Hypocaloric compared with eucaloric nutritional support and its effect on infection rates in a surgical intensive care unit: a randomized controlled trial

Association Between Energy Delivery and Outcomes in Adult Critically Ill Patients Diagnosed With or At Risk of Malnutrition: A Systematic Review and Meta-analysis With Trial Sequential Analysis

CONTEXT

There is a common belief that adult critically ill patients diagnosed with or at risk of malnutrition would benefit from higher energy delivery.

OBJECTIVE

This systematic review and meta-analysis aimed to evaluate the association between energy delivery and mortality in adult critically ill patients diagnosed with or at risk of malnutrition.

DATA SOURCES

Databases including Medline, Embase, Scopus, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Central, and Google Scholar were searched from inception to November 20, 2023.

DATA EXTRACTION

Randomized controlled trials (RCTs) and observational studies that (1) included critically ill patients (aged ≥18 years) diagnosed with or at risk of malnutrition using validated tools following intensive care unit (ICU) admission, (2) had at least 20% energy difference between intervention and comparison groups, and (3) reported mortality outcomes were included. The random-effects model was used to pool the data.

DATA ANALYSIS

Two RCTs (4681 at-risk patients) and 5 observational studies (1587 at-risk patients [including 389 high-risk patients]) were included. The pooled mean energy delivered during the first 7-14 days of ICU admission in higher vs lower energy groups was 25.6 ± 5.9 vs 9.7 ± 5.6 kcal/kg per day (P = .004) in RCTs and 21.0 ± 5.2 vs 13.3 ± 5.3 kcal/kg per day (P < .001) in observational studies. No mortality difference was found between higher vs lower energy groups in at-risk patients (risk ratio: 0.99; 95% CI: 0.85, 1.17; P = .94) in RCTs and high-risk patients (adjusted odds ratio: 1.37; 95% CI: 0.43, 4.32; P = .59) in observational studies. Trial sequential analysis was performed and 31 232 patients were required to show a potential treatment effect.

CONCLUSION

These data do not support the prevailing belief that higher energy delivery improves survival in adult critically ill patients diagnosed with or at risk of malnutrition.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021274378.

The Japanese Critical Care Nutrition Guideline 2024

Nutrition therapy is important in the management of critically ill patients and is continuously evolving as new evidence emerges. The Japanese Critical Care Nutrition Guideline 2024 (JCCNG 2024) is specific to Japan and is the latest set of clinical practice guidelines for nutrition therapy in critical care that was revised from JCCNG 2016 by the Japanese Society of Intensive Care Medicine. An English version of these guidelines was created based on the contents of the original Japanese version. These guidelines were developed to help health care providers understand and provide nutrition therapy that will improve the outcomes of children and adults admitted to intensive care units or requiring intensive care, regardless of the disease. The intended users of these guidelines are all healthcare professionals involved in intensive care, including those who are not familiar with nutrition therapy. JCCNG 2024 consists of 37 clinical questions and 24 recommendations, covering immunomodulation therapy, nutrition therapy for special conditions, and nutrition therapy for children. These guidelines were developed in accordance with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system by experts from various healthcare professionals related to nutrition therapy and/or critical care. All GRADE-based recommendations, good practice statements (GPS), future research questions, and answers to background questions were finalized by consensus using the modified Delphi method. Strong recommendations for adults include early enteral nutrition (EN) within 48 h and the provision of pre/synbiotics. Weak recommendations for adults include the use of a nutrition protocol, EN rather than parenteral nutrition, the provision of higher protein doses, post-pyloric EN, continuous EN, omega-3 fatty acid-enriched EN, the provision of probiotics, and indirect calorimetry use. Weak recommendations for children include early EN within 48 h, bolus EN, and energy/protein-dense EN formulas. A nutritional assessment is recommended by GPS for both adults and children. JCCNG 2024 will be disseminated through educational activities mainly by the JCCNG Committee at various scientific meetings and seminars. Since studies on nutritional treatment for critically ill patients are being reported worldwide, these guidelines will be revised in 4 to 6 years. We hope that these guidelines will be used in clinical practice for critically ill patients and in future research.

Clinical Outcomes of Hypocaloric/Hyperproteic vs Normocaloric Enteral Feeding in the Acute Phase of Critical Illness among Patients Admitted in the Intensive Care Unit: A Systematic Review with Meta-analysis

Objectives

To examine the effect of hypocaloric/hyperproteic enteral feeding vs normocaloric feeding on the survival of critically ill patients in the acute phase in the intensive care unit (ICU).

Methodology

Randomized clinical trials utilizing hypocaloric, hyperproteic, and normocaloric enteral feeding in the ICU were searched using the following terms ((((critically ill) OR (intensive care) OR (mechanically ventilated)) AND ((low-calorie enteral feeding) OR (high-protein enteral feeding)))) in MEDLINE, PubMed, Scopus, and Google Scholar by two independent authors.

Results

There were no significant differences in hospital mortality [odds ratio (OR), 1.0; 95% confidence interval (CI), 0.77, 1.31; p = 0.99, I 2 = 0%], days on mechanical ventilation (MD, -0.05; 95% CI, -0.37, 0.28; p = 0.78, I 2 = 0%), the odds of acquiring infectious complications (OR, 0.90; 95% CI, 0.71, 1.14; p = 0.38, I 2 = 0%), and the length of ICU stay (MD, 0.60; 95% CI, -2.39, 3.59; p = 0.69, I 2 = 96%). The length of hospital stay was significantly lower by 4.18 days in the normocaloric group (MD, 4.18; 95% CI, 2.50, 5.85; p < 0.00001, I 2 = 0%).

Conclusion

This meta-analysis showed no significant differences in mortality, infectious complications, days of mechanical ventilation, and ICU length of stay between groups. Findings on hospital length of stay were interpreted with caution due to the low quality of evidence and clinical heterogeneity.

How to cite this article

Permejo CC, Evangelista TJP. Clinical Outcomes of Hypocaloric/Hyperproteic vs Normocaloric Enteral Feeding in the Acute Phase of Critical Illness among Patients Admitted in the Intensive Care Unit: A Systematic Review with Meta-analysis. Indian J Crit Care Med 2024;28(11):1069-1083.

Optimal energy provision early in ICU stay for critically ill patients receiving parenteral nutrition

BACKGROUND

Literature on optimal energy provision via parenteral nutrition (PN) is limited and the evidence quality is low. The purpose of this study is to determine if there is a difference in outcomes in adult critically ill patients when receiving lower vs higher calorie provision via PN early in intensive care unit (ICU) stay.

METHODS

Adult patients initiated on PN within the first 10 days of ICU stay from May 2014 to June 2021 were included in this retrospective study. The primary outcome was to determine the impact of lower (<20 kcal/kg/day) vs higher (>25 kcal/kg/day) calorie provision on all-cause, in-hospital mortality. Secondary outcomes were to determine the impact of calorie provision on hospital or ICU length of stay and incidence of complications.

RESULTS

This study included 133 patients: a lower calorie provision group (n = 77) and a higher calorie provision group (n = 56). There was a significant difference in all-cause, in-hospital mortality between the lower and the higher calorie provision groups (36.36% and 17.86%, respectively; P = 0.02). However, upon a multivariate analysis of death at discharge, the specific calorie provision group did not affect the probability of death at hospital discharge. The secondary outcomes were not significantly different between groups.

CONCLUSION

When comparing lower calorie provision with higher calorie provision in adult critically ill patients receiving PN early within their ICU stay, there were no differences in outcomes after controlling for significant confounders. Future larger prospective studies should further evaluate optimal caloric provision via PN in this population.

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.

Efficacy of permissive underfeeding for critically ill patients: an updated systematic review and trial sequential meta-analysis

BACKGROUND

Our previous study in 2011 concluded that permissive underfeeding may improve outcomes in patients receiving parenteral nutrition therapy. This conclusion was tentative, given the small sample size. We conducted the present systematic review and trial sequential meta-analysis to update the status of permissive underfeeding in patients who were admitted to the intensive care unit (ICU).

METHODS

Seven databases were searched: PubMed, Embase, Web of Science, China National Knowledge Infrastructure, Wanfang, Chinese Biomedical Literature Database, and Cochrane Library. Randomized controlled trials (RCTs) were included. The Revised Cochrane risk-of-bias tool (ROB 2) was used to assess the risk of bias in the enrolled trials. RevMan software was used for data synthesis. Trial sequential analyses (TSA) of overall and ICU mortalities were performed.

