The impact of L-alanyl-L-glutamine dipeptide supplemented total parenteral nutrition on clinical outcome in critically patients

Glutamine Supplementation as a Novel Metabolic Therapeutic Strategy for LIG3-Dependent Chronic Intestinal Pseudo-obstruction

BACKGROUND & AIMS

We recently identified a recessive syndrome due to DNA ligase 3 (LIG3) mutations in patients with chronic intestinal pseudo-obstruction, leukoencephalopathy, and neurogenic bladder. LIG3 mutations affect mitochondrial DNA maintenance, leading to defective energy production. We aimed at identifying altered molecular pathways and developing possible targeted treatments to revert/ameliorate the cellular energy impairment.

METHODS

Whole transcriptome analysis was performed on patient-derived fibroblasts total RNA and controls. Mitochondrial function, mitophagy, and l-glutamine supplementation effects were analyzed by live cell analysis, immunostaining, and Western blot. Patients were treated with Dipeptiven (Fresenius-Kabi) according to standard protocols. Patients' symptoms were analyzed by the Gastrointestinal Symptom Rating Scale questionnaire.

RESULTS

We identified deregulated transcripts in mutant fibroblasts vs controls, including overexpression of genes involved in extracellular matrix development and remodeling and mitochondrial functions. Gut biopsy specimens of LIG3-mutant patients documented collagen and elastic fiber accumulation. Mutant fibroblasts exhibited impaired mitochondrial mitophagy indicative of dysfunctional turnover and altered Ca2+ homeostasis. Supplementation with l-glutamine (6 mmol/L), previously shown to increase mitochondrial DNA-defective cell survival, improved growth rate and adenosine 5'-triphosphate production in LIG3-mutant fibroblasts. These data led us to provide parenterally a dipeptide containing l-glutamine to 3 siblings carrying biallelic LIG3 mutations. Compared with baseline, gastrointestinal and extra-gastrointestinal symptoms significantly improved after 8 months of treatment.

CONCLUSIONS

LIG3 deficiency leads to mitochondrial dysfunction. High levels l-glutamine supplementation were beneficial in LIG3-mutant cells and improved symptom severity without noticeable adverse effects. Our results provide a proof of concept to design ad hoc clinical trials with l-glutamine in LIG3-mutant patients.

Critically Ill Older Adults' Representation in Intervention Trials: A Systematic Review

OBJECTIVES

Older adults may be under-represented in critical care research, and results may not apply to this specific population. Our primary objective was to evaluate the prevalence of inclusion of older adults across critical care trials focused on common ICU conditions or interventions. Our secondary objective was to evaluate whether older age was used as a stratification variable for randomization or outcome analysis.

DESIGN SETTING AND SUBJECTS

We performed a systematic review of previously published systematic reviews of randomized controlled trials (RCTs) in critical care. We searched PubMed, Ovid, CENTRAL, and Cochrane from 2009 to 2022. Systematic reviews of any interventions across five topics: acute respiratory distress syndrome (ARDS), sepsis/shock, nutrition, sedation, and mobilization were eligible.

MAIN RESULTS

We identified 216 systematic reviews and included a total of 253 RCTs and 113,090 patients. We extracted baseline characteristics and the reported proportion of older adults. We assessed whether any upper age limit was an exclusion criterion for trials, whether age was used for stratification during randomization or data analysis, and if age-specific subgroup analysis was present. The most prevalent topic was sepsis (78 trials, 31%), followed by nutrition (62 trials, 25%), ARDS (39 trials, 15%), mobilization (38 trials, 15%), and sedation (36 trials, 14%). Eighteen trials (7%) had exclusion criteria based on older age. Age distribution with information on older adults prevalence was given in six trials (2%). Age was considered in the analysis of ten trials (5%) using analytic methods to evaluate the outcome stratified by age.

Conclusions

In this systematic review, the proportion of older critically ill patients is undetermined, and it is unclear how age is or is not an effect modifier or to what extent the results are valid for older adult groups. Reporting age is important to guide clinicians in personalizing care. These results highlight the importance of incorporating older critically ill patients in future trials to ensure the results are generalizable to this growing population.

