Autophagy and Its Implications Against Early Full Nutrition Support in Critical Illness

Association of energy delivery with short-term survival in mechanically ventilated critically ill adult patients: a secondary analysis of the NEED trial

BACKGROUND AND AIMS

The optimal energy delivery for mechanically ventilated patients is controversial, particularly during the first week of ICU admission. This study aimed to investigate the association between different caloric adequacy and 28-day mortality in a cohort of critically ill adults on mechanical ventilation.

METHODS

This is a secondary analysis of a multicenter, cluster-randomized controlled trial. Eligible patients were divided into four quartiles (Q1-Q4) according to caloric adequacy calculated by the actual average daily energy delivery during the first seven days of ICU stay divided by energy requirement as a percentage. Cox proportional hazards models were used to examine the impact of different quartiles of caloric adequacy on 28-day mortality in the whole cohort and subgroups with different nutritional risk status at enrollment.

RESULTS

A total of 1587 patients were included in this study, with an overall 28-day mortality of 15.8%. The average caloric adequacy was 26.3 ± 11.9% (Q1), 52.5 ± 5.5% (Q2), 71.7 ± 6.4% (Q3), 107.0 ± 22.2% (Q4), respectively (p < 0.001 among quartiles). Compared with Q1, Q3 was associated with lower mortality in the unadjusted model (hazard ratio [HR] = 0.536; 95% confidence interval [CI], 0.375-0.767; P = 0.001) and adjusted model (adjusted HR = 0.508; 95% CI, 0.339-0.761; P = 0.001). This association remained valid in the subgroup of high nutritional risk patients (unadjusted HR = 0.387; 95% CI, 0.238-0.627; P < 0.001 and adjusted HR = 0.369; 95% CI, 0.216-0.630; P < 0.001, respectively), but not in those with low risk.

CONCLUSIONS

Energy delivery near the 70% energy requirements in the first week of ICU stay was associated with reduced 28-day mortality among mechanically ventilated critically ill patients, especially in patients with high nutrition risk at admission.

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.

Females have a different metabolic response to critical illness, measured by comprehensive amino acid flux analysis

BACKGROUND

The trajectory from healthy to critical illness is influenced by numerous factors, including metabolism, which differs substantially between males and females. Whole body protein breakdown is substantially increased in critically ill patients, but it remains unclear whether there are sex differences that could explain the different health outcomes. Hence, we performed a secondary analysis of a study, where we used a novel pulse isotope method in critically ill and matched healthy males and females.

METHODS

In 51 critically ill ICU patients (26 males, 15 females) and 49 healthy controls (36 males and 27 females), we assessed their general and disease characteristics and collected arterial(ized) blood in the postabsorptive state after pulse administration of 8 ml of a solution containing 18 stable AA tracers. In contrast to the original study, we now fitted the decay curves and calculated non-compartmental whole body amino acid production (WBP) and compartmental measurements of metabolism, including intracellular amino acid production. We measured amino acid enrichments and concentrations by LC-MS/MS and derived statistics using AN(C)OVA.

RESULTS

Critically ill males and females showed an increase in the WBP of many amino acids, including those related to protein breakdown, but females showed greater elevations, or in the event of a reduction, attenuated reductions. Protein breakdown-independent WBP differences remained between males and females, notably increased glutamine and glutamate WBP. Only severely ill females showed a lower increase in WBP of many amino acids in comparison to moderately ill females, suggesting a suppressed metabolism. Compartmental analysis supported the observations.

CONCLUSIONS

The present study shows that females have a different response to critical illness in the production of several amino acids and changes in protein breakdown, observations made possible using our innovative stable tracer pulse approach.

CLINICAL TRIAL REGISTRY

Data are from the baseline measurements of study NCT02770092 (URL: https://clinicaltrials.gov/ct2/show/NCT02770092) and NCT03628365 (URL: https://clinicaltrials.gov/ct2/show/NCT03628365).

Surgery-Related Muscle Loss after Pancreatic Resection and Its Association with Postoperative Nutritional Intake

To study the occurrence of surgery-related muscle loss (SRML) and its association with in-hospital nutritional intake, we conducted a prospective observational cohort study including patients who underwent pancreatic surgery because of (suspected) malignant diseases. Muscle diameter was measured by using bedside ultrasound 1 day prior to surgery and 7 days postoperatively. Clinically relevant SRML was defined as ≥10% muscle diameter loss in minimally one arm and leg muscle within 1 week after surgery. Protein and caloric intake was measured by nutritional diaries. The primary endpoint included the number of patients with SRML. Secondary endpoints included the association between SRML and postoperative nutritional intake. Of the 63 included patients (60.3% men; age 67.1 ± 10.2 years), a total of 24 patients (38.1%) showed SRML. No differences were observed in severe complication rate or length of hospital stay between patients with and without SRML. During the first postoperative week, patients with clinically relevant SRML experienced more days without any nutritional intake compared with the non-SRML group (1 [0-4] versus 0 [0-1] days, p = 0.007). Significantly lower nutritional intake was found in the SRML group at postoperative days 2, 3 and 5 (p < 0.05). Since this study shows that SRML occurred in 38.1% of the patients and most of the patients failed to reach internationally set nutritional goals, it is suggested that more awareness concerning direct postoperative nutritional intake is needed in our surgical community.

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.

Association between body mass index change and mortality in critically ill patients: A retrospective observational study

OBJECTIVE

Previous studies have emphasized the association between baseline body mass index (BMI) and mortality in patients during a stay in the intensive care unit (ICU). However, to our knowledge, few studies have focused on BMI change during an ICU stay. The aim of this study was to explore the prognostic value of BMI change during ICU hospitalization.

