Burn Classification, Treatment, and Referral Criteria

Introduction

Burns are injuries to skin and underlying tissue caused by thermal, electrical, chemical, or radiation energy. They are among the most painful and resource-intensive injuries. Proper initial management significantly affects outcome. Approximately 500,000 burn injuries require medical treatment annually in the United States, with 40,000 requiring hospitalization.

Burn Classification by Depth

Traditional Depth Classification

Degree	Depth	Structures Involved	Appearance	Sensation	Healing
First degree (superficial)	Epidermis only	Intact epidermal barrier	Red, dry, no blister	Painful	3-7 days, no scarring
Second degree (partial thickness) - superficial	Epidermis + upper dermis	Upper dermal capillaries	Red, moist, blisters, weeping	Very painful	7-21 days, minimal scarring
Second degree (partial thickness) - deep	Epidermis + deep dermis	Deep dermal appendages	Pale/patchy white-red, dry	Painful to pressure	21-35 days, significant scarring
Third degree (full thickness)	All layers of skin	Subcutaneous tissue	White, waxy, charred, leathery	No pain (nerve destroyed)	Requires skin grafting
Fourth degree	Skin + underlying structures	Muscle, tendon, bone	Charred, black, eschar	No sensation	Requires amputation/reconstruction

Clinical Depth Assessment

Feature	Superficial Partial	Deep Partial	Full Thickness
Color	Bright red, blanch	Pale, mottled red-white	White, brown, black
Blisters	Small, thin-walled	Large, thick-walled	Absent (may see ruptured)
Capillary refill	Brisk (<2 sec)	Sluggish	Absent
Sensation	Painful	Painful to pressure only	Anesthetic
Bleeding when pricked	Bright red, brisk	Dark, sluggish	None or thrombosed vessels
Texture	Supple	Thicker	Leathery, firm

TBSA Estimation

Rule of Nines (Adult)

Body Region	Percentage of Total BSA
Head and neck	9% (anterior 4.5%, posterior 4.5%)
Anterior trunk	18% (chest 9%, abdomen 9%)
Posterior trunk	18% (upper back 9%, lower back 9%)
Each arm	9% (anterior 4.5%, posterior 4.5%)
Each leg	18% (anterior 9%, posterior 9%)
Perineum/genitalia	1%
Total	100%

Rule of Nines (Child)

Child proportions differ from adults due to relatively larger head and smaller legs.

Body Region	Percentage of Total BSA
Head and neck	18% (adult 9%)
Each arm	9%
Anterior trunk	18%
Posterior trunk	18%
Each leg	13.5% (adult 18%)
Perineum	1%
Total	100%

Alternative Estimation Methods

Method	Description	Best For
Rule of Nines	Standard percentages by body region	Adults, rapid estimation
Lund-Browder chart	Age-adjusted percentages (more accurate for children)	Children, hospitalized patients
Palmer method	Patient’s palm (including fingers) = ~1% TBSA	Small or scattered burns
Handprint method	Patient’s palm without fingers = ~0.5% TBSA	Pinpoint accuracy for small burns

Burn Severity Classification

Criteria for Burn Severity

Severity	Criteria
Minor	<10% TBSA in adults, <5% in children/elderly; <2% full thickness; no face/hands/feet/perineum involvement; no inhalation injury; no concomitant trauma
Moderate	10-20% TBSA adults, 5-10% children/elderly; 2-5% full thickness; or face/hands/feet/perineum involvement
Major	>20% TBSA adults, >10% children/elderly; >5% full thickness; inhalation injury; high-voltage electrical; concomitant major trauma; significant chemical burns

Initial Burn Management

First Aid at Scene

Step	Action	Rationale
1	Stop the burning process	Remove from heat source, stop-drop-roll
2	Remove constrictive items	Remove clothing, jewelry, belts before swelling
3	Cool burn	Cool running water for 10-20 minutes (NOT ice)
4	Cover burn	Clean, dry cloth or sterile dressing
5	Transport to care	Based on severity

Cooling Protocol

Aspect	Recommendation
Temperature	Cool (not cold) running water, 15-25C (59-77F)
Duration	10-20 minutes
Timing window	Within 1 hour of injury for maximal benefit
Ice	DO NOT use ice (causes vasoconstriction, further tissue damage, hypothermia)
Large burns (>20%)	Limit cooling to body surface area; risk of hypothermia
Chemical burns	Copious irrigation with water for 20-60 minutes

