Updated July 2026 · 10 min read
Part of the ICU Emergencies Hub — every emergency guide in this library, organized by system.
The number the formula spits out is a starting guess, not a prescription. Burn resuscitation is one of the few places in critical care where you titrate a continuous infusion to a single physiologic target — hourly urine output — and where giving too much fluid is as dangerous as giving too little.
A major thermal injury does not just damage skin — it triggers a body-wide inflammatory response. Mediators released from burned tissue make capillaries leak, so protein-rich plasma escapes the circulation into the interstitium. In burns larger than roughly 20–25% total body surface area (TBSA), this leak is generalized: even tissue far from the burn swells. The result is intravascular volume depletion despite a normal or high total body water — the patient is edematous and hypovolemic at the same time. Left uncorrected, this progresses to hypoperfusion, organ injury, and death. The purpose of resuscitation is to keep the intravascular space full enough to perfuse organs through the peak leak, which typically eases over the first 24 hours.
Every formula depends on the burn size, and an inaccurate TBSA estimate is the single biggest source of resuscitation error. Two bedside methods dominate:
| Method | How it works | Best for |
|---|---|---|
| Rule of Nines | Body divided into regions of 9% (or multiples): each arm 9%, each leg 18%, anterior trunk 18%, posterior trunk 18%, head 9%, perineum 1% (adult) | Quick adult estimate of medium-to-large burns |
| Palmar (rule of palm) | The patient's whole palm including fingers ≈ 1% TBSA | Small or scattered/patchy burns |
| Lund-Browder chart | Age-adjusted regional percentages | Most accurate, and essential in children (big heads, small legs) |
The classic Parkland (Baxter) formula estimates the first 24 hours of crystalloid, usually lactated Ringer's:
A worked example makes the timing clear. An 80 kg patient with a 40% TBSA burn: 4 × 80 × 40 = 12,800 mL over 24 hours. Half of that, 6,400 mL, is due in the first 8 hours post-burn. If the patient arrives two hours after the injury, that 6,400 mL now has to run over the remaining 6 hours — roughly 1,070 mL/hr — to stay on schedule. Missing the burn-time clock is a common early error.
Many burn centers now start at the lower end of the range. The modified Brooke formula uses 2 mL/kg/%TBSA as a starting point, and consensus guidance has trended toward starting lower (around 2 mL) and letting urine output pull the rate up if needed — precisely to combat fluid creep. Whatever the starting multiplier, the principle is identical: the formula picks the opening rate; the patient picks every rate after that.
This is the concept that separates safe burn resuscitation from dangerous number-chasing. Once the infusion is running, the formula is essentially retired. You adjust the rate hourly against a urine output target:
| Patient | Hourly urine output target |
|---|---|
| Adult | ~0.5 mL/kg/hr (roughly 30–50 mL/hr) |
| Child (<30 kg) | ~1 mL/kg/hr |
| High-voltage electrical / rhabdomyolysis | Higher target (often 1–1.5 mL/kg/hr) to clear pigment |
If urine output is below target, the intravascular space is under-filled — increase the rate (a common step is +20% or up-titration per unit protocol). If urine output climbs above target, the patient is being over-resuscitated — decrease the rate. The reflex to fight is the one that says "the formula says keep it wide open." A patient making 120 mL/hr on a formula-calculated rate does not need that rate; they need it turned down. Note the electrical-injury exception: with rhabdomyolysis and pigmenturia (see electrical injury), you deliberately run a higher urine target to protect the kidneys, and you avoid over-diuresing away the volume the myoglobin clearance needs.
For decades the danger in burns was under-resuscitation. Today, with liberal early fluids and easy infusion pumps, the more common problem is fluid creep — cumulative volumes far exceeding what the patient needs, driven by rate increases that are never walked back down. The consequences are mechanical: too much interstitial fluid causes complications that can be as lethal as the burn itself.
| Over-resuscitation complication | Why it happens |
|---|---|
| Abdominal compartment syndrome | Bowel and retroperitoneal edema raise intra-abdominal pressure, compromising organ perfusion and ventilation |
| Extremity/limb compartment syndrome | Edema under inelastic burned skin (may require escharotomy) |
| Pulmonary edema / worsening oxygenation | Excess fluid floods the lungs, especially with inhalation injury |
| Orbital compartment syndrome | Periorbital edema threatens vision |
| Conversion of burn depth | Excess edema can worsen tissue ischemia and deepen the wound |
Some protocols add albumin after the first 8–12 hours, when the capillary leak begins to close and colloid can stay intravascular and reduce total crystalloid needs — a "colloid rescue" for patients trending into fluid creep. After 24 hours, the strategy shifts entirely: maintenance fluids, ongoing losses from the wound, nutrition (burns are hypermetabolic and need early enteral feeding), and evaporative free-water replacement take over. The Parkland formula covers only that first turbulent day.
Resuscitation happens alongside the rest of burn care. Keep the burn patient warm (large burns lose heat fast and coagulopathy worsens with hypothermia — see accidental hypothermia). Screen every enclosed-space or facial burn for carbon monoxide and cyanide exposure, and watch the airway closely for inhalation injury, because edema can close it over hours. Anticipate escharotomy for circumferential full-thickness burns, elevate burned limbs, and remove rings and constricting items before swelling sets in. Provide generous, scheduled analgesia — burn dressing changes and repositioning are among the most painful things done in an ICU.
On the CRNA path, burn patients bring almost every hard anesthesia problem into one room: a threatened airway that must be secured early, massive volume shifts, altered drug pharmacokinetics from the edema and hypermetabolism, the succinylcholine-after-24-hours warning (upregulated receptors risk lethal hyperkalemia), and the need to titrate resuscitation to a physiologic endpoint. The reasoning you build titrating LR to urine output at the bedside is the exact reasoning you will use managing fluids across a long burn excision case.
Burn shock is a capillary-leak problem: fill the intravascular space enough to perfuse organs through the first 24 hours. Estimate TBSA accurately (partial- and full-thickness only), let the Parkland or modified Brooke formula set your opening rate timed from the burn, then titrate to urine output hour by hour — up when it's low, down when it's high. Respect fluid creep as a real and lethal complication, watch the cumulative volume, and remember that the burn is rarely the only injury in the room.
This article is general educational information for licensed clinicians and students, not medical advice or a substitute for your institution's protocols, burn-center guidance, or a provider's orders. Always follow facility policy and verify every calculation and dose independently.
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