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

Perioperative Glutamine Supplementation May Restore Atrophy of Psoas Muscles in Gastric Adenocarcinoma Patients Undergoing Gastrectomy

BACKGROUND

Sarcopenia, characterized by degenerative skeletal muscle loss, is increasingly linked to poor surgical outcomes. Glutamine, an immune-modulating formula, may stimulate muscle protein synthesis and inhibit degradation. We used the psoas major muscle area (PMMA) at the third lumbar vertebra, normalized for height (PMMA index), as a skeletal muscle indicator. This study investigates whether perioperative glutamine supplementation mitigates psoas muscle atrophy.

METHODS

We enrolled gastric adenocarcinoma (GA) patients undergoing gastrectomy. Computed tomography assessed the psoas muscle short axis. Muscle atrophy was estimated by changes between preoperative and three-month post-gastrectomy scans. Perioperative glutamine supplementation (PGS) comprised five-day parenteral plus one-month oral use. Propensity score matching minimized potential bias. A linear regression model predicted the association.

RESULTS

Of 516 patients analyzed (2016-2019), 100 (19.4%) received PGS. After propensity score matching, each group contained 97 cases. The PGS group showed a significantly higher median PMMA index change than the non-PGS group (0.3 vs. -0.3 cm2/m2, p = 0.004). Multivariate analysis revealed that PGS was significantly associated with increased PMMA index (coefficient = 0.60; 95% CI: 0.19-1.01; p = 0.005).

CONCLUSIONS

PGS may help restore psoas muscle atrophy in GA patients undergoing gastrectomy. The underlying mechanisms likely relate to glutamine's role in protein metabolism and immune function. Further studies are needed to elucidate these mechanisms fully.

Pharmaconutrition: Which substrates?

With the term "pharmaconutrition" or "immunonutrition" is intended the use of specific nutritional substrates having the ability of modulating specific mechanisms involved in several immune and inflammatory pathways. To achieve these goals, these substrates have to be administered with over physiologic dose. Glutamine and omega-3 polyunsaturated fatty acids, used as single substrate, did not show clear clinical advantages on solid endpoints such as postoperative complications. Despite several multiple substrate enteral feeds are available on the market, very few of them have been tested in randomized clinical trial to prove efficacy. The most extensive investigated formulation is a combination of arginine, omega-3 fatty acids, ribonucleic acid with or without glutamine. Several meta-analyses of randomized clinical trials have been conducted to compare the effects of enteral immunonutrition with control diets on post-surgical morbidity. The results consistently showed that the use of enteral multiple substrate formulas significantly reduced infectious complications and duration of hospitalization. In a more contemporary view, pharmaconutrition should be tested more accurately in the contest of enhanced recovery programs, during neoadjuvant chemotherapy, and in the prehabilitation setting.

Postoperative nutrition in the setting of enhanced recovery programmes

Patients undergoing major surgery for gastrointestinal cancer are at high risk of developing or worsening malnutrition and sarcopenia. In malnourished patients, preoperative nutritional support may not be sufficient and so postoperative support is advised. This narrative review addresses several aspects of postoperative nutritional care in the setting of enhanced recovery programmes. Early oral feeding, therapeutic diet, oral nutritional supplements, immunonutrition, and probiotics are discussed. When postoperative intake is insufficient, nutritional support favouring the enteral route is recommended. Whether this approach should use a nasojejunal tube or jejunostomy is still a matter of debate. In the setting of enhanced recovery programmes with early discharge, nutritional follow-up and care should be continued beyond the short time in hospital. In enhanced recovery programmes, the main specific aspects of nutrition are patient education, early oral intake, and post-discharge care. The other aspects do not differ from conventional care.

Glutamine Supplementation as an Anticancer Strategy: A Potential Therapeutic Alternative to the Convention

Glutamine, a multifaceted nonessential/conditionally essential amino acid integral to cellular metabolism and immune function, holds pivotal importance in the landscape of cancer therapy. This review delves into the intricate dynamics surrounding both glutamine antagonism strategies and glutamine supplementation within the context of cancer treatment, emphasizing the critical role of glutamine metabolism in cancer progression and therapy. Glutamine antagonism, aiming to disrupt tumor growth by targeting critical metabolic pathways, is challenged by the adaptive nature of cancer cells and the complex metabolic microenvironment, potentially compromising its therapeutic efficacy. In contrast, glutamine supplementation supports immune function, improves gut integrity, alleviates treatment-related toxicities, and improves patient well-being. Moreover, recent studies highlighted its contributions to epigenetic regulation within cancer cells and its potential to bolster anti-cancer immune functions. However, glutamine implementation necessitates careful consideration of potential interactions with ongoing treatment regimens and the delicate equilibrium between supporting normal cellular function and promoting tumorigenesis. By critically assessing the implications of both glutamine antagonism strategies and glutamine supplementation, this review aims to offer comprehensive insights into potential therapeutic strategies targeting glutamine metabolism for effective cancer management.

Chemical composition, pharmacology and pharmacokinetic studies of GuHong injection in the treatment of ischemic stroke

GuHong injection is composed of safflower and N-acetyl-L-glutamine. It is widely used in clinical for cerebrovascular diseases, such as ischemic stroke and related diseases. The objective of this review is to comprehensively summarize the most recent information related to GuHong in the treatment of stroke, including chemical composition, clinical studies, potential pharmacological mechanisms and pharmacokinetics. Additionally, it examines possible scientific gaps in current study and aims to provide a reliable reference for future GuHong studies. The systematic review reveals that the chemical composition of safflower in GuHong is more than 300 chemical components in five categories. GuHong injection is primarily used in clinical applications for acute ischemic stroke and related diseases. Pharmacological investigations have indicated that GuHong acts in the early and recovery stages of ischemic stroke by anti-inflammatory, anti-oxidative stress, anti-coagulation, neuroprotective and anti-apoptotic mechanisms simultaneously. Pharmacokinetic studies found that the main exposed substances in rat plasma after GuHong administration are hydroxysafflor yellow A and N-acetyl-L-glutamine, and N-acetyl-L-glutamine could exert its pharmacological effect across the blood-brain barrier. As a combination of Chinese herb and chemical drug, GuHong injection has great value in drug research and clinical treatment, especially for ischemic stroke disease. This article represents a comprehensive and systematic review of existing studies on GuHong injection, including chemical composition, pharmacological mechanism, and pharmacokinetics, which provides reference significance for the clinical treatment of ischemic stroke with GuHong, as well as provides guidance for further study.

The Efficacy of Glutamine Supplementation in Severe Adult Burn Patients: A Systematic Review With Trial Sequential Meta-Analysis

OBJECTIVES

Evidence supporting glutamine supplementation in severe adult burn patients has created a state of uncertainty due to the variability in the treatment effect reported across small and large randomized controlled trials (RCTs). We aimed to systematically review the effect of glutamine supplementation on mortality in severe adult burn patients.

