Effect of Calories Delivered on Clinical Outcomes in Critically Ill Patients: Systemic Review and Meta-analysis

Relevance of Protein Intake for Weaning in the Mechanically Ventilated Critically Ill: Analysis of a Large International Database

OBJECTIVES

The association between protein intake and the need for mechanical ventilation (MV) is controversial. We aimed to investigate the associations between protein intake and outcomes in ventilated critically ill patients.

DESIGN

Analysis of a subset of a large international point prevalence survey of nutritional practice in ICUs.

SETTING

A total of 785 international ICUs.

PATIENTS

A total of 12,930 patients had been in the ICU for at least 96 hours and required MV by the fourth day after ICU admission at the latest.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We modeled associations between the adjusted hazard rate (aHR) of death in patients requiring MV and successful weaning (competing risks), and three categories of protein intake (low: < 0.8 g/kg/d, standard: 0.8-1.2 g/kg/d, high: > 1.2 g/kg/d). We compared five different hypothetical protein diets (an exclusively low protein intake, a standard protein intake given early (days 1-4) or late (days 5-11) after ICU admission, and an early or late high protein intake). There was no evidence that the level of protein intake was associated with time to weaning. However, compared with an exclusively low protein intake, a standard protein intake was associated with a lower hazard of death in MV: minimum aHR 0.60 (95% CI, 0.45-0.80). With an early high intake, there was a trend to a higher risk of death in patients requiring MV: maximum aHR 1.35 (95% CI, 0.99-1.85) compared with a standard diet.

CONCLUSIONS

The duration of MV does not appear to depend on protein intake, whereas mortality in patients requiring MV may be improved by a standard protein intake. Adverse effects of a high protein intake cannot be excluded.

Early parenteral nutrition comparing to enteral nutrition cannot reduce 28-day mortality in critically ill patients: a retrospective comparative cohort study based on the MIMIC‑IV database

Background

Enteral nutrition (EN) is recommended as the first choice by guidelines for critical ill patients. But the timing of safe and effective delivery of parenteral nutrition (PN) is unclear and the results of previous studies are controversial. There is insufficient evidence for the use of early PN, so we designed this cohort study to compared the clinical outcomes of critical ill patients who received early PN with those who did not.

Methods

This retrospective study conducted using the Medical Information Mart for Intensive Care (MIMIC)-IV database. Patients who received nutrition therapy within 3 days of ICU admission were included and we categorized them as patients who received any kind of PN (PN group) or only enteral nutrition (EN group). Confounding factors were adjusted by propensity-score matching (PSM). The primary outcome was the 28-day mortality rate, and secondary outcomes included length of stay (LOS) in the hospital and ICU, hospital infection, and mechanical ventilation time.

Results

A total of 5,019 patients (PN group, 357; EN group, 4,662) were included in the analyses. The 28-day mortality rates showed no significant intergroup difference (EN, 22.3% vs. PN, 20.2%; P=0.378). The PN group showed a shorter median ICU LOS (EN, 8.14 vs. PN, 6.89 days, P=0.00955), and a longer median hospital LOS (PN, 21.55 vs. EN, 15.1 days, P<0.001). After PSM, each group included 355 patients, with no significant intergroup difference in the 28-day mortality rate (EN, 18.9% vs. PN, 20.3%; P=0.705). The PN group still showed a longer hospital LOS (median LOS: PN, 21.45 vs. EN, 14.81 days, P<0.001), but the other outcomes showed no differences.

Conclusions

PN within 3 days of ICU admission did not reduce the 28-day mortality rate and could extend hospital LOS. This study supports further fundamental and clinical research to ascertain the effect of PN for ICU patients.

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.