The Effect of Amino Acids on Wound Healing: A Systematic Review and Meta-Analysis on Arginine and Glutamine

Under stress conditions, the metabolic demand for nutrients increases, which, if not met, may slow down or indeed stop the wound from healing, thus, becoming chronic wounds. This study aims to perform a systematic review and meta-analysis of the effect of arginine and glutamine supplementation on wound healing. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed for the systematic review and ten electronic databases were used. Five and 39 human studies met the inclusion criteria for arginine and glutamine, respectively. The overall meta-analysis demonstrated a significant effect of arginine supplementation on hydroxyproline content (MD: 4.49, 95% CI: 3.54, 4.45, p < 0.00001). Regarding glutamine supplementation, there was significant effect on nitrogen balance levels (MD: 0.39, 95% CI: 0.21, 0.58, p < 0.0001), IL-6 levels (MD: −5.78, 95% CI: −8.71, −2.86, p = 0.0001), TNFα levels (MD: −8.15, 95% CI: −9.34, −6.96, p < 0.00001), lactulose/mannitol (L/M) ratio (MD: −0.01, 95% CI: −0.02, −0.01, p < 0.00001), patient mortality (OR: 0.48, 95% CI: 0.32, 0.72, p = 0.0004), C-reactive protein (CRP) levels (MD: −1.10, 95% CI: −1.26, −0.93, p < 0.00001) and length of hospital stay (LOS) (MD: −2.65, 95% CI: −3.10, −2.21, p < 0.00001). Regarding T-cell lymphocytes, a slight decrease was observed, although it failed to reach significance (MD: −0.16, 95% CI: −0.33, 0.01, p = 0.07). Conclusion: The wound healing might be enhanced in one or at various stages by nutritional supplementation in the right dose.

Glutamine dipeptide-supplemented parenteral nutrition improves the clinical outcomes of critically ill patients: A systematic evaluation of randomised controlled trials

BACKGROUND & AIMS

Early randomised controlled trials (RCTs) testing whether parenteral nutrition regimens that include glutamine dipeptides improves the outcomes of critically ill patients demonstrated convincingly that this regimen associates with reduced mortality, infections, and hospital stays. However, several new RCTs on the same question challenged this. To resolve this controversy, the present meta-analysis was performed. Stringent eligibility criteria were used to select only those RCTs that tested the outcomes of critically ill adult patients without hepatic and/or renal failure who were haemodynamically and metabolically stabilised and who were administered glutamine dipeptide strictly according to current clinical guidelines (via the parenteral route at 0.3-0.5 g/kg/day; max. 30% of the prescribed nitrogen supply) in combination with adequate nutrition.

METHODS

The literature research (PubMed, Embase, Cochrane Central Register of Controlled Trials) searched for English and German articles that had been published in peer-review journals (last entry March 31, 2015) and reported the results of RCTs in critically ill adult patients (major surgery, trauma, infection, or organ failure) who received parenteral glutamine dipeptide as part of an isoenergetic and isonitrogenous nutrition therapy. The following data were extracted: infectious complications, lengths of stay (LOS) in the hospital and intensive care unit (ICU), duration of mechanical ventilation, days on inotropic support, and ICU and hospital mortality rates. The selection of and data extraction from studies were performed by two independent reviewers.

RESULTS

Fifteen RCTs (16 publications) fulfilled all selection criteria. They involved 842 critically ill patients. None had renal and/or hepatic failure. The average study quality (Jadad score: 3.8 points) was well above the predefined cut-off of 3.0. Common effect estimates indicated that parenteral glutamine dipeptide supplementation significantly reduced infectious complications (relative risk [RR] = 0.70, 95% CI 0.60, 0.83, p < 0.0001), ICU LOS (common mean difference [MD] -1.61 days, 95% CI -3.17, -0.05, p = 0.04), hospital LOS (MD -2.30 days, 95% CI -4.14, -0.45, p = 0.01), and mechanical ventilation duration (MD -1.56 days, 95% CI -2.88, -0.24, p = 0.02). It also lowered the hospital mortality rate by 45% (RR = 0.55, 95% CI 0.32, 0.94, p = 0.03) but had no effect on ICU mortality. Visual inspection of funnel plots did not reveal any potential selective reporting of studies.

CONCLUSIONS

This meta-analysis clearly confirms that when critically ill patients are supplemented with parenteral glutamine dipeptide according to clinical guidelines as part of a balanced nutrition regimen, it significantly reduces hospital mortality, infectious complication rates, and hospital LOS. The latter two effects indicate that glutamine dipeptide supplementation also confers economic benefits in this setting. The present analysis indicates the importance of delivering glutamine dipeptides together with adequate parenteral energy and nitrogen so that the administered glutamine serves as precursor in various biosynthetic pathways rather than simply as a fuel.