DATA SOURCES

MEDLINE, Embase, CINAHL, and Cochrane Central were searched from inception to February 10, 2023.

STUDY SELECTION

RCTs evaluating the effect of enteral or IV glutamine supplementation alone in severe adult burn patients were included.

DATA EXTRACTION

Two reviewers independently extracted data on study characteristics, burn injury characteristics, description of the intervention between groups, adverse events, and clinical outcomes.

DATA SYNTHESIS

Random effects meta-analyses were performed to estimate the pooled risk ratio (RR). Trial sequential analyses (TSA) for mortality and infectious complications were performed. Ten RCTs (1,577 patients) were included. We observed no significant effect of glutamine supplementation on overall mortality (RR, 0.65, 95% CI, 0.33-1.28; p = 0.21), infectious complications (RR, 0.83; 95% CI, 0.63-1.09; p = 0.18), or other secondary outcomes. In subgroup analyses, we observed no significant effects based on administration route or burn severity. We did observe a significant subgroup effect between single and multicenter RCTs in which glutamine significantly reduced mortality and infectious complications in singe-center RCTs but not in multicenter RCTs. However, TSA showed that the pooled results of single-center RCTs were type 1 errors and further trials would be futile.

CONCLUSIONS

Glutamine supplementation, regardless of administration, does not appear to improve clinical outcomes in severely adult burned patients.

Glutamine supplementation reverses manganese neurotoxicity by eliciting the mitochondrial unfolded protein response

Excessive exposure to manganese (Mn) can cause neurological abnormalities, but the mechanism of Mn neurotoxicity remains unclear. Previous studies have shown that abnormal mitochondrial metabolism is a crucial mechanism underlying Mn neurotoxicity. Therefore, improving neurometabolic in neuronal mitochondria may be a potential therapy for Mn neurotoxicity. Here, single-cell sequencing revealed that Mn affected mitochondrial neurometabolic pathways and unfolded protein response in zebrafish dopaminergic neurons. Metabolomic analysis indicated that Mn inhibited the glutathione metabolic pathway in human neuroblastoma (SH-SY5Y) cells. Mechanistically, Mn exposure inhibited glutathione (GSH) and mitochondrial unfolded protein response (UPR^mt). Furthermore, supplementation with glutamine (Gln) can effectively increase the concentration of GSH and triggered UPR^mt which can alleviate mitochondrial dysfunction and counteract the neurotoxicity of Mn. Our findings highlight that UPR^mt is involved in Mn-induced neurotoxicity and glutathione metabolic pathway affects UPR^mt to reverse Mn neurotoxicity. In addition, Gln supplementation may have potential therapeutic benefits for Mn-related neurological disorders.

Exploring choices of early nutritional support for patients with sepsis based on changes in intestinal microecology

BACKGROUND

Sepsis exacerbates intestinal microecological disorders leading to poor prognosis. Proper modalities of nutritional support can improve nutrition, immunity, and intestinal microecology.

AIM

To identify the optimal modality of early nutritional support for patients with sepsis from the perspective of intestinal microecology.

METHODS

Thirty patients with sepsis admitted to the intensive care unit of the General Hospital of Ningxia Medical University, China, between 2019 and 2021 with indications for nutritional support, were randomly assigned to one of three different modalities of nutritional support for a total of 5 d: Total enteral nutrition (TEN group), total parenteral nutrition (TPN group), and supplemental parenteral nutrition (SPN group). Blood and stool specimens were collected before and after nutritional support, and changes in gut microbiota, short-chain fatty acids (SCFAs), and immune and nutritional indicators were detected and compared among the three groups.

RESULTS

In comparison with before nutritional support, the three groups after nutritional support presented: (1) Differences in the gut bacteria (Enterococcus increased in the TEN group, Campylobacter decreased in the TPN group, and Dialister decreased in the SPN group; all P < 0.05); (2) different trends in SCFAs (the TEN group showed improvement except for Caproic acid, the TPN group showed improvement only for acetic and propionic acid, and the SPN group showed a decreasing trend); (3) significant improvement of the nutritional and immunological indicators in the TEN and SPN groups, while only immunoglobulin G improved in the TPN group (all P < 0.05); and (4) a significant correlation was found between the gut bacteria, SCFAs, and nutritional and immunological indicators (all P < 0.05).

CONCLUSION

TEN is recommended as the preferred mode of early nutritional support in sepsis based on clinical nutritional and immunological indicators, as well as changes in intestinal microecology.

Re-examining chemically defined liquid diets through the lens of the microbiome

Trends in nutritional science are rapidly shifting as information regarding the value of eating unprocessed foods and its salutary effect on the human microbiome emerge. Unravelling the evolution and ecology by which humans have harboured a microbiome that participates in every facet of health and disease is daunting. Most strikingly, the host habitat has sought out naturally occurring foodstuff that can fulfil its own metabolic needs and also the needs of its microbiota, each of which remain inexorably connected to one another. With the introduction of modern medicine and complexities of critical care, came the assumption that the best way to feed a critically ill patient is by delivering fibre-free chemically defined sterile liquid foods (that is, total enteral nutrition). In this Perspective, we uncover the potential flaws in this assumption and discuss how emerging technology in microbiome sciences might inform the best method of feeding malnourished and critically ill patients.

[Glutamine as a component of nutritional and metabolic therapy for surgical patients in ICU]

Glutamine is the most abundant amino acid in the human body that is involved in various metabolic processes. The development of hypermetabolic and hypercatabolic syndrome that accompanies critical conditions of ICU patients is associated with a decrease in the concentration of glutamine, especially in the blood plasma and muscles. This process may last for quite a long time and lead to a number of complications up to a fatal outcome. This review was aimed to analyze clinical studies conducted over the past 20 years that demonstrate the effect of intravenous infusion of glutamine dipeptide as part of balanced parenteral nutrition on the perioperative period: the severity of inflammatory response; the state of the intestinal mucosa; the incidence and severity of complications; mortality; the duration of stay in the ICU and hospital in general, etc. The analysis was performed using systematic reviews and meta-analyses based on randomized double-blind, placebo-controlled trials in different countries selected in the main databases (PubMed, EMBASE, Web of Science, The Cochrane Library, etc.). Most of the reports state that the inclusion of glutamine dipeptide in nutritional and metabolic therapy (NMT) in surgical patients reduces the frequency and severity of infectious complications and mortality, reduces the length of stay in ICU and in hospital in general, improves the biochemical parameters that reflect the condition of patients, and reduces the treatment costs. Thus, the conducted systematic reviews and meta-analyses confirm that the use of the parenteral form of glutamine dipeptide (Dipeptiven 20%) as part of balanced standard parenteral nutrition (PN) is a clinically and pharmacoeconomically justified strategy of NMT in surgical ICU patients.

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.

Exudative glutamine losses contribute to high needs after burn injury

Background

Burnpatients characteristically have increased energy, glucose, and protein requirements. Glutamine supplementation is strongly recommended during early‐phase treatment and is associated with improved immunity, wound healing, and reduced mortality. This study evaluated if early burn exudative losses might contribute to higher supplementation needs.

