Assessment
Burn TBSA Estimation and Severity
Using body surface area rules to estimate burn extent and identify patients who need burn center or critical care resources.
Rule of nines and depth
Total body surface area (TBSA) burned drives fluid resuscitation formulas and burn center referral. The rule of nines assigns 9% to each arm, 18% to each leg, 18% to the chest, 18% to the back, 9% to the head (modified for children), and 1% to the perineum. Only partial-thickness and full-thickness burns count—simple erythema without blistering is excluded.1
MedlinePlus describes depth categories: superficial (red, painful), partial-thickness (blisters, severe pain), and full-thickness (leathery, may be insensate).2 Circumferential burns threaten circulation and ventilation when eschar forms; document location (face, hands, joints) even when TBSA is small.
When burns become critical
Burn center criteria commonly include TBSA greater than 20% in adults, higher-risk zones (face, hands, feet, genitals, major joints), inhalation injury, electrical or chemical mechanism, and burns with concurrent trauma. The CDC burn prevention program emphasizes that inhalation injury can exist without external flame burns—singed nasal hair, soot in mouth, and stridor are warning signs.1
Cover burns with clean dry dressings, prevent hypothermia, and provide high-flow oxygen when inhalation is suspected. EMT-Basic scope focuses on rapid transport, airway support, and pain management per protocol rather than field fluid calculations reserved for advanced providers.
Practice this skill
Apply what you read with a hands-on Burn Scoring drill — instant feedback on every scenario.