RESULTS

Twenty-three RCTs involving 11,444 critically ill patients were included. There were no significant differences in overall mortality, hospital mortality, length of hospital stays, and incidence of overall infection. Compared with the control group, permissive underfeeding significantly reduced ICU mortality (risk ratio [RR] = 0.90; 95% confidence interval [CI], [0.81, 0.99]; P = 0.02; I2 = 0%), and the incidence of gastrointestinal adverse events decreased (RR = 0.79; 95% CI, [0.69, 0.90]; P = 0.0003; I2 = 56%). Furthermore, mechanical ventilation duration was reduced (mean difference (MD) = - 1.85 days; 95% CI, [- 3.44, - 0.27]; P = 0.02; I2 = 0%).

CONCLUSIONS

Permissive underfeeding may reduce ICU mortality in critically ill patients and help to shorten mechanical ventilation duration, but the overall mortality is not improved. Owing to the sample size and patient heterogeneity, the conclusions still need to be verified by well-designed, large-scale RCTs. Trial Registration The protocol for our meta-analysis and systematic review was registered and recorded in PROSPERO (registration no. CRD42023451308). Registered 14 August 2023.

Japanese Clinical Practice Guidelines for Rehabilitation in Critically Ill Patients 2023 (J-ReCIP 2023)

Providing standardized, high-quality rehabilitation for critically ill patients is a crucial issue. In 2017, the Japanese Society of Intensive Care Medicine (JSICM) promulgated the "Evidence-Based Expert Consensus for Early Rehabilitation in the Intensive Care Unit" to advocate for the early initiation of rehabilitations in Japanese intensive care settings. Building upon this seminal work, JSICM has recently conducted a rigorous systematic review utilizing the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. This endeavor resulted in the formulation of Clinical Practice Guidelines (CPGs), designed to elucidate best practices in early ICU rehabilitation. The primary objective of this guideline is to augment clinical understanding and thereby facilitate evidence-based decision-making, ultimately contributing to the enhancement of patient outcomes in critical care settings. No previous CPGs in the world has focused specifically on rehabilitation of critically ill patients, using the GRADE approach. Multidisciplinary collaboration is extremely important in rehabilitation. Thus, the CPGs were developed by 73 members of a Guideline Development Group consisting of a working group, a systematic review group, and an academic guideline promotion group, with the Committee for the Clinical Practice Guidelines of Early Mobilization and Rehabilitation in Intensive Care of the JSICM at its core. Many members contributed to the development of the guideline, including physicians and healthcare professionals with multiple and diverse specialties, as well as a person who had been patients in ICU. Based on discussions among the group members, eight important clinical areas of focus for this CPG were identified. Fourteen important clinical questions (CQs) were then developed for each area. The public was invited to comment twice, and the answers to the CQs were presented in the form of 10 GRADE recommendations and commentary on the four background questions. In addition, information for each CQ has been created as a visual clinical flow to ensure that the positioning of each CQ can be easily understood. We hope that the CPGs will be a useful tool in the rehabilitation of critically ill patients for multiple professions.

Isocaloric nutritional support reduces ventilator duration time in major trauma patients

AIMS

Major trauma patients need adequate nutrition for recovery. This study aimed to evaluate the adequacy of nutritional supply and the correlation between nutritional supply and clinical outcome.

METHODS

A single-centre retrospective observational study was undertaken, describing the amounts of energy and proteins provided to 320 critically ill trauma patients during the first 10 days after admission. The data were collected from the electronic medical records of patients admitted to the trauma intensive care unit during the study period and descriptive statistical analyses were performed with the SPSS software.

RESULTS

The mean proportion of supplied energy to recommended energy during the first 10 days after admission was 57.5%, and the mean percentage of supplied protein to recommended protein intake was 51.3%. The patients were divided into those who received ≥70% (isocaloric nutrition group) and those who received <70% (hypocaloric nutrition group) of their estimated requirements. Both the duration of ventilator use (12.7 ± 10.5 vs. 16.0 ± 15.8 days, respectively, p = 0.009) and duration of parenteral nutrition (1.1 ± 1.4 vs. 2.0 ± 2.0 days, respectively, p = 0.001) were shorter in the isocaloric nutrition group (n = 83) than in the hypocaloric nutrition group (n = 237).

CONCLUSION

Total energy and the amount of protein supplied were insufficient compared to the recommended amount. The duration of ventilator use was shorter in the isocaloric nutrition group than in the hypocaloric nutrition group. The association between shortened ventilator use and isocaloric nutrition requires further investigation as a potential intervention to reduce the risk of complications such as ventilator-related pneumonia.

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.

Association between early nutrition support and 28-day mortality in critically ill patients: the FRANS prospective nutrition cohort study

BACKGROUND

Current guidelines suggest the introduction of early nutrition support within the first 48 h of admission to the intensive care unit (ICU) for patients who cannot eat. In that context, we aimed to describe nutrition practices in the ICU and study the association between the introduction of early nutrition support (< 48 h) in the ICU and patient mortality at day 28 (D28) using data from a multicentre prospective cohort.

METHODS

The 'French-Speaking ICU Nutritional Survey' (FRANS) study was conducted in 26 ICUs in France and Belgium over 3 months in 2015. Adult patients with a predicted ICU length of stay > 3 days were consecutively included and followed for 10 days. Their mortality was assessed at D28. We investigated the association between early nutrition (< 48 h) and mortality at D28 using univariate and multivariate propensity-score-weighted logistic regression analyses.

RESULTS

During the study period, 1206 patients were included. Early nutrition support was administered to 718 patients (59.5%), with 504 patients receiving enteral nutrition and 214 parenteral nutrition. Early nutrition was more frequently prescribed in the presence of multiple organ failure and less frequently in overweight and obese patients. Early nutrition was significantly associated with D28 mortality in the univariate analysis (crude odds ratio (OR) 1.69, 95% confidence interval (CI) 1.23-2.34) and propensity-weighted multivariate analysis (adjusted OR (aOR) 1.05, 95% CI 1.00-1.10). In subgroup analyses, this association was stronger in patients ≤ 65 years and with SOFA scores ≤ 8. Compared with no early nutrition, a significant association was found of D28 mortality with early enteral (aOR 1.06, 95% CI 1.01-1.11) but not early parenteral nutrition (aOR 1.04, 95% CI 0.98-1.11).

CONCLUSIONS

In this prospective cohort study, early nutrition support in the ICU was significantly associated with increased mortality at D28, particularly in younger patients with less severe disease. Compared to no early nutrition, only early enteral nutrition appeared to be associated with increased mortality. Such findings are in contrast with current guidelines on the provision of early nutrition support in the ICU and may challenge our current practices, particularly concerning patients at low nutrition risk. Trial registration ClinicalTrials.gov Identifier: NCT02599948. Retrospectively registered on November 5th 2015.

Impact of Energy and Protein Delivery to Critically Ill Patients: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Optimal energy and protein delivery goals for critically ill patients remain unknown. The purpose of this systematic review and meta-analysis was to compare the impact of energy and protein delivery during the first 4 to 10 days of an ICU stay on physical impairments. We performed a systematic literature search of MEDLINE, CENTRAL, and ICHUSHI to identify randomized controlled trials (RCTs) that compared energy delivery at a cut-off of 20 kcal/kg/day or 70% of estimated energy expenditure or protein delivery at 1 g/kg/day achieved within 4 to 10 days after admission to the ICU. The primary outcome was activities of daily living (ADL). Secondary outcomes were physical functions, changes in muscle mass, quality of life, mortality, length of hospital stay, and adverse events. Fifteen RCTs on energy delivery and 14 on protein were included in the analysis. No significant differences were observed in any of the outcomes included for energy delivery. However, regarding protein delivery, there was a slight improvement in ADL (odds ratio 21.55, 95% confidence interval (CI) −1.30 to 44.40, p = 0.06) and significantly attenuated muscle loss (mean difference 0.47, 95% CI 0.24 to 0.71, p < 0.0001). Limited numbers of RCTs were available to analyze the effects of physical impairments. In contrast to energy delivery, protein delivery ≥1 g/kg/day achieved within 4 to 10 days after admission to the ICU significantly attenuated muscle loss and slightly improved ADL in critically ill patients. Further RCTs are needed to investigate their effects on physical impairments.

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.

Effect of Early Low-Calorie Enteral Nutrition Support in Critically Ill Patients: A Systematic Review and Meta-analysis

Objective

The purpose of this research was to rigorously assess the impact of early low-fever enteral feeding supplementation in critically sick patients.