Glutamine Supplementation in Intensive Care Patients: A Meta-Analysis of Randomized Clinical Trials

The role of glutamine (GLN) supplementation in critically ill patients is controversial. Our aim was to analyze its potential effect in patients admitted to intensive care unit (ICU).We performed a systematic literature review through Medline, Embase, Pubmed, Scopus, Ovid, ISI Web of Science, and the Cochrane-Controlled Trials Register searching for randomized clinical trials (RCTs) published from 1983 to 2014 and comparing GLN supplementation to no supplementation in patients admitted to ICU. A random-effect meta-analysis for each outcome (hospital and ICU mortality and rate of infections) of interest was carried out. The effect size was estimated by the risk ratio (RR).Thirty RCTs were analyzed with a total of 3696 patients, 1825 (49.4%) receiving GLN and 1859 (50.6%) no GLN (control groups). Hospital mortality rate was 27.6% in the GLN patients and 28.6% in controls with an RR of 0.93 (95% CI = 0.81-1.07; P = 0.325, I = 10.7%). ICU mortality was 18.0 % in the patients receiving GLN and 17.6% in controls with an RR of 1.01 (95% CI = 0.86-1.19; P = 0.932, I = 0%). The incidence of infections was 39.7% in GLN group versus 41.7% in controls. The effect of GLN was not significant (RR = 0.88; 95% CI = 0.76-1.03; P = 0.108, I = 56.1%).These results do not allow to recommend GLN supplementation in a generic population of critically ills. Further RCTs are needed to explore the effect of GLN in more specific cohort of patients.

Glutamine supplementation for critically ill adults

BACKGROUND

Glutamine is a non-essential amino acid which is abundant in the healthy human body. There are studies reporting that plasma glutamine levels are reduced in patients with critical illness or following major surgery, suggesting that glutamine may be a conditionally essential amino acid in situations of extreme stress. In the past decade, several clinical trials examining the effects of glutamine supplementation in patients with critical illness or receiving surgery have been done, and the systematic review of this clinical evidence has suggested that glutamine supplementation may reduce infection and mortality rates in patients with critical illness. However, two recent large-scale randomized clinical trials did not find any beneficial effects of glutamine supplementation in patients with critical illness.

OBJECTIVES

The objective of this review was to:1. assess the effects of glutamine supplementation in critically ill adults and in adults after major surgery on infection rate, mortality and other clinically relevant outcomes;2. investigate potential heterogeneity across different patient groups and different routes for providing nutrition.

SEARCH METHODS

We searched the Cochrane Anaesthesia Review Group (CARG) Specialized Register; Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2013, Issue 5); MEDLINE (1950 to May 2013); EMBASE (1980 to May 2013) and Web of Science (1945 to May 2013).

SELECTION CRITERIA

We included controlled clinical trials with random or quasi-random allocation that examined glutamine supplementation versus no supplementation or placebo in adults with a critical illness or undergoing elective major surgery. We excluded cross-over trials.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the relevant information from each included study using a standardized data extraction form. For infectious complications and mortality and morbidity outcomes we used risk ratio (RR) as the summary measure with the 95% confidence interval (CI). We calculated, where appropriate, the number needed to treat to benefit (NNTB) and the number needed to treat to harm (NNTH). We presented continuous data as the difference between means (MD) with the 95% CI.

MAIN RESULTS

Our search identified 1999 titles, of which 53 trials (57 articles) fulfilled our inclusion criteria. The 53 included studies enrolled a total of 4671 participants with critical illness or undergoing elective major surgery. We analysed seven domains of potential risk of bias. In 10 studies the risk of bias was evaluated as low in all of the domains. Thirty-three trials (2303 patients) provided data on nosocomial infectious complications; pooling of these data suggested that glutamine supplementation reduced the infectious complications rate in adults with critical illness or undergoing elective major surgery (RR 0.79, 95% CI 0.71 to 0.87, P ＜ 0.00001, I² = 8%, moderate quality evidence). Thirty-six studies reported short-term (hospital or less than one month) mortality. The combined rate of mortality from these studies was not statistically different between the groups receiving glutamine supplement and those receiving no supplement (RR 0.89, 95% CI 0.78 to 1.02, P = 0.10, I² = 22%, low quality evidence). Eleven studies reported long-term (more than six months) mortality; meta-analysis of these studies (2277 participants) yielded a RR of 1.00 (95% CI 0.89 to 1.12, P = 0.94, I² = 30%, moderate quality evidence). Subgroup analysis of infectious complications and mortality outcomes did not find any statistically significant differences between the predefined groups. Hospital length of stay was reported in 36 studies. We found that the length of hospital stay was shorter in the intervention group than in the control group (MD -3.46 days, 95% CI -4.61 to -2.32, P < 0.0001, I² = 63%, low quality evidence). Slightly prolonged intensive care unit (ICU) stay was found in the glutamine supplemented group from 22 studies (2285 participants) (MD 0.18 days, 95% CI 0.07 to 0.29, P = 0.002, I² = 11%, moderate quality evidence). Days on mechanical ventilation (14 studies, 1297 participants) was found to be slightly shorter in the intervention group than in the control group (MD - 0.69 days, 95% CI -1.37 to -0.02, P = 0.04, I² = 18%, moderate quality evidence). There was no clear evidence of a difference between the groups for side effects and quality of life, however results were imprecise for serious adverse events and few studies reported on quality of life. Sensitivity analysis including only low risk of bias studies found that glutamine supplementation had beneficial effects in reducing the length of hospital stay (MD -2.9 days, 95% CI -5.3 to -0.5, P = 0.02, I² = 58%, eight studies) while there was no statistically significant difference between the groups for all of the other outcomes.

