81 / 208
Use of indirect calorimetry to detect overfeeding
79
4
this specific group of children. This hypometabolic state was reflected in an increased ratio
caloric intake/mREE of 145%
43
. We also found that children identified as being overfed by the
ratio caloric intake/mREE, had a significantly lower SD-score, compared to children without
overfeeding. This contrasting combination of loweredmREE and caloric overfeeding described
in malnourished children, might be linked to an amplification of mitochondrial dysfunction
associated with the stress response
43,44
. Therefore the effect of nutritional status on the risk of
overfeeding may be intertwined with the phases of critical illness.
Because the difference of RQ-RQ
macr
reflects the use of different macronutrients within a
patient, it acts as a more functional parameter to describe overfeeding throughout the course
of illness and for different age groups. The use of this parameter might be, however, limited
when caloric intake is less than mREE
45
and during the acute phase of critical illness when
endogenous energy production is present, even with adequate energy provision
46
. RQ is also
affected by factors unrelated to feeding
29
.
Our study is further limited by the small number of patients, the lack of clinical endpoints,
and the fact that we only performed single measurements. Therefore, it should be followed
by larger prospective studies on the effect of intake on clinical outcomes, preferably with a
longitudinal design.
To conclude, the proportion of mechanically ventilated patients identified as overfed ranged
widely from 23% to 50% depending on the criteria applied. The currently used definitions to
describe overfeeding fail to take into account several relevant factors associated with critical
ill children and are therefore not generally applicable to the PICU population. We advocate the
development of a definition for overfeeding dependent on age, nutritional status and phase
of illness, preferably based on clinical outcome measures.