Methods

PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature, and Physiotherapy Evidence Database were searched for randomized controlled trials related to enteral nutrition support of critically ill patients (retrieval time was limited to June 30, 2021); data were extracted after screening the literature, and the quality of meta-analysis was evaluated.

Results

When compared to adequate caloric enteral nutrition support, early low caloric enteral nutrition support reduces the incidence of intolerance to nutrition support (MD = 0.60, 95 percent CI: -0.18 to 1.39, P = 0.13) and the insulin dose during enteral nutrition support (MD = -17.21, 95 percent CI: -19.91 to -14.51, P = 0.00001). However, it had no effect on intensive care unit (ICU) treatment duration (MD = 0.60, 95 percent CI: -0.18 to 1.39, P = 0.13), in-hospital mortality (MD = 0.60, 95 percent CI: -0.18 to 1.39, P = 0.13), or infection incidence (OR = 1.00, 95 percent CI: 0.85, 1.19, P = 0.98).

Conclusion

When compared to sufficient caloric enteral nutrition support, early low-calorie enteral nutrition support lowers the risk of severe illness. The rate of intolerance to nutritional assistance and the decrease in insulin dosage supplied had no effect on the length of ICU therapy, patient death, or infection incidence.

Comparison of the effects of different calorie amounts of enteral nutrition in hypercatabolism associated with ghrelin-POMC in endotoxemic rats

Background

Hypercatabolism often occurs in critically ill patients, and it increases infection rates and mortality in these patients. Enteral nutrition (EN) is commonly used in case of hypercatabolism. However, the effect of amount of calories in EN on hypercatabolism remains unexplored.

Objective

Here, we compared the effect of low-calorie, medium-calorie and high-calorie EN on hypercatabolism in the acute phase of endotoxemia, which is associated with gastrointestinal hormones and hypothalamic neuropeptide proopiomelanocortin (POMC).

Methods

Overall 84 adult male Sprague–Dawley rats were used for research. A set of rats were divided into 5 groups, Control (NS) and lipopolysaccharide (LPS) groups were fed a standard chow diet; LPS + L (LPS + 40 kcal/kg/day EN), LPS + M (LPS + 80 kcal/kg/day EN) and LPS + H (LPS + 120 kcal/kg/day EN) groups received EN through a gastric tube for 3 days. Another set of rats were used for parallel control experiment and divided into 5 groups: NS + F (saline + fasting) and LPS + F (LPS + fasting) groups were given no food, NS + L (saline + 40 kcal/kg/day EN), NS + M (saline + 80 kcal/kg/day EN) and NS + H (saline + 120 kcal/kg/day EN) groups received EN through a gastric tube for 3 days. Hypercatabolism was evaluated by assessing skeletal muscle protein synthesis and atrophy, insulin resistance, and corticosterone levels. Moreover, serum inflammatory factors, gastrointestinal hormones, hypothalamic ghrelin, growth hormone secretagogue receptor-1α, hypothalamic neuropeptide, and intestinal injury indicators were detected.

Results

Low-calorie EN effectively increased serum and hypothalamic ghrelin possibly due to slight intestinal barrier damage, thereby decreasing hypothalamic POMC expression; consequently, it alleviated rat insulin resistance, reduced blood cortisol levels and muscle atrophy, and improved the survival rate of rats in the acute phase of endotoxemia. Interestingly, with an increase in calories in enteral nutrition, the aforementioned effects did not increase.

Conclusions

Low-calorie EN could effectively increase gastrointestinal hormone ghrelin by reducing intestinal damage and suppressing POMC expression to ameliorate hypercatabolism when compared with medium-calorie and high-calorie EN. Therefore Low-calorie EN may be preferred for providing EN in the acute stage of endotoxemia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-022-00663-7.

Guidelines for the provision of nutrition support therapy in the adult critically Ill patient: American society for parenteral and enteral nutrition

BACKGROUND

New randomized controlled trials have been conducted since publication of the 2016 ASPEN/SCCM critical care nutrition guideline. This guideline updates recommendations for foundational questions central to critical care nutrition support.

METHODS

The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) process was used to develop and summarize evidence for clinical practice recommendations. Clinical outcomes were assessed for (1) higher vs lower energy dose (2) higher vs lower protein dose (3) exclusive isocaloric PN vs EN (4) supplemental PN (SPN) plus EN vs EN alone (5a) mixed oil lipid injectable emulsions (ILE) vs soybean oil, and (5b) Fish oil (FO) containing ILE vs non-FO ILE. To assess safety, weight based energy intake was plotted against hospital mortality when study heterogeneity precluded meaningful Forest plot inferences.

RESULTS

Between 1/1/2001 and 07/15/2020, 2,320 citations were identified and data were abstracted from 39 trials, including 20,578 participants. Patients receiving FO had decreased pneumonia rates of uncertain clinical significance. Otherwise, there were no differences for any outcome in any question. Due to lack in certainty regarding harm, the energy prescription recommendation was decreased to 12-25kcal/kg/day.

CONCLUSION

No differences in clinical outcomes were identified among numerous nutritional interventions, including higher energy or protein intake, isocaloric PN or EN, supplemental PN, or different ILEs. As more consistent critical care nutrition support data become available, more precise recommendations will be possible. In the meantime, clinical judgment and close monitoring are needed. This paper was approved by the ASPEN Board of Directors.  This article is protected by copyright. All rights reserved.

Immediate vs. gradual advancement to goal of enteral nutrition after elective abdominal surgery: A multicenter non-inferiority randomized trial

BACKGROUND & AIMS

The strategy of increasing the postoperative enteral nutrition dose to the target goal has not yet been clarified. This study aimed to determine whether an immediate goal-dose enteral nutrition (IGEN) strategy is non-inferior to a gradual goal-dose enteral nutrition (GGEN) strategy in reducing infections in patients undergoing abdominal surgery involving the organs of the digestive system.

METHODS

This randomized controlled trial enrolled postoperative patients with nutritional risk screening 2002 scores ≥3 from 11 Chinese hospitals. Energy targets were calculated as 25 kcal/kg and 30 kcal/kg of ideal body weight for women and men, respectively. Patients were randomly assigned 1:1 to IGEN or GGEN group after enteral tolerance was confirmed (30% of the target on day 2). The IGEN group immediately started receiving 100% of the caloric requirements on day 3, while the GGEN group received 40% progressing to 80% of target on day 7. The primary endpoint was the infection rate until discharge, based on the intention-to-treat population.

RESULTS

A total of 411 patients were enrolled and randomized to the IGEN and GGEN groups, and five patients did not receive the allocated intervention. A total of 406 patients were included in the primary analysis, with 199 and 207 in the IGEN and GGEN groups, respectively. Infection was observed in 17/199 (8.5%) in the IGEN group and 19/207 (9.2%) in the GGEN group, respectively (difference, -0.6%; [95% confidence interval (CI), -6.2%-4.9%]; P = 0.009 for non-inferiority test). There were significantly more gastrointestinal intolerance events with IGEN than with GGEN (58/199 [29.1%] vs. 32/207 [15.5%], P < 0.001). All other secondary endpoints were non-significant.

CONCLUSIONS

Among postoperative patients at nutritional risk, IGEN was non-inferior to GGEN in regards to infectious complications. IGEN was associated with more gastrointestinal intolerance events. It showed that IGEN cannot be considered to be clinically directive. ClinicalTrials.gov (#NCT03117348).

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members.As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

The Influence of Timing in Critical Care Nutrition

Proper timing of critical care nutrition has long been a matter of controversy. Critical illness waxes and wanes in stages, creating a dynamic flux in energy needs that we have only begun to examine. Furthermore, response to nutrition support likely differs greatly at the level of the individual patient in regard to genetic status, disease stage, comorbidities, and more. We review the observational and randomized literature concerning timing in nutrition support, discuss mechanisms of harm in feeding critically ill patients, and highlight the role of precision nutrition for moving the literature beyond the realm of blunt population averages into one that accounts for the patient-specific complexities of critical illness and host genetics. Expected final online publication date for the Annual Review of Nutrition, Volume 41 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Nutrition in the Neurocritical Care Unit: a New Frontier

PURPOSE OF REVIEW

This review presents the most current recommendations for providing nutrition to the neurocritical care population. This includes updates on initiation of feeding, immunonutrition, and metabolic substrates including ketogenic diet, cerebral microdialysis (CMD) monitoring, and the microbiome.

