By Dr Kwok Ka Ming, UCH
Background:Under- and over-feeding are associated with adverse outcomes in critically ill patients. Appropriate nutrition therapy requires accurate determination of energy expenditure. Despite being the gold standard, the availability of indirect calorimetry is limited. Prediction equations are still commonly used in clinical practice.
Objective: The aim of this study was to compare resting energy expenditure measured by indirect calorimetry (MREE) with energy expenditure estimated by prediction equations in septic, critically ill patients in Chinese population.
Methods:Resting energy expenditure was measured by indirect calorimetry in septic, mechanically ventilated Chinese patients admitted to intensive care unit. The Harris-Benedict, Ireton-Jones, Penn State and Swinamer equations were used to estimate energy expenditure. Statistical analyses were performed by Bland-Altman plot and Pearson's correlation coefficient. Percentages of estimates within 90% and 110% of MREE were calculated as a measure of accuracy.
Results:A total of 40 patients were included for comparison. Agreement between the prediction equations and indirect calorimetry was poor. The limits of agreement were wide for all evaluated equations. None of the equations showed good correlation with indirect calorimetry. Penn State equation demonstrated the best accuracy among these equations; but still only 40% of estimates were within 90% and 110% of MREE.
Conclusions:None of the prediction equations evaluated demonstrated high accuracy in estimating energy expenditure in critically ill, septic patients in Chinese population. Indirect calorimetry remains to be the gold standard in the determination of energy expenditure in these patients.