Continuous or intermittent feeding: pros and cons

Risk prediction model for adult intolerance to enteral nutrition feeding - A literature review

Enteral nutrition is an important clinical nutritional supplementation method, especially for adult patients who are unable to eat normally or require additional nutritional support. However, many patients experience intolerance to enteral nutrition, such as delayed gastric emptying, bloating, and diarrhea, which not only affect the patient's nutritional status but also increase the risk of medical complications. In recent years, medical researchers have been dedicated to identifying and analyzing various factors that contribute to enteral nutrition intolerance, including the patient's disease status, nutritional formula, feeding method, and rate. In addition, research is also exploring the establishment of risk prediction models to more accurately predict which patients may develop enteral nutrition intolerance. These models typically combine clinical parameters, biomarkers, and patient individual characteristics, aiming to assist clinicians in better planning and adjusting nutritional treatment plans, thereby reducing the occurrence of intolerance events. This review summarizes the research progress on enteral nutrition intolerance in adult patients, with a focus on the latest developments in intolerance factors and risk prediction models, providing valuable guidance for clinical practice and helping improve patients' nutritional status and overall health.

Intermittent enteral nutrition shortens the time to achieve nutritional goals in critically ill patients

Nutritional support is associated with improved clinical outcomes in critically ill patients; however, loss of muscle mass during critical illness leads to weakness, delayed return to work, and increased healthcare consumption. Animal data have suggested that intermittent feeding decreases protein catabolism. This study was aimed at determining whether the mode of enteral nutrition administration might lead to differences in meeting nutritional goals, tolerance, and complications. A prospective, randomized, single-center clinical trial was conducted in four intensive care units in the Czech Republic. Critically ill adult patients with high nutritional risk were randomized to continuous or intermittent enteral nutrition administration through a tolerance-driven protocol. The primary outcome was the time to reach the energetic target. Secondary outcomes included assessment of tolerance (high gastric residual volume, vomitus, and diarrhea), complications (aspiration or ventilator-associated pneumonia), and 28-day mortality. A total of 300 patients were randomized, and 294 were analyzed: 148 in the continuous arm and 146 in the intermittent arm. Regarding the primary outcome, log-rank test indicated that the intermittent group, compared with continuous group, had a statistically significantly shorter time (p = 0.009) and greater diarrhea occurrence (7 (4.7%) vs. 16 (11%), p = 0.049). No statistically significant differences in ventilator-associated pneumonia incidence (18 (12.2%) vs. 18 (12.3%), p = 0.965), 28-day mortality (46 (31.1%) vs. 40 (27.4%), p = 0.488), and other secondary outcomes were observed between groups. Thus, intermittent enteral nutrition was superior to continuous enteral nutrition in terms of time to reach the energetic target with the tolerance-driven administration protocol but was associated with higher diarrhea incidence. No statistically significant differences in the other secondary outcomes were observed.

Nine Myths about Enteral Feeding in Critically Ill Adults: An Expert Perspective

Malnutrition is a well-studied and significant prognostic risk factor for morbidity and mortality in critically ill perioperative patients. Common nutrition myths in the critically ill may prevent early, consistent, and adequate delivery of enteral nutrition. We outlined 9 common intensive care unit (ICU) nutrition misconceptions and our recommendations to optimize enteral nutrition in critically ill patients based on the review of available literature. Our approach is to treat every patient admitted to the ICU as at risk for malnutrition and to initiate enteral nutrition upon admission in the absence of contraindications. Early enteral nutrition via the gastric route is more beneficial than delaying feeding while awaiting small bowel access and daytime-intermittent nutrition support can safely be initiated over continuous feeding. Gastric residual volumes to assess feeding tolerance should no longer be routinely measured. For perioperative nutrition, we recommend continuing enteral nutrition for most patients with secure airways undergoing anesthesia and resuming nutrition within 24 h of abdominal surgery; even patients with open abdomens can be safely fed in the absence of bowel injury. Critically ill patients who are proned, paralyzed, and on vasopressors can usually continue enteral nutrition. Finally, continuing enteral nutrition before extubation may optimize nutrition without compromising extubation success. In this review, we highlight several common misconceptions regarding ICU nutrition that may prevent achieving nutrition goals and subsequently lead to increased malnutrition, morbidity, and mortality. This knowledge may contribute to increased implementation of early and consistent enteral nutrition strategies to improve outcomes in critically ill adult patients.

Does intermittent nutrition enterally normalise hormonal and metabolic responses to feeding in critically ill adults? A protocol for the DINE-Normal proof-of-concept randomised parallel-group study

INTRODUCTION

Over half of patients who spend >48 hours in the intensive care unit (ICU) are fed via a nasogastric (NG) tube. Current guidance recommends continuous delivery of feed throughout the day and night. Emerging evidence from healthy human studies shows that NG feeding in an intermittent pattern (rather than continuous) promotes phasic hormonal, digestive and metabolic responses that are important for effective nutrition. It is not yet known whether this will translate to the critically ill population. Here, we present the protocol for a proof-of-concept study comparing diurnal intermittent vs continuous feeding on hormonal and metabolic outcomes for patients in the ICU.

METHODS AND ANALYSIS

The study is a single-centre, prospective, randomised, open-label trial comparing intermittent enteral nutrition with the current standard practice of continuous enteral feeding. It aims to recruit participants (n=30) needing enteral nutrition via an NG tube for >24 hours who will be randomised to a diurnal intermittent or a continuous feeding regimen with equivalent nutritional value. The primary outcome is peak plasma insulin/c-peptide within 3 hours of delivering the morning intermittent feed on the second study day, compared with that seen in the continuous feed delivery group at the same time point. Secondary outcomes include feasibility, tolerability, efficacy and metabolic/hormonal profiles.