RECENT FINDINGS

Little evidence exists to support differences in feeding practices among the neurocritical care population. New areas of interest with limited data include use of immunonutrition, pre/probiotics for microbiome manipulation, ketogenic diet, and use of CMD catheters for substrate utilization monitoring.

SUMMARY

Acute neurologic injury incites a cascade of adrenergic and neuroendocrine events resulting in a pro-inflammatory and hypercatabolic state, which is associated with an increase in morbidity and mortality. Nutritional support provides substrates to mitigate the damaging effects of hypermetabolism. Despite this practice, studies on feeding delivery outcomes remain inconsistent. Guidelines suggest use of early enteral nutrition using standard polymeric formulas. Population heterogeneity, variability in interventions, complexities of the metabolic and inflammatory responses, and paucity of nutrition research in patients requiring neurocritical care have led to controversies in the field. It is imperative that more pragmatic and reproducible research be conducted to better understand underlying pathophysiology and develop interventions that may improve outcomes.

Point-Counterpoint: Indirect Calorimetry Is not Necessary for Optimal Nutrition Therapy in Critical Illness

Clinicians have widely recognized that indirect calorimetry (IC) is the "gold standard" for measuring energy expenditure (EE) and thus would intuitively anticipate that its use would be needed to provide optimal nutrition support in critical illness. Recent studies in the literature as well as dramatic changes in clinical practice over the past decade, though, would suggest that such a precise measure by IC to set energy goals is not required to maximize clinical benefit from early feeding in the intensive care unit (ICU). Results from randomized controlled trials evaluating permissive underfeeding, use of supplemental parenteral nutrition to achieve tight calorie control, and caloric density of formulas to increase energy delivery have provided an important perspective on 3 pertinent issues. First, a simple weight-based predictive equation (25 kcal/kg/day) provides a clinically useful approximation of EE. Second, a precise measure of EE by IC does not appear to improve outcomes compared with use of this less accurate estimation of energy requirements. And third, providing some percentage of requirements (50%-80%), achieves similar clinical benefit to full feeding (100%) in the early phases of critical illness. The value from IC use lies in the determination of caloric requirements in conditions for which weight-based equations are rendered inaccurate (anasarca, amputation, severe obesity) or the clinical state is markedly altered (such as the prolonged hyperinflammatory state of coronavirus disease 2019 [COVID-19]). In most other circumstances, routine use of IC would not be expected to change clinical outcomes from early nutrition therapy in the ICU.

Effect of the Timing of Nutritional Support Team Intervention on Nutritional Status on Patients Receiving Enteral Nutrition

Many hospitalized patients usually have a high risk of malnutrition, which delays the therapy process and can lead to severe complications. Despite of the potential benefits, the effects of timely intervention by nutrition support team (NST) on the nutritional status of admitted patients are not well established. This study aimed to compare the nutritional status between patients with early and delayed NST supports and to assess the effect of the timing of NST support initiation on the nutritional status of enteral nutrition patients. In a simple comparison between the two groups, the early NST intervention group had shorter hospital stays and fewer tube feeding periods than the delayed NST intervention group. The increase in the amount of energy intake from first to last NST intervention was 182.3 kcal in patients in the early NST intervention group, higher than that in patients in the delayed intervention group (p = 0.042). The extent of reduction in serum albumin and hemoglobin levels between the initial and last NST intervention tended to be lower in the early NST intervention group than in the delayed NST intervention group. The mean odds ratio for the patients who were severely malnourished in the early NST intervention group was 0.142 (95% confidence interval, 0.045–0.450) after adjusting for hospital stay and age. The results of this study indicate that early NST intervention can improve patients' overall nutritional status.

Refeeding risks in patients requiring intravenous nutrition support: Results of a two-centre, prospective, double-blind, randomised controlled trial

BACKGROUND/AIMS

Refeeding syndrome can result following excessive feeding of malnourished patients. The syndrome remains poorly defined but encompasses a range of adverse effects including electrolyte shifts, hyperglycaemia and other less well-defined phenomena. There are additional risks of underfeeding malnourished individuals. Studies of refeeding syndrome have generally focussed on critical care environments or patients with anorexia nervosa. Here we have conducted a two-centre, prospective, double-blind, randomised controlled trial amongst all patients referred to hospital nutrition support teams for intravenous nutrition support. We sought to determine whether electrolyte and other abnormalities suggestive of refeeding syndrome risk varied depending on initial rate of intravenous feeding.

METHODS

Patients at moderate or high risk of refeeding syndrome, as defined by United Kingdom National Institute of Health and Care Excellence guidelines, were screened for inclusion. Patients were randomised to receive either high (30 kcal/kg/day, 0.25 gN/kg/day) or low (15 kcal/day, 0.125 gN/kg/day) rate feeding for the first 48 h prior to escalation to standard parenteral nutrition regimens. The primary outcome was rates of potential refeeding risks within the first 7 days as defined by electrolyte imbalance or hyperglycaemia requiring insulin. Secondary outcomes included effects on QTc interval, infections and length of hospital stay. Statistical analysis was performed with χ² or Wilcoxon rank sum tests and all analysis was intention-to-treat. Problems with study recruitment led to premature termination of the trial. Registered on the EU Clinical Trials Register (EudraCT number 2007-005547-17).

RESULTS

534 patients were screened and 104 randomised to either high or low rate feeding based on risk of refeeding syndrome. Seven patients were withdrawn prior to collection of baseline demographics and were excluded from analysis. 48 patients were analysed for the primary outcome with potential refeeding risks identified in 46%. No differences in risks were seen between high and low rate feeding (p > 0.99) or high and moderate risk feeding (p = 0.68). There were no differences in QTc abnormalities, infection rates, or hospital length of stay between groups.

CONCLUSIONS

In this randomised trial of rates of refeeding risk, in patients pre-stratified as being at high or moderate risk, we found no evidence of increased refeeding related disturbances in those commenced on high rate feeding compared to low rate. No differences were seen in secondary endpoints including cardiac rhythm analysis, infections or length of stay. Our study reflects real world experience of patients referred for nutrition support and highlights challenges encountered when conducting clinical nutrition research.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members. As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

Impact of MnSOD and GPx1 Genotype at Different Levels of Enteral Nutrition Exposure on Oxidative Stress and Mortality: A Post hoc Analysis From the FeDOx Trial

BACKGROUND

Converting nutrition support to energy results in mitochondrial free radical production, possibly increasing oxidative stress. Highly prevalent single nucleotide variants (SNV) exist for the genes encoding antioxidant enzymes responsible for the detoxification of reactive oxygen species. Our objective was to explore the interaction between nutrition support and genetic SNV's for two anti-oxidant proteins (rs4880 SNV for manganese superoxide dismutase and rs1050450 SNV for glutathione peroxidase 1) on oxidative stress and secondarily on intensive care unit (ICU) mortality.

METHODS

We performed a post-hoc analysis on 34 mechanically ventilated sepsis patients from a randomized control feeding trial. Participants were dichotomized into those who carried both the rs4880 and the rs1050450 at-risk alleles (Risk Group) versus all others (Nonrisk Group). We explored the interaction between genotype and percent time spent in the upper median of energy exposure on oxidative stress and ICU mortality.

RESULTS

Adjusting for confounders, the slope of log F2-isoprostane levels across percentage of days spent in the upper median of daily kilocalories per kilogram (kcal/kg) was 0.01 higher in the Risk Group compared to the Non-Risk Group (p=0.01). Every 1 percent increase in days spent in the upper median of daily kcal/kg was associated with an adjusted 10.3 percent increased odds of ICU mortality amongst participants in the Risk Group (odds ratio [OR]=1.103, p=0.06) but was highly insignificant in the Nonrisk group (OR=0.991, P=0.79).

CONCLUSION

Nutrition support may lead to increased oxidative stress and worse clinical outcomes in a large percent of ICU patients with an at-risk genotype.

Refeeding Hypophosphatemia in Patients Receiving Parenteral Nutrition: Prevalence, Risk Factors, and Predicting Its Occurrence

BACKGROUND

Patients receiving parenteral nutrition (PN) support may develop refeeding hypophosphatemia (RH), and its prevalence is highly variable in the literature. Identifying at-risk patients is crucial to minimize clinical complications. The National Institute for Health and Clinical Excellence (NICE) guidelines are used widely to assess the risk of RH, but they lack validation. We aim to (1) identify the prevalence of RH by multiple diagnostic criteria; (2) assess the predictive ability of the NICE guidelines for RH; and (3) identify important risk factors for RH and evaluate their predictive abilities for RH in a new model.

