Enteral feeding and the microbiome in critically ill children: a narrative review

Abstract

This narrative review summarizes our current knowledge on the interplay between enteral nutrition (EN) and gut microbiota in critically ill children, using examples from two commonly encountered diagnoses in the pediatric intensive care unit (PICU): severe sepsis and acute respiratory distress syndrome (ARDS). This review will also highlight potential areas of therapeutic interventions that should be explored in future studies.Background: Critically ill children display extreme dysbiosis in their gut microbiome. Factors within the PICU that are often associated with dysbiosis include the use of broad-spectrum antibiotics, protonpump inhibitors (PPIs), intravenous morphine, and fasting. Dysbiosis can potentially lead to adverse clinical outcomes (e.g., nosocomial infection, and prolonged hospitalization). EN may modulate dysbiosis. The gut microbiota is involved in the breaking down of macronutrients, mainly carbohydrates and proteins.Fermentation of undigestible carbohydrate (e.g., inulin and oligosaccharides), and amino acids by large intestine microbiota produces short chain fatty acids (SCFAs). SCFAs serve as the main fuel source for enterocytes and help to maintain healthy gut lining. Changes to selected components of macronutrients can result in alterations in gut microbiome and have potentially beneficial effects in patients in the PICU.Methods: A comprehensive search of the MEDLINE, Cochrane Library and Google Scholar databases was conducted using appropriate MESH terms and keywords. In this narrative review, we provide a summary of current knowledge on effect of EN on gut microbiota in pediatric studies, but also describes animal-and labbased, as well as adult studies where relevant. Conclusions:The gut microbiome can be altered by dietary modifications and common PICU practices and treatment. Although there are strong associations in restoring eubiosis and improvement in clinical outcomes, proving causality remains challenging. Further microbiome research is needed to provide mechanistic insights into the impact of the ever changing gut microbiome. In the future, new microbiota targeted therapies could potentially be the treatment of challenging PICU conditions and restore homeostasis in these children.

The impact of freezing on the post-mortem human microbiome

“…One thing of note in their record was their gastrostomy status which showed that this donor had a feeding tube antemortem. Studies have shown that enteral feeding tubes can cause alterations in the human microbiome, particularly oral (Takeshita et al, 2011) and gut (Whelan et al, 2009;Fan and Lee, 2021) microbiota. More importantly however, despite the reasons for this alteration, our study shows that complex or deviant microbiomes of donors -even those with complicated medical histories antemortem -can be preserved by freezing, as the microbial shift in D22's samples prior to and after freezing was not significant.…”

Investigating the effect of oral synbiotic on enteral feeding tolerance in critically ill patients: A double‐blinded controlled clinical trial of gut microbiota

“…This puts ICU patients at the risk of EFI. 4 Typically, measured gastric residual volume is considered as a marker for EFI. 5 It seems that probiotics can improve the condition of these patients without imposing further complications.…”

“…9 Therefore, the results of previous studies on the effectiveness of prebiotics/probiotics and synbiotics in maintaining the bacterial flora are insufficient, and further studies are needed in this regard. 4,11,12 Therefore, this study aimed to evaluate the efficacy of synbiotics in improving the EFI by measuring the gastric residual volume in critically ill patients. In addition to improving EFI as our primary end point, we evaluated the secondary end points of duration of mechanical ventilation, length of ICU stay, level of consciousness, and the number of oropharyngeal aspirations.…”

“…These patients frequently develop dysbiosis, defined as an imbalance in intestinal commensal microflora. This puts ICU patients at the risk of EFI 4 . Typically, measured gastric residual volume is considered as a marker for EFI 5 .…”

“…Nevertheless, the studies on the effect of synbiotics in critically ill patients investigated their possible role in the incidence of VAP and have not evaluated enteral tolerance as the primary end point 9 . Therefore, the results of previous studies on the effectiveness of prebiotics/probiotics and synbiotics in maintaining the bacterial flora are insufficient, and further studies are needed in this regard 4,11,12 …”