Glutamine and acute illness

Residual gastric volume evaluation with ultrasonography after ingestion of carbohydrate- or carbohydrate plus glutamine-enriched beverages: a randomized, crossover clinical trial with healthy volunteers

BACKGROUND

- Abbreviation of preoperative fasting to 2 hours with maltodextrin (CHO)-enriched beverage is a safe procedure and may enhance postoperative recovery. Addition of glutamine (GLN) to CHO beverages may include potential benefits to the metabolism. However, by adding a nitrogenous source to CHO beverages, gastric emptying may be delayed and increase the risk of bronchoaspiration during anesthesia.

OBJECTIVE

- In this study of safety, we aimed at investigating the residual gastric volume (RGV) 2 hours after the intake of either CHO beverage alone or CHO beverage combined with GLN.

METHODS

- We performed a randomized, crossover clinical trial. We assessed RGV by means of abdominal ultrasonography (US) in 20 healthy volunteers (10 males and 10 females) after an overnight fast of 8 hours. Then, they were randomized to receive 600 mL (400 mL immediately after US followed by another 200 mL 2 hours afterwards) of either CHO (12.5% maltodextrin) or CHO-GLN (12.5% maltodextrin plus 15 g GLN). Two sequential US evaluations were done at 120 and 180 minutes after ingestion of the second dose. The interval of time between ingestion of the two types of beverages was 2 weeks.

RESULTS

- The mean (SD) RGV observed after 8 hours fasting (13.56±13.25 mL) did not statistically differ (P>0.05) from the RGV observed after ingesting CHO beverage at both 120 (16.32±11.78 mL) and 180 minutes (14.60±10.39 mL). The RGV obtained at 120 (15.63±18.83 mL) and 180 (13.65±10.27 mL) minutes after CHO-GLN beverage also was not significantly different from the fasting condition.

CONCLUSION

- The RGV at 120 and 180 minutes after ingestion of CHO beverage combined with GLN is similar to that observed after an overnight fast.

The clinical role of glutamine supplementation in patients with multiple trauma: a narrative review

Glutamine is considered an essential amino acid during stress and critical illness. Parenteral glutamine supplementation in critically ill patients has been shown to improve survival rate and minimise infectious complications, costs and hospital length-of-stay. However, glutamine supplementation in patients receiving enteral nutrition and the best method of administration are still controversial. The purpose of this article is to provide a narrative review of the current evidence and trials of enteral and parenteral glutamine supplementation in multiple trauma patients. A search in PubMed and EMBASE was conducted and relevant papers that investigated the effect of enteral or parenteral glutamine supplementation in patients with multiple trauma were reviewed. Although recent nutritional guidelines recommend that glutamine supplementation should be considered in these patients, further well-designed trials are required to provide a confirmed conclusion. Due to the inconclusive results of enteral glutamine supplementation trials in patients receiving enteral nutrition, future trials should focus on intravenous glutamine supplementation in patients requiring enteral nutrition and on major clinical outcome measures (e.g. mortality rate, infectious complications).

Enteral nutrition in critical care

There is a consensus that nutritional support, which must be provided to patients in intensive care, influences their clinical outcome. Malnutrition is associated in critically ill patients with impaired immune function and impaired ventilator drive, leading to prolonged ventilator dependence and increased infectious morbidity and mortality. Enteral nutrition is an active therapy that attenuates the metabolic response of the organism to stress and favorably modulates the immune system. It is less expensive than parenteral nutrition and is preferred in most cases because of less severe complications and better patient outcomes, including infections, and hospital cost and length of stay. The aim of this work was to perform a review of the use of enteral nutrition in critically ill patients.

