Differential DNA methylation by early versus late parenteral nutrition in the PICU: a biological basis for its impact on emotional and behavioral problems documented 4 years later

Personalized Nutrition in the Pediatric ICU: Steering the Shift from Acute Stress to Metabolic Recovery and Rehabilitation

BACKGROUND

Nutrition significantly impacts the outcomes of critically ill children in intensive care units (ICUs). Due to the evolving metabolic, neuroendocrine, and immunological disorders associated with severe illness or trauma, there are dynamically changing phases of energy needs requiring tailored macronutrient intake.

OBJECTIVES

This study aims to assess the changing dietary needs from the acute phase through recovery, provide recommendations for implementing evidence-based strategies to ensure adequate energy and nutrient provision in pediatric ICUs, and optimize patient outcomes.

METHODS

A comprehensive search of the MEDLINE-PubMed database was conducted, focusing on randomized controlled trials, meta-analyses, and systematic reviews related to the nutrition of critically ill children. The study highlights recent guidelines using the GRADE approach, supplemented by relevant adult studies, current clinical practices, challenges, gaps in knowledge, and future directions for research aimed at improving nutritional interventions.

RESULTS

Early personalized, incremental enteral feeding helps mitigate the negative energy balance during the acute phase, aids organ function restoration in the stabilization phase, and supports growth during the recovery phase and beyond. Conversely, early full nutritional support, high protein doses, or isolated micronutrient administration have not demonstrated benefits due to anabolic resistance in these patients. Moreover, early parenteral nutrition during the acute phase may suppress autophagy and lead to worse outcomes. Accurate assessment of nutritional status and monitoring of daily energy and protein needs are crucial.

CONCLUSIONS

Strong evidence supports the establishment of a dedicated nutritional team and the implementation of individualized nutritional protocols in the ICU to reduce morbidity and mortality in critically ill children.

Our Scientific Journey through the Ups and Downs of Blood Glucose Control in the ICU

This article tells the story of our long search for the answer to one question: Is stress hyperglycemia in critically ill patients adaptive or maladaptive? Our earlier work had suggested the lack of hepatic insulin effect and hyperglycemia as jointly predicting poor outcome. Therefore, we hypothesized that insulin infusion to reach normoglycemia, tight glucose control, improves outcome. In three randomized controlled trials (RCTs), we found morbidity and mortality benefit with tight glucose control. Moving from the bed to the bench, we attributed benefits to the prevention of glucose toxicity in cells taking up glucose in an insulin-independent, glucose concentration gradient-dependent manner, counteracted rather than synergized by insulin. Several subsequent RCTs did not confirm benefit, and the large Normoglycemia in Intensive Care Evaluation-Survival Using Glucose Algorithm Regulation, or "NICE-SUGAR," trial found increased mortality with tight glucose control associated with severe hypoglycemia. Our subsequent clinical and mechanistic research revealed that early use of parenteral nutrition, the context of our initial RCTs, had been a confounder. Early parenteral nutrition (early-PN) aggravated hyperglycemia, suppressed vital cell damage removal, and hampered recovery. Therefore, in our next and largest "TGC-fast" RCT, we retested our hypothesis, without the use of early-PN and with a computer algorithm for tight glucose control that avoided severe hypoglycemia. In this trial, tight glucose control prevented kidney and liver damage, though with much smaller effect sizes than in our initial RCTs without affecting mortality. Our quest ends with the strong recommendation to omit early-PN for patients in the ICU, as this reduces need of blood glucose control and allows cellular housekeeping systems to play evolutionary selected roles in the recovery process. Once again, less is more in critical care.

Timing of enteral nutrition and parenteral nutrition in the PICU

The timing of nutrition support initiation has the potential to positively impact nutrition and clinical outcomes in infants and children with critical illness. Early enteral nutrition within 24-48 h and attainment of both a 60% energy and protein goal by the end of the first week of pediatric intensive care unit admission are reported to be significantly associated with improved survival in large observational studies. The results of one randomized controlled trial demonstrated increased morbidity in infants and children with critical illness assigned to early vs delayed supplemental parenteral nutrition. Observational studies in this population also suggest increased mortality with exclusive parenteral nutrition and worse nutrition outcomes when parenteral nutrition is delayed. Subsequently, current nutrition support guidelines recommend early enteral nutrition and avoidance of early parenteral nutrition, although the available evidence used to create the guidelines was inadequate to inform bedside nutrition support practice to improve outcomes. These guidelines are limited by the included studies with small numbers and heterogeneity of patients and research design that confound study outcomes and interpretation. This article provides a narrative review of the timing of nutrition support on outcomes in infants and children with critical illness, strategies to optimize timing and adequacy of nutrition support, and literature gaps, including the timing of parenteral nutrition initiation for children with malnutrition and those with contraindications to enteral nutrition and accurate measurement of energy requirements.