Methods

Patients admitted to the burn intensive care unit (ICU) had exudate collection from tight bandages applied to arms or legs during the first week (exudate aliquot twice daily). Seven amino acids (alanine, arginine, cystEine, glutamine, leucine, lysine, and methionine) were quantified by liquid chromatography–mass spectrometry. Descriptive analysis of all results is provided as median and interquartile range or in value ranges.

Results

Eleven patients aged 19–77 years, presenting with burns on 18%–70% of the body surface, with a median simplified acute physiology score II of 33 (range, 16–56) were included during the study period. The highest amino acid losses were observed during the first 3 days with an important interpatient and intrapatient variability. Glutamine and alanine losses were highest, followed by leucine and lysine in all patients; amino acid exudate concentrations were in the range of normal plasma concentrations and were stable over time. Total glutamine losses were correlated to the burned surface (r² = 0.552, P = .012), but not to enteral glutamine supplements.

Conclusions

The study shows significant exudative losses during early‐stage burn recovery and particularly for glutamine and alanine. Glutamine loss generally decreased with wound closure, the subsequent decline of exudation, and the evolving size of burn surfaces.

ESPEN practical guideline: Clinical nutrition in surgery

Early oral feeding is the preferred mode of nutrition for surgical patients. Avoidance of any nutritional therapy bears the risk of underfeeding during the postoperative course after major surgery. Considering that malnutrition and underfeeding are risk factors for postoperative complications, early enteral feeding is especially relevant for any surgical patient at nutritional risk, especially for those undergoing upper gastrointestinal surgery. The focus of this guideline is to cover both nutritional aspects of the Enhanced Recovery After Surgery (ERAS) concept and the special nutritional needs of patients undergoing major surgery, e.g. for cancer, and of those developing severe complications despite best perioperative care. From a metabolic and nutritional point of view, the key aspects of perioperative care include the integration of nutrition into the overall management of the patient, avoidance of long periods of preoperative fasting, re-establishment of oral feeding as early as possible after surgery, the start of nutritional therapy immediately if a nutritional risk becomes apparent, metabolic control e.g. of blood glucose, reduction of factors which exacerbate stress-related catabolism or impaired gastrointestinal function, minimized time on paralytic agents for ventilator management in the postoperative period, and early mobilization to facilitate protein synthesis and muscle function.

Metabolism of Proteins and Amino Acids in Critical Illness: From Physiological Alterations to Relevant Clinical Practice

The clinical impact of nutrition therapy in critically ill patients has been known for years, and relevant guidelines regarding nutrition therapy have emphasized the importance of proteins. During critical illness, such as sepsis or the state following major surgery, major trauma, or major burn injury, patients suffer from a high degree of stress/inflammation, and during this time, metabolism deviates from homeostasis. The increased degradation of endogenous proteins in response to stress hormones is among the most important events in the acute phase of critical illness. Currently published evidence suggests that adequate protein supplementation might improve the clinical outcomes of critically ill patients. The role of sufficient protein supplementation may even surpass that of caloric supplementation. In this review, we focus on relevant physiological alterations in critical illness, the effects of critical illness on protein metabolism, nutrition therapy in clinical practice, and the function of specific amino acids.

Enhanced Recovery after Abdominoplasty Using Perisurgical Nutritional Supplementation

Nutritional supplements are common in other surgical specialties but not widely used in the plastic surgery setting. This study compares the surgical outcomes of patients using our standard ERAS protocol involving arnica and bromelain with an updated ERAS protocol using perisurgical nutritional supplementation using a staged administration of nutraceuticals.

Methods

In total, 300 female abdominoplasty patients were randomly provided with perioperative supplementation consisting of arnica and bromelain, or a 3-stage nutraceutical regimen containing arginine, citrulline, glutamine, bromelain, and vitamin C. Narcotic use in recovery and post-operative drainage were measured, and both groups completed a self-assessment of bruising coloration, days to independent activity, perceived pain, and documented the quantity of narcotic and non-prescription pain killers they took over a 14-day recovery period.

Results

There were 130 patients in the nutraceutical group and 80 in the arnica and bromelain group; patients were excluded due to non-compliance or due to incomplete data. Patients taking the nutraceutical regimen reported a shorter duration of pain and had a 41% reduction in narcotic use in recovery and experienced 48% less post-operative drainage. Home use of narcotic pain killers decreased by 25%. There also was a trend toward decreased and earlier clearing/maturation of bruising as well as return to daily activates without assistance. Patients also reported an increase in satisfaction with their surgical experience.

Conclusions

This study demonstrated that perioperative supplementation with nitric oxide precursors, antioxidants, and proteolytic enzymes in a staged fashion can positively affect post-operative outcomes and is an adjunct to enhanced surgical recovery protocols.

Carbohydrate and Glutamine Supplementation Attenuates the Increase in Rating of Perceived Exertion during Intense Exercise in Hypoxia Similar to 4200 m

The rating of perceived exertion (RPE) indicates the feeling of fatigue. However, hypoxia worsens the condition and can worsen RPE. We evaluated whether carbohydrate and glutamine supplementation alters RPE and physiological markers in running at 70% peak oxygen uptake until exhaustion in a simulated altitude of 4500 m. Nine volunteers underwent three running tests at 70% peak oxygen uptake until exhaustion: (1) hypoxia and placebo, (2) hypoxia and 8% maltodextrin, and (3) hypoxia after six days of glutamine supplementation (20 g/day) and 8% maltodextrin. The exercise and supplementation were randomized and double-blinded. Lactate, heart rate, haemoglobin O₂ saturation (SpO₂%), and RPE (6-20 scale) were analyzed at the 15th and 30th min. The level of significance was set at p ≤ 0.05. SpO₂% decreased at the 15th and 30th minutes compared to resting in placebo, carbohydrate, and glutamine supplementation. RPE increased at the 30th minute compared to the 15th minute in placebo and carbohydrate supplementation; however, there was no difference in the glutamine supplementation condition. Heart rate and lactate increased after the 15th and 30th minutes compared to resting, similar to the three conditions studied. We conclude that previous supplementation with glutamine and carbohydrate during intense exercise in hypoxia similar to 4500 m can attenuate the increase in RPE by the increase in glycemia and can be a useful strategy for people who exercise in these conditions.