ETHICS AND DISSEMINATION

We obtained ethical approval from the Wales Research Ethics Committee 3 prior to data collection (reference 23/WA/0297). We will publish the results of this study in an open-access peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT06115044.

Bolus Versus Continuous Enteral Feeding for Critically Ill Patients: A Systematic Review and Meta-Analysis

Enteral feeding is a crucial aspect of nutritional support for critically ill patients. However, the optimal feeding approach, whether bolus or continuous, remains a subject of debate. This systematic review and meta-analysis aimed to compare the outcomes of bolus feeding and continuous enteral feeding in critically ill patients. A systemic search was carried out in PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL) Ultimate, Web of Science, Scopus, and Google Scholar to identify relevant studies. To ensure that we obtain the latest evidence on the topic, the search was limited to the last five years. Risk of bias assessments and meta-analyses were performed for relevant clinical outcomes. A total of nine randomized controlled trials (RCTs) were included, involving a total of 863 patients. All the studies were published between 2020 and 2023. High-risk performance bias was observed in seven studies, with unclear risk in two studies. In terms of clinical outcomes, no statistically significant differences were found between bolus and continuous enteral feeding in terms of diarrhea (odds ratio {OR} 0.60, 95% CI 0.27 to 1.30, p=0.20), constipation (OR 1.52, 95% CI 0.91 to 2.53, p=0.11), vomiting (OR 0.74, 95% CI 0.36 to 1.49, p=0.39), distention (OR 0.70, 95% CI 0.14 to 3.58, p=0.66), aspiration (OR 0.61, 95% CI 0.16 to 2.73, p=0.48), and gastric residual volume (GRV) (OR 0.80, 95% CI 0.30 to 2.15, p=0.66). Furthermore, no significant differences between bolus and continuous feeding were observed in terms of intensive care unit (ICU) mortality (OR 0.66, 95% CI 0.42 to 1.04, p=0.07), hospital mortality (OR 0.57, 95% CI 0.31 to 1.03, p=0.06), ICU length of stay (OR 0.70, 95% CI 0.50 to 1.90, p=0.25), and hospital length of stay (OR -0.86, 95% CI -3.04 to 1.33, p=0.44). This systematic review and meta-analysis suggest that bolus and continuous enteral feeding methods exhibit comparable outcomes in critically ill patients. However, both ICU mortality and hospital mortality outcomes were close to achieving statistical significance, which favored the continuous feeding approach.

Anorexia Nervosa With Intermittent Fever Due to Diet-Induced Thermogenesis: A Case Report

Diet-induced thermogenesis, influenced primarily by protein intake, generates energy from food. Herein, we present the case of anorexia nervosa in a 30-year-old woman, who developed intermittent fever while transitioning from continuous to intermittent tube feeding, with an increase in protein intake. Extensive investigations ruled out infection- or drug-related causes, indicating that intermittent fever resulted from diet-induced thermogenesis due to high protein administration. Recognizing the potential for diet-induced thermogenesis in cases of fever during tube feeding is crucial to avoid unnecessary antibiotic use and prevent the discontinuation of essential medications.

The metabolic effects of intermittent versus continuous feeding in critically ill patients

Intermittent (or bolus) feeding regimens in critically ill patients have been of increasing interest to clinicians and scientists. Changes in amino acid, fat and carbohydrate metabolites over time might yet deliver other benefits (e.g. modulation of the circadian rhythm and sleep, and impacts on ghrelin secretion, insulin resistance and autophagy). We set out to characterise these changes in metabolite concentration. The Intermittent versus Continuous Feeding in Critically Ill paitents study (NCT02358512) was an eight-centre single-blinded randomised controlled trial. Patients were randomised to received a continuous (control arm) or intermittent (6x/day, intervention arm) enteral feeding regimen. Blood samples were taken on trial days 1, 7 and 10 immediately before and 30 min after intermittent feeds, and at equivalent timepoints in the control arm. A pre-planned targeted metabolomic analysis was performend using Nuclear Resonance Spectroscopy. Five hundred and ninety four samples were analysed from 75 patients. A total of 24 amino acid-, 19 lipid based-, and 44 small molecule metabolite features. Across the main two axes of variation (40-60% and 6-8% of variance), no broad patterns distinguished between intermittent or continuous feeding arms, across intra-day sampling times or over the 10 days from initial ICU admission. Logfold decreases in abundance were seen in metabolites related to amino acids (Glutamine - 0.682; Alanine - 0.594), ketone body metabolism (Acetone - 0.64; 3-Hydroxybutyric Acid - 0.632; Acetonacetic Acid - 0.586), fatty acid (carnitine - 0.509) and carbohydrate metabolism ( Maltose - 0.510; Citric Acid - 0.485). 2-3 Butanediol, a by-product of sugar-fermenting microbial metabolism also decreased (- 0.489). No correlation was seen with change in quadriceps muscle mass for any of the 20 metabolites varying with time (all p > 0.05). Increasing severity of organ failure was related to increasing ketone body metabolism (3 Hydroxybutyric Acid-1 and - 3; p = 0.056 and p = 0.014), carnitine deficiency (p = 0.002) and alanine abundancy (p - 0.005). A 6-times a day intermittent feeding regimen did not alter metabolite patterns across time compared to continuous feeding in critically ill patients, either within a 24 h period or across 10 days of intervention. Future research on intermittent feeding regimens should focus on clinical process benefits, or extended gut rest and fasting.