METHODS

This is a single-center retrospective study on adult patients with PN ≥48 hours. Prevalence of RH was determined by 4 established diagnostic criteria. Prognostic accuracy of the NICE guidelines were assessed by the area under the receiver operating characteristic (ROC) curve. Multivariable logistic regressions were performed to develop a new risk-assessment model.

RESULTS

Of 149 enrolled patients, 23%-48% (35 to 72 of 149 patients) developed RH (depending on the diagnostic criteria used). The NICE guidelines demonstrated poor discrimination across all diagnostic criteria (ROC, 0.43-0.53). Critical illness, the use of diuretics, and hypomagnesemia prior to PN were independently associated with RH. These risk factors formed the new model for predicting RH and had good discrimination (ROC 0.74; 95% confidence interval, 0.66-0.82).

CONCLUSION

Prevalence of RH varied according to established diagnostic criteria. The current NICE guidelines poorly predict the occurrence of RH, and modification is likely beneficial. A new risk-assessment model was developed; nevertheless, further validation is required.

Enteral combined with parenteral nutrition improves clinical outcomes in patients with traumatic brain injury

Objective: To investigate the effect of nutritional support on nutritional status and clinical outcomes of patients with traumatic brain injury (TBI).Methods: Sixty-one patients with TBI from the intensive care unit and neurosurgery of Xianyang Central Hospital from 2017 to 2019 were retrospectively included. General and clinical data of the study subjects were collected. The control group (n = 28) received parenteral nutrition alone, and the observation group (n = 33) received parenteral nutrition combined with enteral nutrition. The general conditions and biochemical indicators of both groups of patients were divided into two groups of ≤8 and ≥9 for stratified analysis to compare the nutritional support status and infection complications during hospitalization Occurrence, ICU length of stay, total length of stay, total cost of stay, and prognostic indicators of the patients were analyzed and compared.Results: There were no significant differences in biochemical indicators between both groups of patients when they were discharged. Among patients with GCS ≤8 points, the incidence of lung infection in the observer was significantly higher than that in the control group (P < 0.001), but the incidence of intracranial infection, stress ulcers, and diarrhea was not statistically different from that in the control group (P = 0.739). No significant differences were observed in hospitalization time and hospitalization costs between both groups (P = 0.306 and P = 0.079, respectively). The observation group was significantly better than the control group in GSC score and long-term quality of life score (P = 0.042 and P = 0.025, respectively). When GCS was ≥ 9 points, there was no statistical difference in the incidence of lung infections and intracranial infections between both groups of patients (P = 0.800 and P = 0.127, respectively). The observation group was significantly higher than the control group in terms of length of hospital stay, nasal feeding time and hospitalization costs (P < 0.001, P < 0.001 and P = 0.006, respectively). The observation group was significantly better than the control group in GSC score and long-term quality of life score (P = 0.001 and P = 0.015, respectively). There was no significant difference in the incidence of pulmonary infection and intracranial infection between both groups of patients (P = 0.800 and P = 0.127, respectively).Conclusion: Enteral nutrition combined with parenteral nutrition intervention has a positive effect on the clinical prognosis of TBI patients.

Real-Time Energy Exposure Is Associated With Increased Oxidative Stress Among Feeding-Tolerant Critically Ill Patients: Results From the FEDOX Trial

Background

Prospective randomized controlled trials (PRCTs) that found harm in patients receiving higher levels of energy exposure have been largely ignored, in part because of the lack of a known mechanism of harm.

Objective

The current 7‐day pilot study is a PRCT and post hoc analysis designed to explore the relationship between energy exposure and oxidative stress (as plasma total F2‐isoprostanes) in mechanically ventilated intensive care unit patients with systemic inflammatory response syndrome.

Methods

Thirty‐five participants were randomized to receive either 100% or 40% of their estimated energy needs. Our intent‐to‐treat model found no differences in F2‐isoprostanes between groups. A post hoc analysis revealed that on days when participants were in the highest tertile of daily kcal/kg, the real‐time energy flow rate within 2 hours of the blood draw was predictive of increased oxidative stress. On these days, participants in the second or third vs the first tertile of real‐time energy flow rate experienced a 41.8% (P = .006) or 26.5% (P = .001) increase in F2‐isoprostane levels, respectively. This was confirmed through a within‐group subanalysis restricted to participants with measurements on both sides of the median of real‐time energy flow rate that found a 28.2% F2‐isoprostane increase on days in the upper vs lower median of flow rate (P = .002).

Conclusion

The benefits of feeding may be more nuanced than previously suspected. Our findings imply a potential mechanism of harm in meeting the current recommendations for nutrition support in the critically ill that warrants further investigation.

Hypoenergetic feeding does not improve outcomes in critically ill patients with premorbid obesity: a post hoc analysis of a randomized controlled trial

Optimal energy goals for adult, obese critically ill surgical patients are unclear. To date, there has been little data comparing feeding regimens for obese and non-obese critically ill surgical patients and the effect on outcomes. The objective was to compare the effect of hypoenergetic and euenergetic feeding goals in critically ill obese patients on outcomes, including infection, intensive care unit length of stay, and mortality. We hypothesized that hypoenergetic feeding of patients with premorbid obesity (body mass index ≥ 30 kg•m^-2) during critical illness does not affect clinical outcomes. Post hoc analyses were performed on critically ill surgical patients enrolled in a randomized controlled trial. Patients were randomized to receive 25-30 kcal•kg^-1•d^-1 (105-126 kJ.kg^-1•d^-1, euenergetic) or 12.5-15 kcal•kg^-1•d^-1 (52-63 kJ.kg^-1 •d^-1, hypoenergetic), with equal protein allocation (1.5 g•kg^-1•d^-1). The effect of feeding regimen on outcomes in obese and nonobese patients were assessed. Of the 83 patients, 30 (36.1%) were obese (body mass index ≥ 30 kg•m^-2). Average energy intake differed based on feeding regimen (hypoenergetic: 982±61 vs euenergetic: 1338±92 kcal•d^-1, P = .02). Comparing obese and nonobese patients, there was no difference in the percentage acquiring an infection (66.7% [20/30] vs 77.4% [41/53], P = .29), intensive care unit length of stay (16.4±3.7 vs 14.3±0.9 days, P = .39), or mortality (10% [3/30] vs 7.6% [4/53], P = .7). Within the subset of obese patients, the percentage acquiring an infection (hypoenergetic: 78.9% [15/19] vs euenergetic: 45.5% [5/11], P = .11) was not affected by the feeding regimen. Within the subset of nonobese patients, there was a trend toward more infections in the euenergetic group (hypoenergetic: 63.6% [14/22] vs euenergetic: 87.1% [27/31], P = .05). Hypoenergetic feeding does not appear to affect clinical outcomes positively or negatively in critically ill patients with premorbid obesity.

Combination of High-Calorie Delivery and Organ Failure Increases Mortality Among Patients With Acute Respiratory Distress Syndrome

OBJECTIVES

Among critically ill patients, the benefits of nutrition support may vary depending on severity of organ dysfunction. The objective of the current article was to explore the relationship between organ failure and calories exposure with hospital mortality during the first week of acute respiratory distress syndrome.

DESIGN

Retrospective observational study.

SETTING

Single-center ICU.

PATIENTS

Adults admitted to the ICU with a diagnosis of acute respiratory distress syndrome.

INTERVENTIONS

Calorie delivery from enteral nutrition, parenteral nutrition, propofol, and dextrose containing fluids were collected for 7 days following intubation. Sequential Organ Failure Assessment score was calculated at ICU admit and for the same 7 days to describe organ dysfunction; four different Sequential Organ Failure Assessment variables were created 1) Sequential Organ Failure Assessment at ICU admit, 2) average Sequential Organ Failure Assessment for the first 7 days following intubation, 3) the highest Sequential Organ Failure Assessment for the first 7 days following intubation, and 4) change in Sequential Organ Failure Assessment from intubation to 7 days later.

MEASUREMENTS AND MAIN RESULTS

A total of 298 patients were included. Sequential Organ Failure Assessment at ICU admit, average Sequential Organ Failure Assessment for the first 7 days following intubation, highest Sequential Organ Failure Assessment for the first 7 days following intubation, change in Sequential Organ Failure Assessment from intubation to 7 days later, and calorie delivery the first 7 days following intubation were all associated with increased likelihood of mortality. Compared with patients with low organ failure and low-calorie delivery, those with high-calorie delivery and low organ failure, low-calorie delivery and high organ failure, and the combination of both high organ failure with high-calorie delivery were associated with an incremental increase in the likelihood or mortality.