[Guidelines for specialized nutritional and metabolic support in the critically-ill patient. Update. Consensus of the Spanish Society of Intensive Care Medicine and Coronary Units-Spanish Society of Parenteral and Enteral Nutrition (SEMICYUC-SENPE): patient with polytrauma]

Patients with polytrauma can be viewed as paradigmatic of the critically-ill patient. These previously healthy patients undergo a life-threatening aggression leading to an organic response that is no different from that in other types of patients. The profile of trauma patients has changed and currently corresponds to patients who are somewhat older, with a higher body mass index and greater comorbidity. Severe injuries lead to intense metabolic stress, posing a risk of malnutrition. Therefore, early nutritional support, preferentially through the enteral route, with appropriate protein intake and glutamine supplementation, provides advantages over other routes and types of nutritional formula. To avoid overnutrition, reduced daily calorie intake can be considered in obese patients and in those with medullary lesions. However, little information on this topic is available in patients with medullary lesions.

Effect of intravenous GLutamine supplementation IN Trauma patients receiving enteral nutrition study protocol (GLINT Study): a prospective, blinded, randomised, placebo-controlled clinical trial

Background Trauma patients are characterised by alterations in the immune system, increased exposure to infectious complications, sepsis and potentially organ failure and death. Glutamine supplementation to parenteral nutrition has been proven to be associated with improved clinical outcomes. However, glutamine supplementation in patients receiving enteral nutrition and its best route are still controversial. Previous trials have been limited by a small sample size, use of surrogate outcomes or a limited period of supplementation. The aim of this trial is to investigate if intravenous glutamine supplementation to trauma patients receiving enteral nutrition is associated with improved clinical outcomes in terms of decreased organ dysfunction, infectious complications and other secondary outcomes. Methods/design Eighty-eight critically ill patients with multiple trauma receiving enteral nutrition will be recruited in this prospective, triple-blind, block-randomised, placebo-controlled clinical trial to receive either 0.5 g/kg/day intravenous undiluted alanyl-glutamine or intravenous placebo by continuous infusion (24 h/day). Both groups will be receiving the same standard enteral nutrition protocol and the same standard intensive care unit care. Supplementation will continue until discharge from the intensive care unit, death or a maximum duration of 3 weeks. The primary outcome will be organ-dysfunction evaluation assessed by the pattern of change in sequential organ failure assessment score over a 10-day period. The secondary outcomes are: the changes in total sequential organ failure assessment score on the last day of treatment, infectious complications during the ICU stay, 60-day mortality, length of stay in the intensive care unit and body-composition analysis. Discussion This study is the first trial to investigate the effect of intravenous alanyl-glutamine supplementation in multiple trauma patients receiving enteral nutrition on reducing severity of organ failure and infectious complications and preservation of lean body mass. Trial registration number This trial is registered at http://www.clinicaltrials.gov. NCT01240291.

"Metabolic staging" after major trauma - a guide for clinical decision making?

Metabolic changes after major trauma have a complex underlying pathophysiology. The early posttraumatic stress response is associated with a state of hyperinflammation, with increased oxygen consumption and energy expenditure. This hypercatabolic state must be recognized early and mandates an early nutritional management strategy. A proactive concept of early enteral "immunonutrition" in severely injured patients, is aimed at counterbalancing the negative aspects of hyperinflammation and hypercatabolism in order to reduce the risk of late complications, including infections and posttraumatic organ failure. Recently, the concept of "metabolic staging" has been advocated, which takes into account the distinct inflammatory phases and metabolic phenotypes after major trauma, including the "ischemia/reperfusion phenotype", the "leukocytic phenotype", and the "angiogenic phenotype". The potential clinical impact of metabolic staging, and of an appropriately adapted "metabolic control" and nutritional support, remains to be determined.

Typhilitis in the pediatric patient

Cancer statistics in children are promising as mortality rates consistently decrease, reflecting newer chemotherapeutic agents and the evolution of hematopoietic stem cell transplant. Typhilitis or neutropenic enterocolitis is a potentially life-threatening complication of cancer treatment often found in immunocompromised children receiving vigorous chemotherapeutic regimens and noted in children post-stem-cell transplant. Recent literature suggests a relationship between typhilitis and other types of cancers and immunocompromised illness occurring in both children and adults. The pathogenesis of typhilitis is poorly understood, with limited evidence regarding incidence. Nursing care and assessment of children receiving oncologic treatment requires vigilance and immediate response to prevent and manage complications, especially gastrointestinally related typhilitis.

