Colloid therapy in burn resuscitation

Overview

Colloid therapy in burn resuscitation aims to restore and maintain intravascular oncotic pressure during the massive capillary leak that characterizes the first 24 hours after major burn injury. Albumin is the most widely used colloid in burn care, administered either as a planned component of resuscitation from the outset or as "rescue" therapy when crystalloid administration exceeds predicted volumes ^[1][2]. The rationale is straightforward: colloids remain in the intravascular space longer than crystalloids when capillary integrity begins to recover, reducing total fluid volume and the downstream complications of overresuscitation. Despite decades of use, high-quality prospective data comparing crystalloid-only resuscitation to colloid-inclusive protocols remain limited ^[6].

Physiologic Rationale

Burn injury destroys the endothelial glycocalyx and increases capillary permeability, driving protein-rich fluid into the interstitium. This results in intravascular protein depletion and progressive loss of oncotic pressure. Crystalloid resuscitation replaces volume but does not restore oncotic gradient, and only about one-quarter of infused crystalloid remains intravascular ^[1]. Albumin, as the principal determinant of plasma oncotic pressure, theoretically addresses this deficit. However, the degree to which exogenous albumin leaks through damaged capillaries during the early hours of resuscitation remains debated. Capillary leak peaks at 8-12 hours and begins to resolve by 18-24 hours, suggesting that colloid administered later in the resuscitation period may be more efficiently retained intravascularly ^[1].

Clinical Evidence

Greenhalgh reviewed the current state of colloid use in burns, noting that albumin consistently reduces total crystalloid requirements and that most burn centers now use albumin either as a planned adjunct or as rescue therapy when crystalloid rates exceed protocol targets ^[1]. The problem of "fluid creep" persists despite modern decision-support tools, and albumin remains the most common intervention when resuscitation volumes run ahead of predictions ^[1].

Comish et al. demonstrated that rescue albumin (25% concentration) administered to patients failing crystalloid-only resuscitation decreased the amount of fluid given per %TBSA during resuscitation and improved urine output as a marker of end-organ perfusion ^[2]. Despite the rescue group having larger burns (40.3% vs 34% TBSA), total crystalloid volumes were not significantly different between groups, suggesting that albumin effectively offset the higher fluid demands of larger injuries ^[2].

Blanco-Schweizer et al. evaluated the BET formula, which incorporates 20% albumin from the start of resuscitation at a 1:1 ratio with crystalloid, decreasing the albumin proportion every 8 hours. Patients resuscitated with this approach received 2.58 mL/kg/%TBSA in the first 24 hours, significantly less than the 4 mL/kg/%TBSA predicted by the Parkland formula ^[3]. Base excess and lactate clearance confirmed adequate resuscitation despite lower volumes ^[3].

A MIMIC-IV database analysis found that early albumin administration (within 24 hours of crystalloid initiation) in critically ill patients was associated with lower 28-day and 60-day mortality compared with crystalloids alone, while late albumin administration (after 24 hours) showed no benefit ^[4].

Curry et al. showed that a revised resuscitation guideline optimizing colloid use alongside a lower starting crystalloid rate (2 mL/kg/%TBSA) resulted in significantly lower 24-hour resuscitation volumes without an increase in composite adverse safety outcomes including acute kidney injury and intra-abdominal hypertension ^[5].

Controversies and Evidence Gaps

The optimal timing of colloid initiation remains unsettled. Traditional teaching delays colloid until after 24 hours based on the assumption that early capillary leak renders colloid ineffective, but multiple recent studies support earlier use ^[1][2][3]. A multicenter randomized trial comparing crystalloid-only resuscitation to early albumin supplementation is underway but results are not yet available ^[1]. Whether fresh frozen plasma is superior to albumin as a colloid in burns is an emerging question with limited comparative data. Nearly all prospective colloid studies in burns are more than a decade old, and modern high-quality evidence remains sparse ^[6]. The appropriate concentration (5% vs 25% albumin) and dosing strategy are also unresolved.

References

[1] Greenhalgh DG. "Current Thoughts on Burn Resuscitation." Adv Surg 2024;58(1):1-17. PMID: 39089770 [2] Comish P et al. "Adoption of rescue colloid during burn resuscitation decreases fluid administered and restores end-organ perfusion." Burns 2021;47(8):1844-1850. PMID: 33658146 [3] Blanco-Schweizer P et al. "Resuscitation with albumin using BET formula keeps at bay fluid administration in burned patients." Burns 2020;46(4):860-867. PMID: 31848084 [4] Yalan Q et al. "Early high-volume resuscitation with crystalloid solution combined with albumin improves survival of critically ill patients." Burns 2024;50(4):893-902. PMID: 38278752 [5] Curry D et al. "Revision of an Adult Burn Center's Resuscitation Guideline Leads to Lower Resuscitation Requirements." J Burn Care Res 2024;45(6):1499-1504. PMID: 38824401 [6] Cartotto R et al. "Burn State of the Science: Fluid Resuscitation." J Burn Care Res 2017;38(3):e735-e751. PMID: 28328669