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

Dynamic assessment of prealbumin for nutrition support effectiveness in critically ill patients

BACKGROUND & AIMS

Serum prealbumin is considered to be a sensitive predictor of clinical outcomes and a quality marker for nutrition support. However, its susceptibility to inflammation restricts its usage in critically ill patients according to current guidelines. We assessed the performance of the initial value of prealbumin and dynamic changes for predicting the ICU mortality and the effectiveness of nutrition support in critically ill patients.

METHODS

This monocentric study included patients admitted to the ICU between 2009 and 2016, having at least one initial prealbumin value available. Prospectively recorded data were extracted from the electronic ICU charts. We used both univariable and multivariable logistic regressions to estimate the performance of prealbumin for the prediction of ICU mortality. Additionally, the association between prealbumin dynamic changes and nutrition support was assessed via a multivariable linear mixed-effects model and multivariable linear regression. Performing subgroup analysis assisted in identifying patients for whom prealbumin dynamic assessment holds specific relevance.

RESULTS

We included 3136 patients with a total of 4942 prealbumin levels available. Both prealbumin measured at ICU admission (adjusted odds-ratio (aOR) 0.04, confidence interval (CI) 95% 0.01-0.23) and its change over the first week (aOR 0.02, CI 95 0.00-0.19) were negatively associated with ICU mortality. Throughout the entire ICU stay, prealbumin dynamic changes were associated with both cumulative energy (estimate: 33.2, standard error (SE) 0.001, p < 0.01) and protein intakes (1.39, SE 0.001, p < 0.01). During the first week of stay, prealbumin change was independently associated with mean energy (6.03e-04, SE 2.32e-04, p < 0.01) and protein intakes (1.97e-02, SE 5.91e-03, p < 0.01). Notably, the association between prealbumin and energy intake was strongest among older or malnourished patients, those suffering from increased inflammation and those with high disease severity. Finally, prealbumin changes were associated with a positive mean nitrogen balance at day 7 only in patients with SOFA <4 (p = 0.047).

CONCLUSION

Prealbumin measured at ICU admission and its change during the first-week serve as an accurate predictor of ICU mortality. Prealbumin dynamic assessment may be a reliable tool to estimate the effectiveness of nutrition support in the ICU, especially among high-risk patients.

Nutrition in the intensive care unit: from the acute phase to beyond

Recent randomized controlled trials (RCTs) have shown no benefit but  dose-dependent harm by early full nutritional support in critically ill patients. Lack of benefit may be explained by anabolic resistance, suppression of cellular repair processes, and aggravation of hyperglycemia and insulin needs. Also early high amino acid doses did not provide benefit, but instead associated with harm in patients with organ dysfunctions. However, most studies focused on nutritional interventions initiated during the first days after intensive care unit admission. Although the intervention window of some RCTs extended into the post-acute phase of critical illness, no large RCTs studied nutritional interventions initiated beyond the first week. Hence, clear evidence-based guidance on when and how to initiate and advance nutrition is lacking. Prolonged underfeeding will come at a price as there is no validated metabolic monitor that indicates readiness for medical nutrition therapy, and an adequate response to nutrition, which likely varies between patients. Also micronutrient status cannot be assessed reliably, as inflammation can cause redistribution, so that plasma micronutrient concentrations are not necessarily reflective of total body stores. Moreover, high doses of individual micronutrients have not proven beneficial. Accordingly, current evidence provides clear guidance on which nutritional strategies to avoid, but the ideal nutritional regimen for individual patients remains unclear. In this narrative review, we summarize the findings of recent studies, discuss possible mechanisms explaining the results, point out pitfalls in interpretation of RCTs and their effect on clinical practice, and formulate suggestions for future research.

Nutritional support in the cardiac intensive care unit

Optimal care of critically ill patients in the cardiac intensive care unit includes adequate nutritional support. This review highlights the high prevalence of malnutrition in acute heart failure, acute coronary syndrome, cardiogenic shock, and post-cardiac arrest and its adverse impact on prognosis. There is a lack of robust evidence regarding appropriate nutritional support in this patient population. Initiation of nutritional support with a comprehensive assessment of the patient's nutritional status is critical. High-risk cardiac patients who are not critically ill can receive oral nutrition adapted to individual risk factors or deficiencies, although overfeeding should be avoided in the acute phase. For critically ill patients at risk of or with malnutrition on admission, general principles include initiation of nutritional support within 48 h of admission, preference for enteral over parenteral nutrition, preference for hypocaloric nutrition in the first week of intensive care unit admission, and adequate micronutrient supplementation. Enteral nutrition in haemodynamically unstable patients carries a risk, albeit low, of intestinal ischaemia. In the case of malnutrition, the risk of refeeding syndrome should always be considered.