CONCLUSIONS

Organ failure appears to modify the relationship between calorie exposure and ICU outcome. Additional research is needed to identify appropriate thresholds for safe calorie exposure with increased organ failure.

Relationship between Nutrition Intake and 28-Day Mortality Using Modified NUTRIC Score in Patients with Sepsis

In critically ill patients, malnutrition is known to increase morbidity and mortality. We investigated the relationship between nutritional support and 28-day mortality using the modified NUTrition RIsk in the Critically ill (NUTRIC) score in patients with sepsis. This retrospective cohort study included patients with sepsis admitted to the medical intensive care unit (ICU) between January 2011 and June 2017. Nutritional support for energy and protein intakes at day 7 of ICU admission were categorized into <20, 20 to <25, and ≥25 kcal/kg and <1.0, 1.0 to <1.2, and ≥1.2 g/kg, respectively. NUTRIC scores ≥4 were considered to indicate high nutritional risk. Among patients with low nutritional risk, higher intakes of energy (≥25 kcal/kg) and protein (≥1.2 g/kg) were not significantly associated with lower 28-day mortality. In patients with high nutritional risk, higher energy intakes of ≥25 kcal/kg were significantly associated with lower 28-day mortality compared to intakes of <20 kcal/kg (adjusted hazard ratio (aHR): 0.569, 95% confidence interval (CI): 0.339-0.962, p = 0.035). Higher protein intakes of ≥1.2 g/kg were also significantly associated with lower 28-day mortality compared to intakes of <1.0 g/kg (aHR: 0.502, 95% CI: 0.280-0.900, p = 0.021). Appropriate energy (≥25 kcal/kg) and protein (≥1.2 g/kg) intakes during the first week may improve outcomes in patients with sepsis having high nutritional risk.

Muscle weakness: Understanding the principles of myopathy and neuropathy in the critically ill patient and the management options

Myo-neuropathy of the critically ill patient is a difficult nosological entity to understand and manage. It appears soon after injury, and it is estimated that 20-30% of patients admitted to Intensive Care Units will develop it in some degree. Although muscular and nervous involvement are related, the former has a better prognosis. Myo-neuropathy associates to more morbidity, longer stay in Intensive Care Unit and in hospital, and also to higher costs and mortality. It is considered part of the main determinants of the new entities: the Chronic Critical Patient and the Post Intensive Care Syndrome. This update focuses on aetiology, pathophysiology, diagnosis and strategies that can prevent, alleviate and/or improve muscle (or muscle-nerve) weakness.

Effect of combined parenteral and enteral nutrition versus enteral nutrition alone for critically ill patients: A systematic review and meta-analysis

BACKGROUND AND AIM

The increased mortality rate and other poor prognosis make malnutrition a serious issue for adult critically ill patients in intensive care unit care. This study was to compare outcomes between combined parenteral and enteral nutrition and enteral nutrition alone for adult critically ill patients.

MATERIALS AND METHODS

The PubMed (June 30, 2018), EMBASE (June 30, 2018), and Cochrane library databases (June 30, 2018) were searched systematically. Randomized controlled trials (RCTs) of comparing combined PN and EN with EN alone were eligible. Relative risks (RRs), mean differences (MDs), and 95% confidence intervals (CIs) were calculated for dichotomous and continuous outcomes.

RESULTS

Eight RCTs involving 5360 patients met the inclusion criteria. Compared with combined PN and EN, fewer respiratory infections (RR, 1.13 [95% CI 1.01-1.25]) and shorter length of days at hospital (MD, 1.83 [95% CI 1.05-2.62]) were observed in EN alone group. And no significant differences were found on hospital mortality (RR, 0.91 [95% CI 0.74-1.12]), length of days in ICU (MD, -0.23 [95% CI -1.79 to 1.32]), duration of ventilatory support (MD, -1.10 [95% CI -3.15 to 0.94]), albumin (MD, -0.04 [95% CI, -0.12 to 0.21]), or prealbumin (MD, -0.77 [95% CI -0.22 to 1.75]) between theses 2 groups.

CONCLUSION

Receiving EN alone decreased the respiratory infections and length of days at hospital for critically ill patients. Combined PN and EN did not add up the potential risk from PN and EN on hospital mortality, length of days in ICU, duration of ventilatory support, albumin, and prealbumin.

ESPEN guideline on clinical nutrition in the intensive care unit

Following the new ESPEN Standard Operating Procedures, the previous guidelines to provide best medical nutritional therapy to critically ill patients have been updated. These guidelines define who are the patients at risk, how to assess nutritional status of an ICU patient, how to define the amount of energy to provide, the route to choose and how to adapt according to various clinical conditions. When to start and how to progress in the administration of adequate provision of nutrients is also described. The best determination of amount and nature of carbohydrates, fat and protein are suggested. Special attention is given to glutamine and omega-3 fatty acids. Particular conditions frequently observed in intensive care such as patients with dysphagia, frail patients, multiple trauma patients, abdominal surgery, sepsis, and obesity are discussed to guide the practitioner toward the best evidence based therapy. Monitoring of this nutritional therapy is discussed in a separate document.

Intensive Care Nutrition and Post-Intensive Care Recovery

Intensive care unit (ICU)-acquired weakness frequently complicates critical illness, which prolongs intensive care dependency and causes long-term burden. Observational studies have suggested that prolonged underfeeding could aggravate ICU-acquired weakness and impair outcome. However, recent large randomized controlled trials have failed to show a benefit of early enhanced nutrition to critically ill patients. Moreover, early parenteral nutrition was even shown to increase ICU-acquired weakness and prolong organ failure and intensive care dependency, which may be explained by feeding-induced suppression of autophagy. Currently, the ideal timing of artificial nutrition for critically ill patients as well as the optimal dose and composition remain unclear.

Prescribed hypocaloric nutrition support for critically-ill adults

BACKGROUND

There are controversies about the amount of calories and the type of nutritional support that should be given to critically-ill people. Several authors advocate the potential benefits of hypocaloric nutrition support, but the evidence is inconclusive.

OBJECTIVES

To assess the effects of prescribed hypocaloric nutrition support in comparison with standard nutrition support for critically-ill adults SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL, Cochrane Library), MEDLINE, Embase and LILACS (from inception to 20 June 2017) with a specific strategy for each database. We also assessed three websites, conference proceedings and reference lists, and contacted leaders in the field and the pharmaceutical industry for undetected/unpublished studies. There was no restriction by date, language or publication status.

SELECTION CRITERIA

We included randomized and quasi-randomized controlled trials comparing hypocaloric nutrition support to normo- or hypercaloric nutrition support or no nutrition support (e.g. fasting) in adults hospitalized in intensive care units (ICUs).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We meta-analysed data for comparisons in which clinical heterogeneity was low. We conducted prespecified subgroup and sensitivity analyses, and post hoc analyses, including meta-regression. Our primary outcomes were: mortality (death occurred during the ICU and hospital stay, or 28- to 30-day all-cause mortality); length of stay (days stayed in the ICU and in the hospital); and Infectious complications. Secondary outcomes included: length of mechanical ventilation. We assessed the quality of evidence with GRADE.

MAIN RESULTS

We identified 15 trials, with a total of 3129 ICU participants from university-associated hospitals in the USA, Colombia, Saudi Arabia, Canada, Greece, Germany and Iran. There are two ongoing studies. Participants suffered from medical and surgical conditions, with a variety of inclusion criteria. Four studies used parenteral nutrition and nine studies used only enteral nutrition; it was unclear whether the remaining two used parenteral nutrition. Most of them could not achieve the proposed caloric targets, resulting in small differences in the administered calories between intervention and control groups. Most studies were funded by the US government or non-governmental associations, but three studies received funding from industry. Five studies did not specify their funding sources.The included studies suffered from important clinical and statistical heterogeneity. This heterogeneity did not allow us to report pooled estimates of the primary and secondary outcomes, so we have described them narratively.When comparing hypocaloric nutrition support with a control nutrition support, for hospital mortality (9 studies, 1775 participants), the risk ratios ranged from 0.23 to 5.54; for ICU mortality (4 studies, 1291 participants) the risk ratios ranged from 0.81 to 5.54, and for mortality at 30 days (7 studies, 2611 participants) the risk ratios ranged from 0.79 to 3.00. Most of these estimates included the null value. The quality of the evidence was very low due to unclear or high risk of bias, inconsistency and imprecision.Participants who received hypocaloric nutrition support compared to control nutrition support had a range of mean hospital lengths of stay of 15.70 days lower to 10.70 days higher (10 studies, 1677 participants), a range of mean ICU lengths of stay 11.00 days lower to 5.40 days higher (11 studies, 2942 participants) and a range of mean lengths of mechanical ventilation of 13.20 days lower to 8.36 days higher (12 studies, 3000 participants). The quality of the evidence for this outcome was very low due to unclear or high risk of bias in most studies, inconsistency and imprecision.The risk ratios for infectious complications (10 studies, 2804 participants) of each individual study ranged from 0.54 to 2.54. The quality of the evidence for this outcome was very low due to unclear or high risk of bias, inconsistency and imprecisionWe were not able to explain the causes of the observed heterogeneity using subgroup and sensitivity analyses or meta-regression.

