# Nutrition in Pediatric Intensive Care: A Narrative Review
## 8 Enteral Nutrition  
Enteral nutrition is a preferred option of nutrition support in critically ill pediatric patients unless contraindicated. Enteral feeding (also in small dosing) has a positive effect on gastrointestinal mucosal integrity and a trophic effect on enterocytes [1]. The most natural route of intake is oral, if possible. Patients in the PICU should therefore be evaluated on daily basis, and oral intake should be encouraged as well as early support of breastfeeding. In the case of consciousness disorder, deep sedation, or the inability to swallow or drink, a gastric tube (preferentially nasogastric) can be used for specific enteral nutrition formula or (fortified) breast milk delivery. In the case of gastric feeding intolerance or a severe risk of aspiration, a possible option is post-pyloric feeding (post-pyloric feeding tube inserted and floated further in the jejunum or inserted by an endoscopist). In chronic intensive care (a stay of 6 weeks or longer), a possible route for enteral feeding could be the percutaneous gastroostomy (PEG) or jejuncostomy (PEG-) or surgical jejuncostomy). There are several methods for enteral nutrition administration: continuous feeding involves administration of EN over 24 h assisted by a feeding pump; cyclic feeding involves administration of EN over a time period of <24 h generally assisted by a feeding pump; intermittent feeding involves administration of EN over 20-60 min every 4-6 h via pump assist or gravity assist; and bolus feeding involves administration of EN over a 4 to 10 min period using a syringe (5-6 times per day, up to 7-8 times in small infants) [45]. The continuous or cyclic application is preferred in the case of insufficient enteral feeding tolerance. The aim is to reach the estimated E and protein delivery in a stepwise approach [1] 2-3 days after PICU admission [4], as ideally defined in implemented local-based nutrition/feeding protocol [1]. For a possible stepwise approach to enteral nutrition, see Figure 1.  
The aim of enteral feeding is to reach at least 2/3 of target E delivery during the first 7 days [1]. The standard polymeric enteral formula can be used initially in the majority of patients. In patients not tolerating enteral feeding, an oligomeric or peptide-based formula can improve the tolerance [1]. The majority of nutrition formulas on the market are \begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{3}{c}{**Trace minerals/elements**} \\ \hline Iron & 50–250 ug/kg/d up to 5 mg/d \\ Zinc & 50–500 ug/kg/d up to 5 mg/d \\ Copper & 20–40 ug/kg/d up to 0.5 mg/d \\ Iodine & 1–10 ug/kg/d \\ Selenium & 2–7 ug/kg/d up to 100 mg/d \\ Manganese & \(\leq\)1 ug/kg/d up to 50 mg/d \\ Molybdenum & 0.25–1 ug/kg/d up to 5 mg/d \\ \hline Adopted from [43; 44]. & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: _Cont._  
Figure 1: Example of a stepwise approach to enteral nutrition. isocaloric (1 kcal/mL). The dense/hypercaloric formulas (>1 kcal/mL) can be used to limit to total daily enteral feeding volume. Breast milk should be preferentially used to cover the energy and nutrient needs of very small critically ill infants. In the case of absence of breast milk, specific hypocaloric (around 0.65-0.7 kcal/mL) infant formulas or formula milk is to be used. Routine gastric residual volume (GRV) assessment in entrally fed critically ill children is not recommended for enteral feeding tolerance evaluation anymore [1; 4; 18], but nevertheless can still be implemented in the regional feeding protocols. Enteral feeding intolerance is a clinical condition diagnosed by the intensive care nurse and/or clinician based on the presence of nausea/vomiting, abdominal distension, abdominal discomfort, diarrhea or GRV > 3 mL/kg (if used, in \(\geq\)2 subsequent measurements). When dealing with enteral feeding intolerance, several methods are available, and clinicians should follow their local nutrition protocol.