Metabolic effects of arginine addition to the enteral feeding of critically ill patients

The Japanese Critical Care Nutrition Guideline 2024

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

A systematic review to assess the impact of amino acids or their derivatives on skeletal muscle wasting in critically ill patients

BACKGROUND

It is plausible that supplementation with specific amino acids or metabolites could attenuate skeletal muscle wasting during critical illness. The aim of this systematic review was to explore if amino acids or their derivatives impact skeletal muscle wastage in critically ill adults.

METHODS

Four databases were systematically searched to identify randomised control trials which delivered enteral supplemental amino acids, or their metabolites compared with placebo, standard care or no intervention, to critically ill patients and reported outcomes of skeletal muscle mass, plasma amino acids, nitrogen balance, or muscle strength. Two authors independently completed screening, data extraction, and risk of bias assessment using the Cochrane Risk of Bias 2 Tool. A meta-analysis was planned but heterogeneity in the type of intervention used and outcome assessment precluded this. Therefore, data were synthesised using vote counting.

RESULTS

Thirty randomised control trials, comprising 1976 patients were included. The most frequently studied interventional amino acid or metabolite was glutamine (n = 12 trials), a combination (n = 9), arginine (n = 6), β-hydroxy β-methylbutyrate (HMB) (n = 2) or ornithine (n = 1). Six trials (including 284 participants) measured skeletal muscle following supplementation, four of which used HMB alone or in combination as the intervention. Of these, one trial observed an attenuation of muscle wasting with a combination of amino acids, one observed an exacerbation of muscle wasting with HMB, three trials observed no impact on muscle wasting with HMB or a combination of amino acids and one trial reported no information.

CONCLUSION

Six trials have investigated the effect of enteral amino acid or amino acid metabolite supplementation on muscle mass in critically ill. Heterogeneity of interventions, outcome assessments and direction of effects limits the certainty regarding the effect of supplemental amino acids, or their metabolites, on skeletal muscle wasting during critical illness. The trial protocol is registered on PROSPERO (CRD42021275989).

Citrulline supplementation exacerbates sepsis severity in infected preterm piglets via early induced immunosuppression

Arginine (ARG)/Citrulline (CIT) deficiency is associated with increased sepsis severity after infection. Supplementation of CIT to susceptible patients with ARG/CIT deficiency such as preterm newborns with suspected infection might prevent sepsis, via maintaining immune and vascular function. Caesarean-delivered, parenterally nourished preterm pigs were treated with CIT (1g/kg bodyweight) via oral or continuous intravenous supplementation, then inoculated with live Staphylococcus epidermidis and clinically monitored for 14 h. Blood, liver, and spleen samples were collected for analysis. In vitro cord blood stimulation was performed to explore how CIT and ARG affect premature blood cell responses. After infection, oral CIT supplementation led to higher mortality, increased blood bacterial load, and systemic and hepatic inflammation. Intravenous CIT administration showed increased inflammation and bacterial burdens without significantly affecting mortality. Liver transcriptomics and data from in vitro blood stimulation indicated that CIT induces systemic immunosuppression in preterm newborns, which may impair resistance response to bacteria at the early stage of infection, subsequently causing later uncontrollable inflammation and tissue damage. The early stage of CIT supplementation exacerbates sepsis severity in infected preterm pigs, likely via inducing systemic immunosuppression.

Bench to bedside review: therapeutic modulation of nitric oxide in sepsis-an update

Nitric oxide is a signalling molecule with an extensive range of functions in both health and disease. Discovered in the 1980s through work that earned the Nobel prize, nitric oxide is an essential factor in regulating cardiovascular, immune, neurological and haematological function in normal homeostasis and in response to infection. Early work implicated exaggerated nitric oxide synthesis as a potentially important driver of septic shock; however, attempts to modulate production through global inhibition of nitric oxide synthase were associated with increased mortality. Subsequent work has shown that regulation of nitric oxide production is determined by numerous factors including substrate and co-factor availability and expression of endogenous regulators. In sepsis, nitric oxide synthesis is dysregulated with exaggerated production leading to cardiovascular dysfunction, bioenergetic failure and cellular toxicity whilst at the same time impaired microvascular function may be driven in part by reduced nitric oxide synthesis by the endothelium. This bench to bedside review summarises our current understanding of the ways in which nitric oxide production is regulated on a tissue and cellular level before discussing progress in translating these observations into novel therapeutic strategies for patients with sepsis.

