What are the guidelines for fluid resuscitation and renal replacement therapy (RRT) in severe burn patients?

Fluid Resuscitation and Renal Replacement Therapy in Severe Burns

Initial Fluid Resuscitation Strategy

Begin resuscitation with 2-4 mL/kg/%TBSA of balanced crystalloid (Ringer's Lactate preferred) over 24 hours, with half administered in the first 8 hours post-burn, then immediately adjust based on urine output targeting 0.5-1 mL/kg/hour in adults. 1

Crystalloid Administration Protocol

• Adults: Calculate initial fluid requirements using the Parkland formula (2-4 mL/kg/%TBSA over 24 hours), though recognize this often underestimates actual needs 1, 2
• Children: Require higher volumes (~6 mL/kg/%TBSA over 48 hours) due to greater surface area-to-weight ratio, plus add maintenance fluids using the 4-2-1 rule for burns >10% TBSA 1, 3
• Administer 50% of calculated volume in first 8 hours, remaining 50% over next 16 hours 1, 4
• Use Ringer's Lactate as first-line fluid; avoid normal saline due to hyperchloremic acidosis and acute kidney injury risk 4

Critical Monitoring Parameters

Titrate fluid rates primarily to urine output (0.5-1 mL/kg/hour in adults), not rigidly to formulas, as both under-resuscitation and "fluid creep" increase morbidity and mortality. 1

• Monitor hourly urine output as the fastest, most practical endpoint 1
• Add arterial lactate levels and advanced hemodynamic monitoring (echocardiography, cardiac output monitoring) in patients with persistent oliguria or hemodynamic instability 1
• In children, positive fluid balance on Day 3 correlates with increased mechanical ventilation time and hospital stay 1
• Transpulmonary thermodilution in children with TBSA >30% may reduce fluid volumes and morbidity, though the 2024 American Burn Association guidelines do not recommend this for routine use 1, 2

Albumin Administration

Add human albumin (5% solution) after the first 6-8 hours in patients with burns >30% TBSA to reduce crystalloid volumes, decrease abdominal compartment syndrome, and potentially reduce mortality. 1, 4

Evidence-Based Albumin Protocol

• Initiate 5% albumin at 8-12 hours post-burn for TBSA >30% 1, 4
• Target serum albumin levels >30 g/L with doses of 1-2 g/kg/day 4
• Meta-analysis shows albumin reduces mortality (OR 0.34,95% CI 0.19-0.58) when high-bias studies excluded 1
• Albumin decreases abdominal compartment syndrome from 15.4% to 2.8% (OR 0.19,95% CI 0.07-0.5) 1
• Benefits include reduced crystalloid volumes and decreased organ failure incidence 1, 4, 2

Contraindicated Colloids

• Never use hydroxyethyl starches (HES) - contraindicated by European Medicines Agency in burn patients 4
• Avoid gelatins and synthetic starches due to coagulation and platelet dysfunction 4

Avoiding Resuscitation Complications

Preventing "Fluid Creep" (Over-Resuscitation)

Both insufficient and excessive fluid administration increase morbidity; adjust rates continuously rather than following formulas blindly. 1

• Excessive fluids cause abdominal compartment syndrome, acute kidney injury, respiratory complications, and prolonged mechanical ventilation 1, 4
• Computer-based decision support systems may limit over-resuscitation risk 1
• Patients with low TBSA or low BMI require proportionally more fluid per kg/%TBSA; those with high TBSA or high BMI require less 5
• Deep burns require higher fluid rates than superficial burns 5

Managing Persistent Hypotension

• If hypotension persists despite adequate fluid resuscitation, evaluate cardiac function with echocardiography before adding vasopressors 1, 4
• Assess intravascular volume status with advanced hemodynamic monitoring 1

Renal Replacement Therapy Considerations

While the provided guidelines do not establish specific RRT initiation criteria for burn patients, monitor closely for acute kidney injury given the high risk from hypovolemia, myoglobinuria (especially in electrical burns), and fluid overload. 4, 6

AKI Prevention Strategies

• Maintain adequate urine output (0.5-1 mL/kg/hour) to prevent acute kidney injury from hypovolemia 1
• In electrical burns with muscle damage, target higher urine output (1-2 mL/kg/hour) to clear myoglobin 6
• Monitor for myoglobinuria in electrical burns requiring additional fluid volumes 6
• The 2024 American Burn Association guidelines note insufficient evidence to recommend early continuous RRT as an adjunct during burn shock resuscitation 2

Special Populations

Pediatric Modifications

• Children with 10-20% TBSA may benefit from reduced fluid volumes (shorter hospital stay, fewer grafts) 1
• Use Lund-Browder chart for accurate TBSA calculation in children 3
• Urine output remains the key monitoring parameter in pediatric patients 1

Electrical Burns

• Expect deeper tissue damage than surface appearance suggests, requiring higher fluid volumes 4, 6
• Monitor aggressively for compartment syndrome 6
• Maintain higher urine output to prevent myoglobin-induced renal injury 6

Key Pitfalls to Avoid

• Do not rigidly follow resuscitation formulas - they provide starting estimates only; actual needs vary by 33-61% from calculated values 1, 7
• Do not delay albumin in burns >30% TBSA - initiate at 6-8 hours for mortality benefit 1, 2
• Do not use urine output alone in hemodynamically unstable patients - add lactate and advanced monitoring 1
• Do not underestimate electrical burn fluid needs - tissue damage exceeds visible injury 4, 6