Plasma beta-hydroxy-beta-methylbutyrate availability after enteral administration during critical illness after trauma: An exploratory study

BACKGROUND

During critical illness skeletal muscle wasting occurs rapidly. Although beta-hydroxy-beta-methylbutyrate (HMB) is a potential treatment to attenuate this process, the plasma appearance and muscle concentration is uncertain.

METHODS

This was an exploratory study nested within a blinded, parallel group, randomized clinical trial in which critically ill patients after trauma received enteral HMB (3 g daily) or placebo. Plasma samples were collected at 0, 60, and 180 min after study supplement administration on day 1. Needle biopsies of the vastus lateralis muscle were collected (baseline and day 7 of the HMB treatment intervention period). An external standard curve was used to calculate HMB concentrations in plasma and muscle.

RESULTS

Data were available for 16 participants (male n = 12 (75%), median [interquartile range] age 50 [29-58] years) who received placebo and 18 participants (male n = 14 (78%), age 49 [34-55] years) who received HMB. Plasma HMB concentrations were similar at baseline but increased after HMB (T = 60 min: placebo 0.60 [0.44-1.31]  µM; intervention 51.65 [22.76-64.72]  µM). Paired muscle biopsies were collected from 11 participants (placebo n = 7, HMB n = 4). Muscle HMB concentrations were similar at baseline between groups (2.35 [2.17-2.95]; 2.07 [1.78-2.31] µM). For participants in the intervention group who had the repeat biopsy within 4 h of HMB administration, concentrations were greater (7.2 and 12.3 µM) than those who had the repeat biopsy >4 h after HMB (2.7 and 2.1 µM).

CONCLUSION

In this exploratory study, enteral HMB administration increased plasma HMB availability. The small sample size limits interpretation of the muscle HMB findings.

Navigating Nutritional Strategies: Permissive Underfeeding in Critically Ill Patients

Nutritional support is a critical component of care for critically ill patients, impacting their recovery and overall prognosis. Traditional approaches to feeding in the intensive care unit (ICU) have focused on meeting estimated energy requirements, often resulting in unintended consequences such as overfeeding and associated complications. Permissive underfeeding, a concept gaining attention recently, offers a more controlled approach by intentionally providing fewer calories than traditionally recommended. This comprehensive review explores the rationale, evidence, and practical considerations surrounding permissive underfeeding in critically ill patients. We discuss the physiological basis of permissive underfeeding, its potential benefits in mitigating the risks of overfeeding, and the challenges associated with implementation in clinical practice. Through an analysis of critical studies and clinical trials, we evaluate the comparative effectiveness of permissive underfeeding versus traditional feeding methods and examine its impact on patient outcomes. Recommendations for patient selection, monitoring, and future research directions are provided to guide clinicians in optimizing nutritional support strategies for critically ill individuals. By considering the role of permissive underfeeding alongside traditional feeding approaches, healthcare professionals can tailor nutritional interventions to individual patient needs, ultimately improving outcomes in the ICU.

Protein loss and glucose absorption in children with AKI treated with peritoneal dialysis

BACKGROUND

Protein loss and glucose absorption in children on acute peritoneal dialysis (PD) is important to inform dietary prescription, yet data are lacking in this regard. This study was a secondary analysis of a previously published crossover randomised controlled trial, aiming to describe glucose uptake and protein loss into dialysate among children with acute kidney injury (AKI) receiving PD.

METHODS

This secondary analysis described and compared dialysate albumin loss and glucose absorption in 15 children with AKI receiving PD or continuous flow peritoneal dialysis (CFPD). In addition, correlations between albumin loss, glucose absorption and other patient and dialysis factors were analysed.