l-Citrulline Supplementation: Impact on Cardiometabolic Health

Diminished bioavailability of nitric oxide (NO), the gaseous signaling molecule involved in the regulation of numerous vital biological functions, contributes to the development and progression of multiple age- and lifestyle-related diseases. While l-arginine is the precursor for the synthesis of NO by endothelial-nitric oxide synthase (eNOS), oral l-arginine supplementation is largely ineffective at increasing NO synthesis and/or bioavailability for a variety of reasons. l-citrulline, found in high concentrations in watermelon, is a neutral alpha-amino acid formed by enzymes in the mitochondria that also serves as a substrate for recycling l-arginine. Unlike l-arginine, l-citrulline is not quantitatively extracted from the gastrointestinal tract (i.e., enterocytes) or liver and its supplementation is therefore more effective at increasing l-arginine levels and NO synthesis. Supplementation with l-citrulline has shown promise as a blood pressure lowering intervention (both resting and stress-induced) in adults with pre-/hypertension, with pre-clinical (animal) evidence for atherogenic-endothelial protection. Preliminary evidence is also available for l-citrulline-induced benefits to muscle and metabolic health (via vascular and non-vascular pathways) in susceptible/older populations. In this review, we examine the impact of supplementing this important urea cycle intermediate on cardiovascular and metabolic health outcomes and identify future directions for investigating its therapeutic impact on cardiometabolic health.

Safety and performance benefits of arginine supplements for military personnel: a systematic review

CONTEXT

Dietary supplements are widely used by military personnel and civilians for promotion of health.

OBJECTIVE

The objective of this evidence-based review was to examine whether supplementation with l-arginine, in combination with caffeine and/or creatine, is safe and whether it enhances athletic performance or improves recovery from exhaustion for military personnel.

DATA SOURCES

Information from clinical trials and adverse event reports were collected from 17 databases and 5 adverse event report portals.

STUDY SELECTION

Studies and reports were included if they evaluated the safety and the putative outcomes of enhanced performance or improved recovery from exhaustion associated with the intake of arginine alone or in combination with caffeine and/or creatine in healthy adults aged 19 to 50 years.

DATA EXTRACTION

Information related to population, intervention, comparator, and outcomes was abstracted. Of the 2687 articles screened, 62 articles meeting the inclusion criteria were analyzed. Strength of evidence was assessed in terms of risk of bias, consistency, directness, and precision.

RESULTS

Most studies had few participants and suggested risk of bias that could negatively affect the results. l-Arginine supplementation provided little enhancement of athletic performance or improvements in recovery. Short-term supplementation with arginine may result in adverse gastrointestinal and cardiovascular effects. No information about the effects of arginine on the performance of military personnel was available.

CONCLUSIONS

The available information does not support the use of l-arginine, either alone or in combination with caffeine, creatine, or both, to enhance athletic performance or improve recovery from exhaustion. Given the information gaps, an evidence-based review to assess the safety or effectiveness of multi-ingredient dietary supplements was not feasible, and therefore the development of a computational model-based approach to predict the safety of multi-ingredient dietary supplements is recommended.

Acquired Amino Acid Deficiencies: A Focus on Arginine and Glutamine

Nonessential amino acids are synthesized de novo and therefore not diet dependent. In contrast, essential amino acids must be obtained through nutrition since they cannot be synthesized internally. Several nonessential amino acids may become essential under conditions of stress and catabolic states when the capacity of endogenous amino acid synthesis is exceeded. Arginine and glutamine are 2 such conditionally essential amino acids and are the focus of this review. Low arginine bioavailability plays a pivotal role in the pathogenesis of a growing number of varied diseases, including sickle cell disease, thalassemia, malaria, acute asthma, cystic fibrosis, pulmonary hypertension, cardiovascular disease, certain cancers, and trauma, among others. Catabolism of arginine by arginase enzymes is the most common cause of an acquired arginine deficiency syndrome, frequently contributing to endothelial dysfunction and/or T-cell dysfunction, depending on the clinical scenario and disease state. Glutamine, an arginine precursor, is one of the most abundant amino acids in the body and, like arginine, becomes deficient in several conditions of stress, including critical illness, trauma, infection, cancer, and gastrointestinal disorders. At-risk populations are discussed together with therapeutic options that target these specific acquired amino acid deficiencies.

Thirteen-Week Oral Toxicity Study of l-Arginine in Rats

The amino acid l-arginine (Arg) has been used extensively in dietary and pharmacological products. This study evaluated toxicological and behavioral effects of Arg produced by Ajinomoto Co. (Tokyo, Japan) during a dosing study with male and female Sprague-Dawley rats. The amino acid was incorporated into a standard diet at doses equal to 1.25%, 2.5%, and 5.0% ( w/w). A control group of rats received only a standard diet. All diets were administered ad libitum for 13 continuous weeks. To examine recoverability of any potential effects, the administration period was followed by a 5-week-long recovery, during which only a standard diet was provided. In male and female rats in each concentration group, treatment-related changes were not observed for clinical signs, body weights, diet consumption, ophthalmology, gross pathology, organ weight, or histopathology. An elevated level of plasma glucose was detected in some male rats (5.0%, w/ w) during the analysis conducted in the fifth week of administration; however, the degree of the change was within the physiological range, and no changes were observed at the end of the administration period. In the same group, an increase in hemoglobin, together with a tendency toward an increase in the red blood cell counts, was found, but the change was considered toxicologically insignificant. The no-observed-adverse-effect level (NOAEL) for Arg was estimated at 5.0% ( w/w) for both genders (males, 3.3 ±0.1 g/kg/day; females, 3.9 ±0.2 g/kg/day).