The Role of Immunonutrition in Patients Undergoing Pancreaticoduodenectomy

Pancreaticoduodenectomy (PD) is one of the most difficult and complex surgical procedures in abdominal surgery. Malnutrition and immune dysfunction in patients with pancreatic cancer (PC) may lead to a higher risk of postoperative infectious complications. Although immunonutrition (IN) is recommended for enhanced recovery after surgery (ERAS) in patients undergoing PD for 5-7 days perioperatively, its role in patients undergoing pancreatectomy is still unclear and controversial. It is known that the proper surgical technique is very important in order to reduce a risk of postoperative complications, such as a pancreatic fistula, and to improve disease-free survival in patients following PD. However, it has been proven that IN decreases the risk of infectious complications, and shortens hospital stays in patients undergoing PD. This is a result of the impact on altered inflammatory responses in patients with cancer. Both enteral and parenteral, as well as preoperative and postoperative IN, using various nutrients, such as glutamine, arginine, omega-3 fatty acids and nucleotides, is administered. The most frequently used preoperative oral supplementation is recommended. The aim of this paper is to present the indications and benefits of IN in patients undergoing PD.

Effects of glutamine supplementation on critically ill patients: Focus on efficacy and safety. An overview of systematic reviews

OBJECTIVES

The aim of this overview of systematic reviews was to synthesize, appraise, and present all systematic review (SR) evidence on the clinical efficacy of glutamine administration to severely ill patients.

METHODS

Medline, Scopus, the Cochrane Library, and Prospero were searched up to March 2020. Systematic reviews and meta-analyses of randomized controlled trials published in English, comparing immunomodulating diets-containing exclusively glutamine-with standard diets for critically ill adult patients were selected. Data were collected from each selected systematic review and all available primary studies. The primary outcome was overall mortality; secondary outcomes were rate of infectious complications, hospital and intensive care unit (ICU) length of stay (LOS).

RESULTS

Seventeen SRs were eligible for inclusion. Of the SRs, 16 included meta-analyses with moderate degree of overlap (corrected covered area = 10%). These included 117 randomized controlled trials with 9933 patients. Glutamine supplementation was not associated with overall mortality and ICU LOS. However, it may reduce the rate of infectious complications overall (N = 3666, risk ratio, 0.82; 95% confidence interval [CI], 0.73-0.92; I² = 33%: low quality of evidence). LOS was limited with the supplementation of glutamine (N = 4353 weighted mean difference, -2.90; 95% CI, -3.66 to -2.15; I² = 81%: very low quality of evidence), but this effect was diminished when only studies with low risk for bias were synthesized.

CONCLUSION

Glutamine could demonstrate a beneficial role in critical care patients of diminishing the rate of infectious complications and hospital and ICU LOS. However, future studies with better quality would confirm this finding.

Effects of parenteral glutamine in critically ill surgical patients: a systematic review and meta-analysis

Introduction

Introduction: glutamine (GLN), the most abundant non-essential amino acid in the plasma, tends to be rapidly depleted in cells in situations of metabolic stress. Some studies have demonstrated the benefits of GLN supplementation on mortality, infection, and length of hospital stay. The objective of this review was to analyze whether parenteral supplementation with GLN has any relevant effect in critically ill surgical patients. Methods: based on a systematic database search, randomized clinical trials (RCTs) published since 1985 were included if they had evaluated the effect of parenteral GLN supplementation in critical surgical patients. The statistical analysis was performed using the RevMan 5.3 software. Results: seven RCTs were eligible for the meta-analysis. Parenteral glutamine supplementation was associated with a non-significant 24 % reduction in mortality (RR = 0.76; 95 % CI: 0.50-1.15). Infections were significantly reduced (RR = 0.60; 95 % CI: 0.45-0.80), and length of hospital stay was 4.09 days shorter (95 % CI: -6.71 to -1.46). Conclusion: parenteral GLN usage in critical surgical patients seems to decrease infection and length of hospital stay, but we could not demonstrate a significant reduction in mortality.

Parenteral glutamine supplementation improves serum albumin values in surgical cancer patients

INTRODUCTION

Patients with gastric adenocarcinoma (GA) often develop malnutrition, which deteriorates after cancer surgery and negatively affects surgical outcomes. Despite being an abundant and versatile amino acid involved in the immune system and metabolic functions, glutamine levels are significantly depleted among patients who are critically ill or hypercatabolic. Therefore, this study aimed to investigate whether parenteral glutamine supplementation may improve nutritional status and surgical outcomes.

METHODS

This retrospective, single-center cohort study included patients with GA who underwent gastrectomy between January 2007 and June 2019. Patients were classified into either the non-glutamine or glutamine group. Propensity score matching was used to minimize the bias in patient demographics. Furthermore, the average parenteral glutamine dose from the day of surgery to postoperative day four was calculated in g/kg/day. Surgical outcomes (length of hospitalization, major complication, and mortality) and changes in lymphocyte count and serum albumin levels 7 days post-surgery were assessed in both matched groups using adjusted models.

RESULTS

A total of 1950 patients were reviewed, among whom 522 (26.8%) received parenteral glutamine supplementation (glutamine dose ranging from 0.05 to 0.49 g/kg/day). Among the included patients, 57.2% were males, and the median age was 64.9 years. After matching, there were 478 cases in each group. No differences in surgical outcomes and changes in lymphocyte count were observed between both matched groups. The glutamine group exhibited a smaller decrease in serum albumin levels compared to the non-glutamine group (-0.6 vs. -1.1 g/dL; P < 0.001). The adjusted matched model showed that glutamine dose contributed significantly toward increasing serum albumin levels (coefficient = 0.08 per 0.1 g/day/kg increment in glutamine; 95% confidence interval: 0.04 to 0.10; P < 0.001).

CONCLUSIONS

Perioperative parenteral glutamine supplementation had a positive dose-dependent impact on the recovery of serum albumin levels among patients with GA undergoing gastrectomy, implying that glutamine supplementation improved postoperative nutritional suppression and ameliorated stress-associated inflammation. Although glutamine supplementation was not associated with surgical outcomes, further studies should be conducted to evaluate the clinical significance of serum albumin restoration.

The glutamine debate in surgery and critical care

PURPOSE OF REVIEW

Glutamine (GLN) is a versatile amino acid, long believed to have important implications in ICU and surgical patients. An extensive body of data examining GLN supplementation of TPN demonstrated a consistent signal of improved outcomes. However, recently signals of risk have come from two large-scale multicenter trials evaluating GLN (and other nutrients) at high dose and as primary pharmaconutrients, not as supplementation to complete nutrition. These trials indicate a risk of increased mortality when GLN is given to patients in shock, renal failure, and early in acute phase of critical care.

RECENT FINDINGS

Recent literature continues to confirm that low and high admission GLN levels are associated with increased ICU mortality and adverse outcomes. Further, a recent meta-analysis examined trials utilizing GLN-supplemented TPN in stabile ICU patients consistent with current clinical guidelines. This analysis showed GLN supplementation of TPN led to reduced infections, LOS and hospital mortality.

SUMMARY

Three recent meta-analyses have confirmed traditional GLN-supplemented (or 'GLN-Complemented' - providing GLN for completeness of amino acid content) TPN is safe, reduces mortality and improves outcome in surgical and ICU patients. Patients in need of TPN, burns, trauma or malignancies should continue to benefit from supplemental GLN, administered either intravenously at less than 0.35 g/kg/day or enterally at less than 0.5 g/kg/day. Further, a large trial of EN GLN supplementation in burns is ongoing. Thus, when used per guideline recommendations, the GLN story is likely still relevant to ICU outcomes and research.

