpO2 unreliable
•ECG - essential in electrical burns to identify arrhythmias
•Urinalysis and urine output - myoglobinuria (dark urine) indicates rhabdomyolysis; target urine output 0.5-1 mL/kg/hour in adults
•FBC, U&E, group and save - baseline; haematocrit rises with haemoconcentration
Method
Use
Key detail
Rule of Nines
Adults
Head & neck 9%, each arm 9%, anterior trunk 18%, posterior trunk 18%, each leg 18%, perineum 1%
Lund and Browder
Gold standard (all ages)
Corrects for age - in infants head up to 18%, legs proportionally smaller
Palm of patient's hand (+ fingers)
Small/irregular burns
~1% TBSA

Differential diagnosis

•Staphylococcal scalded skin syndrome (SSSS) - staphylococcal exotoxin in children; no burn history, systemic sepsis signs
•Toxic epidermal necrolysis (TEN) - drug-induced; mucosal involvement, drug history
•Non-accidental injury (NAI) - especially children; uniform-depth scald with clear demarcation (immersion), cigarette burns, unusual locations, inconsistent history

Management

Step 1 · First aid
  1. 1Cool running water for 20 minutes (do not use ice)
  2. 2Remove jewellery and non-adherent clothing
  3. 3Cover with cling film (not circumferentially)
Step 2 · Airway
  1. 1Early anaesthetic review if inhalation injury suspected
  2. 2High-flow 100% oxygen via non-rebreathe mask (treats CO poisoning)
Step 3 · Fluid resuscitation (burns ≥15% TBSA adults, ≥10% children)
  1. 1Parkland formula: 4 mL × weight (kg) × %TBSA = total crystalloid over 24 hours
  2. 2First half given in first 8 hours FROM TIME OF BURN; second half over next 16 hours
  3. 3Use Hartmann's solution (lactated Ringer's)
Step 4 · Wound care
  1. 1Superficial partial thickness: non-adherent dressings (e.g. Mepitel); review at 48-72 hours
  2. 2Deep partial/full thickness: refer to burns unit; surgical debridement and skin grafting required
  3. 3Escharotomy for circumferential full thickness burns causing limb or respiratory compromise
Step 5 · Additional measures
  1. 1Tetanus prophylaxis (all burns with dermal breach)
  2. 2Adequate analgesia
  3. 3Early nasogastric feeding in major burns (hypermetabolic state)
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The 8-hour clock for the first half of Parkland fluid runs from the TIME OF BURN, not arrival in hospital. A patient arriving 3 hours post-burn has only 5 hours left for the first half - this is frequently tested.

Complications

•Burn shock - hypovolaemic and distributive; prevented by early Parkland fluid resuscitation
•Wound infection and sepsis - *Pseudomonas aeruginosa* and *Staphylococcus aureus* common; leading cause of late mortality
•AKI - from hypovolaemia, myoglobinuria (rhabdomyolysis in electrical/deep burns), and sepsis
•Contracture - fibrous scar across joints; prevented by physiotherapy and pressure garments
•Marjolin's ulcer - squamous cell carcinoma arising in chronic burn scar

Prognosis

•Revised Baux score = age + %TBSA + 17 (if inhalation injury); score >140 associated with very high mortality
•Burns healing within 14 days - excellent cosmetic outcome; burns healing after 21 days or requiring grafting - significant hypertrophic scarring

Referral to burns unit

Indications for burns unit referral
Burns >10% TBSA (adults) or >5% (children)
Full thickness burns any size
Burns to face, hands, feet, genitalia, perineum, or joints
Circumferential burns
Inhalation injury
Electrical or chemical burns
Burns at extremes of age
Burns with co-morbidities or suspected NAI