METHODS

This was a multicenter, retrospective cohort study with data extracted from the eICU Collaborative Research Database. Logistic regression models were used to explore the relationship between BMI change and mortality in ICU patients. BMI change was calculated as follows: {[discharge ICU weight (kg) - admission ICU weight (kg)] / height (m)²]}. Interaction and subgroup analyses were conducted for patients grouped with baseline BMI on ICU admission (≥30 versus 25-29.9 versus <25 kg/m²), Acute Physiology and Chronic Health Evaluation (APACHE) IV score (<53 versus ≥53), and ICU length of stay (≥3 versus <3 d).

RESULTS

Compared with those with weight loss (n = 17 134), patients with weight gain during ICU hospitalization (n = 17 436) were associated with higher hospital mortality (odds ratio [OR], 1.251; 95% confidence interval [CI], 1.155-1.356; P < 0.001) and ICU mortality (OR, 1.360; 95% CI, 1.227-1.506; P < 0.001) after multivariable adjustment. The associations remained robust in patients with different baseline BMI levels and were especially remarkable among those with higher APACHE IV score and the longer ICU stay.

CONCLUSIONS

The present study exposed the potential hazard of increasing BMI for hospital and ICU mortalities during ICU hospitalization and indicating that patients in the ICU may benefit from a more balanced nutritional strategy.

When is enteral nutrition indicated?

Enteral nutrition (EN) is a vital component of nutrition around the world. EN allows for delivery of nutrients to those who cannot maintain adequate nutrition by oral intake alone. Common questions regarding EN are when to initiate and in what scenarios it is safe. The answers to these questions are often complex and require an evidence-based approach. The Board of Directors of the American Society for Parenteral and Enteral Nutrition (ASPEN) established an Enteral Nutrition Committtee to address the important questions surrounding the indications for EN. Consensus recommendations were established based on eight extremely clinically relevant questions regarding EN indications as deemed by the Enteral Nutrition Committee. These consensus recommendations may act as a guide for clinicians and stakeholders on difficult questions pertaining to indications for EN. This paper was approved by the ASPEN Board of Directors.

Enteral feeding, even when the gut does not feel very good?

PURPOSE OF REVIEW

To summarize knowledge on the gut function in relation to enteral nutrition.

RECENT FINDINGS

The gut is certainly suffering during critical illness but our understanding of the exact mechanisms involved is limited. Physicians at bedside are lacking tools to identify how well or bad the gut is doing and whether the gut is responding adequately to critical illness. Sensing nutrition as a signal is important for the gut and microbiome. Enteral nutrition has beneficial effects for the gut perfusion and function. However, early full enteral nutrition in patients with shock was associated with an increased number of rare but serious complications.

SUMMARY

Whenever synthesizing knowledge in physiology and available evidence in critically ill, we suggest that enteral nutrition has beneficial effects but may turn harmful if provided too aggressively. Contraindications to enteral nutrition are listed in recent guidelines. For patients with gastrointestinal dysfunction but without these contraindications, we suggest considering early enteral nutrition as a signal to the gut and to the body rather than an energy and protein provision. With this rationale, we think that low dose of enteral nutrition could and probably should be provided also when the gut does not feel very good. Understanding the feedback from the gut in response to enteral nutrition would be important, however, monitoring tools are currently limited to clinical assessment only.

Nutrition priorities in obese critically ill patients

PURPOSE OF REVIEW

During critical illness, several neuroendocrine, inflammatory, immune, adipokine, and gastrointestinal tract hormone pathways are activated; some of which are more intensified among obese compared with nonobese patients. Nutrition support may mitigate some of these effects. Nutrition priorities in obese critically ill patients include screening for nutritional risk, estimation of energy and protein requirement, and provision of macronutrients and micronutrients.

RECENT FINDINGS

Estimation of energy requirement in obese critically ill patients is challenging because of variations in body composition among obese patients and absence of reliable predictive equations for energy expenditure. Whereas hypocaloric nutrition with high protein has been advocated in obese critically ill patients, supporting data are scarce. Recent studies did not show differences in outcomes between hypocaloric and eucaloric nutrition, except for better glycemic control. Sarcopenia is common among obese patients, and the provision of increased protein intake has been suggested to mitigate catabolic changes especially after the acute phase of critical illness. However, high-quality data on high protein intake in these patients are lacking. Micronutrient deficiencies among obese critically ill patients are common but the role of their routine supplementation requires further study.

SUMMARY

An individualized approach for nutritional support may be needed for obese critically ill patients but high-quality evidence is lacking. Future studies should focus on nutrition priorities in this population, with efficient and adequately powered studies.

Nutritional Support Protocol for patients with COVID-19

Background & aims

COVID-19 is a hypercatabolic disease with possible pulmonary and gastrointestinal symptoms, and consequent deterioration of the nutritional status and the worst clinical prognosis. This study presents a protocol to guide the nutritional care of adult and elderly people non-critically and critically ill with COVID-19.

Methods

A critical review of the literature was carried out in the databases PubMed, Scielo, Bireme, and Science Direct, in search of articles and guidelines that presented assessment criteria and nutritional conduct for COVID-19 and Severe Acute Respiratory Syndrome (SARS), as well as guidelines for managing the symptoms presented by patients.

