What is the Parkland Formula?
The Parkland formula (also known as the Baxter formula) is the most widely used method for estimating initial crystalloid fluid resuscitation requirements in burn patients. Developed by Dr. Charles Baxter at Parkland Memorial Hospital in Dallas, Texas, in the 1960s, it provides a starting point for fluid replacement in the critical first 24 hours following a major burn injury.
The formula estimates the volume of Lactated Ringer's (LR) solution needed based on the patient's body weight and the percentage of total body surface area (TBSA) affected by second- and third-degree burns. First-degree (superficial) burns are not included in the TBSA calculation as they do not cause the capillary leak that necessitates aggressive fluid resuscitation.
The Parkland Formula
The calculated volume is administered as follows:
- First 8 hours: 50% of the total volume (timed from the moment of burn, not from hospital arrival)
- Next 16 hours: Remaining 50% of the total volume
Next 16 hr Rate (mL/hr) = (Total × 0.5) ÷ 16
Critical timing note: The 8-hour window begins at the time of the burn injury, not at the time of hospital presentation. If a patient arrives 2 hours after a burn, the first half of the fluid must be delivered in the remaining 6 hours, requiring a higher infusion rate.
Rule of Nines
The Wallace Rule of Nines is a rapid method for estimating the percentage of total body surface area (TBSA) affected by burns in adults. Each major body region is assigned a percentage that is a multiple of 9:
| Body Region | Adult %TBSA | Child (1-4 yr) %TBSA |
|---|---|---|
| Head & Neck | 9% | 18% |
| Each Upper Extremity (arm) | 9% each | 9% each |
| Anterior Trunk (chest & abdomen) | 18% | 18% |
| Posterior Trunk (back) | 18% | 18% |
| Each Lower Extremity (leg) | 18% each | 14% each |
| Perineum / Genitalia | 1% | 1% |
| Total | 100% | 100% |
For children, the Lund-Browder chart provides a more accurate assessment as it accounts for the proportionally larger head and smaller limbs in pediatric patients. The Rule of Nines is less accurate for children and obese patients.
Rule of Nines Diagram
Burn Resuscitation
Fluid resuscitation is a critical component of early burn management. Major burns (typically >20% TBSA in adults or >10% in children) cause a systemic inflammatory response with massive capillary leak, leading to intravascular volume depletion, tissue edema, and potentially burn shock.
Key principles of burn resuscitation:
- Fluid choice: Lactated Ringer's solution is the preferred crystalloid. Normal saline carries a risk of hyperchloremic metabolic acidosis with large volumes.
- Starting point, not endpoint: The Parkland formula provides an estimate. Actual fluid delivery must be titrated to clinical endpoints, primarily urine output.
- Avoid over-resuscitation: Excessive fluid ("fluid creep") can lead to abdominal compartment syndrome, extremity compartment syndrome, and pulmonary edema.
- Colloid consideration: Some centers add 5% albumin after 8-12 hours or in patients requiring significantly more fluid than calculated.
Modified Brooke Formula
The modified Brooke formula is an alternative to the Parkland formula, using a lower crystalloid volume:
| Formula | Crystalloid Factor | First 24hr Fluid | Colloid |
|---|---|---|---|
| Parkland (Baxter) | 4 mL/kg/%TBSA | Lactated Ringer's only | None in first 24 hrs |
| Modified Brooke | 2 mL/kg/%TBSA | Lactated Ringer's | 0.3-0.5 mL/kg/%TBSA after 24 hrs |
| Evans | 1 mL/kg/%TBSA | Normal saline + 2L D5W | 1 mL/kg/%TBSA colloid |
The Parkland formula tends to over-estimate fluid requirements in clinical practice. The American Burn Association recommends starting with 2-4 mL/kg/%TBSA and titrating to urine output. Many burn centers use a "rule of 10" for rapid estimation: for every 10% TBSA burned, the initial rate is approximately (body weight in kg) × 10 mL/hr, adjusted to urine output.
Urine Output Monitoring
Urine output is the single most important parameter for guiding fluid resuscitation in burn patients. A Foley catheter should be placed in all patients requiring resuscitation.
| Patient | Target Urine Output | Action if Below Target | Action if Above Target |
|---|---|---|---|
| Adults (≥30 kg) | 0.5 – 1.0 mL/kg/hr | Increase infusion rate by 20% | Decrease infusion rate by 20% |
| Children (<30 kg) | 1.0 mL/kg/hr | Increase infusion rate by 20% | Decrease infusion rate by 20% |
| Electrical burns | 1.0 – 1.5 mL/kg/hr | Increase fluid; consider mannitol for myoglobinuria | Gradual reduction |
If urine output remains inadequate despite escalating crystalloid rates, consider vasopressors, colloid supplementation, or reassessment of the TBSA estimate. Persistently low urine output may also indicate renal injury or abdominal compartment syndrome.
Worked Example
An 80 kg adult sustains 30% TBSA burns in a house fire. The patient arrives at the emergency department 2 hours after the burn.
— Already 2 hrs elapsed, so 4,800 mL must be given in 6 remaining hours
— Rate = 4,800 ÷ 6 = 800 mL/hr for the next 6 hours
— Rate = 4,800 ÷ 16 = 300 mL/hr for hours 8-24
Target urine output: 0.5-1.0 mL/kg/hr = 40-80 mL/hr for this patient. Adjust fluid rate every hour based on urine output. If urine output falls below 40 mL/hr, increase the rate by 20%. If above 80 mL/hr, decrease by 20%.
Frequently Asked Questions
When should the Parkland formula be used?
The Parkland formula should be used for patients with significant burn injuries, typically >20% TBSA in adults or >10% TBSA in children. It is also indicated for burns involving the airway (inhalation injury), electrical burns, and delayed presentation. Minor burns usually do not require IV fluid resuscitation and can be managed with oral hydration.
What fluid should be used?
Lactated Ringer's solution is the recommended crystalloid for burn resuscitation. It is preferred over normal saline because large volumes of normal saline can cause hyperchloremic metabolic acidosis. Colloids (albumin) are generally not used in the first 12-24 hours as capillary permeability makes them less effective during this period.
What if the patient arrives late?
The Parkland formula timing starts from the time of burn, not hospital arrival. If a patient arrives 3 hours after the burn, the first half of the calculated fluid must be infused in the remaining 5 hours (not 8 hours), requiring a higher infusion rate. This is a common source of under-resuscitation in delayed presentations.
Does the formula apply to children?
Yes, but with modifications. Children, especially those under 30 kg, may also require maintenance fluids (D5 0.45% NS) in addition to resuscitation fluid, as they are prone to hypoglycemia. The target urine output for children is 1 mL/kg/hr (higher than adults). The Lund-Browder chart should be used instead of the Rule of Nines for accurate TBSA estimation in pediatric patients.
What is "fluid creep"?
Fluid creep refers to the administration of volumes significantly exceeding the Parkland formula calculation, often 6-8 mL/kg/%TBSA or more. It occurs when clinicians aggressively increase fluid rates in response to transient oliguria without considering the overall trajectory. Complications include abdominal compartment syndrome, extremity compartment syndrome, pulmonary edema, and orbital compartment syndrome. Prevention requires frequent reassessment and adherence to urine output targets rather than reflexive rate increases.