Errors in estimating energy expenditure in critically ill surgical patients
V. Cortes and L. D. Nelson
Department of Surgery, University of Miami School of Medicine.
Thirty-one critically ill surgical patients were receiving central
parenteral nutrition. All were intubated, and 29 were receiving mechanical
ventilatory support. Nutritional and metabolic data were recorded at the
time of indirect calorimetry. Measured energy expenditure (MEE) was
compared with predictions of basal energy expenditure (BEE) and calculated
energy expenditure, defined as the product of BEE and a stress factor
estimated by the nutrition support service to account for severity of
illness and activity. The MEE was significantly greater than the BEE and
significantly less than the calculated energy expenditure. The estimated
stress factor was significantly greater than the actual MEE/BEE ratio, and
the correlation between these values was poor. Clinical assessment may
overestimate energy expenditure in critically ill patients because of the
apparent degree of illness used to determine the stress factor. Bedside
indirect calorimetry may be useful to assess more accurately energy
expenditure and optimize nutritional support.