AUTHORS' CONCLUSIONS

This review found moderate evidence that glutamine supplementation reduced the infection rate and days on mechanical ventilation, and low quality evidence that glutamine supplementation reduced length of hospital stay in critically ill or surgical patients. It seems to have little or no effect on the risk of mortality and length of ICU stay, however. The effects on the risk of serious side effects were imprecise. The strength of evidence in this review was impaired by a high risk of overall bias, suspected publication bias, and moderate to substantial heterogeneity within the included studies.

Parenteral glutamine supplementation in critical illness: a systematic review

Introduction

The potential benefit of parenteral glutamine (GLN) supplementation has been one of the most commonly studied nutritional interventions in the critical care setting. The aim of this systematic review was to incorporate recent trials of traditional parenteral GLN supplementation in critical illness with previously existing data.

Methods

All randomized controlled trials of parenterally administered GLN in critically ill patients conducted from 1997 to 2013 were identified. Studies of enteral GLN only or combined enteral/parenteral GLN were excluded. Methodological quality of studies was scored and data was abstracted by independent reviewers.

Results

A total of 26 studies involving 2,484 patients examining only parenteral GLN supplementation of nutrition support were identified in ICU patients. Parenteral GLN supplementation was associated with a trend towards a reduction of overall mortality (relative risk (RR) 0.88, 95% confidence interval (CI) 0.75, 1.03, P = 0.10) and a significant reduction in hospital mortality (RR 0.68, 95% CI 0.51, 0.90, P = 0.008). In addition, parenteral GLN was associated with a strong trend towards a reduction in infectious complications (RR 0.86, 95% CI 0.73, 1.02, P = 0.09) and ICU length of stay (LOS) (WMD –1.91, (95% CI -4.10, 0.28, P = 0.09) and significant reduction in hospital LOS (WMD -2.56, 95% CI -4.71, -0.42, P = 0.02). In the subset of studies examining patients receiving parenteral nutrition (PN), parenteral GLN supplementation was associated with a trend towards reduced overall mortality (RR 0.84, 95% CI 0.71, 1.01, P = 0.07).

Conclusions

Parenteral GLN supplementation given in conjunction with nutrition support continues to be associated with a significant reduction in hospital mortality and hospital LOS. Parenteral GLN supplementation as a component of nutrition support should continue to be considered to improve outcomes in critically ill patients.

Glutamine in the intensive care unit

PURPOSE OF REVIEW

To analyze the recent literature (2011-2013) on glutamine supplementation of parenteral and enteral nutrition in critically ill patients. Potential confounding factors that may explain conflicting results are suggested.

RECENT FINDINGS

Some recent, prospective, multicenter trials and two small trials yielded conflicting results that weigh heavily in the conclusions of a recent meta-analysis. Heterogeneity of the patients enrolled (especially in terms of injury severity, age, and basal nutritional status) and difficulties in identifying patients truly in need of glutamine supplementation may explain the discrepancies.

SUMMARY

Glutamine supplementation has been recognized as beneficial in acutely injured patients. However, recent conflicting results in either 'real-life conditions' or very severe situations suggest that its indications need to be more precisely determined.

A systematic literature review and meta-analysis of randomized clinical trials of parenteral glutamine supplementation

BACKGROUND & AIMS

Glutamine supplementation has been associated with reduced mortality, infections and hospital length of stay in critically ill patients and patients undergoing major surgery. We carried out a meta-analysis to examine randomized clinical trial (RCT)-based evidence of these effects.

METHODS

Based on a systematic database search, RCTs published since 1990 were included if they evaluated the effect of parenteral glutamine supplementation against a background of parenteral nutrition. Enteral (tube) feeding in a proportion of patients was allowable. Information on RCT methodology, quality and outcomes was extracted. Random effects meta-analysis followed the DerSimonian-Laird approach.

RESULTS

Forty RCTs were eligible for meta-analysis. Parenteral glutamine supplementation was associated with a non-significant 11% reduction in short-term mortality (RR = 0.89; 95% CI, 0.77-1.04). Infections were significantly reduced (RR = 0.83; 95% CI, 0.72-0.95) and length of stay was 2.35 days shorter (95% CI, -3.68 to -1.02) in the glutamine arms. Meta-analysis results were strongly influenced by one recent trial. An element of publication bias could not be excluded.

CONCLUSION

Parenteral glutamine supplementation in severely ill patients may reduce infections, length of stay and mortality, but substantial uncertainty remains. Unlike previous meta-analyses, we could not demonstrate a significant reduction in mortality.