Glutamine as a modulator of the immune system of critical care patients: effect on Toll-like receptor expression. A preliminary study

OBJECTIVE

We evaluated the expression of Toll-like receptors 2 and 4 (TLR-2 and TLR-4) in circulating monocytes from peripheral blood of critical care patients treated with and without glutamine. Because no research has been published to date on the effect of glutamine on TLR receptors in critical patients, it was determined in an initial sample of 30 patients.

METHODS

This was a prospective, randomized, single-blind study with 15 patients assigned to receive parenteral nutrition with a daily glutamine supplement of 0.35 g/kg. The control group received isocaloric-isonitrogenous parenteral nutrition. Blood samples were extracted before beginning the treatment and at 5 and 14 d. Expressions of CD14, TLR-2, and TLR-4 were determined by flow cytometry. Levels of TLRs were expressed as mean fluorescence intensity (mfi).

RESULTS

Basal characteristics were similar in both groups. The expressions of TLR-2 in the treatment group with glutamine were 4.67 +/- 3.82 mfi before treatment, 3.91 +/- 2.04 mfi at 5 d, and 4.28 +/- 2.47 mfi at 14 d. The expressions of TLR-2 in the control group were 5.49 +/- 3.20 mfi before treatment, 4.48 +/- 2.15 mfi at 5 d, and 4.36 +/- 2.36 mfi at 14 d. The expressions of TLR-4 in the treatment group were 1.65 +/- 1.89 mfi before treatment, 1.23 +/- 1.10 mfi at 5 d, and 1.77 +/- 1.97 at 14 d. The expressions of TLR-4 in the control group were 1.51 +/- 1.76 mfi before treatment, 1.36 +/- 0.99 mfi at 5 d, and 1.26 +/- 0.59 mfi at 14 d. Infections were detected in 11 patients who received glutamine and 13 control patients (P = 0.51).

CONCLUSION

In critical care patients, parenteral nutrition supplemented with glutamine does not increase the expression of TLR-2 or TLR-4 in peripheral blood monocytes.

Role of biological modifiers regulating the immune response after trauma

Trauma induces a profound immunological dysfunction. This is characterised by an early state of hyperinflammation, followed by a phase of immunosuppression with increased susceptibility to infection and multiple organ failure. Therapeutic strategies directed at restoring immune homeostasis after traumatic injuries have largely failed in translation from "bench to bedside". The present review illustrates the role of biological modifiers of the posttraumatic immune response by portraying different modalities of therapeutic immune modulation. The emphasis is placed on anti-inflammatory (steroids) and immune-stimulatory (interferon) pharmacological strategies and modified resuscitative strategies, as well as more unconventional immunomodulatory approaches, such as immunonutrition.

Glutamine Supplementation in Critical Illness: Evidence, Recommendations, and Implications for Clinical Practice in Burn Care

Glutamine is considered a conditionally essential amino acid in metabolic stress. Depletion of plasma and muscle glutamine is observed in acute burn injury and contributes to muscle wasting, weight loss, and infection. In critical illness, supplementation has been shown in patients to minimize these effects and reduce the rate of mortality and length of stay. The evidence for glutamine use and its implications for burn care practice are considered here. Work published to February 2006, which investigated enteral and parenteral glutamine supplementation in burns and critical care, is reviewed. Randomized controlled trials in burns, systematic reviews, and nutrition support practice guidelines are considered. Randomized controlled trials in burns suggest significant clinical benefit in terms of morbidity, mortality, and length of stay but are limited by sample size. Parenteral glutamine studies are under-represented. Systematic reviews and practice guidelines generally support glutamine supplementation in critical illness but vary in the level of recommendations for its use in burns. There also are features unique to burn injury that require consideration. Patients with severe burns or inhalation injury may have a prolonged critical illness phase. In large burns, inflammation and hypermetabolism may persist well beyond 4 weeks of injury. The justification and safety of long-term glutamine supplementation is yet to be established. The outlook for glutamine therapy in burns is promising. However, to strengthen recommendations for routine therapy in burns, further research focusing on larger-scale enteral glutamine studies, parenteral glutamine supplementation, and long-term use of the substrate is necessary.

