How To Burn Fluid Calculation
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Burn Fluid Resuscitation: Complete Guide
Step 1 - Estimate Burn Size (%TBSA)
Only second- and third-degree burns are counted. First-degree burns (simple redness/sunburn) are excluded.
Rule of Nines (Adults)
| Body Region | % TBSA |
|---|---|
| Head & Neck | 9% |
| Each Upper Limb | 9% (×2 = 18%) |
| Anterior Trunk | 18% |
| Posterior Trunk | 18% |
| Each Lower Limb | 18% (×2 = 36%) |
| Genitalia/Perineum | 1% |
| Total | 100% |
In children, the head is proportionally larger (up to 18% in toddlers) and the legs smaller - use the Lund-Browder chart for accuracy.
Palm method: The patient's palm (including fingers) = approximately 1% TBSA - useful for small or irregular burns.
Step 2 - Choose the Formula
The Parkland (Baxter) Formula - Most Widely Used
Total fluid in first 24 hours = 4 mL × body weight (kg) × %TBSA
- Fluid: Lactated Ringer's (LR) solution only
Timing:
- First 8 hours from time of burn: give ½ of total volume
- Next 16 hours (hours 9-24): give remaining ½
Important: The 24-hour clock starts at time of burn, not time of arrival to hospital. If the patient arrives 2 hours after injury, the first 8-hour half must be infused over only 6 hours.
ABLS (Advanced Burn Life Support) Modified Formula
The 2011 ABLS Manual notes that the classic 4 mL Parkland formula frequently causes over-resuscitation ("fluid creep"). It recommends:
| Patient | Formula |
|---|---|
| Adults | 2 mL LR × kg × %TBSA (24 hours) |
| Children ≤14 yrs / <40 kg | 3 mL LR × kg × %TBSA + add maintenance fluids (use dextrose-containing maintenance in infants) |
| High-voltage electrical burns (with deep tissue injury or pigmenturia) | 4 mL LR × kg × %TBSA |
Consensus / Baxter Formula (Mulholland)
2-4 mL × %TBSA × weight (kg) in first 24 hours
Half in first 8 hours, half over next 16 hours - same timing as Parkland.
Worked example: 70 kg patient with 20% TBSA burn at 10:00 AM, presenting at 12:00 PM (2 hrs later):
- Total fluid = 4 mL × 70 kg × 20% = 5,600 mL
- First 8-hr half = 2,800 mL - but only 6 hours remain to the 8-hr mark
- Rate = 2,800 mL ÷ 6 hours = ~467 mL/hr for first 6 hrs
- Then 2,800 mL over next 16 hrs = 175 mL/hr
Step 3 - The Rule of 10 (US Army / Prehospital Simplified Formula)
A simpler bedside estimate for adult patients weighing 40-80 kg:
%TBSA × 10 = initial fluid rate in mL/hr
- For every 10 kg above 80 kg, add 100 mL/hr
(Round %TBSA to the nearest 10 for quick calculation)
Step 4 - Monitor and Titrate
Formulas are starting points only - titrate hourly based on urine output:
| Patient | Target Urine Output |
|---|---|
| Adults | 0.5 mL/kg/hr |
| Children (<40 kg) | 1.0 mL/kg/hr |
| Adults with electrical/pigment injury | 1.0 mL/kg/hr (to clear myoglobin) |
Insert a Foley catheter in all major burns for accurate hourly measurement.
Additional monitoring parameters:
- Lactate (trend for perfusion)
- Heart rate & blood pressure (note: burn patients are often tachycardic regardless)
- Urine color (clear vs. dark/pigmented)
- Intra-abdominal pressure (risk of compartment syndrome with >300 mL/kg in 24 hrs)
Step 5 - Second 24 Hours
- Continue LR to maintain urine output and perfusion parameters
- Begin tapering fluids after 24-36 hrs (reduce by ~⅓ if urine output adequate)
- Colloid (5% albumin at 0.3-0.5 mL/kg per %TBSA over 24 hrs) can be added after initial crystalloid resuscitation
- Consider albumin if patient requires >1.5× the calculated Parkland volume (reduces abdominal compartment syndrome risk)
- Pediatric patients under 1 year: use D5-LR for maintenance to prevent hypoglycemia
Key Clinical Points
- Fluid of choice: Lactated Ringer's - preferred over normal saline (avoids hyperchloremic acidosis) and over colloids in the first 24 hours
- "Fluid creep" (over-resuscitation) causes pulmonary edema, fasciotomy-requiring compartment syndrome, raised intraocular pressure, and conversion of superficial to deep burns
- IV fluid is indicated for burns >20% TBSA in adults and >10% TBSA in children
- Electrical burns: fluid requirements are often greater than predicted by surface burns because of deep tissue destruction; start with 4 mL/kg/%TBSA and titrate up
- Inhalation injury, delayed resuscitation, or concomitant trauma all increase fluid requirements beyond formula predictions
Sources:
- Roberts and Hedges' Clinical Procedures in Emergency Medicine, Box 38.2-38.3
- Mulholland and Greenfield's Surgery, p. 735-736 (Consensus Formula)
- Miller's Anesthesia 10e, Box 43.1 (Parkland Formula)
- Tintinalli's Emergency Medicine, Table 219-4
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