Clinical efficacy of enteral nutrition feeding modalities in critically ill patients: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

In intensive care units (ICUs), both continuous and intermittent feeding are commonly used for early enteral nutrition (EN). However, whether continuous feeding is a preferable feeding modality compared to intermittent feeding remains unclear. Therefore, this meta-analysis assessed the clinical efficacy of both EN feeding modalities in critically ill patients.

METHODS

The PubMed, Embase, and Cochrane Library databases were searched from their inception dates to December 29, 2022. The search did not involve language restrictions (PROSPERO CRD42022371756). Randomized controlled trials (RCTs) comparing the clinical efficacy and safety of continuous feeding and intermittent feeding in critically ill patients in ICUs were included.

RESULTS

We included 13 RCTs involving 785 patients. Compared with intermittent feeding, continuous feeding was associated with a lower mortality rate (relative risk [RR], 0.68; 95% confidence interval [CI], 0.47, 0.98; p = 0.04) but a higher risk of constipation (RR, 1.57; 95% CI, 1.02, 2.43; p = 0.04). Trial sequential analysis (TSA) for mortality rate presented a cumulative Z-curve crossing the traditional boundary, but the curve did not cross the TSA boundary for benefit. No significant differences were found in the aspiration/pneumonia rate (RR, 1.19; 95% CI, 0.51, 2.75; p = 0.69), diarrhea rate (RR, 0.82; 95% CI, 0.58, 1.16; p = 0.26), or increased gastric residual volumes (RR, 1.05; 95% CI, 0.58, 1.90; p = 0.86) between the groups.

CONCLUSION

Despite the low certainty of evidence, compared with intermittent feeding, continuous feeding may reduce the mortality rate in critically ill patients in ICU. Additional studies are needed to provide more evidence and validate the findings.

The effect of intermittent versus continuous enteral feeding for critically ill patients: a meta-analysis of randomized controlled trials

Objectives

The appropriate strategy for enteral feeding in critically ill patients still remains controversial. Therefore, we conducted this meta-analysis to compare the effect of intermittent versus continuous enteral feeding method for critically ill patients.

Methods

Electronic databases including PubMed, Embase, Scopus, and Cochrane Library were searched up to April 10th, 2023 for randomized controlled trials evaluating the effect of intermittent versus continuous enteral feeding for critically ill patients. The primary outcomes were feeding intolerances, including diarrhea, vomiting, distension, constipation, gastric retention, and aspiration pneumonia. The secondary outcomes were mortality in intensive care unit (ICU), length of stay in ICU, and achievement of nutritional goal.

Results

Thirteen studies with a total of 884 patients were analyzed in this meta-analysis. Overall, the use of intermittent enteral feeding was associated with higher incidence of diarrhea (OR 1.66, 95%CI 1.13 to 2.43, I2 = 16%) and distension (OR 2.29, 95%CI 1.16 to 4.51, I2 = 0%), lower incidence of constipation (OR 0.58, 95%CI 0.37 to 0.90, I2 = 0%), and longer length of ICU stay (MD 1.09, 95%CI 0.53 to 1.64, I2 = 0%). Moreover, no significant difference was identified for other outcome measures.

Conclusion

In critically ill patients, the implementation of intermittent enteral feeding was associated with higher incidence of diarrhea and distension, longer length of ICU stay, but lower occurrence of constipation. Nevertheless, the absence of sufficient high-quality randomized controlled clinical trials precludes any definitive conclusions regarding the optimal approach to enteral feeding in this population. There is an imperative need for more studies to further assess the efficacy of the two enteral feeding strategies.

Toward nutrition improving outcome of critically ill patients: How to interpret recent feeding RCTs?

Although numerous observational studies associated underfeeding with poor outcome, recent randomized controlled trials (RCTs) have shown that early full nutritional support does not benefit critically ill patients and may induce dose-dependent harm. Some researchers have suggested that the absence of benefit in RCTs may be attributed to overrepresentation of patients deemed at low nutritional risk, or to a too low amino acid versus non-protein energy dose in the nutritional formula. However, these hypotheses have not been confirmed by strong evidence. RCTs have not revealed any subgroup benefiting from early full nutritional support, nor benefit from increased amino acid doses or from indirect calorimetry-based energy dosing targeted at 100% of energy expenditure. Mechanistic studies attributed the absence of benefit of early feeding to anabolic resistance and futile catabolism of extra provided amino acids, and to feeding-induced suppression of recovery-enhancing pathways such as autophagy and ketogenesis, which opened perspectives for fasting-mimicking diets and ketone supplementation. Yet, the presence or absence of an anabolic response to feeding cannot be predicted or monitored and likely differs over time and among patients. In the absence of such monitor, the value of indirect calorimetry seems obscure, especially in the acute phase of illness. Until now, large feeding RCTs have focused on interventions that were initiated in the first week of critical illness. There are no large RCTs that investigated the impact of different feeding strategies initiated after the acute phase and continued after discharge from the intensive care unit in patients recovering from critical illness.

Comparison of continuous versus intermittent enteral feeding in critically ill patients: a systematic review and meta-analysis

Background

The enteral route is commonly utilised to support the nutritional requirements of critically ill patients. However, there is paucity of data guiding clinicians regarding the appropriate method of delivering the prescribed dose. Continuous enteral feeding is commonly used; however, a bolus or intermittent method of administration may provide several advantages such as minimising interruptions. The purpose of this meta-analysis is to compare a continuous versus an intermittent or bolus enteral nutrition administration method.