Results

The results are recommendations based on the literature and the professional experience of nutritionists who provide nutritional assistance to individuals hospitalized with COVID-19 since the beginning of the pandemic in Brazil. We present tools and suggestions for assessing the nutritional status, calculating nutritional needs, initiating nutritional therapy and monitoring tolerance to it, nutritional monitoring during hospitalization, and guidelines for hospital discharge.

Conclusion

Patients with COVID-19 are at nutritional risk. A complete nutritional assessment (anthropometric, dietary, and laboratory assessment) enables the establishment of an individualized nutritional approach in order to contribute to better clinical and nutritional prognoses.

How much underfeeding can the critically ill adult patient tolerate?

Critical illness leads to significant metabolic alterations that should be considered when providing nutritional support. Findings from key randomized controlled trials (RCTs) indicate that underfeeding (<70% of energy expenditure [EE]) during the acute phase of critical illness (first 7 days of intensive care unit [ICU] admission) may not be harmful and could instead promote autophagy and prevent overfeeding in light of endogenous energy production. However, the optimal energy target during this period is unclear and full starvation is unlikely to be beneficial. There are limited data regarding the effects of prolonged underfeeding on clinical outcomes in critically ill patients, but recent studies show that oral food intake is suboptimal both in the ICU and following discharge to the acute care setting. It is hypothesized that provision of full nutrition (70-100% of EE) may be important in the recovery phase of critical illness (>7 days of ICU admission) for promoting recovery and rehabilitation; however, studies on nutritional intervention delivered from ICU admission through hospital discharge are needed. The aim of this review is to provide a narrative synthesis of the existing literature on metabolic alterations experienced during critical illness and the impact of underfeeding on clinical outcomes in the critically ill adult patient.

Nutrition support for critically ill patients

Nutrition support is an important aspect of the management of critically ill patients. This review highlights the emerging evidence on critical care nutrition and focuses on the pathophysiologic interplay between critical illness, the gastrointestinal tract, and nutrition support and the evidence on the best route, dose, and timing of nutrition. Although indirect calorimetry is recommended to measure energy expenditure, predictive equations are commonly used but are limited by their inaccuracy in individual patients. The current evidence supports early enteral nutrition (EN) in most patients, with a gradual increase in the daily dose over the first week. Delayed EN is warranted in patients with severe shock. According to recent trials, parenteral nutrition seems to be as effective as EN and may be started if adequate EN is not achieved by the first week of critical illness. A high protein dose has been recommended, but the best timing is unclear. Immuno-nutrition should not be routinely provided to critically ill patients. Patients receiving artificial nutrition should be monitored for metabolic derangements. Additional adequately powered studies are still needed to resolve many unanswered questions.

Role of ketones, ketogenic diets and intermittent fasting in ICU

PURPOSE OF REVIEW

To summarize the clinical evidence for beneficial effects of ketones, ketogenic diets and intermittent fasting in critical illness, and to review potential mechanisms behind such effects.

RECENT FINDINGS

Recent evidence demonstrates that activation of a metabolic fasting response may be beneficial to recover from critical insults. Potential protective mechanisms are, among others, activation of ketogenesis and of damage removal by autophagy. Novel feeding strategies, including ketone supplements, ketogenic diets and intermittent fasting regimens, can activate these pathways - at least partially - in critically ill patients. Randomized controlled trials (RCTs) studying these novel feeding strategies as compared with standard care, are scarce and have not shown consistent benefit. Yet, all RCTs were small and underpowered for clinical endpoints. Moreover, in intermittent fasting studies, the duration of the fasting interval may have been too short to develop a sustained metabolic fasting response.

SUMMARY

These findings open perspectives for the further development of fasting-mimicking diets. Ultimately, clinical benefit should be confirmed by RCTs that are adequately powered for clinically relevant, patient-centered endpoints.

Associations between early parenteral nutrition and in-hospital outcomes in underweight patients with gastrointestinal surgery

BACKGROUND & AIMS

Guidelines recommend early parenteral nutrition for malnourished patients. However, the effectiveness of early parenteral nutrition in underweight patients has not been established. This study aimed to determine whether in-hospital outcomes were associated with early parenteral nutrition in underweight gastrointestinal surgery patients with short-term contraindications to early enteral nutrition.

METHODS

We identified underweight adult gastrointestinal surgery patients with short-term contraindications to early enteral nutrition using the Japanese Diagnosis Procedure Combination database from July 2010 to March 2018. We performed propensity-score overlap weighting to compare in-hospital outcomes between patients with and without early parenteral nutrition. The primary outcome was length of hospital stay. The secondary outcomes were total hospitalization cost, hospital-acquired pneumonia, hospital-acquired urinary tract infection, central line-associated bloodstream infection, and all-cause 28-day in-hospital mortality.

RESULTS

We identified 31,898 eligible patients. Early parenteral nutrition was associated with longer hospital stay (19.2 vs. 18.4 days; difference, 0.7 days; 95% CI, 0.1 to 1.4). There were no differences between the patients with and without early parenteral nutrition in total hospitalization cost (difference, US$60; 95% CI, -277 to 397), hospital-acquired pneumonia (risk difference, -0.11%; 95% CI, -0.78 to 0.55), hospital-acquired urinary tract infection (risk difference, 0.03%; 95% CI, -0.08 to 0.14), central line-associated bloodstream infection (risk difference, 0.08%; 95% CI, -0.02 to 0.18), and all-cause 28-day in-hospital mortality (risk difference, 0.31%; 95% CI, -0.07 to 0.69).

