161 / 208
General discussion
159
8
The use of REE to identify overfeeding is also presumed to be limited to the stable and recovery
phase. Overfeeding in the most general sense is defined by a worsening of outcome due to an
excess of nutrients. Despite the current lack of outcome-based definitions, detrimental effects
from overfeeding have been identified (Chapter 1 and 4). Different concepts of overfeeding,
such as excessive amounts of caloric intake or separate macronutrients (glucose, amino acids
or lipids) can occur isolated or simultaneously, and are associated with specific disadvantages.
Early caloric overfeeding is associated with increased mortality in critically ill adults
23
, and
with liver dysfunction and hepatobiliary complications in children
24,25
. Current definitions of
caloric overfeeding based on IC measurements are inaccurate and show a varying specificity.
Depending on the definition used, up to 61% of children on the PICU were identified as being
overfed
26
. The risk of caloric overfeeding and its complications are presumed to be influenced
by age and nutritional status of the child (Chapter 4), the phase of critical illness (Chapter 1 and
4), and by the route of nutrition. In order to prevent the adverse effects of overfeeding during
these phases, a new definition of overfeeding needs to be identified (Chapter 4) and should
preferably be calibrated on clinical outcome measures.
Since overfeeding and underfeeding both depend on the same requirements, it can be
presumed that underfeeding is influenced by similar patient- and disease related factors.
Therefore, IC-derived definitions to identify underfeeding
27
are likely to be just as inaccurate as
those for overfeeding (Chapter 4). Whereas full nutrition in the acute phase will easily result in
overfeeding, the risk of underfeeding is highest during the stable and recovery phase due to
increasing requirements (Chapter 1). If requirements are not met during these last two phases,
recovery and (catch-up) growth are hampered, thereby affecting outcome.
SUPPLEMENTAL PARENTERAL NUTRITION
The beneficial effect of withholding PN up to day 8 after PICU admission
The use of EN exclusively puts the patient at risk for the development of substantial
macronutrient deficits during PICU stay. Despite the aim of most PICUs to meet caloric targets
within 3 days by the enteral route, the point prevalence measurement showed that 40% of
PICUs failed to achieve this (Chapter 2). Although solid evidence for use of PN in the PICU is
lacking (Chapter 5), the survey showed that in 40% of PICUs PN is already started when EN
fails to meet 80% of caloric targets (Chapter 2). These specific PICUs represent approximately
36.000 admissions per year. As 16% of PICUs was estimated to participate in the survey, this
means that each year at least 200.000 critically ill children receive a medical treatment with
only very limited clinical evidence. This is in line with the estimation that 30-50% of critically
ill children in Europe and the United States receive this therapy, representing 118.000-196.000
children, based on the number of PICU beds and average length of stay in the United States
28
.