Plasma Glutamine Levels in Relation to Intensive Care Unit Patient Outcome

Low and high plasma glutamine levels are associated with increased mortality. This study aimed to measure glutamine levels in critically ill patients admitted to the intensive care unit (ICU) , correlate the glutamine values with clinical outcomes, and identify proxy indicators of abnormal glutamine levels. Patients were enrolled from three ICUs in South Africa, provided they met the inclusion criteria. Clinical and biochemical data were collected. Plasma glutamine was categorized as low (<420 µmol/L), normal (420-700 µmol/L), or high (>700 µmol/L). Three hundred and thirty patients (median age 46.8 years, 56.4% male) were enrolled (median APACHE II score) 18.0 and SOFA) score 7.0). On admission, 58.5% had low (median 299.5 µmol/L) and 14.2% high (median 898.9 µmol/L) plasma glutamine levels. Patients with a diagnosis of polytrauma and sepsis on ICU admission presented with the lowest, and those with liver failure had the highest glutamine levels. Admission low plasma glutamine was associated with higher APACHE II scores (p = 0.003), SOFA scores (p = 0.003), C-reactive protein (CRP) values (p < 0.001), serum urea (p = 0.008), and serum creatinine (p = 0.023) and lower serum albumin (p < 0.001). Low plasma glutamine was also associated with requiring mechanical ventilation and receiving nutritional support. However, it was not significantly associated with length of stay or mortality. ROC curve analysis revealed a CRP threshold value of 87.9 mg/L to be indicative of low plasma glutamine levels (area under the curve (AUC) 0.7, p < 0.001). Fifty-nine percent of ICU patients had low plasma glutamine on admission, with significant differences found between diagnostic groupings. Markers of infection and disease severity were significant indicators of low plasma glutamine.

Surviving sepsis campaign international guidelines for the management of septic shock and sepsis-associated organ dysfunction in children

OBJECTIVES

To develop evidence-based recommendations for clinicians caring for children (including infants, school-aged children, and adolescents) with septic shock and other sepsis-associated organ dysfunction.

DESIGN

A panel of 49 international experts, representing 12 international organizations, as well as three methodologists and three public members was convened. Panel members assembled at key international meetings (for those panel members attending the conference), and a stand-alone meeting was held for all panel members in November 2018. A formal conflict-of-interest policy was developed at the onset of the process and enforced throughout. Teleconferences and electronic-based discussion among the chairs, co-chairs, methodologists, and group heads, as well as within subgroups, served as an integral part of the guideline development process.

METHODS

The panel consisted of six subgroups: recognition and management of infection, hemodynamics and resuscitation, ventilation, endocrine and metabolic therapies, adjunctive therapies, and research priorities. We conducted a systematic review for each Population, Intervention, Control, and Outcomes question to identify the best available evidence, statistically summarized the evidence, and then assessed the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation approach. We used the evidence-to-decision framework to formulate recommendations as strong or weak, or as a best practice statement. In addition, "in our practice" statements were included when evidence was inconclusive to issue a recommendation, but the panel felt that some guidance based on practice patterns may be appropriate.

RESULTS

The panel provided 77 statements on the management and resuscitation of children with septic shock and other sepsis-associated organ dysfunction. Overall, six were strong recommendations, 49 were weak recommendations, and nine were best-practice statements. For 13 questions, no recommendations could be made; but, for 10 of these, "in our practice" statements were provided. In addition, 52 research priorities were identified.

CONCLUSIONS

A large cohort of international experts was able to achieve consensus regarding many recommendations for the best care of children with sepsis, acknowledging that most aspects of care had relatively low quality of evidence resulting in the frequent issuance of weak recommendations. Despite this challenge, these recommendations regarding the management of children with septic shock and other sepsis-associated organ dysfunction provide a foundation for consistent care to improve outcomes and inform future research.

Surviving Sepsis Campaign International Guidelines for the Management of Septic Shock and Sepsis-Associated Organ Dysfunction in Children

OBJECTIVES

To develop evidence-based recommendations for clinicians caring for children (including infants, school-aged children, and adolescents) with septic shock and other sepsis-associated organ dysfunction.

DESIGN

A panel of 49 international experts, representing 12 international organizations, as well as three methodologists and three public members was convened. Panel members assembled at key international meetings (for those panel members attending the conference), and a stand-alone meeting was held for all panel members in November 2018. A formal conflict-of-interest policy was developed at the onset of the process and enforced throughout. Teleconferences and electronic-based discussion among the chairs, co-chairs, methodologists, and group heads, as well as within subgroups, served as an integral part of the guideline development process.

METHODS

The panel consisted of six subgroups: recognition and management of infection, hemodynamics and resuscitation, ventilation, endocrine and metabolic therapies, adjunctive therapies, and research priorities. We conducted a systematic review for each Population, Intervention, Control, and Outcomes question to identify the best available evidence, statistically summarized the evidence, and then assessed the quality of evidence using the Grading of Recommendations Assessment, Development, and Evaluation approach. We used the evidence-to-decision framework to formulate recommendations as strong or weak, or as a best practice statement. In addition, "in our practice" statements were included when evidence was inconclusive to issue a recommendation, but the panel felt that some guidance based on practice patterns may be appropriate.

RESULTS

The panel provided 77 statements on the management and resuscitation of children with septic shock and other sepsis-associated organ dysfunction. Overall, six were strong recommendations, 52 were weak recommendations, and nine were best-practice statements. For 13 questions, no recommendations could be made; but, for 10 of these, "in our practice" statements were provided. In addition, 49 research priorities were identified.

CONCLUSIONS

A large cohort of international experts was able to achieve consensus regarding many recommendations for the best care of children with sepsis, acknowledging that most aspects of care had relatively low quality of evidence resulting in the frequent issuance of weak recommendations. Despite this challenge, these recommendations regarding the management of children with septic shock and other sepsis-associated organ dysfunction provide a foundation for consistent care to improve outcomes and inform future research.

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).

Glutamine in Burn Injury

Burn injury is the most devastating of survivable injuries and is a worldwide public health crisis. Burn injury is among the most severe metabolic stresses a patient can sustain. A major burn leads to an inflammatory response and catabolism that, when compounded by burn wound nutrient losses, can lead to severe nutrition losses and deficiencies. These losses can impair immune function and wound healing and place burn patients at high risk for organ injury and mortality. Experimental data indicate glutamine (GLN) is well positioned mechanistically, perhaps above and beyond in any other intensive care unit setting, to improve outcome in burn-injured patients. Initial clinical trial data have also shown a consistent signal of reduced mortality and reduced hospital length of stay in burn-injured subjects, without signals of clinical risk. A number of GLN clinical trials demonstrate significant reductions of gram-negative bacteremia in burn injury, perhaps via maintenance of the gut barrier or gut immune function. Current societal recommendations continue to suggest the use of GLN in burn injury. The promising clinical data in burn-injured patients, with no signals of harm, have warranted study of GLN in the definitive RE-ENERGIZE trial, which is now ongoing.

