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Vol. 27, No. 1
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degree of accuracy that no further adjustments needed
to be made for patient or nursing care activity. The
issues related to steady state become even more impor-
tant with greater variation in energy expenditure and
metabolic instability. Metabolic instability may not
always be evident clinically. Achieving steady state by
the most stringent criteria in these patients may be
more difficult but assures a continued high correlation
and accuracy for the “snapshot” REE. In these
patients, short-term interval testing or use of steady-
state criteria of lesser stringency results in consider-
able deterioration in correlation and accuracy. Failure
to achieve steady state does not necessarily invalidate
the study but does signify the introduction of greater
error and less accuracy in representing or extrapolat-
ing the short-term REE to the 24-hour TEE.
Although the results of this study help standardize
the methodology for performing IC, the statistical dif-
ferences between the various steady-state and interval
criteria do not necessarily represent clinically impor-
tant differences. Greater accuracy in designing nutri-
tion support regimens for enteral tube feeding or TPN
seems empirically important to reduce consequences
from over- or underfeeding. However, it is beyond the
scope of this study to determine what degree of accu-
racy in determining caloric requirements is necessary
to specifically reduce complications from artificial
nutrition support.
Based on the results of this study, the following
recommendations can be made regarding the method-
ology for performing IC testing. Steady state should be
defined by change in VO and VCO of Ͻ10% over a
2
2
period of 5 consecutive minutes. IC testing may be
terminated when the patient achieves this steady
state. The values for the mean REE from this steady-
state period, with no further adjustments (in the
absence of fever), can be used as an accurate represen-
tation of the 24-hour TEE. In patients who fail to
achieve steady state, interval testing for as little as 30
minutes may be adequate to provide an accurate REE
if the CV for VO over the first 30 minutes of the testing
period is Յ9.0.2For that patient who fails to achieve
steady state and is metabolically unstable, more pro-
longed testing is required (minimum of 60 minutes),
and 24-hour IC monitoring should be considered.
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women. Am J Clin Nutr 46:622–630, 1987