CONCLUSIONS

Early parenteral nutrition for underweight gastrointestinal surgery patients with short-term contraindications to early enteral nutrition was associated with longer hospital stay.

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.

Nutrition in the critically ill surgical patient

PURPOSE OF REVIEW

The aim of this study was to discuss recent findings related to providing adequate and well tolerated nutrition to the critically ill surgical patient.

RECENT FINDINGS

The majority of nutritional studies in the critically ill have been performed on well nourished patients, but validated scoring systems can now identify high nutrition risk patients. Although it remains well accepted that early enteral nutrition with protein supplementation is key, mechanistic data suggest that hypocaloric feeding in septic patients may be beneficial. For critically ill patients unable to tolerate enteral nutrition, randomized pilot data demonstrate improved functional outcomes with early supplemental parenteral nutrition. Current guidelines also recommend early total parenteral nutrition in high nutrition risk patients with contraindications to enteral nutrition. When critically ill patients require low or moderate-dose vasopressors, enteral feeding appears well tolerated based on a large database study, while randomized prospective data showed worse outcomes in patients receiving high-dose vasopressors.

SUMMARY

Current evidence suggests early enteral nutrition with protein supplementation in critically ill surgical patients with consideration of early parenteral nutrition in high nutrition risk patients unable to achieve nutrition goals enterally. Despite established guidelines for nutritional therapy, the paucity of data to support these recommendations illustrates the critical need for additional studies.

Low-Protein, Hypocaloric Nutrition with Glutamine versus Full-Feeding in the Acute Phase in ICU Patients with Severe Traumatic Brain Injury

OBJECTIVE

To investigate the 28-day mortality, the length of ICU stay, days in the hospital, days of ventilator use, adverse events, and nosocomial infection events of low-protein, hypocaloric nutrition with glutamine in the first 7 days of the intensive care unit (ICU) patients with severe traumatic brain injury (STBI).

PATIENTS AND METHODS

A total of 53 patients diagnosed with STBI enrolled from the third affiliated hospital of Nanchang University (Nanchang, China), from January 2019 to July 2020, were divided into two groups. We performed a randomized prospective controlled trial. The intervention group (n=27) was nutritional supported (intestinal or parenteral) with a caloric capacity of 20-40% of European Conference on Clinical Nutrition and Metabolism (ESPEN) recommendations; specifically, low-protein intake was 0.5-0.7g/kg per day (containing the amount of alanyl-glutamine), glutamine was 0.3 g/kg per day, and the intervention treatment lasted for 7 days. The control group (n=26) was nutritionally supported with a caloric capacity of 70-100% of ESPEN recommendations, and the protein intake was 1.2-1.7 g/kg per day. The primary endpoint was 28-day mortality. Secondary endpoints were the length of ICU stay, days in the hospital, days of ventilator use, adverse events and nosocomial infection events.

RESULTS

There were no differences in baseline characteristics between groups. Survival curve analysis using the Kaplan-Meier method revealed no significant difference in 28-day mortality between the two groups (P=0.31) while adverse events (χ ²= 5.853, P=0.016), nosocomial infection rate (χ ² = 4.316, P=0.038), the length of ICU stay (t=-2.617, P=0.012), hospitalization time (t=-2.169, P=0.036), and days of ventilator use (t=-2.144,P=0.037) of patients in the intervention group were significantly lower than those in the control group.

CONCLUSION

Low-protein, hypocaloric nutrition with glutamine did not show different outcomes in 28-day mortality compared to full-feeding nutritional support in the ICU patients with STBI. However, low-protein, hypocaloric nutrition with glutamine could provide a lower need for ICU time, hospitalization time, and ventilator time in the ICU patients with STBI.

Full Versus Trophic Feeds in Critically Ill Adults with High and Low Nutritional Risk Scores: A Randomized Controlled Trial

Although energy intake might be associated with clinical outcomes in critically ill patients, it remains unclear whether full or trophic feeding is suitable for critically ill patients with high or low nutrition risk. We conducted a prospective study to determine which feeding energy intakes were associated with clinical outcomes in critically ill patients with high or low nutrition risk. This was an investigator-initiated, single center, single blind, randomized controlled trial. Critically ill patients were allocated to either high or low nutrition risk based on their Nutrition Risk in the Critically Ill score, and then randomized to receive either the full or the trophic feeding. The feeding procedure was administered for six days. No significant differences were observed in hospital, 14-day and 28-day mortalities, the length of ventilator dependency, or ICU and hospital stay among the four groups. There were no associations between energy and protein intakes and hospital, 14-day and 28-day mortalities in any of the four groups. However, protein intake was positively associated with the length of hospital stay and ventilator dependency in patients with low nutrition risk receiving trophic feeding. Full or trophic feeding in critically ill patients showed no associations with clinical outcomes, regardless of nutrition risk.

The clinical potential of GDF15 as a "ready-to-feed indicator" for critically ill adults

Background

Circulating growth-differentiation factor-15 (GDF15), a cellular stress marker, abruptly increases during critical illness, but its later time course remains unclear. GDF15 physiologically controls oral intake by driving aversive responses to nutrition. Early parenteral nutrition (PN) in ICU patients has overall been shown not beneficial. We hypothesized that low GDF15 can identify patients who benefit from early PN, tolerate enteral nutrition (EN), and resume spontaneous oral intake.

