Calculation of metabolic expenditure and substrate utilization from gas exchange measurements.
At least nine different equations have been published for calculating metabolic expenditure by indirect calorimetry. This study examined the differences between equations when they are used for the nutritional assessment in an intensive care unit (ICU). Oxygen consumption and carbon dioxide production were measured in 36 ICU patients and used to calculate metabolic expenditure with the nine equations. The equations produced differences in metabolic expenditure which averaged from 0.8-96 kcal/day. The largest difference produced by any two of the nine equations was 189 kcal/day. Although differences in original stoichiometric data have resulted in numerous different equations for the calculation of metabolic expenditure, these differences are not clinically important. It makes little difference which equation is used for nutritional assessment in an ICU.
Westenskow
D R
DR
Department of Anesthesiology, University of Utah School of Medicine, Salt Lake City.
Schipke
C A
CA
Raymond
J L
JL
Saffle
J R
JR
Becker
J M
JM
Young
E W
EW
Cutler
C A
CA
D004040:Dietary Carbohydrates / Q000378:metabolism*; D004041:Dietary Fats / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism*; D004734:Energy Metabolism; D006801:Humans; D008432:Mathematical Computing; D009584:Nitrogen / Q000378:metabolism / Q000652:urine; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D009584:Nitrogen