Early enteral nutrition does not decrease hypermetabolism associated with burn injury. Effects of early enteral feeding on the prevention of enterogenic infection in severely burned patients.
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. The aim of the study was to analyse the effects of early enteral feeding on the prevention of enterogenic infection in severely burned patients. A total of 22 patients with severe burns were randomly divided into an early enteral feeding group (EF) and a delayed enteral feeding group (DF). The levels of serum endotoxin and TNF-alpha were dynamically detected in the members of both groups, and two unmetabolized sugars (lactulose and mannitol) were orally administered to these patients 1, 3 and 5 days postburn. Intestinal permeability was evaluated by detecting the concentrations of lactulose and mannitol in the urine and the lactulose-mannitol ratio (L/M) ratio. The levels of serum endotoxin and TNF-alpha in severely burned patients were significantly higher than in normal subjects (P<0.01). The endotoxin level was positively related to the TNF-alpha level (rEF=0.93, P<0.01; rDF=0.80, P<0.05). The urinary lactulose levels in both groups were significantly higher than in normal (P<0.01), the urinary mannitol levels showed no obvious changes (P>0.05). The urinary L/M ratios in both groups were significantly higher than in normal subjects (P<0.01). The urinary L/M ratio was positively related to the serum endotoxin level (r=0.95, P<0.01). The urinary lactulose levels and the urinary L/M ratios in the EF group were significantly lower than in the DF group (P<0.01). The levels of serum endotoxin and TNF-alpha in the EF group were significantly lower than in the DF group (P<0.01). It is suggested that intestinal permeability was markedly higher after burns than normal, and was positively related to the gut-derived endotoxemia. Early enteral feeding may decrease intestinal permeability, preserve the intestinal mucosal barrier and have a beneficial effect on the reduction of enterogenic infection.
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.