Methods

In secondary analyses of the EPaNIC-RCT on timing of PN initiation (early PN versus late PN) and the prospective observational DAS study, we documented the time course of circulating GDF15 in ICU (N = 1128) and 1 week post-ICU (N = 72), compared with healthy subjects (N = 65), and the impact hereon of randomization to early PN versus late PN in propensity score-matched groups (N = 564/group). Interaction between upon-admission GDF15 and randomization for its outcome effects was investigated (N = 4393). Finally, association between GDF15 and EN tolerance in ICU (N = 1383) and oral intake beyond ICU discharge (N = 72) was studied.

Results

GDF15 was elevated throughout ICU stay, similarly in early PN and late PN patients, and remained high beyond ICU discharge (p < 0.0001). Upon-admission GDF15 did not interact with randomization to early PN versus late PN for its outcome effects, but higher GDF15 independently related to worse outcomes (p ≤ 0.002). Lower GDF15 was only weakly related to gastrointestinal tolerance (p < 0.0001) and a steeper drop in GDF15 with more oral intake after ICU discharge (p = 0.05).

Conclusion

In critically ill patients, high GDF15 reflected poor prognosis and may contribute to aversive responses to nutrition. However, the potential of GDF15 as “ready-to-feed indicator” appears limited.

Trial registration

ClinicalTrials.gov, NCT00512122, registered 31 July 2007, https://www.clinicaltrials.gov/ct2/show/NCT00512122 (EPaNIC trial) and ISRCTN, ISRCTN 98806770, registered 11 November 2014, http://www.isrctn.com/ISRCTN98806770 (DAS trial)

Effect of early activity combined with early nutrition on acquired weakness in ICU patients

INTRODUCTION

Intensive care unit-acquired weakness (ICU-AW) occurs in 25% to 100% of critically ill patients, and is associated with prolonged mechanical ventilation, extended ICU stay, and total hospital stay, increased hospital costs, higher risk of death, impaired physical function, and decreased quality of life. However, there are not any current guidelines that mention management of ICU-AW. The present study will evaluate the effects of a combination of early nutrition and early exercise compared to those of either early exercise alone or the standard care for patients in ICUs.

METHODS

This is a 3-arm, parallel, randomized controlled trial including an estimated 147 critically ill patients aged ≥18 years recruited from the ICUs of 2 hospitals in Heilongjiang, China. Patients will be prospectively randomized 1:1:1 to receive early mobilization, early nutrition combined with early mobilization, or standard care (minimal exercises, experience-based initiation and enrollment of nutrition support). Outcomes are assessed at ICU discharge after baseline. The primary outcome is occurrence of ICU-AW according to the Medical Research Council scale at the end of treatment. Muscle strength, organ failure, functional independence, self-care ability, time of ICU stay, duration of mechanical ventilation, and ICU mortality are secondary outcome measures.

DISCUSSION

This trial has the potential to identify a novel strategy for preventing or managing ICU-AW. The findings may increase the clinical knowledge about nutrition and mobilization interventions for people with ICU-AW, and contribute to the formation of practice guidelines for managing this condition.

TRIAL REGISTRATION NUMBER

ChiCTR2000033482.

Towards a fasting-mimicking diet for critically ill patients: the pilot randomized crossover ICU-FM-1 study

BACKGROUND

In two recent randomized controlled trials, withholding parenteral nutrition early in critical illness improved outcome as compared to early up-to-calculated-target nutrition, which may be explained by beneficial effects of fasting. Outside critical care, fasting-mimicking diets were found to maintain fasting-induced benefits while avoiding prolonged starvation. It is unclear whether critically ill patients can develop a fasting response after a short-term nutrient interruption. In this randomized crossover pilot study, we investigated whether 12-h nutrient interruption initiates a metabolic fasting response in prolonged critically ill patients. As a secondary objective, we studied the feasibility of monitoring autophagy in blood samples.

METHODS

In a single-center study in 70 prolonged critically ill patients, 12-h up-to-calculated-target feeding was alternated with 12-h fasting on day 8 ± 1 in ICU, in random order. Blood samples were obtained at the start of the study, at the crossover point, and at the end of the 24-h study period. Primary endpoints were a fasting-induced increase in serum bilirubin and decrease in insulin requirements to maintain normoglycemia. Secondary outcomes included serum insulin-like growth factor I (IGF-I), serum urea, plasma beta-hydroxybutyrate (BOH), and mRNA and protein markers of autophagy in whole blood and isolated white blood cells. To obtain a healthy reference, mRNA and protein markers of autophagy were assessed in whole blood and isolated white blood cells of 23 matched healthy subjects in fed and fasted conditions. Data were analyzed using repeated-measures ANOVA, Fisher's exact test, or Mann-Whitney U test, as appropriate.

RESULTS

A 12-h nutrient interruption significantly increased serum bilirubin and BOH and decreased insulin requirements and serum IGF-I (all p ≤ 0.001). Urea was not affected. BOH was already increased from 4 h fasting onwards. Autophagic markers in blood samples were largely unaffected by fasting in patients and healthy subjects.

CONCLUSIONS

A 12-h nutrient interruption initiated a metabolic fasting response in prolonged critically ill patients, which opens perspectives for the development of a fasting-mimicking diet. Blood samples may not be a good readout of autophagy at the tissue level.

TRIAL REGISTRATION

ISRCTN, ISRCTN98404761. Registered 3 May 2017.

Enteral vs. parenteral nutrition in septic shock: are they equivalent?

PURPOSE OF REVIEW

The current review focuses on recent clinical evidence and updated guideline recommendations on the effects of enteral vs. parenteral nutrition in adult critically ill patients with (septic) shock.