Role of heat shock protein and cytokine expression as markers of clinical outcomes with glutamine-supplemented parenteral nutrition in surgical ICU patients

BACKGROUND

Nutrients, such as glutamine (GLN), have been shown to effect levels of a family of protective proteins termed heat shock proteins (HSPs) in experimental and clinical critical illness. HSPs are believed to serve as extracellular inflammatory messengers and intracellular cytoprotective molecules. Extracellular HSP70 (eHSP70) has been termed a chaperokine due to ability to modulate the immune response. Altered levels of eHSP70 are associated with various disease states. Larger clinical trial data on GLN effect on eHSP expression and eHSP70's association with inflammatory mediators and clinical outcomes in critical illness are limited.

OBJECTIVE

Explore effect of longitudinal change in serum eHSP70, eHSP27 and inflammatory cytokine levels on clinical outcomes such as pneumonia and mortality in adult surgical intensive care unit (SICU) patients. Further, evaluate effect of parenteral nutrition (PN) supplemented with GLN (GLN-PN) versus GLN-free, standard PN (STD-PN) on serum eHSP70 and eHSP27 concentrations.

METHODS

Secondary observational analysis of a multicenter clinical trial in 150 adults after cardiac, vascular, or gastrointestinal surgery requiring PN support and SICU care conducted at five academic medical centers. Patients received isocaloric, isonitrogenous PN, with or without GLN dipeptide. Serum eHSP70 and eHSP27, interleukin-6 (IL-6), and 8 (IL-8) concentrations were analyzed in patient serum at baseline (prior to study PN) and over 28 days of follow up.

RESULTS

eHSP70 declined over time in survivors during 28 days follow-up, but non-survivors had significantly higher eHSP70 concentrations compared to survivors. In patients developing pneumonia, eHSP70, eHSP27, IL-8, and IL-6 were significantly elevated. Adjusted relative risk for hospital mortality was reduced 75% (RR = 0.25, p = 0.001) for SICU patients with a faster decline in eHSP70. The area under the receiver operating characteristic curve was 0.85 (95% CI: 0.76 to 0.94) for the final model suggesting excellent discrimination between SICU survivors and non-survivors. GLN-PN did not alter eHSP70 or eHSP27 serum concentrations over time compared to STD-PN.

CONCLUSION

Our results suggest that serum HSP70 concentration may be an important marker for severity of illness and likelihood of recovery in the SICU. GLN-supplemented-PN did not increase eHSP70.

Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation

Glutamine is the most abundant and versatile amino acid in the body. In health and disease, the rate of glutamine consumption by immune cells is similar or greater than glucose. For instance, in vitro and in vivo studies have determined that glutamine is an essential nutrient for lymphocyte proliferation and cytokine production, macrophage phagocytic plus secretory activities, and neutrophil bacterial killing. Glutamine release to the circulation and availability is mainly controlled by key metabolic organs, such as the gut, liver, and skeletal muscles. During catabolic/hypercatabolic situations glutamine can become essential for metabolic function, but its availability may be compromised due to the impairment of homeostasis in the inter-tissue metabolism of amino acids. For this reason, glutamine is currently part of clinical nutrition supplementation protocols and/or recommended for immune suppressed individuals. However, in a wide range of catabolic/hypercatabolic situations (e.g., ill/critically ill, post-trauma, sepsis, exhausted athletes), it is currently difficult to determine whether glutamine supplementation (oral/enteral or parenteral) should be recommended based on the amino acid plasma/bloodstream concentration (also known as glutaminemia). Although the beneficial immune-based effects of glutamine supplementation are already established, many questions and evidence for positive in vivo outcomes still remain to be presented. Therefore, this paper provides an integrated review of how glutamine metabolism in key organs is important to cells of the immune system. We also discuss glutamine metabolism and action, and important issues related to the effects of glutamine supplementation in catabolic situations.

Glutamine: Metabolism and Immune Function, Supplementation and Clinical Translation

Glutamine is the most abundant and versatile amino acid in the body. In health and disease, the rate of glutamine consumption by immune cells is similar or greater than glucose. For instance, in vitro and in vivo studies have determined that glutamine is an essential nutrient for lymphocyte proliferation and cytokine production, macrophage phagocytic plus secretory activities, and neutrophil bacterial killing. Glutamine release to the circulation and availability is mainly controlled by key metabolic organs, such as the gut, liver, and skeletal muscles. During catabolic/hypercatabolic situations glutamine can become essential for metabolic function, but its availability may be compromised due to the impairment of homeostasis in the inter-tissue metabolism of amino acids. For this reason, glutamine is currently part of clinical nutrition supplementation protocols and/or recommended for immune suppressed individuals. However, in a wide range of catabolic/hypercatabolic situations (e.g., ill/critically ill, post-trauma, sepsis, exhausted athletes), it is currently difficult to determine whether glutamine supplementation (oral/enteral or parenteral) should be recommended based on the amino acid plasma/bloodstream concentration (also known as glutaminemia). Although the beneficial immune-based effects of glutamine supplementation are already established, many questions and evidence for positive in vivo outcomes still remain to be presented. Therefore, this paper provides an integrated review of how glutamine metabolism in key organs is important to cells of the immune system. We also discuss glutamine metabolism and action, and important issues related to the effects of glutamine supplementation in catabolic situations.

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.

Beta-Hydroxy-Beta-Methyl-Butyrate, L-glutamine, and L-arginine Supplementation Improves Radiation-Induce Acute Intestinal Toxicity

We aimed to evaluate effects of β-hydroxy-β-methylbutyrate, L-glutamine, and L-arginine (HMB/GLN/ARG) on radiation-induced acute intestinal toxicity. Forty rats were divided into four groups: group (G) 1 was defined as control group, and G2 was radiation therapy (RT) control group. G3 and G4 were HMB/GLN/ARG control and RT plus HMB/GLN/ARG groups, respectively. HMB/GLN/ARG started from day of RT and continued until the animals were sacrificed 10 days after RT. The extent of surface epithelium smoothing, villous atrophy, lamina propria inflammation, cryptitis, crypt distortion, regenerative atypia, vascular dilatation and congestion, and fibrosis were quantified on histological sections of intestinal mucosa. Statistical analyses were performed using the analysis of variance (ANOVA) test. There were significant differences between study groups regarding extent of surface epithelium smoothing, villous atrophy, lamina propria inflammation, cryptitis and crypt distortion, regenerative atypia, vascular dilatation and congestion, and fibrosis (p values were 0.019 for fibrosis, <.001 for the others). Pair-wise comparisons revealed significant differences regarding surface epithelium smoothing, villous atrophy, lamina propria inflammation, cryptitis, vascular dilatation, and congestion between G2 and G4 (p values were <.001, .033, <.001, .007, and <.001, respectively). Fibrosis score was significantly different only between G1 and G2 (p = .015). Immunohistochemical TGF-β score of G2 was significantly higher than G1 and G3 (p values were .006 and .017, respectively). There was no difference between TGF-β staining scores of G2 and G4. Concomitant use of HMB/GLN/ARG appears to ameliorate radiation-induced acute intestinal toxicity; however, this finding should be clarified with further studies.