Burn Dressing

Initial Dressing Selection

Burn Type	Dressing	Change Frequency
Superficial (1st degree)	Aloe vera or soothing moisturizer, no bandage needed	N/A
Superficial partial (2nd degree)	Silver sulfadiazine (Silvadene) or bacitracin, non-adherent gauze, wrapping	Daily
Deep partial (2nd degree)	Silver sulfadiazine, mafenide acetate (if eschar present), non-adherent gauze	Daily or twice daily
Full thickness (3rd/4th)	Mafenide acetate for eschar, then surgical excision and grafting	Surgical

Topical Antimicrobials for Burns

Agent	Spectrum	Advantages	Disadvantages
Silver sulfadiazine (Silvadene)	Broad (gram+, gram-, yeast)	Painless application, eschar penetration	Delays epithelialization, transient leukopenia, not on face
Mafenide acetate (Sulfamylon)	Broad, includes Pseudomonas, anaerobes	Excellent eschar penetration	Painful on application, metabolic acidosis (carbonic anhydrase inhibitor)
Bacitracin	Gram+	Good for face, nootoxicity	Minimal gram- coverage
Mupirocin	MRSA, Streptococcus	MRSA coverage	Expensive, limited spectrum
Silver nitrate 0.5%	Broad	Inexpensive, good for large burns	Stains everything black, electrolyte dilution
Medical honey	Broad (gram+, gram-, MRSA, VRE)	Natural, debriding properties	Sticky, requires frequent changes

Blister Management

Blister Type	Management	Rationale
Intact, small (<1 cm)	Leave intact, cover with dressing	Natural barrier against infection
Intact, large (>1 cm)	Controversial: many debriders prefer to leave intact	Risk of rupture, but if left may expand
Ruptured	Debride loose skin, clean, apply topical antimicrobial	Remove dead tissue that promotes infection
Palms/soles (thick skin)	Usually leave intact	Thicker epithelium, slower re-epithelialization
Contaminated or dirty blisters	Debride	Prevent infection

Pain Management in Burns

Pain Type	Characteristics	Management
Background pain	Constant, ongoing	Scheduled acetaminophen, NSAIDs, long-acting opioids
Procedural pain	During dressing changes, debridement	Short-acting potent opioids (fentanyl, morphine), ketamine, anxiolytics
Breakthrough pain	Between doses, with movement	Short-acting opioids, non-pharmacologic (distraction, VR therapy)
Neuropathic pain	Burning, shooting after healing	Gabapentin, pregabalin, TCAs
Itching (post-burn)	During healing, scar maturation	Antihistamines, moisturizers, silicone sheeting

Electrical Burns

Types of Electrical Injury

Type	Description	Examples
Low-voltage (<1000V)	Household current	Wall socket, appliance
High-voltage (>1000V)	Power lines, lightning	Downed lines, lightning strike
Arc/flash	Electrical arc causes thermal burn without current passage	Working on live panel
Lightning	Massive instantaneous current	Outdoor storm exposure

Electrical Burn Management

Aspect	Consideration
Entrance wound	Small, charred, deep (disguises extensive internal damage)
Exit wound	Larger, explosive appearance
Internal damage	Muscle necrosis along current path (compartment syndrome risk)
Cardiac effects	Arrhythmias, myocardial necrosis, cardiac arrest
Renal effects	Myoglobinuria from rhabdomyolysis, acute kidney injury
Neurologic effects	Peripheral nerve damage, spinal cord injury, cognitive changes
Fractures	From muscle contractions/tetany or fall
IV fluids	High-volume crystalloid to prevent AKI (goal urine output 75-100 mL/hr)

Chemical Burns

Common Chemical Burns

Chemical	Mechanism	Specific Management
Acid (HCl, H2SO4, HF)	Coagulation necrosis	Copious water irrigation; HF: calcium gluconate gel/injection
Alkali (NaOH, KOH, cement, bleach)	Liquefactive necrosis (worse than acid)	Prolonged water irrigation (hours); continue until pH normalizes
Hydrofluoric acid (HF)	Deep, painful, hypocalcemia	Copious irrigation, calcium gluconate (topical, subcutaneous, IV), monitor calcium
White phosphorus	Embedded particles ignite in air	Keep wound wet (water or saline), remove visible particles, copper sulfate to identify
Tar/asphalt	Thermal + chemical	Cool with water, remove with petroleum-based solvent (neomycin, bacitracin)
Phenol	Deep penetration, systemic toxicity	Polyethylene glycol 300 irrigation (or water if unavailable)