RECENT FINDIGS

The largest multicenter randomized-controlled trial showed that the route of nutrient supply was unimportant for 28-day and 90-day mortality, infectious morbidity and length of stay in mechanically ventilated patients with shock. The enteral route, however, was associated with lower macronutrient intake and significantly higher frequency of hypoglycemia and moderate-to-severe gastrointestinal complications. Integrating these findings into recent meta-analyses confirmed that the route per se has no effect on mortality and that interactions with (infectious) morbidity are inconsistent or questionable.

SUMMARY

The strong paradigm of favoring the enteral over the parenteral route in critically ill patients has been challenged. As a consequence, updated guidelines recommend withholding enteral nutrition in patients with uncontrolled shock. It is still unclear, however, whether parenteral nutrition is advantageous in patients with shock although benefits are conceivable in light of less gastrointestinal complications. Thus far, no guideline has addressed indications for parenteral nutrition in these patients. By considering recent scientific evidence, specific guideline recommendations, and expert opinions, we present a clinical algorithm that may facilitate decision-making when feeding critically ill patients with shock.

Is slower advancement of enteral feeding superior to aggressive full feeding regimens in the early phase of critical illness

PURPOSE OF REVIEW

An excessive caloric intake during the acute phase of critical illness is associated with adverse effects, presumably related to overfeeding, inhibition of autophagy and refeeding syndrome. The purpose of this review is to summarize recently published clinical evidence in this area.

RECENT FINDINGS

Several observational studies, a few interventional trials, and systematic reviews/metaanalyses were published in 2017-2019. Most observational studies reported an association between caloric intakes below 70% of energy expenditure and a better vital outcome. In interventional trials, or systematic reviews, neither a benefit nor a harm was related to increases or decreases in caloric intake. Gastrointestinal dysfunction can be worsened by forced enteral feeding, whereas the absorption of nutrients can be impaired.

SUMMARY

Owing to the risks of the delivery of an excessive caloric intake, a strategy of permissive underfeeding implying a caloric intake matching a maximum of 70% of energy expenditure provides the best risk-to-benefit ratio during the acute phase of critical illness.

Nutritional support in sepsis: when less may be more

Despite sound basis to suspect that aggressive and early administration of nutritional support may hold therapeutic benefits during sepsis, recommendations for nutritional support have been somewhat underwhelming. Current guidelines (ESPEN and ASPEN) recognise a lack of clear evidence demonstrating the beneficial effect of nutritional support during sepsis, raising the question: why, given the perceived low efficacy of nutritionals support, are there no high-quality clinical trials on the efficacy of permissive underfeeding in sepsis? Here, we review clinically relevant beneficial effects of permissive underfeeding, motivating the urgent need to investigate the clinical benefits of delaying nutritional support during sepsis.

Protein intake and outcome in critically ill patients

PURPOSE OF REVIEW

The objective of this review is to describe the impact of protein intake on the outcomes of critically ill patients in the literature published in the preceding 2 years.

RECENT FINDINGS

Observational studies showed inconsistent results regarding the association of higher protein intake and outcomes of critically ill patients. Randomized controlled trials that directly compared higher versus lower protein intake in ICU patients are scarce, varied considerably in their designs and primary outcomes, and generally had relatively small differences in the amount of delivered protein between the study arms. Systematic reviews of existing studies showed no difference in mortality with higher protein intake. In addition, there is uncertainty regarding high protein provision in the early phase of critical illness.

SUMMARY

The optimal amount of protein intake in critically ill patients remains largely unclear and is considered a high priority for research. Ongoing clinical trials are likely to provide additional evidence on several important questions including the dose, timing, type of protein and the interaction with caloric intake and exercise.

What do we know about optimal nutritional strategies in children with pediatric acute respiratory distress syndrome?

Nutrition in pediatric acute respiratory distress syndrome (PARDS) is an essential aspect of therapy, with potential to modify outcomes. The gut is slowly establishing its place as the motor of critical illness, and the 'gut-lung' axis has been shown to be in play in the systemic inflammatory response. Thus, utilizing the gut to modify outcomes in PARDS is an exciting prospect. PARDS is associated with high mortality in low- and middle-income countries (LMIC), where malnutrition is also prevalent and may worsen during hospital stay. Mortality may be higher in this subgroup of patients. At present, the gold standard to estimate resting energy expenditure (REE) in critically ill children is indirect calorimetry. However, it is a cumbersome and expensive procedure, as a result of which its routine practice is limited to very few units across the world. Therefore, predictive equations, which may under- or over-estimate REE, are relied upon to approximate calorie and protein needs of children with PARDS. Despite having target calorie and protein requirements, studies have found that a large proportion of critically ill children do not achieve these levels even at the end of a week in pediatric intensive care unit (PICU). The preferred mode of nutrition delivery is enteral, and if possible, early enteral nutrition (EEN). Immunonutrition has been a lucrative subject of research, and while there have been some strides, no therapy has yet conclusively demonstrated benefit in terms of mortality or reduced length of stay in PICU or the hospital. Probable immunonutrients in PARDS include omega-3 fatty acids, arginine, glutamine and vitamin D, though none are a part of any recommendations yet.