Influence of nutritional status on postoperative outcome in patients with colorectal cancer - the emerging role of the microbiome

Many patients with colorectal cancer are overweight. Even then, nutritional status is a frequently underestimated risk factor for perioperative complications. Enhanced Recovery after Surgery is the goal for perioperative management, and preoperative nutritional risk screening should be a standard. In case of nutritional risk, perioperative nutrition therapy should be started without delay and should follow recent guideline recommendations. The preservation of the microbiome has an emerging role in preventing postoperative anastomotic leakage and septic complications. The time window for recovery after neoadjuvant treatment for rectal cancer may be used for conditioning appropriate-risk patients in a “prehabilitation” program. In order to assess metabolic recovery and the prognosis for long-term survival, C-reactive protein/albumin ratio may be a promising parameter, which has to be validated in the future. This narrative review summarizes recent strategies and guideline recommendations.

Nutrition Therapy in Sepsis

Sepsis is characterized by early massive catabolism, lean body mass (LBM) loss, and escalating hypermetabolism persisting for months to years. Early enteral nutrition should attempt to correct micronutrient/vitamin deficiencies, deliver adequate protein and moderated nonprotein calories, as well-nourished patients can generate reasonable endogenous energy. After resuscitation, increasing protein/calories are needed to attenuate LBM loss and promote recovery. Malnutrition screening is essential, and parenteral nutrition can be safely added when enteral nutrition is failing based on preillness malnutrition. Following discharge from intensive care unit, significantly increased protein/calorie delivery is required for months to years to facilitate functional and LBM recovery.

Pharmacological Therapy for the Prevention and Treatment of Weakness After Critical Illness: A Systematic Review

OBJECTIVES

ICU-acquired weakness is a common complication of critical illness and can have significant effects upon functional status and quality of life. As part of preliminary work to inform the design of a randomized trial of a complex intervention to improve recovery from critical illness, we sought to identify pharmacological interventions that may play a role in this area.

DATA SOURCES

We systematically reviewed the published literature relating to pharmacological intervention for the treatment and prevention of ICU-acquired weakness.

STUDY SELECTION

We searched MEDLINE, EMBASE, CINAHL+, Web of Science, and both U.S. and European trial registries up to July 2014 alongside reviews and reference lists from populations with no age or language restrictions. We included studies that reported a measure of muscle structure or physical function as an outcome measure.

DATA EXTRACTION

We estimated pooled odds ratios and 95% CI using data extracted from published articles or where available, original data provided by the authors. Assessment of bias was performed using the Cochrane Collaboration's risk of bias tool.

DATA SYNTHESIS

Ten studies met the inclusion criteria. The current body of evidence does not support the use of any pharmacological agent in this setting, although maintaining euglycemia may reduce the prevalence of critical illness polyneuropathy.

CONCLUSIONS

At present, no pharmacological intervention can be recommended to prevent or treat ICU-acquired weakness. Further research is required into this field to include more novel agents such as myostatin inhibitors. Challenges in the conduct of research in this area are highlighted.

Nutrition in the critically ill patient

PURPOSE OF REVIEW

To summarize recent relevant studies regarding nutrition during critical illness and provide recommendations for clinical practice.

RECENT FINDINGS

Recently acquired knowledge regarding nutritional status and risk assessment, body composition, gastric residual volume, prokinetics, tube positioning, enteral vs parenteral nutrition, nutritional dose and timing of initiation, pharmaconutrition, dysbiosis and probiotics are discussed.

SUMMARY

Body composition especially lean body mass is associated with clinical outcomes. The modified NUTrition Risk in the Critically ill score was validated for nutritional risk assessment and identifies patients that benefit from higher nutritional intake; however, caloric restriction decreases mortality in refeeding syndrome. Gastric residual volume monitoring is debated, as abandoning its application doesn't worsen outcome. There is no consensus regarding benefits of gastric vs postpyloric tube placement. Current prokinetics temporarily reduce feeding intolerance, new prokinetics are developed. Enteral remains preferable over parenteral nutrition, although no inferiority of parenteral nutrition is reported in recent studies. Studies imply no harm of hypocaloric feeding when protein requirements are met. Optimal protein provision may be more important than caloric adequacy. Pharmaconutrition confers no superior outcomes and may even confer harm. Dysbiosis is frequently encountered and associated with worse outcomes. Probiotics reduce infectious complications, but not mortality, and may contribute to earlier recovery of gut function.

Therapeutic benefits of glutamine: An umbrella review of meta-analyses

Glutamine may be an essential amino acid in patients with catabolic disease, as it has been demonstrated that circulating glutamine levels drop during critical illness and following major surgery; this may result in an increase in secondary infection risk, recovery time and mortality rates. However, there is much discrepancy in the literature with regards to randomized controlled studies, and therefore, the present study is an umbrella review of published meta-analyses, conducted to examine the effectiveness of glutamine's role as a therapeutic agent. A search using PubMed, Cochrane Library and CINAHL from January 1st, 1980 to December 31st, 2016 was conducted using the following strategy: 'Glutamine AND (meta-analysis OR systematic review)' and publications were retrieved, which provided quantitative statistical analysis of pooled treatment effects on the relative risks of infectious complications, mortality and length of stay in hospital. A total of 22 meta-analyses were entered into the current umbrella review. As displayed in Tables I, II and III, these analyses are split into three groups, based on different parameters. Of the 19 meta-analyses investigating the effects of infectious complications, 15 identified statistically significant reductions in complications, with relative risks ranging between 0.42 and 0.93. In addition, 12 of the 18 meta-analyses analyzing the length of hospital stays presented statistically significant reductions in the length of stay, with reductions ranging between 0.19 to 4.73 days. Only 4 of the 15 meta-analyses studying mortality effects identified statistically significant reductions in mortality with relative risks ranging between 0.64 and 1.28. Statistically significant heterogeneity was observed in 16 of 22 meta-analyses, and publication bias was observed in five of 11 meta-analyses. Glutamine supplementation for critically ill or surgical patients through parenteral or enteral routes appears to reduce the rate of hospital acquired infectious complications and shortening of the length of stay in hospital. Furthermore, glutamine supplementation appeared to reduce the rate of in-patient mortality, but the majority of meta-analyses did not reach statistical significance. However, researchers must appreciate the positive results with caution in light of the fact that there exists statistically significant heterogeneity for the majority of meta-analyses, and statistically significant publication bias in almost half.

Is the glutamine story over?