AUTHORS' CONCLUSIONS

The included studies had substantial clinical heterogeneity. We found very low-quality evidence about the effects of prescribed hypocaloric nutrition support on mortality in hospital, in the ICU and at 30 days, as well as in length of hospital and ICU stay, infectious complications and the length of mechanical ventilation. For these outcomes there is uncertainty about the effects of prescribed hypocaloric nutrition, since the range of estimates includes both appreciable benefits and harms.Given these limitations, results must be interpreted with caution in the clinical field, considering the unclear balance of the risks and harms of this intervention. Future research addressing the clinical heterogeneity of participants and interventions, study limitations and sample size could clarify the effects of this intervention.

Volume-based feeding improves nutritional adequacy in surgical patients

BACKGROUND

Critically ill surgical patients often receive inadequate enteral nutrition using traditional rate-based feeding methods. An alternative strategy is volume-based feeding, in which feeding rates are adjusted to deliver a goal volume per day.

METHODS

This prospective quality improvement study in a single surgical, trauma, and burn ICU compared volume-based feeding to rate-based feeding in a before-and-after design. Outcomes included calories and protein delivered, length of stay, infection, and mortality.

RESULTS

A total of 50 patients received volume-based feeding and 49 rate-based feeding. The volume-based group received a higher proportion of goal calories (84.5% vs. 73.4%; p = 0.005) and protein (86.2% vs. 77.4%; p = 0.01), as well as increased total daily calories (1604 vs. 1356 kcal; p = 0.02). There was no difference in length of stay, mortality, aspiration, or gastrointestinal intolerance.

CONCLUSIONS

Volume-based feeding improved nutritional intake in critically ill surgical patients, although this study was underpowered to determine differences in clinical outcomes.

High-Protein Hypocaloric Nutrition for Non-Obese Critically Ill Patients

High-protein hypocaloric nutrition, tailored to each patient's muscle mass, protein-catabolic severity, and exogenous energy tolerance, is the most plausible nutrition therapy in protein-catabolic critical illness. Sufficient protein provision could mitigate the rapid muscle atrophy characteristic of this disease while providing urgently needed amino acids to the central protein compartment and sites of tissue injury. The protein dose may range from 1.5 to 2.5 g protein (1.8-3.0 g free amino acids)/kg dry body weight per day. Nutrition should be low in energy (≈70% of energy expenditure or ≈15 kcal/kg dry body weight per day) because efforts to match energy provision to energy expenditure are physiologically irrational, risk toxic energy overfeeding, and have repeatedly failed in large clinical trials to demonstrate clinical benefit. The American Society for Parenteral and Enteral Nutrition currently suggests high-protein hypocaloric nutrition for obese critically ill patients. Short-term high-protein hypocaloric nutrition is physiologically and clinically sensible for most protein-catabolic critically ill patients, whether obese or not.

Effect of hypocaloric normoprotein or trophic feeding versus target full enteral feeding on patient outcomes in critically ill adults: a systematic review

Uncertainty surrounds the optimal approach to feeding the critically ill, with increasing interest in the concept of intentional underfeeding to reduce metabolic stress while maintaining gut integrity. Conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, this systematic review evaluates clinical outcomes reported in studies comparing hypocaloric normonitrogenous or trophic feeding (collectively 'intentional underfeeding') targeted full energy feeding administered via enteral nutrition to adult critically ill patients. Electronic databases including PubMed, CINAHL, EMBASE and CENTRAL were searched up to September 2017 for trials evaluating intentional underfeeding versus targeted energy feeding interventions on clinical outcomes (mortality, length of stay, duration of ventilation, infective complications, feeding intolerance and glycaemic control) among critically ill adult patients. Bias of included studies was assessed using the Cochrane risk of bias tool. Of the 595 articles identified, seven studies (six randomised controlled trials, one non-randomised trial) met the inclusion criteria, representing 2,684 patients (hypocaloric normonitrogenous n=668; trophic n=681; full energy feeding n=1335). Across the studies, there was considerable heterogeneity in study methodology, population, feeding strategy and outcomes and their timepoints. We observed no evidence that intentional underfeeding, when compared to targeting full energy feeding, reduced mortality or duration of ventilation or length of stay. However, limited trial evidence is available on the impact of intentional underfeeding on post-discharge functional and quality of life outcomes.

Permissive or Trophic Enteral Nutrition and Full Enteral Nutrition Had Similar Effects on Clinical Outcomes in Intensive Care: A Systematic Review of Randomized Clinical Trials

The aim of this study was to systematically review the effect of permissive underfeeding/trophic feeding on the clinical outcomes of critically ill patients. A systematic review of randomized clinical trials to evaluate the mortality, length of stay, and mechanical ventilation duration in patients randomized to either hypocaloric or full-energy enteral nutrition was performed. Data sources included PubMed and Scopus and the reference lists of the articles retrieved. Two independent reviewers participated in all phases of this systematic review as proposed by the Cochrane Handbook, and the review was reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A total of 7 randomized clinical trials that included a total of 1,717 patients were reviewed. Intensive care unit length of stay and mechanical ventilation duration were not statistically different between the intervention and control groups in all randomized clinical trials, and mortality rate was also not different between the groups. In conclusion, hypocaloric enteral nutrition had no significantly different effects on morbidity and mortality in critically ill patients when compared with full-energy nutrition. It is still necessary to determine the safety of this intervention in this group of patients, the optimal amount of energy provided, and the duration of this therapy.

Early Exposure to Recommended Calorie Delivery in the Intensive Care Unit Is Associated With Increased Mortality in Patients With Acute Respiratory Distress Syndrome

BACKGROUND

The Intensive Nutrition in Acute Lung Injury: Clinical Trial (INTACT), designed to evaluate outcomes of calorie delivery from acute respiratory distress syndrome (ARDS) diagnosis through hospital discharge, was stopped due to higher mortality in the intervention group. Post hoc analysis found timing and dose of calorie delivery influenced mortality. The objective of this retrospective cohort study was to determine if early vs late calorie exposure changed the hazard of death among a larger sample of patients with ARDS.

METHODS

Adult patients who met the eligibility criteria for INTACT but did not participate were included. Daily calorie delivery was collected from the date INTACT eligibility was determined to extubation or death. Cox proportional hazards regression was used to model the relationship between hazard of hospital death with average calorie exposure received over increasing study days and after day 7.

RESULTS

A total of 298 patients were included; overall mortality was 33%. Among patients who remained intubated at 1 week (n = 202), higher kcal/kg received from intensive care unit (ICU) days 1-6 increased hazards of subsequent death on days 7+ (hazard ratio [HR], 1.04; 95% confidence interval [CI], 1.01-1.06); kcal/kg received after ICU day 7 decreased the hazards of death on day 7+ (HR, 0.53; 95% CI, 0.33-0.84).

CONCLUSIONS

Higher calorie exposure between ICU days 1 and 7 was associated with higher subsequent hazard of mortality, and provision of high-calorie exposure after day 8 decreased the hazards of death.

Controversies Surrounding Critical Care Nutrition: An Appraisal of Permissive Underfeeding, Protein, and Outcomes

Over the past few years, numerous studies have called into question the optimal dose, timing, composition, and advancement rate of nutrition during the early acute phase of critical illness. These studies suggest permissive underfeeding with slow advancement may be more beneficial than aggressive full feeding. These counterintuitive results were possibly explained by enhanced autophagy, less hyperglycemia, or prevention of refeeding syndrome. This review underscores the controversies surrounding permissive underfeeding, aims to answer whether permissive underfeeding is appropriate for all critically ill patients, describes the impact of optimal protein delivery on critical care outcomes, discusses nutrition risk, and cogitates on the impact of nutrition on critical care outcomes.

