Thermogenic and metabolic response to amino acid solution in brain-dead patients

There is a strong correlation between amino acid infusion and increase in energy expenditure and thermogenesis. In this study, the effects of amino acid solutions on thermogenesis and energy expenditure were investigated in intensive care patients who were diagnosed as brain death.

Twenty-six brain-dead patients were included in the study. The patients received a 4 h infusion of standard amino acid solution. Energy expenditure was measured by indirect calorimetric method. ANOVA and Bonferroni tests were used for statistical analysis.

The predicted energy expenditure (PEE) values were higher than the resting energy expenditure (REE) values in 24 patients. The mean REE/PEE value in all patients indicated that there was a 29% decrease in REE when compared to PEE. Body temperature and energy expenditure values were not increased during the parenteral infusion of amino acid solutions. There was no statistically significant difference between mean metabolic measurements and basal values at any time interval during the study period.

We conclude that the stimulatory effect of amino acid solution on energy expenditure and thermogenesis is abolished in brain-dead patients. This result may indicate a possible central pathway responsible for the increase in energy expenditure and thermogenesis.