Inhalation Injury

Diagnosis

Feature	Assessment
History	Enclosed space fire, steam exposure, prolonged extrication
Physical exam	Facial burns, singed nasal hair, carbonaceous sputum, hoarseness, stridor
Mechanism	Thermal injury (upper airway), chemical injury (lower airway, pulmonary parenchyma)
Carbon monoxide	COHb >10% from smoke inhalation (check co-oximetry)
Cyanide	Suspect in enclosed-space fire with soot, metabolic acidosis

Airway Management

Finding	Action
Stridor, hoarseness, dysphagia	Early intubation (before airway edema worsens)
Carbonaceous sputum	Bronchoscopy for diagnosis and clearance
CO poisoning	100% oxygen via non-rebreather; hyperbaric oxygen if COHb >25% or neurologic symptoms
Bronchospasm	Inhaled beta-agonists
ARDS	Lung-protective ventilation

Burn Center Referral Criteria

American Burn Association Referral Criteria

Criterion	Detail
Partial-thickness burns >10% TBSA	Any age group
Burns involving face, hands, feet, genitalia, perineum, or major joints	Functional and cosmetic concerns
Full-thickness burns	Any size requires specialized care
Electrical burns (including lightning)	Cardiac monitoring, deep tissue assessment
Chemical burns	Risk of ongoing injury, systemic effects
Inhalation injury	Airway management, pulmonary support
Burns in patients with pre-existing conditions	Diabetes, cardiac disease, immunosuppression
Burns with concomitant trauma	Increased complexity, multisystem involvement
Burns in children	Pediatric burn center if <10 years with >5% TBSA or any significant burn
Burns in elderly (>60 years)	Increased morbidity and mortality
Burns in pregnant patients	Fetal assessment and multidisciplinary care
Non-accidental burns (abuse/neglect)	Mandatory reporting, social services

Burn Shock and Fluid Resuscitation

Resuscitation Formulas

Formula	Crystalloid	Calculation (first 24 hours)
Parkland (modified Brooke)	Lactated Ringer’s	4 mL x TBSA% x weight (kg); 1/2 in first 8 hours, 1/2 in next 16 hours
Brooke	Lactated Ringer’s	2 mL x TBSA% x weight (kg); same timing
Consensus formula	Lactated Ringer’s	2-4 mL x TBSA% x weight (kg); titrate to urine output
Pediatric (Galveston)	Lactated Ringer’s + D5	5000 mL/m2 TBSA burned + 2000 mL/m2 total BSA; maintenance with D5LR

Fluid Monitoring

Parameter	Target
Urine output (adult)	30-50 mL/hour
Urine output (child)	1 mL/kg/hour
Heart rate	Decreasing trend toward normal
Blood pressure	Maintain mean arterial pressure >65 mmHg
Base deficit	Normalizing (-2 to +2)
Hematocrit	Decreasing as fluid mobilizes
Central venous pressure	8-12 mmHg

Escharotomy

Indications for Escharotomy

Indication	Description
Circumferential full-thickness burn	Eschar is inelastic, cannot expand with edema
Compartment syndrome	Distal paresthesias, pulselessness, pallor, pain on passive stretch, paralysis
Chest wall restriction	Impaired ventilation from circumferential trunk burn
Extremity ischemia	Absent Doppler signals, elevated compartment pressures
Timing	Perform within 4-6 hours of injury if indicated

Prognosis

Factors Affecting Burn Prognosis

Factor	Worse Prognosis
Age	Children <5 years, elderly >60 years have higher mortality
TBSA	Mortality increases with %TBSA; >40% carries high mortality
Inhalation injury	Adds significantly to mortality
Full thickness burns	Higher mortality than partial thickness of same size
Delay to presentation	Increases infection risk, fluid shifts
Comorbidities	Diabetes, COPD, cardiovascular disease, obesity
Sepsis	Leading cause of late mortality in burn patients

Survival Predictors (Baux Score)

Score	Calculation	Interpretation
Baux score	Age + TBSA%	Mortality ~ 50% when score = 100; ~90% when score = 140
Revised Baux score	Age + TBSA% + (17 x inhalation injury [1=yes, 0=no])	More accurate with inhalation injury
R-Baux	(Age + TBSA% + 17 x inhalation injury) / 90	Values >1 predict death