Review of evolution and current status of protein requirements and provision in acute illness and critical care

Nutrition therapy, by enteral, parenteral, or both routes combined, is a key component of the management of critically ill, surgical, burns, and oncology patients. Established evidence indicates overfeeding (provision of excessive calories) results in increased risk of infection, morbidity, and mortality. This has led to the practice of "permissive underfeeding" of calories; however, this can often lead to inadequate provision of guideline-recommended protein intakes. Acutely ill patients requiring nutritional therapy have high protein requirements, and studies demonstrate that provision of adequate protein can result in reduced mortality and improvement in quality of life. However, a significant challenge to adequate protein delivery is the current lack of concentrated protein solutions. Patients often have fluid administration restrictions and existing protein solutions are frequently not sufficiently concentrated to deliver a patient's protein requirements. This has led to the development of new enteral and parenteral nutrition solutions incorporating higher levels of protein in smaller volumes. This review article summarizes current evidence supporting the role of higher protein intakes, especially during the early phases of nutrition therapy in acute illness, methods for assessing protein requirements, as well as, the currently available high-protein enteral and parenteral nutrition solutions. There is sufficient evidence (albeit limited from true randomized, controlled studies) to indicate that earlier provision of guideline-recommended protein intakes may be key to improving patient outcomes and that nutritional therapy that tailors caloric and protein intake to the patients' needs should be considered a desired standard of care.

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.

Selenium and hydrogen selenide: essential micronutrient and the fourth gasotransmitter?

Selenium (Se) is an essential micronutrient required by organisms of diverse lineage. Dietary Se is converted to hydrogen selenide either enzymatically or by endogenous antioxidant proteins. This convergent biochemical step crucially underlies the subsequent biological activity of Se and argues for inclusion of hydrogen selenide as the fourth endogenous gasotransmitter alongside nitric oxide, carbon monoxide and hydrogen sulfide.Endogenously generated hydrogen selenide is incorporated into numerous 'selenoprotein' oxidoreductase enzymes, essential for maintaining redox-status homeostasis in health and disease. Direct effects of endogenous hydrogen selenide on cellular and molecular targets are currently unknown. Given exogenously, hydrogen selenide acts as a modulator of metabolism via transient inhibition of mitochondrial cytochrome C oxidase. Here we provide an overview of Se biology, its impact on several physiological systems (immune, endocrine, cardiovascular and metabolic) and its utility as a supplement in acute and critical illness states. We further explore the evidence base supporting its role as the fourth gasotransmitter and propose a strategic case towards generation of novel selenomimetic therapeutics.

Feasibility of using the "modified NUTrition Risk In the Critically ill" nutritional risk screening tool to identify nutritionally at-risk patients in an Australian intensive care unit

BACKGROUND

The modified NUTrition Risk In the Critically ill (mNUTRIC) score has been demonstrated to accurately quantify the risk of negative patient outcomes and discriminate which patients will benefit the most from nutrition intervention in an intensive care unit (ICU) setting. Calculation of an mNUTRIC score, however, may be time-intensive and unable to be performed within available resources. This may prevent high-risk patients from being identified and reviewed by a dietitian.

OBJECTIVES

The purpose of this study was to assess the feasibility of using the mNUTRIC tool to screen for patients at increased nutrition risk and to determine the proportion of those high-risk patients who were reviewed by a dietitian.

SUBJECTS/METHODS

A retrospective observational study of 260 critically ill patients was conducted between 01/01/2017 and 30/05/2017 in a 20-bed Australian tertiary ICU. Participants included all adults admitted to the ICU for more than 72 h. Feasible implementation was defined as calculating an mNUTRIC score in <5 min per patient where all data were available for >90% of patients.

RESULTS

A median time of 4 min and 54 s (interquartile range: 4.3-5.6 min) was required to calculate each mNUTRIC score, with 96% of scores calculated in <10 min. Data were available to calculate mNUTRIC scores for 93% (241/260) of patients. The mNUTRIC tool identified 81 patients at high nutrition risk, 44% (36/81) of whom were not reviewed by a dietitian. There were 21 high-risk patients who were purposefully excluded from dietetic review for various clinical reasons, leaving 15 high-risk patients (19%) who were not reviewed by a dietitian.

CONCLUSIONS

Implementation of the mNUTRIC tool was not feasible in our ICU, given the set dietetic resources (0.6 full-time equivalent). Shared responsibility of nutrition screening or automating the calculation may be possible solutions to increase feasibility of mNUTRIC screening.