The epigenetic legacy of ICU feeding and its consequences

PURPOSE OF REVIEW

Many critically ill patients face physical, mental or neurocognitive impairments up to years later, the etiology remaining largely unexplained. Aberrant epigenetic changes have been linked to abnormal development and diseases resulting from adverse environmental exposures like major stress or inadequate nutrition. Theoretically, severe stress and artificial nutritional management of critical illness thus could induce epigenetic changes explaining long-term problems. We review supporting evidence.

RECENT FINDINGS

Epigenetic abnormalities are found in various critical illness types, affecting DNA-methylation, histone-modification and noncoding RNAs. They at least partly arise de novo after ICU-admission. Many affect genes with functions relevant for and several associate with long-term impairments. As such, de novo DNA-methylation changes in critically ill children statistically explained part of their disturbed long-term physical/neurocognitive development. These methylation changes were in part evoked by early-parenteral-nutrition (early-PN) and statistically explained harm by early-PN on long-term neurocognitive development. Finally, long-term epigenetic abnormalities beyond hospital-discharge have been identified, affecting pathways highly relevant for long-term outcomes.

SUMMARY

Epigenetic abnormalities induced by critical illness or its nutritional management provide a plausible molecular basis for their adverse effects on long-term outcomes. Identifying treatments to further attenuate these abnormalities opens perspectives to reduce the debilitating legacy of critical illness.

Neonatal frontal-limbic connectivity is associated with externalizing behaviours in toddlers with Congenital Heart Disease

Children with Congenital Heart Disease (CHD) are at increased risk of neurodevelopmental impairments. The neonatal antecedents of impaired behavioural development are unknown. 43 infants with CHD underwent presurgical brain diffusion-weighted MRI [postmenstrual age at scan median (IQR) = 39.29 (38.71-39.71) weeks] and a follow-up assessment at median age of 22.1 (IQR 22.0-22.7) months in which parents reported internalizing and externalizing problem scores on the Child Behaviour Checklist. We constructed structural brain networks from diffusion-weighted MRI and calculated edge-wise structural connectivity as well as global and local brain network features. We also calculated presurgical cerebral oxygen delivery, and extracted perioperative variables, socioeconomic status at birth and a measure of cognitively stimulating parenting. Lower degree in the right inferior frontal gyrus (partial ρ = -0.687, p < 0.001) and reduced connectivity in a frontal-limbic sub-network including the right inferior frontal gyrus were associated with higher externalizing problem scores. Externalizing problem scores were unrelated to neonatal clinical course or home environment. However, higher internalizing problem scores were associated with earlier surgery in the neonatal period (partial ρ = -0.538, p = 0.014). Our results highlight the importance of frontal-limbic networks to the development of externalizing behaviours and provide new insights into early antecedents of behavioural impairments in CHD.

Physical, Emotional/Behavioral, and Neurocognitive Developmental Outcomes From 2 to 4 Years After PICU Admission: A Secondary Analysis of the Early Versus Late Parenteral Nutrition Randomized Controlled Trial Cohort

OBJECTIVES

PICU patients face long-term developmental impairments, partially attributable to early parenteral nutrition (PN) versus late-PN. We investigated how this legacy and harm by early-PN evolve over time.

DESIGN

Preplanned secondary analysis of the multicenter PEPaNIC-RCT (ClinicalTrials.gov, NCT01536275) that enrolled 1,440 critically ill children from 2012 to 2015 and its 2- (2014-2018) and 4-year (2016-2019) cross-sectional follow-up studies.

SETTING

PICUs of Leuven (Belgium), Rotterdam (The Netherlands), and Edmonton (Canada).

PATIENTS

Patients and demographically matched healthy control children that underwent longitudinal assessment for physical/emotional/behavioral/neurocognitive functions at both follow-up time points.

INTERVENTIONS

In the PEPaNIC-RCT, patients were randomly allocated to early-PN versus late-PN.