Multitargeted Feeding Strategies Improve Nutrition Outcome and Are Associated With Reduced Pneumonia in a Level 1 Trauma Intensive Care Unit

BACKGROUND

Factors impeding delivery of adequate enteral nutrition (EN) to trauma patients include delayed EN initiation, frequent surgeries and procedures, and postoperative ileus. We employed 3 feeding strategies to optimize EN delivery: (1) early EN initiation, (2) preoperative no nil per os feeding protocol, and (3) a catch-up feeding protocol. This study compared nutrition adequacy and clinical outcomes before and after implementation of these feeding strategies.

METHODS

All trauma patients aged ≥18 years requiring mechanical ventilation for ≥7 days and receiving EN were included. Patients who sustained nonsurvivable injuries, received parenteral nutrition, or were readmitted to the intensive care unit (ICU) were excluded. EN data were collected until patients received an oral diet or were discharged from the ICU. The improvement was quantified by comparing nutrition adequacy and outcomes between April 2014-May 2015 (intervention) and May 2012-June 2013 (baseline).

RESULTS

The intervention group (n = 118) received significantly more calories (94% vs 75%, P < .001) and protein (104% vs 74%, P < .001) than the baseline group (n = 121). The percentage of patients receiving EN within 24 and 48 hours of ICU admission increased from 41% to 70% and from 79% to 96% respectively after intervention (P < .001). Although there were fewer 28-ay ventilator-free days in the intervention group than in the baseline group (12 vs 16 days, P = .03), receipt of the intervention was associated with a significant reduction in pneumonia (odds ratio, 0.53; 95% confidence interval, 0.31-0.89; P = .017) after adjusting sex and Injury Severity Score.

CONCLUSIONS

Implementation of multitargeted feeding strategies resulted in a significant increase in nutrition adequacy and a significant reduction in pneumonia.

Feeding During Phases of Altered Mitochondrial Activity: A Theory

Decisions surrounding the timing and dosing of nutrition support are made for thousands of ICU patients daily and yet remain a topic of controversy. Nutrition support designed to replenish resting energy expenditure (REE) early in critical illness has led to worse clinical outcomes in at least three recent prospective randomized clinical trials. Producing sufficient energy from nutrient substrates requires use of the mitochondrial electron transport chain (ETC). This process is functionally linked to the creation of a tightly regulated series of chemical messengers known as reactive oxygen species (ROS). In health, ROS are kept at low levels by a system of mitochondrial/cellular enzymes and antioxidants, allowing ROS to act as a signal for the redox health of the cell. In inflammatory conditions, however, this system is altered, leading to changes in the physiologic function of the ETC such that its usage produces greater ROS per unit of substrate. This increased ROS is capable of deactivating antioxidant systems, as well as activating further ROS-producing pathways and stimulating localized inflammatory activity. We propose that exacerbation of this process at this time by the forced influx of exogenously acquired nutrient substrates leads to mitochondrial damage, amplified ROS production, increased inflammation, decreased ATP-productive capacity, and, eventually, the death of the cell by either apoptosis or necrosis. Knowledge of this process is vital to determining the safe dosing and timing of nutrition support in the ICU. It is possible that the physiologic cost of meeting the REE under these conditions of mitochondrial stress may simply be too high. This paper details the proposed process by which inappropriately timed feeding in critically ill patients may damage the very mitochondria required for its utilization.

Critical Care Nutrition: Where's the Evidence?

The surgical critically ill patient is subject to a variable and complex metabolic response, which has detrimental effects on immunity, wound healing, and preservation of lean body muscle. The concept of nutrition support has evolved into nutrition therapy, whereby the primary objectives are to prevent oxidative cell injury, modulate the immune response, and attenuate the metabolic response. This review outlines the metabolic response to critical illness, describes nutritional risk; reviews the evidence for the role, dose, and timing of enteral and parenteral nutrition, and reviews the evidence for immunonutrition in the surgical intensive care unit.

Effects on nutritional care practice after implementation of a flow chart-based nutrition support protocol in an intensive care unit

Background

Enteral nutrition (EN) is associated with improved outcome in critically ill patients and is more affordable. We compared nutritional care practice in our ICU before and after modification of our nutrition support protocol: Several comprehensive documents were substituted with one flow chart and early EN was encouraged.

Design

Retrospective observational study.

Methods

Nutritional data were collected from admission up to 7 days in 25 patients before and 25 patients after protocol modification.

Results

The percentage of patients receiving EN within 72 hr of admission increased from 64% before to 88% after protocol modification. Cumulative percentage energy from EN during ICU days 1–4 increased from 26–89% of total kcal. Overall amount of nutrition administered enterally increased, with a corresponding marked decline in use of parenteral nutrition. Pre‐modification, >80% of patients received >65% of their calculated nutrition requirements by ICU Day 4; post‐modification this goal was achieved by Day 7.

Current clinical nutrition practices in critically ill patients in Latin America: a multinational observational study

Background

Malnutrition in critically ill adults in the intensive care unit (ICU) is associated with a significantly elevated risk of mortality. Adequate nutrition therapy is crucial to optimise outcomes. Currently, there is a paucity of such data in Latin America. Our aims were to characterise current clinical nutrition practices in the ICU setting in Latin America and evaluate whether current practices meet caloric and protein requirements in critically ill patients receiving nutrition therapy.

Methods

We conducted a cross-sectional, retrospective, observational study in eight Latin American countries (Argentina, Brazil, Chile, Colombia, Ecuador, Mexico, Panama, and Peru). Eligible patients were critically ill adults hospitalised in the ICU and receiving enteral nutrition (EN) and/or parenteral nutrition (PN) on the Screening Day and the previous day (day −1). Caloric and protein balance on day –1, nutritional status, and prescribed nutrition therapy were recorded. Multivariable logistic regression analysis was performed to identify independent predictors of reaching daily caloric and protein targets.

Results

The analysis included 1053 patients from 116 hospitals. Evaluation of nutritional status showed that 74.1% of patients had suspected/moderate or severe malnutrition according to the Subjective Global Assessment. Prescribed nutrition therapy included EN alone (79.9%), PN alone (9.4%), and EN + PN (10.7%). Caloric intake met >90% of the daily target in 59.7% of patients on day –1; a caloric deficit was present in 40.3%, with a mean (±SD) daily caloric deficit of –688.8 ± 455.2 kcal. Multivariable logistic regression analysis showed that combined administration of EN + PN was associated with a statistically significant increase in the probability of meeting >90% of daily caloric and protein targets compared with EN alone (odds ratio, 1.56; 95% confidence interval, 1.02–2.39; p = 0.038).

Conclusions

In the ICU setting in Latin America, malnutrition was highly prevalent and caloric intake failed to meet targeted energy delivery in 40% of critically ill adults receiving nutrition therapy. Supplemental administration of PN was associated with improved energy and protein delivery; however, PN use was low. Collectively, these findings suggest an opportunity for more effective utilisation of supplemental PN in critically ill adults who fail to receive adequate nutrition from EN alone.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1805-z) contains supplementary material, which is available to authorized users.

Energy, Protein, Carbohydrate, and Lipid Intakes and Their Effects on Morbidity and Mortality in Critically Ill Adult Patients: A Systematic Review

The guidelines for nutritional support in critically ill adult patients differ in various aspects. The optimal amount of energy and nutritional substrates supplied is important for reducing morbidity and mortality, but unfortunately this is not well known, because the topic is complex and every patient is individual. The aim of this review was to gather recent pertinent information concerning the nutritional support of critically ill patients in the intensive care unit (ICU) with respect to the energy, protein, carbohydrate, and lipid intakes and the effect of their specific utilization on morbidity and mortality. Enteral nutrition (EN) is generally recommended over parenteral nutrition (PN) and is beneficial when administered within 24-48 h after ICU admission. In contrast, early PN does not provide substantial advantages in terms of morbidity and mortality, and the time when it is safe and beneficial remains unclear. The most advantageous recommendation seems to be administration of a hypocaloric (<20 kcal · kg^-1 · d^-1), high-protein diet (amino acids at doses of ≥2 g · kg^-1 · d^-1), at least during the first week of critical illness. Another important factor for reducing morbidity is the maintenance of blood glucose concentrations at 120-150 mg/dL, which is accomplished with the use of insulin and lower doses of glucose of 1-2 g · kg^-1 · d^-1, because this prevents the risk of hypoglycemia and is associated with a better prognosis according to recent studies. A fat emulsion is used as a source of required calories because of insulin resistance in the majority of patients. In addition, lipid oxidation in these patients is ∼25% higher than in healthy subjects.