Arginine Supplementation Does Not Enhance Serum Nitric Oxide Levels in Elderly Nursing Home Residents With Pressure Ulcers

The purpose of this study was to determine whether arginine supplementation enhances in vitro (neutrophil burst and mitogen-induced lymphocyte proliferation) and in vivo (delayed-type hypersensitivity [DTH] and serum nitric oxide) measures of immune function in nursing home elders with pressure ulcers. Twenty-six elders, 65 years of age or older, with one or more pressure ulcers, were randomized to receive 8.5 g of arginine or an isonitrogenous supplement for 4 weeks. Immune function studies and serum arginine, ornithine, citrulline, and nitric oxide were measured at baseline, 4 weeks postsupplementation (Week 4) and after a 6-week washout (Week 10). At Week 4, serum ornithine increased (p = .01) and arginine trended to increase (p = .055), but there was no increase in citrulline or nitric oxide with arginine supplementation. There were no differences in neutrophil burst or DTH responses between groups. Whole blood mitogen–induced proliferation decreased significantly atWeek 10 in the isonitrogenous but not in the arginine-supplemented group. There is mounting concern that arginine supplementation during an inflammatory state could be detrimental due to overwhelming nitric oxide production. A key finding of this study is that arginine supplementation did not increase serum nitric oxide levels over that observed in elders with pressure ulcers given an isonitrogenous supplement.

Arginine and citrulline and the immune response in sepsis

Arginine, a semi-essential amino acid is an important initiator of the immune response. Arginine serves as a precursor in several metabolic pathways in different organs. In the immune response, arginine metabolism and availability is determined by the nitric oxide synthases and the arginase enzymes, which convert arginine into nitric oxide (NO) and ornithine, respectively. Limitations in arginine availability during inflammatory conditions regulate macrophages and T-lymfocyte activation. Furthermore, over the past years more evidence has been gathered which showed that arginine and citrulline deficiencies may underlie the detrimental outcome of inflammatory conditions, such as sepsis and endotoxemia. Not only does the immune response contribute to the arginine deficiency, also the impaired arginine de novo synthesis in the kidney has a key role in the eventual observed arginine deficiency. The complex interplay between the immune response and the arginine-NO metabolism is further underscored by recent data of our group. In this review we give an overview of physiological arginine and citrulline metabolism and we address the experimental and clinical studies in which the arginine-citrulline NO pathway plays an essential role in the immune response, as initiator and therapeutic target.

Surviving sepsis campaign: international guidelines for management of severe sepsis and septic shock: 2012

OBJECTIVE

To provide an update to the "Surviving Sepsis Campaign Guidelines for Management of Severe Sepsis and Septic Shock," last published in 2008.

DESIGN

A consensus committee of 68 international experts representing 30 international organizations was convened. Nominal groups were assembled at key international meetings (for those committee members attending the conference). A formal conflict of interest policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independent of any industry funding. A stand-alone meeting was held for all subgroup heads, co- and vice-chairs, and selected individuals. Teleconferences and electronic-based discussion among subgroups and among the entire committee served as an integral part of the development.

METHODS

The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to guide assessment of quality of evidence from high (A) to very low (D) and to determine the strength of recommendations as strong (1) or weak (2). The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized. Some recommendations were ungraded (UG). Recommendations were classified into three groups: 1) those directly targeting severe sepsis; 2) those targeting general care of the critically ill patient and considered high priority in severe sepsis; and 3) pediatric considerations.