Methods

A systematic review and meta-analysis were performed with studies identified from the PubMed, EMBASE, Cochrane Library and Web of Science databases. Studies were included if they compared a continuous with either an intermittent or bolus administration method of enteral nutrition in adult patients admitted to the intensive care unit. Study quality was assessed using the PEDro and Newcastle–Ottawa scoring systems. Review Manager was used for performing the random-effects meta-analysis on the outcomes of mortality, constipation, diarrhoea, increased gastric residuals, pneumonia, and bacterial colonisation.

Results

A total of 5546 articles were identified, and 133 were included for full text review. Fourteen were included in the final analysis. There was an increased risk of constipation with patients receiving continuous enteral nutrition (relative risk 2.24, 95% confidence interval 1.01–4.97, p = 0.05). No difference was identified in other outcome measures. No appreciable bias was identified.

Conclusion

The current meta-analysis has not identified any clinically relevant difference in most outcome measures relevant to the care of critically ill patients. However, there is a paucity of high-quality randomised controlled clinical trials to guide this decision. Therefore, clinicians may consider either dosing regimen in the context of the patient’s care requirements.

Critical illness and bone metabolism: where are we now and what is next?

Critical illness refers to the clinical signs of severe, variable and life-threatening critical conditions, often accompanied by insufficiency or failure of one or more organs. Bone health of critically ill patients is severely affected during and after ICU admission. Therefore, clinical work should focus on ICU-related bone loss, and early development and implementation of related prevention and treatment strategies: optimized and personalized nutritional support (high-quality protein, trace elements and intestinal prebiotics) and appropriate physiotherapy and muscle training should be implemented as early as possible after ICU admission and discharge. At the same time, the drug regulates excessive metabolism and resists osteoporosis.

Intermittent feeding and circadian rhythm in critical illness

PURPOSE OF REVIEW

Circadian rhythms, i.e., periodic oscillations in internal biological processes, modulate metabolic processes such as hormonal signalling, nutrient absorption, and xenobiotic detoxification. Meal timing is a strong entraining cue for peripheral clocks in various organs, and eating out of circadian phases can impair glucose, gastrointestinal, and muscle metabolism. Sleep/wake cycles and circadian rhythms are extremely disrupted during critical illness. Timing of nutritional support may help preserve circadian rhythms and improve post-Intensive Care Unit (ICU) recovery. This review summarises circadian disruptors during ICU admission and evaluates the potential benefits of intermittent feeding on metabolism and circadian rhythms.

RECENT FINDINGS

Rhythmic expression of core clock genes becomes rapidly disturbed during critical illness and remains disturbed for weeks. Intermittent, bolus, and cyclic enteral feeding have been directly compared to routine continuous feeding, yet no benefits on glycaemic control, gastrointestinal tolerance, and muscle mass have been observed and impacts of circadian clocks remain untested.

SUMMARY

Aligning timing of nutritional intake, physical activity, and/or medication with circadian rhythms are potential strategies to reset peripheral circadian rhythms and may enhance ICU recovery but is not proven beneficial yet. Therefore, selecting intermittent feeding over continuous feeding must be balanced against the pros and cons of clinical practice.

Intragastric prepyloric enteral nutrition, bolus vs continuous in the adult patient: A systematic review and meta-analysis

Bolus and continuous nutrition are commonly used enteral nutrition (EN) administration methodologies. Currently, there is insufficient evidence to establish which is the most effective method for reducing gastrointestinal complications in adult patients. The aim of this review is to evaluate the impact of bolus/intermittent EN compared with continuous EN for the following outcomes: diarrhea, constipation, emesis/vomiting, gastric residual volume, aspiration, and glycemic control in adult patients receiving intragastric prepyloric EN in the hospital setting. Bibliographical research was performed on the following databases: PubMed, Embase, CINAHL, and the Cochrane Central Register of Controlled Trials. The review included all randomized and nonrandomized controlled trials of patients aged ≥18 years with preserved gastrointestinal function. Meta-analysis was performed by Review Manager V.5.3. Seven studies including 551 patients were included in the meta-analysis. Five of these studies reported that the diarrhea rate was higher in the bolus feeding group (risk ratio [RR] = 2.50; 95% CI, 1.17-5.34; P = 0.02), and another five of these studies indicated that the aspiration rate was higher in the continuous feeding group (RR = 0.55; 95% CI, 0.35-0.87; P = 0.01). There were no significant differences for the other outcomes. In conclusion, intermittent EN appears to reduce the incidence of aspiration in the hospital setting; however, it may increase the risk of diarrhea. For future research, we hypothesize the joint use of continuous nutrition until the patient reaches tolerance and then passing to bolus nutrition, thus reducing the incidence of aspiration and enabling a physiological nutrition intake.