RESULTS

Median (range) age and weight of participants were 6.0 (0.2-14) months and 5.8 (2.3-14.0) kg, respectively. Patients received approximately 8 h of dialysis on each modality; however, results were extrapolated and expressed per day. The mean ± SD albumin loss on conventional PD and CFPD was 0.3 ± 0.19 g/kg/day and 0.56 ± 0.5 g/kg/day, respectively, and the mean ± SD glucose absorption was 4.67 ± 2.87 g/kg/day and 3.85 ±4.1 g/kg/day, respectively. There was a moderate correlation between ultrafiltration and albumin loss during CFPD only (Pearson's R = 0.61; p = 0.02). There were no significant differences between PD and CFPD for either glucose absorption or albumin loss; however, the study was not powered for this outcome.

CONCLUSIONS

Protein losses and glucose absorption in children on PD with AKI are significant and should be considered when prescribing nutritional content. Protein losses on CFPD were twice as high as on conventional PD.

Abnormal DNA methylation within HPA-axis genes years after paediatric critical illness

BACKGROUND

Critically ill children suffer from impaired physical/neurocognitive development 2 years later. Glucocorticoid treatment alters DNA methylation within the hypothalamus-pituitary-adrenal (HPA) axis which may impair normal brain development, cognition and behaviour. We tested the hypothesis that paediatric-intensive-care-unit (PICU) patients, sex- and age-dependently, show long-term abnormal DNA methylation within the HPA-axis layers, possibly aggravated by glucocorticoid treatment in the PICU, which may contribute to the long-term developmental impairments.

RESULTS

In a pre-planned secondary analysis of the multicentre PEPaNIC-RCT and its 2-year follow-up, we identified differentially methylated positions and differentially methylated regions within HPA-axis genes in buccal mucosa DNA from 818 former PICU patients 2 years after PICU admission (n = 608 no glucocorticoid treatment; n = 210 glucocorticoid treatment) versus 392 healthy children and assessed interaction with sex and age, role of glucocorticoid treatment in the PICU and associations with long-term developmental impairments. Adjusting for technical variation and baseline risk factors and correcting for multiple testing (false discovery rate < 0.05), former PICU patients showed abnormal DNA methylation of 26 CpG sites (within CRHR1, POMC, MC2R, NR3C1, FKBP5, HSD11B1, SRD5A1, AKR1D1, DUSP1, TSC22D3 and TNF) and three DNA regions (within AVP, TSC22D3 and TNF) that were mostly hypomethylated. These abnormalities were sex-independent and only partially age-dependent. Abnormal methylation of three CpG sites within FKBP5 and one CpG site within SRD5A1 and AKR1D1 was partly attributable to glucocorticoid treatment during PICU stay. Finally, abnormal methylation within FKBP5 and AKR1D1 was most robustly associated with long-term impaired development.

CONCLUSIONS

Two years after critical illness in children, abnormal methylation within HPA-axis genes was present, predominantly within FKBP5 and AKR1D1, partly attributable to glucocorticoid treatment in the PICU, and explaining part of the long-term developmental impairments. These data call for caution regarding liberal glucocorticoid use in the PICU.

Impact of daily cyclic enteral nutrition versus standard continuous enteral nutrition in critically ill patients: a study protocol for a randomised controlled trial in three intensive care units in France (DC-SCENIC)

INTRODUCTION

Current guidelines on clinical nutrition of ventilated patients in the intensive care unit (ICU) recommend initiating continuous enteral nutrition within 48 hours of ICU admission when feasible. However, discontinuous feeding regimens, alternating feeding and fasting intervals, may have an impact on clinical and patient centred outcomes. The ongoing "Impact of daily cyclic enteral nutrition versus standard continuous enteral nutrition in critically ill patients" (DC-SCENIC) trial aims to compare standard continuous enteral feeding with daily cyclic enteral feeding over 10 hours to evaluate if implementing a fasting-mimicking diet can decrease organ failure in ventilated patients during the acute phase of ICU management.

METHODS AND ANALYSIS

DC-SCENIC is a randomised, controlled, multicentre, open-label trial comparing two parallel groups of patients 18 years of age or older receiving invasive mechanical ventilation and having an indication for enteral nutrition through a gastric tube. Enteral feeding is continuous in the control group and administered over 10 hours daily in the intervention group. Both groups receive isocaloric nutrition with 4 g of protein per 100 mL, and have the same 20 kcal/kg/day caloric target. The primary endpoint is the change in the Sequential Organ Failure Assessment score at 7 days compared with the day of inclusion in the study. Secondary outcomes include daily caloric and protein delivery, digestive, respiratory and metabolic tolerance as well as 28-day mortality, duration of mechanical ventilation and ventilator-free days. Outcomes will be analysed on an intention-to-treat basis. Recruitment started in June 2023 in 3 French ICU's and a sample size of 318 patients is expected by February 2026.