Clinical Nutrition in Critical Care Medicine - Guideline of the German Society for Nutritional Medicine (DGEM)

PURPOSE

Enteral and parenteral nutrition of adult critically ill patients varies in terms of the route of nutrient delivery, the amount and composition of macro- and micronutrients, and the choice of specific, immune-modulating substrates. Variations of clinical nutrition may affect clinical outcomes. The present guideline provides clinicians with updated consensus-based recommendations for clinical nutrition in adult critically ill patients who suffer from at least one acute organ dysfunction requiring specific drug therapy and/or a mechanical support device (e.g., mechanical ventilation) to maintain organ function.

METHODS

The former guidelines of the German Society for Nutritional Medicine (DGEM) were updated according to the current instructions of the Association of the Scientific Medical Societies in Germany (AWMF) valid for a S2k-guideline. According to the S2k-guideline classification, no systematic review of the available evidence was required to make recommendations, which, therefore, do not state evidence- or recommendation grades. Nevertheless, we considered and commented the evidence from randomized-controlled trials, meta-analyses and observational studies with adequate sample size and high methodological quality (until May 2018) as well as from currently valid guidelines of other societies. The liability of each recommendation was described linguistically. Each recommendation was finally validated and consented through a Delphi process.

RESULTS

In the introduction the guideline describes a) the pathophysiological consequences of critical illness possibly affecting metabolism and nutrition of critically ill patients, b) potential definitions for different disease phases during the course of illness, and c) methodological shortcomings of clinical trials on nutrition. Then, we make 69 consented recommendations for essential, practice-relevant elements of clinical nutrition in critically ill patients. Among others, recommendations include the assessment of nutrition status, the indication for clinical nutrition, the timing and route of nutrient delivery, and the amount and composition of substrates (macro- and micronutrients); furthermore, we discuss distinctive aspects of nutrition therapy in obese critically ill patients and those treated with extracorporeal support devices.

CONCLUSION

The current guideline provides clinicians with up-to-date recommendations for enteral and parenteral nutrition of adult critically ill patients who suffer from at least one acute organ dysfunction requiring specific drug therapy and/or a mechanical support device (e.g., mechanical ventilation) to maintain organ function. The period of validity of the guideline is approximately fixed at five years (2018-2023).

Calorie intake and short-term survival of critically ill patients

BACKGROUND & AIMS

The association between calorie supply and outcome of critically ill patients is unclear. Results from observational studies contradict findings of randomized studies, and have been questioned because of unrecognized confounding by indication. The present study wanted to re-examine the associations between the daily amount of calorie intake and short-term survival of critically ill patients using several novel statistical approaches.

METHODS

9661 critically ill patients from 451 ICUs were extracted from an international database. We examined associations between survival time and three pragmatic nutritional categories (I: <30% of target, II: 30-70%, III: >70%) reflecting different amounts of total daily calorie intake. We compared hazard ratios for the 30-day risk of dying estimated for different hypothetical nutrition support plans (different categories of daily calorie intake during the first 11 days after ICU admission). To minimize indication bias, we used a lag time between nutrition and outcome, we particularly considered daily amounts of calorie intake, and we adjusted results to the route of calorie supply (enteral, parenteral, oral).

RESULTS

1974 patients (20.4%) died in hospital before day 30. Median of daily artificial calorie intake was 1.0 kcal/kg [IQR 0.0-4.1] in category I, 12.3 kcal/kg [9.4-15.4] in category II, and 23.5 kcal/kg [19.5-27.8] in category III. When compared to a plan providing daily minimal amounts of calories (category I), the adjusted minimal hazard ratios for a delayed (from day 5-11) or an early (from day 1-11) mildly hypocaloric nutrition (category II) were 0.71 (95% confidence interval [CI], 0.54 to 0.94) and 0.56 (95% CI, 0.38 to 0.82), respectively. No substantial hazard change could be detected, when a delayed or an early, near target calorie intake (category III) was compared to an early, mildly hypocaloric nutrition.

CONCLUSIONS

Compared to a severely hypocaloric nutrition, a mildly hypocaloric nutrition is associated with a decreased risk of death. In unselected critically ill patients, this risk cannot be reduced further by providing amounts of calories close to the calculated target.

STUDY REGISTRATION

ID number ISRCTN17829198, website http://www.isrctn.org.