Anterior pituitary function in critical illness

Critical illness is hallmarked by major changes in all hypothalamic-pituitary-peripheral hormonal axes. Extensive animal and human studies have identified a biphasic pattern in circulating pituitary and peripheral hormone levels throughout critical illness by analogy with the fasting state. In the acute phase of critical illness, following a deleterious event, rapid neuroendocrine changes try to direct the human body toward a catabolic state to ensure provision of elementary energy sources, whereas costly anabolic processes are postponed. Thanks to new technologies and improvements in critical care, the majority of patients survive the acute insult and recover within a week. However, an important part of patients admitted to the ICU fail to recover sufficiently, and a prolonged phase of critical illness sets in. This prolonged phase of critical illness is characterized by a uniform suppression of the hypothalamic-pituitary-peripheral hormonal axes. Whereas the alterations in hormonal levels during the first hours and days after the onset of critical illness are evolutionary selected and are likely beneficial for survival, endocrine changes in prolonged critically ill patients could be harmful and may hamper recovery. Most studies investigating the substitution of peripheral hormones or strategies to overcome resistance to anabolic stimuli failed to show benefit for morbidity and mortality. Research on treatment with selected and combined hypothalamic hormones has shown promising results. Well-controlled RCTs to corroborate these findings are needed.

The association between nutritional adequacy and 28-day mortality in the critically ill is not modified by their baseline nutritional status and disease severity

Background

During the initial phase of critical illness, the association between the dose of nutrition support and mortality risk may vary among patients in the intensive care unit (ICU) because the prevalence of malnutrition varies widely (28 to 78%), and not all ICU patients are severely ill. Therefore, we hypothesized that a prognostic model that integrates nutritional status and disease severity could accurately predict mortality risk and classify critically ill patients into low- and high-risk groups. Additionally, in critically ill patients placed on exclusive nutritional support (ENS), we hypothesized that their risk categories could modify the association between dose of nutrition support and mortality risk.

Methods

A prognostic model that predicts 28-day mortality was built from a prospective cohort study of 440 patients. The association between dose of nutrition support and mortality risk was evaluated in a subgroup of 252 mechanically ventilated patients via logistic regressions, stratified by low- and high-risk groups, and days of exclusive nutritional support (ENS) [short-term (≤ 6 days) vs. longer-term (≥ 7 days)]. Only the first 6 days of ENS was evaluated for a fair comparison.

Results

The prognostic model demonstrated good discrimination [AUC 0.78 (95% CI 0.73–0.82), and a bias-corrected calibration curve suggested fair accuracy. In high-risk patients with short-term ENS (≤ 6 days), each 10% increase in goal energy and protein intake was associated with an increased adjusted odds (95% CI) of 28-day mortality [1.60 (1.19–2.15) and 1.47 (1.12–1.86), respectively]. In contrast, each 10% increase in goal protein intake during the first 6 days of ENS in high-risk patients with longer-term ENS (≥ 7 days) was associated with a lower adjusted odds of 28-day mortality [0.75 (0.57–0.99)]. Despite the opposing associations, the mean predicted mortality risks and prevalence of malnutrition between short- and longer-term ENS patients were similar.

Conclusions

Combining baseline nutritional status and disease severity in a prognostic model could accurately predict 28-day mortality. However, the association between the dose of nutrition support during the first 6 days of ENS and 28-day mortality was independent of baseline disease severity and nutritional status.

Electronic supplementary material

The online version of this article (10.1186/s13054-019-2500-z) contains supplementary material, which is available to authorized users.

Energy balance in obese, mechanically ventilated intensive care unit patients

OBJECTIVES

The aims of this study were, first, to compare the predicted (calculated) energy requirements based on standard equations with target energy requirement based on indirect calorimetry (IC) in critically ill, obese mechanically ventilated patients; and second, to compare actual energy intake to target energy requirements.

METHODS

We conducted a prospective cohort study of mechanically ventilated critically ill patients with body mass index ≥30.0 kg/m² for whom enteral feeding was planned. Clinical and demographic data were prospectively collected. Resting energy expenditure was measured by open-circuit IC. American Society of Parenteral and Enteral Nutrition (APSPEN)/Society of Critical Care Medicine (SCCM) 2016 equations were used to determine predicted (calculated) energy requirements. Target energy requirements were set at 65% to 70% of measured resting energy expenditure as recommended by ASPEN/SCCM. Nitrogen balance was determined via simultaneous measurement of 24-h urinary nitrogen concentration and protein intake.

RESULTS

Twenty-five patients (mean age: 64.5 ± 11.8 y, mean body mass index: 35.2 ± 3.6 kg/m²) underwent IC. The mean predicted energy requirement was 1227 kcal/d compared with mean measured target energy requirement of 1691 kcal/d. Predicted (calculated) energy requirements derived from ASPEN/SCCM equations were less than the target energy requirements in most cases. Actual energy intake from enteral nutrition met 57% of target energy requirements. Protein intake met 25% of target protein requirement and the mean nitrogen balance was -2.3 ± 5.1 g/d.

CONCLUSIONS

Predictive equations underestimated target energy needs in this population. Further, we found that feeding to goal was often delayed resulting in failure to meet both protein and energy intake goals.

Adequacy of enteral nutritional support in intensive care units does not affect the short- and long-term prognosis of mechanically ventilated patients: a pilot study

OBJECTIVE

To correlate short-term (duration of mechanical ventilation and length of intensive care unit stay) and long-term (functional capacity) clinical outcomes of patients who reached nutritional adequacy ≥ 70% of predicted in the first 72 hours of hospitalization in the intensive care unit.

METHODS

This was a prospective observational pilot study conducted in an 18-bed intensive care unit. A total of 100 mechanically ventilated patients receiving exclusive enteral nutritional support and receiving intensive care for more than 72 hours were included. Patients who never received enteral nutrition, those with spinal cord trauma, pregnant women, organ donors and cases of family refusal were excluded. The variables studied were nutritional adequacy ≥ 70% of predicted in the first 72 hours of hospitalization, length of intensive care unit stay, duration of mechanical ventilation and the ability to perform activities of daily living after 12 months, assessed via telephone contact using the Lawton Activities of Daily Living Scale.