ETHICS AND DISSEMINATION

This study received approval from the national ethics review board on 8 November 2022 (Comité de Protection des Personnes Sud-Est VI, registration number 2022-A00827-36). Patients are included after informed consent. Results will be submitted for publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05627167.

Association between urea trajectory and protein dose in critically ill adults: a secondary exploratory analysis of the effort protein trial (RE-EFFORT)

BACKGROUND

Delivering higher doses of protein to mechanically ventilated critically ill patients did not improve patient outcomes and may have caused harm. Longitudinal urea measurements could provide additional information about the treatment effect of higher protein doses. We hypothesised that higher urea values over time could explain the potential harmful treatment effects of higher doses of protein.

METHODS

We conducted a reanalysis of a randomised controlled trial of higher protein doses in critical illness (EFFORT Protein). We applied Bayesian joint models to estimate the strength of association of urea with 30-day survival and understand the treatment effect of higher protein doses.

RESULTS

Of the 1301 patients included in EFFORT Protein, 1277 were included in this analysis. There were 344 deaths at 30 days post-randomisation. By day 6, median urea was 2.1 mmol/L higher in the high protein group (95% CI 1.1-3.2), increasing to 3.0 mmol/L (95% CI 1.3-4.7) by day 12. A twofold rise in urea was associated with an increased risk of death at 30 days (hazard ratio 1.34, 95% credible interval 1.21-1.48), following adjustment of baseline characteristics including age, illness severity, renal replacement therapy, and presence of AKI. This association persisted over the duration of 30-day follow-up and in models adjusting for evolution of organ failure over time.

CONCLUSIONS

The increased risk of death in patients randomised to a higher protein dose in the EFFORT Protein trial was estimated to be mediated by increased urea cycle activity, of which serum urea is a biological signature. Serum urea should be taken into consideration when initiating and continuing protein delivery in critically ill patients.

CLINICALTRIALS

gov Identifier: NCT03160547 (2017-05-17).

A Narrative Review: Analysis of Supplemental Parenteral Nutrition in Adults at the End of Life

"End of life" is a stage defined by the existence of an irreversible prognosis that ends with a person's death. One of the aspects of interest regarding end of life focuses on parenteral nutrition, which is usually administered in order to avoid malnutrition and associated complications. However, parenteral nutrition can be adapted to specific circumstances and evolve in its functionality through supplementation with certain nutrients that can have a beneficial effect. This narrative review aims to carry out a situation analysis of the role that could be adopted by supplemental parenteral nutrition in attenuating alterations typical of end of life and potential improvement in quality of life.

Impact of critical illness on cholesterol and fatty acids: insights into pathophysiology and therapeutic targets

Critical illness is characterized by a hypercatabolic response encompassing endocrine and metabolic alterations. Not only the uptake, synthesis and metabolism of glucose and amino acids is majorly affected, but also the homeostasis of lipids and cholesterol is altered during acute and prolonged critical illness. Patients who suffer from critically ill conditions such as sepsis, major trauma, surgery or burn wounds display an immediate and sustained reduction in low plasma LDL-, HDL- and total cholesterol concentrations, together with a, less pronounced, increase in plasma free fatty acids. The severity of these alterations is associated with severity of illness, but the underlying pathophysiological mechanisms are multifactorial and only partly clarified. This narrative review aims to provide an overview of the current knowledge of how lipid and cholesterol uptake, synthesis and metabolism is affected during critical illness. Reduced nutritional uptake, increased scavenging of lipoproteins as well as an increased conversion to cortisol or other cholesterol-derived metabolites might all play a role in the decrease in plasma cholesterol. The acute stress response to critical illness creates a lipolytic cocktail, which might explain the increase in plasma free fatty acids, although reduced uptake and oxidation, but also increased lipogenesis, especially in prolonged critical illness, will also affect the circulating levels. Whether a disturbed lipid homeostasis warrants intervention or should primarily be interpreted as a signal of severity of illness requires further research.

