Proefschrift Kerklaan

General discussion

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. 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 . SUPPLEMENTAL PARENTERAL NUTRITION

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