Safety and Efficacy of Continuous or Intermittent Enteral Nutrition in ICU Patients: Systematic Review of Clinical Evidence

The best mode of delivering enteral nutrition (EN) in ICU is still debated: several consensus guidelines (ASPEN and ESPEN) suggest that EN in ICU should be preferably delivered continuously rather intermittently but some authors highlight that the first is unphysiological. The aim of this systematic review (SR) is to summarize available clinical evidence related to safety and efficacy of continuous enteral nutrition (C-EN) or intermittent enteral nutrition (I-EN) in ICU patients, in relation to appropriated supply on nutritional status, gastrointestinal symptoms or tolerance, risks on respiratory tract infections. A literature search of Pubmed, EMBASE and Google Scholar was performed comparing C-EN vs I-EN and 4196 published studies were screened. Nineteen studies were selected for this SR reporting types of ICU, nutritional protocols and study period. Effects of C-EN vs I-EN were presented according to the impact on: nutritional status, digestive tract and respiratory tract. The contrasting results confirmed that the optimal delivering mode of EN remains controversial. Future studies dedicated to identify the benefits and limitations of C-EN or I-EN should be realized. This article is protected by copyright. All rights reserved.

The Therapeutic Potential and Limitations of Ketones in Traumatic Brain Injury

Traumatic brain injury (TBI) represents a significant health crisis. To date, no FDA approved pharmacotherapies are available to prevent the neurological deficits caused by TBI. As an alternative to pharmacotherapy treatment of TBI, ketones could be used as a metabolically based therapeutic strategy. Ketones can help combat post-traumatic cerebral energy deficits while also reducing inflammation, oxidative stress, and neurodegeneration. Experimental models of TBI suggest that administering ketones to TBI patients may provide significant benefits to improve recovery. However, studies evaluating the effectiveness of ketones in human TBI are limited. Unanswered questions remain about age- and sex-dependent factors, the optimal timing and duration of ketone supplementation, and the optimal levels of circulating and cerebral ketones. Further research and improvements in metabolic monitoring technology are also needed to determine if ketone supplementation can improve TBI recovery outcomes in humans.

Fine-Tuning of Postprandial Responses via Feeding Frequency and Leucine Supplementation Affects Dietary Performance in Turbot (Scophthalmus maximus L.)

BACKGROUND

Feeding-induced cell signaling and metabolic responses affect utilization of dietary nutrients but are rarely taken advantage of to improve animal nutrition.

OBJECTIVES

We hypothesized that by modulating postprandial kinetics and signaling, improved dietary utilization and growth performance could be achieved in animals.

METHODS

Juvenile turbot (Scophthalmus maximus L.) with an initial mean ± SD weight of 10.1 ± 0.01 g were used. Two feeding frequencies (FFs), either 1 or 3 meals/d at a fixed 2.4% daily body weight ration, and 2 diets that were or were not supplemented with 1% crystalline leucine (Leu), were used in the 10-wk feeding trial. At the end of the trial, a 1-d force-feeding experiment was conducted using the aforementioned FF and experimental diets. Samples were collected for the analysis of postprandial kinetics of aminoacidemia, mechanistic target of rapamycin (mTOR) signaling activities, protein deposition, as well as the mRNA expression levels of key metabolic checkpoints at consecutive time points after feeding.

RESULTS

Increased FF and leucine supplementation significantly enhanced fish growth by 7.68% ± 0.53% (means ±SD) and 7.89% ± 1.25%, respectively, and protein retention by 4.01% ± 0.59% and 4.44% ± 1.63%, respectively, in feeding trial experiments. The durations of postprandial aminoacidemia and mTOR activation were extended by increased FF, whereas leucine supplementation enhanced mTOR signaling without influencing the postprandial free amino acids kinetics. Increased FF and leucine supplementation enhanced muscle protein deposition 21.6% ± 6.85% and 22.3% ± 1.52%, respectively, in a 24-h postfeeding period.

CONCLUSIONS

We provided comprehensive characterization of the postprandial kinetics of nutrient sensing and metabolic responses under different feeding regimens and leucine supplementation in turbot. Fine-tuning of postprandial kinetics could provide a new direction for better dietary utilization and animal performances in aquaculture.

Comparison of sequential feeding and continuous feeding on the blood glucose of critically ill patients: a non-inferiority randomized controlled trial

Background:

Glucose control is an important aspect in managing critically ill patients. The goal of this study was to compare the effects of sequential feeding (SF) and continuous feeding (CF) on the blood glucose of critically ill patients.

Methods:

A non-inferiority randomized controlled trial was adopted in this study. A total of 62 patients who were fed enteral nutritional suspension through gastric tubes were enrolled. After achieving 80% of the nutrition target calories (25 kcal·kg⁻¹·day⁻¹) through CF, the patients were then randomly assigned into SF and CF groups. In the SF group, the feeding/fasting time was reasonably determined according to the circadian rhythm of the human body as laid out in traditional Chinese medicine theory. The total daily dosage of the enteral nutritional suspension was equally distributed among three time periods of 7 to 9 o’clock, 11 to 13 o’clock, and 17 to 19 o’clock. The enteral nutritional suspension in each time period was pumped at a uniform rate within 2 h by an enteral feeding pump. In the CF group, patients received CF at a constant velocity by an enteral feeding pump throughout the study. Blood glucose values at five points (6:00/11:00/15:00/21:00/1:00) were monitored and recorded for seven consecutive days after randomization. Enteral feeding intolerance was also recorded. Non-inferiority testing was adopted in this study, the chi-square test or Fisher test was used for qualitative data, and the Mann-Whitney U test was used for quantitative data to determine differences between groups. In particular, a repeated measure one-way analysis of variance was used to identify whether changes in glucose value variables across the time points were different between the two groups.