Glutamine has been launched as a conditionally indispensible amino acid for the critically ill. Supplementation has been recommended in guidelines from international societies. Although data have been presented pointing out that glutamine supplementation may not be for everybody, recommendations for treatments and design of study protocols have included all critically ill patients. Results from more recent studies and meta-analyses indicate that indiscriminate use of glutamine supplementation in critically ill patients may actually cause harm rather than beneficial effects. This viewpoint sorts out arguments of controversy in the glutamine story.

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.

Prevalence of glutamine deficiency in ICU patients: a cross-sectional analytical study

BACKGROUND

Not only is glutamine deficiency an independent predictor of mortality in intensive care unit (ICU) patients, but glutamine supplementation is also recommended for its proven outcome benefits. However, recent data suggest that early glutamine supplementation in certain patient groups increase mortality. The aim of this study was to investigate plasma glutamine levels of adult ICU patients in the South African setting and to determine relationships between glutamine levels, gender, diagnostic categories and selected inflammatory markers. The data from this study will be used as baseline measurement to support a large scale study that will be undertaken in the South African ICU population.

METHODS

This cross-sectional, analytical study included 60 mixed adult ICU patients within 24 h post ICU admission. Plasma glutamine levels were determined on admission. The relationship between glutamine levels, Interleukin-6 (IL-6) and C-reactive protein (CRP); as well as gender- and diagnosis-related differences in glutamine levels were also investigated. A non-parametric ROC curve was computed to determine the CRP concentration cut-off point above which glutamine becomes deficient.

RESULTS

The median plasma glutamine level (497 μmol/L) was in the normal range; however, 38.3 % (n = 23) of patients had deficient (<420 μmol/L) and 6.7 % (n = 4) had supra-normal glutamine levels (>930 μmol/L). No significant difference could be detected between glutamine levels and gender or diagnosis categories as a group. When only the medical and surgical categories were compared, the median plasma glutamine level of the medical patients were significantly lower than that of the surgical patients (p = 0.042). Glutamine showed inverse associations with CRP levels (r = -0.44, p < 0.05) and IL-6 concentrations (r = -0.23, p = 0.08). A CRP cut-off value of 95.5 mg/L was determined above which glutamine levels became deficient.

CONCLUSIONS

About a third of patients (38 %) were glutamine deficient on admission to ICU, whereas some presented with supra-normal levels. While glutamine levels correlated inversely with inflammatory markers, and a CRP value of above 95.5 mg/L indicated potential glutamine deficiency, the clinical application of this finding needs further investigation.

Efficacy and Safety of Glutamine-supplemented Parenteral Nutrition in Surgical ICU Patients: An American Multicenter Randomized Controlled Trial

OBJECTIVE

To determine whether glutamine (GLN)-supplemented parenteral nutrition (PN) improves clinical outcomes in surgical intensive care unit (SICU) patients.

SUMMARY BACKGROUND DATA

GLN requirements may increase with critical illness. GLN-supplemented PN may improve clinical outcomes in SICU patients.

METHODS

A parallel-group, multicenter, double-blind, randomized, controlled clinical trial in 150 adults after gastrointestinal, vascular, or cardiac surgery requiring PN and SICU care. Patients were without significant renal or hepatic failure or shock at entry. All received isonitrogenous, isocaloric PN [1.5 g/kg/d amino acids (AAs) and energy at 1.3× estimated basal energy expenditure]. Controls (n = 75) received standard GLN-free PN (STD-PN); the GLN group (n = 75) received PN containing alanyl-GLN dipeptide (0.5 g/kg/d), proportionally replacing AA in PN (GLN-PN). Enteral nutrition (EN) was advanced and PN weaned as indicated. Hospital mortality and infections were primary endpoints.

RESULTS

Baseline characteristics, days on study PN and daily macronutrient intakes via PN and EN, were similar between groups. There were 11 hospital deaths (14.7%) in the GLN-PN group and 13 deaths in the STD-PN group (17.3%; difference, -2.6%; 95% confidence interval, -14.6% to 9.3%; P = 0.66). The 6-month cumulative mortality was 31.4% in the GLN-PN group and 29.7% in the STD-PN group (P = 0.88). Incident bloodstream infection rate was 9.6 and 8.4 per 1000 hospital days in the GLN-PN and STD-PN groups, respectively (P = 0.73). Other clinical outcomes and adverse events were similar.

CONCLUSIONS

PN supplemented with GLN dipeptide was safe, but did not alter clinical outcomes among SICU patients.

The intestinal microbiome, barrier function, and immune system in inflammatory bowel disease: a tripartite pathophysiological circuit with implications for new therapeutic directions

We discuss the tripartite pathophysiological circuit of inflammatory bowel disease (IBD), involving the intestinal microbiota, barrier function, and immune system. Dysfunction in each of these physiological components (dysbiosis, leaky gut, and inflammation) contributes in a mutually interdependent manner to IBD onset and exacerbation. Genetic and environmental risk factors lead to disruption of gut homeostasis: genetic risks predominantly affect the immune system, environmental risks predominantly affect the microbiota, and both affect barrier function. Multiple genetic and environmental 'hits' are likely necessary to establish and exacerbate disease. Most conventional IBD therapies currently target only one component of the pathophysiological circuit, inflammation; however, many patients with IBD do not respond to immune-modulating therapies. Hope lies in new classes of therapies that target the microbiota and barrier function.

When Is It Appropriate to Use Glutamine in Critical Illness?

Glutamine is a nonessential amino acid, which under trauma or critical illness can become essential. A number of historic small single-center randomized controlled trials (RCTs) have demonstrated positive treatment effects on clinical outcomes with glutamine supplementation. Meta-analyses based on these trials demonstrated a significant reduction in hospital mortality, intensive care unit (ICU) length of stay (LOS), and hospital LOS with intravenous (IV) glutamine. Similar results were not noted in 2 large multicenter RCTs (REDOXS and MetaPlus) assessing the efficacy of glutamine supplementation in ventilated ICU patients. The REDOXS trial of 40 ICUs randomized 1223 ventilated ICU patients to glutamine (IV and enteral), antioxidants, both glutamine and antioxidants, or placebo. The main conclusions were a trend toward increased 28-day mortality and significant increased hospital and 6-month mortality in those who received glutamine. The MetaPlus trial of 14 ICUs, which randomized 301 ventilated ICU patients to glutamine-enriched enteral vs an isocaloric diet, noted increased 6-month mortality in the glutamine-supplemented group. Newer RCTs have focused on specific populations and have demonstrated benefits in burn and elective surgery patients with glutamine supplementation. Whether larger studies will confirm these findings is yet to be determined. Recent American Society for Parenteral and Enteral Nutrition guidelines recommend that IV and enteral glutamine should not be used in the critical care setting based on the moderate quality of evidence available. We agree with these recommendations and would encourage larger multicenter studies to evaluate the risks and benefits of glutamine in burn and elective surgery patients.