Nutritional requirements in burn patients

Overview

Burns produce the most extreme hypermetabolic state encountered in clinical medicine, with metabolic rates exceeding twice normal for over a year after injury ^[1][2]. Failure to meet these extraordinary energy and protein demands accelerates lean body mass erosion, impairs wound healing, and increases susceptibility to infection and multiorgan dysfunction. Nutritional support in burn patients requires attention to timing, route of delivery, macronutrient composition, and caloric targets, with individualized reassessment throughout recovery.

Pathophysiology

Severe burn injury triggers a biphasic metabolic response: an initial "ebb" phase of decreased metabolism followed by a prolonged "flow" phase characterized by hypermetabolic rates and hyperdynamic circulation ^[1]. The Curreri formula, one of the earliest attempts to quantify burn caloric requirements, established that energy needs scale with both body weight and burn size ^[3]. Practical guidelines emphasize that nutritional assessment is challenging given the metabolic disarray accompanying the inflammatory state, and that determination of nutrient requirements must be individualized and reassessed throughout recovery ^[4].

Timing and route

Early enteral nutrition, initiated within 6 to 12 hours of admission, is now the standard of care. Enteral feeding preserves gut mucosal integrity, reduces bacterial translocation, and may attenuate the hypermetabolic response ^[2][5]. A prospective randomized trial by Peck et al. comparing early (within 24 hours) versus late (7 days) enteral feeding found that early feeding did not decrease average energy expenditure; in fact, the early group trended toward higher daily energy expenditure ^[6]. This suggests that while early nutrition is critical for maintaining lean mass and immune function, it does not directly blunt the hypermetabolic response itself.

Macronutrient composition

A literature review of 11 studies found that high-carbohydrate, low-fat enteral formulas were associated with improved outcomes including fewer infections, shorter hospital stays, improved nitrogen balance, and reduced muscle protein breakdown compared with higher-fat regimens ^[7]. Gottschlich et al. demonstrated in a prospective randomized trial that a modular tube feeding formula enriched with omega-3 fatty acids, arginine, and micronutrients significantly reduced wound infection rates (P < 0.03) and length of stay per percent burn (P < 0.02) compared with standard enteral regimens ^[8]. Seventy percent of deaths occurred in the group receiving the highest proportion of fat and linoleic acid ^[8].

Perioperative nutrition

Perioperative fasting is a common and underappreciated cause of caloric deficits. Pham et al. found that the average fasting duration from NPO order to feeding restart was 14.2 hours, creating an average caloric deficit of 1,765 kcal per surgical episode, and that a postoperative catch-up feeding protocol fully compensated for the deficit only 68.8% of the time ^[9]. A subsequent systematic review and meta-analysis of intraoperative enteral nutrition demonstrated no statistically significant increases in aspiration, pneumonia, or mortality, suggesting that continued intraoperative feeding may be safe and effective at reducing perioperative caloric deficits ^[10]. Gastric residual volume (GRV) measurement is another common cause of unnecessary feeding interruptions; a systematic review found that elevated GRVs do not reliably predict gastrointestinal intolerance or aspiration risk, and recommended adopting a GRV threshold of 500 mL before holding feeds ^[11].

Adjunctive therapies

Glutamine supplementation has been studied as an immune-modulating adjunct. Wilmore reviewed six randomized blinded trials showing that glutamine-supplemented nutrition improved nitrogen balance, corrected intracellular amino acid depletion, and decreased hospital length of stay in postoperative patients ^[12]. In burn patients specifically, glutamine plasma and intramuscular concentrations are low despite accelerated synthesis rates, suggesting supplementation may be warranted ^[12]. Albumin supplementation, by contrast, does not appear beneficial: a prospective randomized trial in pediatric burn patients found no differences in length of stay, complication rates, or mortality between groups maintained at normal versus low albumin levels ^[13].

Contemporary reviews emphasize that nutritional support must be paired with pharmacologic adjuncts to counter the hypermetabolic and catabolic response. Shahrokhi and Jeschke note that adjunctive therapies including oxandrolone, insulin, metformin, and propranolol should be considered alongside adequate nutrition, with anabolic agents administered for the duration of hospitalization and possibly up to 2 to 3 years postburn ^[14]. (Note: Oxandrolone was removed from the US market by the FDA and should be considered historical evidence rather than current standard therapy.)

Controversies and Evidence Gaps

There is no consensus on the optimal caloric formula for burn patients, and indirect calorimetry, the gold standard for measuring resting energy expenditure, is not universally available. The role of glutamine supplementation remains debated: while data in surgical populations are promising, burn-specific randomized trials are limited. Immune-enhancing formulas show benefit in select studies but evidence is often from single centers with small sample sizes. The safety of intraoperative enteral nutrition needs confirmation in larger multicenter trials. Whether perioperative catch-up feeding protocols adequately compensate for caloric deficits remains uncertain. The role of parenteral nutrition as a supplement when enteral targets cannot be met lacks clear burn-specific guidance.

References

[1] Clark A et al. (2017). Nutrition and metabolism in burn patients. PMID: 28428966 [2] Williams FN et al. (2011). What, how, and how much should patients with burns be fed? PMID: 21621699 [3] Curreri PW et al. (1974). Dietary requirements of patients with major burns. PMID: 4213656 [4] Prelack K et al. (2007). Practical guidelines for nutritional management of burn injury and recovery. PMID: 17116370 [5] Peck MD et al. (1999). Nutritional support for burn injuries. PMID: 15539314 [6] Peck MD et al. (2004). Early enteral nutrition does not decrease hypermetabolism associated with burn injury. PMID: 15625442 [7] Shields BA et al. (2019). High-Carbohydrate vs High-Fat Nutrition for Burn Patients. PMID: 31441112 [8] Gottschlich MM et al. (1990). Differential effects of three enteral dietary regimens on selected outcome variables in burn patients. PMID: 2112634 [9] Pham CH et al. (2018). How long are burn patients really NPO in the perioperative period and can we effectively correct the caloric deficit using an enteral feeding "Catch-up" protocol? PMID: 30115532 [10] Pham CH et al. (2020). Evaluating the Safety and Efficacy of Intraoperative Enteral Nutrition in Critically Ill Burn Patients: A Systematic Review and Meta-analysis. PMID: 32147686 [11] Pham CH et al. (2019). Measuring gastric residual volumes in critically ill burn patients - A systematic review. PMID: 29914737 [12] Wilmore DW (2001). The effect of glutamine supplementation in patients following elective surgery and accidental injury. PMID: 11533310 [13] Greenhalgh DG et al. (1995). Maintenance of serum albumin levels in pediatric burn patients: a prospective, randomized trial. PMID: 7636912 [14] Shahrokhi S et al. (2023). Metabolic and Nutritional Support. PMID: 37149383