Early enteral nutrition does not decrease hypermetabolism associated with burn injury. The 2002 Clinical Research Award. An evaluation of the safety of early vs delayed enteral support and effects on clinical, nutritional, and endocrine outcomes after severe burns.
A prospective, randomized study was performed to compare the effects of early versus late enteral feeding on postburn metabolism.
                Burn patients were randomized to receive enteral feedings either within 24 hours (early) or 7 days (late) of injury. Basal energy expenditure (BEE) was calculated from Harris-Benedict equations and resting energy expenditure (REE) was obtained from indirect calorimetry. The average daily energy expenditure (DEE) was expressed as REE/BEE.
                Average age, burn size, infections, and length of stay were similar between groups. Mortality between groups was similar (early, 28%; late, 38%) and not significantly influenced by inhalation injury. When controlled for percentage of total body surface area burn, inhalation injury, and age, the early group had an increased rather than decreased DEE, with a mean DEE calorie 0.17 more than the late group (p = 0.07).
                Early enteral feeding does not decrease the average energy expenditure associated with burn injury. Early enteral support is believed to improve gastrointestinal, immunological, nutritional, and metabolic responses to critical injury; however, this premise is in need of further substantiation by definitive data. The purpose of this prospective study was to examine the effectiveness and safety of early enteral feeding in pediatric patients who had burns in excess of 25% total body surface area. Seventy-seven patients with a mean percent total body surface area burn of 52.5 +/- 2.3 (range 26-91), percent full thickness injury of 44.7 +/- 2.8 (range 0-90), and age ranging from 3.1 to 18.4 (mean 9.3 +/- 0.5) were randomized to two groups: early (feeding within 24 hours of injury) vs control (feeding delayed at least 48 hours postburn). Nutrient intake was measured daily, indirect calorimetry was performed biweekly, and blood and urine samples were obtained for the assay of cortisol, glucagon, insulin, gastrin, epinephrine, norepinephrine, dopamine, triiodothyronine, tetraiodothyronine, albumin, transferrin, prealbumin, retinol-binding protein, glucose, nitrogen balance, and 3-methylhistidine throughout the study period. Three protocol violations occurred, and two patients were transferred to another hospital; these patients were excluded from the study. No patient in either group experienced tube feeding aspiration. No differences were evident in infection, diarrhea, hospital length of stay, or mortality outcomes. A higher incidence of reportable adverse events coincided with early feeding (22 vs 8%), but this was not statistically significant. The delayed feeding group demonstrated a significant caloric deficit during postburn week (PBW) 1 (P <.0001) and PBW2 (P =.0022). Serum insulin (P =.0004) and triiodothyronine (P =.0162) were higher in the early fed group during PBW1. A decrease in 3-methylhistidine output (suggesting a decrease in protein breakdown) was also evident during PBW1 (P =.0138). No other significant trends in study outcome variables were noted. In conclusion, provision of enteral nutrients shortly after burn injury reduces caloric deficits and may stimulate insulin secretion and protein retention during the early phase postburn. These data, however, do not necessarily reaffirm the safety of early enteral feeding, nor do they associate earlier feeding with a direct improvement in endocrine status or a reduction in morbidity, mortality, hypermetabolism, or hospital stay. Future studies are needed to establish precise feeding implementation times that maximize clinical benefit while minimizing morbidity in the critically injured burn patient.
This systematic review has not found sufficient evidence to support or refute the effectiveness of early versus late enteral nutrition support in adults with burn injury. The trials showed some promising results that would suggest early enteral nutrition support may blunt the hypermetabolic response to thermal injury, but this is insufficient to provide clear guidelines for practice. Further research incorporating larger sample sizes and rigorous methodology that utilises valid and reliable outcome measures, is essential.