Results:

There were no significant demographic or physiological differences between the SF and CF groups (P > 0.050). The average glucose level in SF was not higher than that in CF (8.8 [7.3–10.3] vs. 10.7 [9.1–12.1] mmol/L, Z = −2.079, P for non-inferiority = 0.019). Hyperglycemia incidence of each patient was more common in the CF group than that in the SF group (38.4 [19.1–63.7]% vs. 11.8 [3.0–36.7]%, Z = −2.213, P = 0.027). Hypoglycemia was not found in either group. Moreover, there was no significant difference during the 7 days in the incidence of feeding intolerance (P > 0.050).

Conclusions:

In this non-inferiority study, the average blood glucose in SF was not inferior to that in CF. The feeding intolerance in SF was similar to that in CF. SF may be as safe as CF for critically ill patients.

Trial Registration

ClinicalTrials.gov, NCT03439618; https://clinicaltrials.gov/ct2/show/record/NCT03439618

Alteration of gut microbiota and metabolomics in critically ill patients by sequential feeding: A pilot study

BACKGROUND

Sequential feeding (SF) is a new feeding mode for critically ill patients that involves a combination of continuous feeding (CF) in the beginning, rhythmic feeding in the second stage, and oral feeding in the last stage. In this study, we investigated the influence of SF on gut microbiota and metabolomics in critically ill patients.

METHODS

Stool specimens from 20 patients (10 patients with the SF group, 10 patients with the CF group) were collected for full-length 16S ribosomal RNA gene sequencing and untargeted metabolomics analysis.

RESULTS

The proportion of patients with low bacterial diversity (Shannon index < 4) in the SF group was much lower than that in the CF group, but there was no significant difference in the proportions (20% vs 50%, P = .350). The abundances of Actinobacteria/Actinobacteria (at the phylum and class levels), Pseudomonadaceae/Pseudomonas (at the family and genus levels), and Fusobacteria/Fusobacteriaceae/Fusobacteriales/Fusobacteria/Fusobacterium (at the phylum, class, order, family, and genus levels) were all higher in the SF group than in the CF group. Actinobacteria/Actinobacteria (at the phylum and class levels) were the most influential of these gut flora. Retinoic acid and leucine were upregulated in the SF group and were respectively responsible for the intestinal immune network for immunoglobulin A production and the mammalian target of rapamycin signaling pathway in the enriched pathways according to the Kyoto Encyclopedia of Genes and Genomes database classification.

CONCLUSIONS

SF could alter gut microbiota and metabolomics in critically ill patients. Because of the small sample size, further study is required.

Are periods of feeding and fasting protective during critical illness?

PURPOSE OF REVIEW

To review the mechanisms how intermittent feeding regimens could be beneficial in critically ill patients.

RECENT FINDINGS

Large randomized controlled trials (RCTs) have failed to demonstrate consistent benefit of early, enhanced nutritional support to critically ill patients, and some trials even found potential harm. Although speculative, the absence of a clear benefit could be explained by the continuous mode of feeding in these trials, since intermittent feeding regimens had health-promoting effects in healthy animals and humans through mechanisms that also appear relevant in critical illness. Potential protective mechanisms include avoidance of the muscle-full effect and improved protein synthesis, improved insulin sensitivity, better preservation of circadian rhythm, and fasting-induced stimulation of autophagy and ketogenesis. RCTs comparing continuous versus intermittent feeding regimens in critically ill patients have shown mixed results, albeit with different design and inclusion of relatively few patients. In all studies, the fasting interval was relatively short (4-6 h maximum), which may be insufficient to develop a full fasting response and associated benefits.

SUMMARY

These findings open perspectives for the design and clinical validation of intermittent feeding regimens for critically ill patients. The optimal mode and duration of the fasting interval, if any, remain unclear.

Prospective evaluation of a novel enteral feeding guideline based on individual gastric emptying times: an improvement project in a pediatric intensive care unit

BACKGROUND

On a 20-bed, mixed cardiac and general, UK pediatric intensive care unit (PICU), we aimed to determine if a physiologically based enteral feeding guideline for critically ill children, using feed frequency tailored to individual gastric emptying times, resulted in earlier establishment of full feeds (when 100% of fluid allowance (FA) available to be given as intravenous maintenance fluid or feed, defined as free FA [FFA], is given as enteral nutrition [EN]) and an increase in FFA given as EN.

METHODS

Four prospective audits (totaling 331 patients and 19,771 hours) were conducted at 1 year before guideline introduction and 1, 5, and 10 years after. Patient feeding data were collected from admission until day 4 or discharge, including reasons why feed was withheld.

RESULTS

The median time from admission to establishing full feeds decreased from 18 to 10 hours preguideline and postguideline and was sustained over 10 years. After adjustment for 5 confounders, this represented a reduction in the geometric mean time to full feeds of 30% (2009), 29% (2013), and 48% (2019) compared with 2007 (all P < .01). Nil-per-oral (NPO) hours were categorized as due to modifiable and nonmodifiable factors. Preguideline and postguideline NPO hours from modifiable factors decreased from 21 (2007) to 10 (2009) per 100 audit hours, which was sustained across 10 years (all P < .01). Conversely, NPO hours from nonmodifiable factors ranged from 27 to 36 per 100 audit hours throughout the audits, with no consistent trend over time. Similar inconsistency was shown in the proportion of FFA given as EN: 48% (2007), 71% (2009), 51% (2013), and 64% (2019). Continuous nasogastric and hourly bolus feeds decreased over time; they comprised 66% of feeds in 2007 but only 4%-11% in subsequent periods, being replaced with more 2-6 hour bolus, on-demand, or continuous nasojejunal feeds.

CONCLUSION

The guideline was associated with sustained reduction in the time to establishing full feeds and NPO hours due to modifiable factors and more or no less FFA being given as EN.