Body composition and muscle strength at the end of ICU stay are associated with 1-year mortality, a prospective multicenter observational study

BACKGROUND & AIMS

After a prolonged intensive care unit (ICU) stay patients experience increased mortality and morbidity. The primary aim of this study was to assess the prognostic value of nutritional status, body mass composition and muscle strength, as assessed by body mass index (BMI), bioelectrical impedance analysis (BIA), handgrip (HG) test, and that of the biological features to predict one-year survival at the end of a prolonged ICU stay.

METHODS

This was a multicenter prospective observational study. Survivor patients older than 18 years with ICU length of stay >72 h were eligible for inclusion. BIA and HG were performed at the end of the ICU stay. Malnutrition was defined by BMI and fat-free mass index (FFMI). The primary endpoint was one-year mortality. Multivariable logistic regression was performed to determine parameters associated with mortality.

RESULTS

572 patients were included with a median age of 63 years [53.5; 71.1], BMI of 26.6 kg/m2 [22.8; 31.3], SAPS II score of 43 [31; 58], and ICU length of stay of 9 days [6; 15]. Malnutrition was observed in 142 (24.9%) patients. During the 1-year follow-up after discharge, 96 (18.5%) patients died. After adjustment, a low HG test score (aOR = 1.44 [1.11; 1.89], p = 0.01) was associated with 1-year mortality. Patients with low HG score, malnutrition, and Albuminemia <30 g/L had a one-year death rate of 41.4%. Conversely, patients with none of these parameters had a 1-year death rate of 4.1%.

CONCLUSION

BIA to assess FFMI, HG and albuminemia at the end of ICU stay could be used to predict 1-year mortality. Their ability to identify patients eligible for a structured recovery program could be studied.

How to avoid harm with feeding critically ill patients: a synthesis of viewpoints of a basic scientist, dietitian and intensivist

The optimal feeding strategy in critically ill patients is a matter of debate, with current guidelines recommending different strategies regarding energy and protein targets. Several recent trials have added to the debate and question our previous understanding of the provision of nutrition during critical illness. This narrative review aims to provide a summary of interpretation of recent evidence from the view of basic scientist, critical care dietitian and intensivist, resulting in joined suggestions for both clinical practice and future research. In the most recent randomised controlled trial (RCT), patients receiving 6 versus 25 kcal/kg/day by any route achieved readiness for ICU discharge earlier and had fewer GI complications. A second showed that high protein dosage may be harmful in patients with baseline acute kidney injury and more severe illness. Lastly, a prospective observational study using propensity score matched analysis suggested that early full feeding, especially enteral, compared to delayed feeding is associated with a higher 28-day mortality. Viewpoints from all three professionals point to the agreement that early full feeding is likely harmful, whereas important questions regarding the mechanisms of harm as well as on timing and optimal dose of nutrition for individual patients remain unanswered and warrant future studies. For now, we suggest giving low dose of energy and protein during the first few days in the ICU and apply individualised approach based on assumed metabolic state according to the trajectory of illness thereafter. At the same time, we encourage research to develop better tools to monitor metabolism and the nutritional needs for the individual patient accurately and continuously.

Metabolic Support in Acute Respiratory Distress Syndrome: A Narrative Review

Nutritional support for acute respiratory distress syndrome (ARDS) patients shares metabolic notions common to other critically ill conditions. Nevertheless, it generates specific concern regarding the primary limitation of oxygen supply and the complications of carbon dioxide elimination, as well as the significant metabolic alterations due to the body's response to illness. In the present narrative review, after briefly summarizing the pathophysiology of critical illness stress response and patients' metabolic requirements, we focus on describing the characteristics of metabolic and artificial nutrition in patients with acute respiratory failure. In patients with ARDS, several aspects of metabolism assume special importance. The physiological effects of substrate metabolism are described for this setting, particularly regarding energy consumption, diet-induced thermogenesis, and the price of their clearance, transformation, and storage. Moreover, we review the possible direct effects of macronutrients on lung tissue viability during ARDS. Finally, we summarize the noteworthy characteristics of metabolic control in critically ill patients with ARDS and offer a suggestion as to the ideal methods of metabolic support for this problem.