Metabolic changes after polytrauma: an imperative for early nutritional support

Major trauma induces marked metabolic changes which contribute to the systemic immune suppression in severely injured patients and increase the risk of infection and posttraumatic organ failure. The hypercatabolic state of polytrauma patients must be recognized early and treated by an appropriate nutritional management in order to avoid late complications. Clinical studies in recent years have supported the concept of "immunonutrition" for severely injured patients, which takes into account the supplementation of Ω-3 fatty acids and essential aminoacids, such as glutamine. Yet many aspects of the nutritional strategies for polytrauma patients remain controversial, including the exact timing, caloric and protein amount of nutrition, choice of enteral versus parenteral route, and duration. The present review will provide an outline of the pathophysiological metabolic changes after major trauma that endorse the current basis for early immunonutrition of polytrauma patients.

Muscle glutamine depletion in the intensive care unit

Glutamine is primarily synthesized in skeletal muscle and enables transfer of nitrogen to splanchnic tissues, kidneys and immune system. Discrepancy between increasing rates of glutamine utilization at whole body level and relative impairment of de novo synthesis in skeletal muscle leads to systemic glutamine deficiency and characterizes critical illness. Glutamine depletion at whole body level may contribute to gut, liver and immune system disfunctions, whereas its intramuscular deficiency may directly contribute to lean body mass loss. Severe intramuscular glutamine depletion also develops because of outward transport system upregulation, which is not counteracted by increased de novo synthesis. The negative impact of systemic glutamine depletion on critically ill patients is suggested both by the association between a lower plasma glutamine concentration and poor outcome and by a clear clinical benefit after glutamine supplementation. Enteral glutamine administration preferentially increases glutamine disposal in splanchnic tissues, whereas parenteral supplementation provides glutamine to the whole organism. Nonetheless, systemic administration was ineffective in preventing muscle depletion, due to a relative inability of skeletal muscle to seize glutamine from the bloodstream. Intramuscular glutamine depletion could be potentially counteracted by promoting de novo glutamine synthesis with pharmacological or nutritional interventions.

Stressing out over survival: glutamine as an apoptotic modulator

INTRODUCTION

The amino acid glutamine (GLN) has received considerable attention as a potential therapeutic adjuvant in critical illness and in improving postoperative clinical outcomes. Most studies on the role of GLN in cellular physiology have historically focused on its anabolic roles in specific cell types and its contribution to growth in cancer cells. However, an emerging body of work that examines the consequences of GLN deprivation on cellular survival and gene expression has constructed a new paradigm for this amino acid, namely, that limited extracellular GLN supplies modulate stress and apoptotic responses.

METHODS

A survey of the scientific literature was conducted on GLN in cell survival signaling and apoptosis. Work from our laboratory in liver cancer cells also was included in this review.

RESULTS

Most studies on this topic have used mammalian cell lines derived from the gut, immune system (including hybridomas), and various cancers. GLN limitation, even in the presence of an adequate glucose supply, impacts stress-related gene expression, differentially modulates receptor-mediated apoptosis, and directly elicits apoptosis through signaling mechanisms and caspase cascades that are specific to cell type. To date, GLN transporters, cellular hydration, glutaminyl-tRNA synthetase, ATP levels, mRNA stability, and glutathione economy have been variably implicated in GLN-dependent survival signaling.

CONCLUSION

The cell type-specific mechanisms underlying the regulatory role of GLN in cell survival continue to unfold at a steady pace through in vitro studies. These results have collectively provided testable hypotheses for further in vivo studies into their physiological relevance during GLN "nutritional pharmacology."