Define Burns — Assessment & Resuscitation. Describe its management and pathophysiology.

The Concept — Two Early Killers

Burns are dangerous out of all proportion to how they look, and two threats dominate the early hours: airway compromise from inhalation injury, and the massive fluid shift that causes 'burn shock'. Everything in initial management flows from assessing the extent (percentage of body surface burnt) and the depth of the burn, and from protecting the airway before it swells shut.

Assessing the Extent (% Tbsa)

The percentage of total body surface area (TBSA) burnt is estimated with Wallace's Rule of Nines in adults — head 9%, each arm 9%, each leg 18%, the front of the trunk 18%, the back 18%, and the perineum 1%. In children the head is relatively larger and the legs smaller, so a Lund-Browder chart is used for accuracy. A quick rule for scattered burns is that the patient's palm is about 1%. (Simple erythema, as in sunburn, is not counted.)

Assessing the Depth

The Airway — Assess and Secure Early

Inhalation injury is the priority because airway swelling can close the airway within hours. Suspect it with facial or neck burns, singed nasal hairs, soot in the mouth or sputum, hoarseness, stridor, or a fire in an enclosed space. The rule is to intubate early — before oedema makes intubation impossible. Also consider carbon monoxide and cyanide poisoning in enclosed-space fires (give high-flow oxygen).

Fluid Resuscitation — and WHY

A significant burn (> 15–20% TBSA in adults, > 10% in children) causes a massive inflammatory capillary leak, so plasma pours out of the circulation into the burnt and surrounding tissues, producing hypovolaemic 'burn shock'. This is replaced using the Parkland formula: 4 mL × body weight (kg) × %TBSA of Ringer lactate over the first 24 hours, giving half in the first 8 hours (timed from the moment of the burn) and the rest over the next 16 hours — with maintenance fluid added in children. The formula is only a starting estimate; the resuscitation is titrated to urine output (0.5–1 mL/kg/h in adults, higher in children), which is the best bedside marker of adequate perfusion.

Other Management

Give generous IV opioid analgesia; clean the wounds and apply a topical antimicrobial (e.g. Silver sulfadiazine) with dressings; give tetanus prophylaxis; and start early high-calorie, high-protein nutrition because burns cause an intense hypermetabolic state. A circumferential full-thickness burn forms a rigid eschar that constricts — of a limb (compromising circulation) or the chest (restricting breathing) — and needs an urgent escharotomy (incising the eschar to release it). Deep burns require early excision and skin grafting, and major burns are transferred to a specialist burns unit.

Types of Burn & Their Special Problems

• The cause of the burn changes the management.
• Thermal (flame/scald) burns are commonest.
• Electrical burns are deceptive — small entry/exit wounds hide extensive deep tissue damage along the current's path, causing rhabdomyolysis (myoglobinuria and renal failure) and cardiac arrhythmias, so they need cardiac monitoring and generous fluids with a higher urine-output target.
• Chemical burns require prolonged irrigation with water (removing the agent), with alkalis penetrating more deeply than acids. Recognising the type prevents underestimating the injury.

The Pathophysiology of Burn Shock

It is worth understanding why burns cause such profound fluid loss. The burn triggers release of inflammatory mediators that make capillaries leaky, not just locally but systemically, so protein-rich fluid escapes into the interstitium; combined with the loss of the skin's water barrier (huge evaporative losses), the circulating volume falls dramatically over the first 24–48 hours. This is a distributive and hypovolaemic 'burn shock', and it is why fluid resuscitation is front-loaded into the first 8 hours when the leak is greatest.

Complications & Referral

Major burns carry many complications: burn shock, inhalation injury, infection and sepsis (the leading cause of later death), acute kidney injury, hypothermia, a Curling's (stress) gastric ulcer, and later contractures and hypertrophic scarring. Certain injuries warrant transfer to a specialist burns unit — large burns (> 10% in children, > 15–20% in adults), full-thickness burns, burns of the face, hands, feet, perineum or over joints, and electrical, chemical or inhalation injuries.

• Parkland formula — 4 mL/kg/%TBSA of Ringer lactate over 24 h (half in the first 8 h); add maintenance in children.
• Titrate to urine output 0.5–1 mL/kg/h (adults), 1–1.5 mL/kg/h (children).
• Topical silver sulfadiazine; IV opioid analgesia; tetanus prophylaxis.

Urine output, not the formula, is the true guide to resuscitation.

• Two early killers: inhalation airway injury and burn shock (capillary-leak hypovolaemia); assess extent + depth.
• Extent: Rule of Nines (adult), Lund-Browder (children — larger head), palm ≈ 1%. Depth: superficial → full-thickness (full-thickness is painless, leathery, needs grafting).
• Airway: suspect inhalation injury (facial burns, soot, hoarseness, enclosed fire) → intubate early before oedema; consider CO/cyanide.
• Parkland: 4 mL/kg/%TBSA Ringer lactate/24 h (half in first 8 h) + maintenance in children; titrate to urine output.
• Also: opioid analgesia, silver sulfadiazine + dressings, tetanus, high-calorie nutrition, escharotomy for constricting circumferential burns, early excision/grafting, burns-unit referral.