MEASUREMENTS AND MAIN RESULTS

This within-individual longitudinal study investigated changes in physical/emotional/behavioral/neurocognitive functions from 2 to 4 years after PICU admission for 614 patients (297 early-PN and 317 late-PN, tested at mean ± sd age 5.4 ± 4.2 and 7.3 ± 4.3 yr) and for 357 demographically matched healthy children tested at age 5.6 ± 4.3 and 7.5 ± 4.3 years. We determined within-group time-courses, interaction between time and group, and independent impact of critical illness and early-PN on these time-courses. Most deficits in patients versus healthy children remained prominent over the 2 years ( p ≤ 0.01). Deficits further aggravated for height, body mass index, the executive function metacognition, intelligence, motor coordination (alternating/synchronous tapping), and memory learning-index, whereas verbal memory deficits became smaller (working/immediate/delayed memory) ( p ≤ 0.05). Adjustment for risk factors confirmed most findings and revealed that patients "grew-into-deficit" for additional executive functions (flexibility/emotional control/total executive functioning) and "grew-out-of-deficit" for additional memory functions (recognition/pictures) ( p ≤ 0.05). Time-courses were largely unaffected by early-PN versus late-PN, except for weight loss and limited catch-up for visual-motor integration and alertness in early-PN patients ( p ≤ 0.05).

CONCLUSIONS

From 2- to 4-year post-PICU admission, developmental impairments remained prominent. Within that time-window, impaired growth in height, executive functioning and intelligence aggravated, and impaired memory and harm by early-PN only partially recovered. Impact on development into adulthood requires further investigation.

Novel insights in endocrine and metabolic pathways in sepsis and gaps for future research

Sepsis is defined as any life-threatening organ dysfunction caused by a dysregulated host response to infection. It remains an important cause of critical illness and has considerable short- and long-term morbidity and mortality. In the last decades, preclinical and clinical research has revealed a biphasic pattern in the (neuro-)endocrine responses to sepsis as to other forms of critical illness, contributing to development of severe metabolic alterations. Immediately after the critical illness-inducing insult, fasting- and stress-induced neuroendocrine and cellular responses evoke a catabolic state in order to provide energy substrates for vital tissues, and to concomitantly activate cellular repair pathways while energy-consuming anabolism is postponed. Large randomized controlled trials have shown that providing early full feeding in this acute phase induced harm and reversed some of the neuro-endocrine alterations, which suggested that the acute fasting- and stress-induced responses to critical illness are likely interlinked and benefical. However, it remains unclear whether, in the context of accepting virtual fasting in the acute phase of illness, metabolic alterations such as hyperglycemia are harmful or beneficial. When patients enter a prolonged phase of critical illness, a central suppression of most neuroendocrine axes follows. Prolonged fasting and central neuroendocrine suppression may no longer be beneficial. Although pilot studies have suggested benefit of fasting-mimicking diets and interventions that reactivate the central neuroendocrine suppression selectively in the prolonged phase of illness, further study is needed to investigate patient-oriented outcomes in larger randomized trials.

Impact of critical illness and withholding of early parenteral nutrition in the pediatric intensive care unit on long-term physical performance of children: a 4-year follow-up of the PEPaNIC randomized controlled trial

Background

Many critically ill children face long-term developmental impairments. The PEPaNIC trial attributed part of the problems at the level of neurocognitive and emotional/behavioral development to early use of parenteral nutrition (early-PN) in the PICU, as compared with withholding it for 1 week (late-PN). Insight in long-term daily life physical functional capacity after critical illness is limited. Also, whether timing of initiating PN affects long-term physical function of these children remained unknown.

Methods

This preplanned follow-up study of the multicenter PEPaNIC randomized controlled trial subjected 521 former critically ill children (253 early-PN, 268 late-PN) to quantitative physical function tests 4 years after PICU admission in Leuven or Rotterdam, in comparison with 346 age- and sex-matched healthy children. Tests included handgrip strength measurement, timed up-and-go test, 6-min walk test, and evaluation of everyday overall physical activity with an accelerometer. We compared these functional measures for the former critically ill and healthy children and for former critically ill children randomized to late-PN versus early-PN, with multivariable linear or logistic regression analyses adjusting for risk factors.

Results

As compared with healthy children, former critically ill children showed less handgrip strength (p < 0.0001), completed the timed up-and-go test more slowly (p < 0.0001), walked a shorter distance in 6 min (p < 0.0001) during which they experienced a larger drop in peripheral oxygen saturation (p ≤ 0.026), showed a lower energy expenditure (p ≤ 0.024), performed more light and less moderate physical activity (p ≤ 0.047), and walked fewer steps per day (p = 0.0074). Late-PN as compared with early-PN did not significantly affect these outcomes.

Conclusions

Four years after PICU admission, former critically ill children showed worse physical performance as compared with healthy children, without impact of timing of supplemental PN in the PICU. This study provides further support for de-implementing the early use of PN in the PICU.

Trial registration ClinicalTrials.gov, NCT01536275; registered on February 22, 2012.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04010-3.