Comparison of continuous versus intermittent enteral nutrition in critically ill patients (COINN): study protocol for a randomized comparative effectiveness trial

Background

Enteral nutrition is part of the treatment of critically ill patients. Administration of enteral nutrition may be associated with signs of intolerance, such as high gastric residual volumes, diarrhea, and vomiting. Clinical trials regarding the effects of the mode of administration of enteral nutrition on the occurrence of these complications have yielded conflicting results. This trial aims to investigate whether the mode of administration of enteral nutrition affects the time to reach nutritional targets, intolerance, and complications.

Methods

COINN is a randomized, monocentric study for critically ill adult patients receiving enteral nutrition. Patients will be randomly assigned to two groups receiving (1) continuous or (2) intermittent administration of enteral nutrition. Enhancement of enteral nutrition will depend on signs of tolerance, mainly the gastric residual volume. The primary outcome will be the time to reach the energetic target. Secondary outcomes will be the time to reach the protein target, tolerance, complications, hospital and ICU lengths of stay, and 28-day mortality.

Discussion

This trial aims to evaluate whether the mode of application of enteral nutrition affects the time to reach nutritional targets, signs of intolerance, and complications.

Trial registration

ClinicalTrials.gov NCT03573453. Registered on 29 June 2018

Intermittent versus continuous enteral nutrition on feeding intolerance in critically ill adults: A meta-analysis of randomized controlled trials

OBJECTIVES

Enteral formula delivery strategy is an important part of enteral nutrition. We aimed to synthesize up-to-date studies to clarify the effects of intermittent versus continuous feeding on feeding intolerance during enteral nutrition in critically ill adults.

DESIGN

A meta-analysis of randomized controlled trials.

DATA SOURCES

Embase, PubMed, Information Sciences Institute Web of Science, CINAHL EBSCO, Cochrane Central Register of Controlled Trials, Chinese Biomedical Literature Database, China National Knowledge Infrastructure databases were searched from inception to 17th of June 2020.

REVIEW METHODS

The Cochrane "risk of bias" tool was used to assess the quality of individual studies, and the quality of each outcome was assessed by GRADE approach. Fixed or random effect meta-analysis was used pending the presence of heterogeneity. Dichotomous data synthesis was presented as risk ratio and 95% confidence interval, and quantitative data synthesis was shown as mean difference and 95% confidence interval.

RESULTS

Fourteen trials with 1025 critically ill adults were included in the meta-analysis. We found that intermittent feeding could significantly increase the occurrence of feeding intolerance (risk ratio = 1.64, 95% confidence interval = 1.23 to 2.18, P < 0.001) compared with continuous feeding, as well as the incidence of high gastric volume (risk ratio = 3.62, 95% confidence interval = 1.43-9.12, P = 0.006) and aspiration (risk ratio = 3.29, 95% confidence interval = 1.18-9.16, P = 0.02) in > 1-week trial duration, while constipation rate was reduced in intermittent feeding group (risk ratio = 0.66, 95% confidence interval = 0.45-0.98, P = 0.04). Patients in intermittent feeding group received more calories compared with continuous feeding group (mean difference = 184.81, 95% confidence interval = 56.61-313.01, P = 0.005). The quality of all evidence synthesis was "low" or "very low".

CONCLUSIONS

In critically ill adults, continuous feeding was associated with lower overall incidence of feeding intolerance, especially in high gastric volume and aspiration. However, decreased constipation incidence and more calorie intake were observed in intermittent feeding group. Because quality of the synthesized evidence was "low" or "very low", there is considerable uncertainty about this estimate.

Uptake of dietary amino acids into arterial blood during continuous enteral feeding in critically ill patients and healthy subjects

BACKGROUND

Amino acid availability is a regulatory factor of protein anabolism and is partly dependent on enteral amino acid uptake. During continuous enteral feeding, enteral amino acid uptake may vary considerably, but this has not been documented systematically.

METHODS

In this pragmatic study, we investigated patients in the intensive care unit (n = 10) and healthy adults (n = 10). The time course of essential amino acid concentrations in arterial plasma and the uptake of dietary phenylalanine were recorded during 12 hours of continuous enteral feeding, using a ¹³C-labeled phenylalanine tracer.

RESULTS

Plasma essential amino acid concentrations and ¹³C-phenylalanine enrichment reached a tentative steady state after no more than 4.5 h from start of tracer infusion. There was a large intra- and inter-individual variability in both cohorts. No periodicity could be detected in the temporal variation.

CONCLUSION

During continuous enteral feeding, uptake of amino acids shows large intra- and inter-individual variation. A tentative steady state of ¹³C-phenylalanine uptake is eventually reached.

TRIAL REGISTRATION

Registered at Australian New Zealand Clinical Trials Registry, trial ID ACTRN12616000593437.

Effect of Intermittent or Continuous Feed on Muscle Wasting in Critical Illness: A Phase 2 Clinical Trial

BACKGROUND

Acute skeletal muscle wasting in critical illness is associated with excess morbidity and mortality. Continuous feeding may suppress muscle protein synthesis as a result of the muscle-full effect, unlike intermittent feeding, which may ameliorate it.

RESEARCH QUESTION

Does intermittent enteral feed decrease muscle wasting compared with continuous feed in critically ill patients?

