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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Initial burn care follows trauma ABCDE with special attention to inhalation injury and circumferential burns.
- Estimate burn size using Rule of Nines, Lund-Browder chart, or palmar method; exclude first-degree burns from TBSA.
- Major burns need warmed lactated Ringer solution; Parkland formula = 4 mL x kg x %TBSA in first 24 hours from burn time.
- Give half of calculated fluid in first 8 hours from burn time, not arrival time; titrate to urine output.
- Burn center referral for partial-thickness burns >=10% TBSA, full-thickness burns, face/hands/genitals/feet/major joints, electrical/chemical/inhalation injuries, and significant comorbidity.
Overview
Burns cause local tissue injury and, when extensive, systemic inflammatory response with capillary leak, shock, hypothermia, infection risk, and metabolic stress. Depth determines healing potential: superficial burns are painful and erythematous; partial-thickness burns blister; full-thickness burns are leathery, insensate, and require surgical evaluation.
Epidemiology
Burn injuries account for hundreds of thousands of emergency visits annually in the United States. Most are minor scald or flame burns, but high-risk injuries occur with house fires, explosions, occupational exposures, chemicals, electrical sources, and child or elder abuse. Smoke inhalation substantially increases mortality.
Clinical Features
Symptoms
Pain, blistering, erythema, swelling, or loss of sensation in burned area
Hoarseness, dyspnea, cough, wheeze, carbonaceous sputum, or enclosed-space fire exposure
Eye pain or visual symptoms after facial/chemical burns
Numb, painless, white, brown, or charred skin suggesting full-thickness injury
Severe pain out of proportion or tightness under circumferential eschar suggesting compartment compromise
Signs
Facial burns, singed nasal hairs, soot in mouth/nose, oropharyngeal edema, stridor
Partial-thickness burn: blistering, moist surface, blanching, very painful if superficial
Full-thickness burn: leathery, dry, non-blanching, insensate eschar
Circumferential chest burn limiting ventilation
Diminished distal pulses, paresthesia, pain with passive stretch, or high compartment pressure
Investigations
First-line
TBSA estimationRule of Nines in adults; Lund-Browder more accurate in children; patient palm including fingers approximates 1% TBSA. Do not count first-degree burns.
Airway and respiratory assessmentPulse oximetry may be falsely normal in CO poisoning; evaluate voice, soot, edema, and enclosed-space exposure.
Basic labs for major burnsCBC, CMP, lactate, blood gas, CK if electrical/crush, coagulation studies, type and screen when severe.
Second-line
Carboxyhemoglobin levelIndicated after smoke inhalation or enclosed-space fire; standard pulse oximetry cannot distinguish oxyhemoglobin from carboxyhemoglobin.
Chest X-rayMay be normal early in inhalation injury; useful for baseline and tube placement.
BronchoscopySpecialist evaluation for inhalation injury when diagnosis or severity is uncertain.
Specialist
Burn center assessmentFor grafting, escharotomy/fasciotomy, complex wound care, inhalation injury, electrical/chemical burns, and rehabilitation planning.
Management
American Burn Association Burn Patient Referral Guidelines and ATLS burn resuscitation principles1
Immediate actions
- Stop burning process: remove heat source, clothing, jewelry, and contaminated material.
- Cool small thermal burns with cool running water if early; avoid ice and avoid inducing hypothermia.
- Airway first: early intubation if progressive facial/oropharyngeal edema, stridor, deep facial burns, or severe inhalation injury.
- High-flow 100% oxygen for suspected smoke inhalation or carbon monoxide exposure.
- Cover wounds with clean dry sheets; maintain warmth.
2
Fluid resuscitation
- Major burn threshold commonly >20% TBSA in adults or >10-15% in children/older adults.
- Use warmed lactated Ringer solution.
- Parkland formula: 4 mL x body weight (kg) x %TBSA in first 24 hours from time of burn.
- Give half in first 8 hours from burn time, remainder over next 16 hours.
- Titrate to urine output: adults approximately 0.5 mL/kg/h; children approximately 1 mL/kg/h.
3
Wound care and procedures
- Analgesia with IV opioids for significant burns.
- Tetanus prophylaxis according to immunization status.
- Topical antimicrobials and dressings based on depth/location; avoid routine systemic antibiotics without infection.
- Escharotomy for circumferential full-thickness burns causing vascular compromise or ventilatory restriction.
- Chemical burns: remove contaminated clothing, brush off dry powders, copious irrigation.
4
Referral and disposition
- Refer to burn center for partial-thickness >=10% TBSA, full-thickness burns, face/hands/feet/genitals/perineum/major joints, electrical/chemical/inhalation injury.
- Also refer children, older adults, patients with comorbidities, concomitant trauma, suspected abuse, or special rehabilitation needs.
Complications
- Inhalation injury: Airway edema may worsen after fluids and require early intubation
- Burn shock: Capillary leak and evaporative losses cause hypovolemia after major burns
- Compartment syndrome: Circumferential eschar can impair distal perfusion or chest wall expansion
- Infection/sepsis: Risk increases with depth, TBSA, and delayed excision
- Scarring/contractures: Functional impairment especially across joints, hands, face, and neck
USMLE Step 2 CK Exam Tips
- 1Enclosed-space fire + soot/hoarseness = inhalation injury; secure airway early.
- 2Pulse oximetry can be normal in CO poisoning — check carboxyhemoglobin.
- 3Parkland formula uses %TBSA excluding first-degree burns and timing starts at burn time.
- 4Circumferential extremity burn + decreased pulses = escharotomy.
- 5Circumferential chest burn with ventilation difficulty = chest escharotomy.
- 6Do not give prophylactic systemic antibiotics for uncomplicated burns.
- 7Full-thickness burns can be painless because nerves are destroyed.
practicetest your knowledge on burnsApply what you've learnt with USMLE Step 2 CK-style questions from the iatroX Q-Bank — emergency medicine and beyond.
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