RESULTS

The mean duration of mechanical ventilation was 18 ± 9 days, and the mean intensive care unit length of stay was 19 ± 8 days. Only 45% of the patients received more than 70% of the target nutrition in 72 hours. There was no association between nutritional adequacy and short-term (duration of mechanical ventilation, length of stay in the intensive care unit and mortality) or long-term (functional capacity and mortality) clinical outcomes.

CONCLUSION

Critically ill patients receiving caloric intake ≥ 70% in the first 72 hours of hospitalization did not present better outcomes in the short term or after 1 year.

Nutritional support in the recovery phase of critically ill children

PURPOSE OF REVIEW

The metabolic stress response of a critically ill child evolves over time and thus it seems reasonable that nutritional requirements change during their course of illness as well. This review proposes strategies and considerations for nutritional support during the recovery phase to gain optimal (catch-up) growth with preservation of lean body mass.

RECENT FINDINGS

Critical illness impairs nutritional status, muscle mass and function, and neurocognition, but early and high intakes of artificial nutrition during the acute phase cannot resolve this. Although (parenteral) nutrient restriction during the acute phase appears to be beneficial, persistent nutrient restriction, when the metabolic stress response resolves, has short-term and long-term detrimental consequences. Requirements increase markedly during the recovery phase to enable recovery and catch-up growth. Such large amounts of intake demand for alternate approach, especially when intestinal problems constitute a barrier for full enteral feeding. As part of the nutritional recovery, mobilization and exercise are essential to achieve catch-up growth with an optimal body composition.

SUMMARY

During the recovery phase of paediatric critical illness (catch-up) growth and muscle recovery require nutritional intakes at least two times the resting energy expenditure.

Permissive underfeeding, cytokine profiles and outcomes in critically ill patients

Background

During critical illness in humans, the effects of caloric restriction on the inflammatory response are not well understood. The aim of this study is to examine the associations of caloric restriction, inflammatory response profiles and outcomes in critically ill patients.

Methods

This is a sub-study of the PermiT trial (Permissive Underfeeding or Standard Enteral Feeding in Critically Ill Adults Trial- ISRCTN68144998). Serum samples were collected on study days 1, 3, 5, 7 and 14 and analyzed for a panel of 29 cytokines. We used principal component analysis to convert possibly correlated variables (cytokine levels) into a limited number of linearly uncorrelated variables (principal components). We constructed repeated measures mixed linear models to assess whether permissive underfeeding compared to standard feeding was associated with difference cytokine levels over time.

Results

A total of 72 critically ill patients were enrolled in this study (permissive underfeeding n = 36 and standard feeding n = 36). Principal component analysis identified 6 components that were responsible for 78% of the total variance. When adjusted to principal components, permissive underfeeding was not associated with 90-day mortality (adjusted odds ratio 1.75, 95% confidence interval 0.44, 6.95, p = 0.43) or with incident renal replacement therapy. The cytokines did not differ with time between permissive underfeeding and standard feeding groups.

Conclusions

The association of permissive underfeeding compared to standard feeding with mortality was not influenced by the inflammatory profile. Permissive underfeeding compared to standard feeding was not associated with differences in the serum levels of cytokines in critically ill patients.

Hypoalbuminemia: Pathogenesis and Clinical Significance

Hypoalbuminemia is associated with inflammation. Despite being addressed repeatedly in the literature, there is still confusion regarding its pathogenesis and clinical significance. Inflammation increases capillary permeability and escape of serum albumin, leading to expansion of interstitial space and increasing the distribution volume of albumin. The half‐life of albumin has been shown to shorten, decreasing total albumin mass. These 2 factors lead to hypoalbuminemia despite increased fractional synthesis rates in plasma. Hypoalbuminemia, therefore, results from and reflects the inflammatory state, which interferes with adequate responses to events like surgery or chemotherapy, and is associated with poor quality of life and reduced longevity. Increasing or decreasing serum albumin levels are adequate indicators, respectively, of improvement or deterioration of the clinical state. In the interstitium, albumin acts as the main extracellular scavenger, antioxidative agent, and as supplier of amino acids for cell and matrix synthesis. Albumin infusion has not been shown to diminish fluid requirements, infection rates, and mortality in the intensive care unit, which may imply that there is no body deficit or that the quality of albumin “from the shelf” is unsuitable to play scavenging and antioxidative roles. Management of hypoalbuminaemia should be based on correcting the causes of ongoing inflammation rather than infusion of albumin. After the age of 30 years, muscle mass and function slowly decrease, but this loss is accelerated by comorbidity and associated with decreasing serum albumin levels. Nutrition support cannot fully prevent, but slows down, this chain of events, especially when combined with physical exercise.

The role of bile acids in nutritional support

Nutritional support continues to receive much attention as a possible intervention to prevent loss of lean tissue mass, promote recovery and re-establish proper immune function in critical care patients. Yet there remains much controversy regarding the clinical efficacy of such interventions. In addition to the direct effect of nutrition in terms of micro- and macronutrient content, nutritional formulations may exert an effect via the physiological response to feeding. Here, we highlight the key role of postprandial reabsorbed bile acids in attenuating both the inflammatory response and autophagy. These observations suggest that not all patients would benefit from aggressive nutritional support.