STUDY DESIGN AND METHODS

In a phase 2 interventional single-blinded randomized controlled trial, 121 mechanically ventilated adult patients with multiorgan failure were recruited following prospective informed consultee assent. They were randomized to the intervention group (intermittent enteral feeding from six 4-hourly feeds per 24 h, n = 62) or control group (standard continuous enteral feeding, n = 59). The primary outcome was 10-day loss of rectus femoris muscle cross-sectional area determined by ultrasound. Secondary outcomes included nutritional target achievements, plasma amino acid concentrations, glycemic control, and physical function milestones.

RESULTS

Muscle loss was similar between arms (-1.1% [95% CI, -6.1% to -4.0%]; P = .676). More intermittently fed patients received 80% or more of target protein (OR, 1.52 [1.16-1.99]; P < .001) and energy (OR, 1.59 [1.21-2.08]; P = .001). Plasma branched-chain amino acid concentrations before and after feeds were similar between arms on trial day 1 (71 μM [44-98 μM]; P = .547) and trial day 10 (239 μM [33-444 μM]; P = .178). During the 10-day intervention period the coefficient of variation for glucose concentrations was higher with intermittent feed (17.84 [18.6-20.4]) vs continuous feed (12.98 [14.0-15.7]; P < .001). However, days with reported hypoglycemia and insulin usage were similar in both groups. Safety profiles, gastric intolerance, physical function milestones, and discharge destinations did not differ between groups.

INTERPRETATION

Intermittent feeding in early critical illness is not shown to preserve muscle mass in this trial despite resulting in a greater achievement of nutritional targets than continuous feeding. However, it is feasible and safe.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT02358512; URL: www.clinicaltrials.gov.

Metabolic aspects of muscle wasting during critical illness

PURPOSE OF REVIEW

Skeletal muscle wasting during critical illness is the result of disturbed metabolism. No proven effective interventions targeting skeletal muscle mass and function during critical illness currently exist. This review summarizes recent advances regarding the complexity of metabolic factors involved and the challenge of establishing the clinical effects of metabolic interventions targeting the muscle.

RECENT FINDINGS

Although the catabolic state is limited to the acute phase of critical illness, its subsequent impact on muscle mass and function persists long after ICU discharge. Immobilization, inflammation and disturbed muscle energy and nutrient metabolism are key drivers of muscle protein loss. Current research focuses on the effects of enhanced protein provision, specific substrate delivery and physical exercise. Whilst some interventions have been successful at improving muscle mass, these effects do not always carry over into muscle function or strength.

SUMMARY

Increased understanding of metabolic derangements during critical illness provides new potential targets for treatment. The potential of dietary protein to attenuate the muscle protein catabolic state has yet to be established in clinical trials. Basic research should focus on ways to further improve the anabolic potential of nutrition by unravelling mechanisms that regulate anabolic and catabolic pathways and energy metabolism.

Sarcopenia and Psychosocial Variables in Patients in Intensive Care Units: The Role of Nutrition and Rehabilitation in Prevention and Treatment

Critical illness leads to decline in muscle mass that promotes decline in physical function and psychological function and may lead to cognitive decline or dementia. Nurses are key to driving the multidisciplinary interventions that prevent protein loss and promote positive outcomes for critically ill patients.

Changing paradigms in metabolic support and nutrition therapy during critical illness

PURPOSE OF REVIEW

To summarize the most recent advances in acute metabolic care and critical care nutrition.

RECENT FINDINGS

Recent research has demonstrated unknown consequences of high protein and amino acid administration in the early phase of ICU stay associated with dysregulated glucagon release leading to hepatic amino acid breakdown and suggested adverse effects on autophagy and long-term outcome. Progress has been made to measure body composition in the ICU. Refeeding hypophosphatemia and refeeding syndrome are common during critical illness, phosphate monitoring is essential after the start of nutrition therapy, and caloric restriction is recommendable in these patients.In recent studies, enteral nutrition is no longer superior to parenteral nutrition and signals of harm using the enteral route in shock have been suggested. However, during extracorporeal life support, enteral nutrition seems well tolerated. Intermittent or bolus enteral feeding seems an exciting concept concerning its potential anabolic effects. Studies on vitamin C, thiamine, and corticosteroid combinations suggest potential to improve outcome.

SUMMARY

These new findings will probably change the practice of metabolic and nutrition therapy in critical illness and challenge paradigms advocated for long.

Exploring the Potential Effectiveness of Combining Optimal Nutrition With Electrical Stimulation to Maintain Muscle Health in Critical Illness: A Narrative Review

Muscle wasting occurs rapidly within days of an admission to the intensive care unit (ICU). Concomitant muscle weakness and impaired physical functioning can ensue, with lasting effects well after hospital discharge. Early physical rehabilitation is a promising intervention to minimize muscle weakness and physical dysfunction. However, there is an often a delay in commencing active functional exercises (such as sitting on the edge of bed, standing and mobilizing) due to sedation, patient alertness, and impaired ability to cooperate in the initial days of ICU admission. Therefore, there is high interest in being able to intervene early through nonvolitional exercise strategies such as electrical muscle stimulation (EMS). Muscle health characterized as the composite of muscle quantity, as well as functional and metabolic integrity, may be potentially maintained when optimal nutrition therapy is provided in complement with early physical rehabilitation in critically ill patients; however, the type, dosage, and timing of these interventions are unclear. This article explores the potential role of nutrition and EMS in maintaining muscle health in critical illness. Within this article, we will evaluate fundamental concepts of muscle wasting and evaluate the effects of EMS, as well as the effects of nutrition therapy on muscle health and the clinical and functional outcomes in critically ill patients. We will also highlight current research gaps in order to advance the field forward in this important area.