RESULTS

Key recommendations and suggestions, listed by category, include: early quantitative resuscitation of the septic patient during the first 6 hrs after recognition (1C); blood cultures before antibiotic therapy (1C); imaging studies performed promptly to confirm a potential source of infection (UG); administration of broad-spectrum antimicrobials therapy within 1 hr of recognition of septic shock (1B) and severe sepsis without septic shock (1C) as the goal of therapy; reassessment of antimicrobial therapy daily for de-escalation, when appropriate (1B); infection source control with attention to the balance of risks and benefits of the chosen method within 12 hrs of diagnosis (1C); initial fluid resuscitation with crystalloid (1B) and consideration of the addition of albumin in patients who continue to require substantial amounts of crystalloid to maintain adequate mean arterial pressure (2C) and the avoidance of hetastarch formulations (1C); initial fluid challenge in patients with sepsis-induced tissue hypoperfusion and suspicion of hypovolemia to achieve a minimum of 30 mL/kg of crystalloids (more rapid administration and greater amounts of fluid may be needed in some patients) (1C); fluid challenge technique continued as long as hemodynamic improvement, as based on either dynamic or static variables (UG); norepinephrine as the first-choice vasopressor to maintain mean arterial pressure ≥ 65 mm Hg (1B); epinephrine when an additional agent is needed to maintain adequate blood pressure (2B); vasopressin (0.03 U/min) can be added to norepinephrine to either raise mean arterial pressure to target or to decrease norepinephrine dose but should not be used as the initial vasopressor (UG); dopamine is not recommended except in highly selected circumstances (2C); dobutamine infusion administered or added to vasopressor in the presence of a) myocardial dysfunction as suggested by elevated cardiac filling pressures and low cardiac output, or b) ongoing signs of hypoperfusion despite achieving adequate intravascular volume and adequate mean arterial pressure (1C); avoiding use of intravenous hydrocortisone in adult septic shock patients if adequate fluid resuscitation and vasopressor therapy are able to restore hemodynamic stability (2C); hemoglobin target of 7-9 g/dL in the absence of tissue hypoperfusion, ischemic coronary artery disease, or acute hemorrhage (1B); low tidal volume (1A) and limitation of inspiratory plateau pressure (1B) for acute respiratory distress syndrome (ARDS); application of at least a minimal amount of positive end-expiratory pressure (PEEP) in ARDS (1B); higher rather than lower level of PEEP for patients with sepsis-induced moderate or severe ARDS (2C); recruitment maneuvers in sepsis patients with severe refractory hypoxemia due to ARDS (2C); prone positioning in sepsis-induced ARDS patients with a PaO2/FIO2 ratio of ≤ 100 mm Hg in facilities that have experience with such practices (2C); head-of-bed elevation in mechanically ventilated patients unless contraindicated (1B); a conservative fluid strategy for patients with established ARDS who do not have evidence of tissue hypoperfusion (1C); protocols for weaning and sedation (1A); minimizing use of either intermittent bolus sedation or continuous infusion sedation targeting specific titration endpoints (1B); avoidance of neuromuscular blockers if possible in the septic patient without ARDS (1C); a short course of neuromuscular blocker (no longer than 48 hrs) for patients with early ARDS and a Pao2/Fio2 < 150 mm Hg (2C); a protocolized approach to blood glucose management commencing insulin dosing when two consecutive blood glucose levels are > 180 mg/dL, targeting an upper blood glucose ≤ 180 mg/dL (1A); equivalency of continuous veno-venous hemofiltration or intermittent hemodialysis (2B); prophylaxis for deep vein thrombosis (1B); use of stress ulcer prophylaxis to prevent upper gastrointestinal bleeding in patients with bleeding risk factors (1B); oral or enteral (if necessary) feedings, as tolerated, rather than either complete fasting or provision of only intravenous glucose within the first 48 hrs after a diagnosis of severe sepsis/septic shock (2C); and addressing goals of care, including treatment plans and end-of-life planning (as appropriate) (1B), as early as feasible, but within 72 hrs of intensive care unit admission (2C). Recommendations specific to pediatric severe sepsis include: therapy with face mask oxygen, high flow nasal cannula oxygen, or nasopharyngeal continuous PEEP in the presence of respiratory distress and hypoxemia (2C), use of physical examination therapeutic endpoints such as capillary refill (2C); for septic shock associated with hypovolemia, the use of crystalloids or albumin to deliver a bolus of 20 mL/kg of crystalloids (or albumin equivalent) over 5 to 10 mins (2C); more common use of inotropes and vasodilators for low cardiac output septic shock associated with elevated systemic vascular resistance (2C); and use of hydrocortisone only in children with suspected or proven "absolute"' adrenal insufficiency (2C).

CONCLUSIONS

Strong agreement existed among a large cohort of international experts regarding many level 1 recommendations for the best care of patients with severe sepsis. Although a significant number of aspects of care have relatively weak support, evidence-based recommendations regarding the acute management of sepsis and septic shock are the foundation of improved outcomes for this important group of critically ill patients.

Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock, 2012

OBJECTIVE

To provide an update to the "Surviving Sepsis Campaign Guidelines for Management of Severe Sepsis and Septic Shock," last published in 2008.

DESIGN

A consensus committee of 68 international experts representing 30 international organizations was convened. Nominal groups were assembled at key international meetings (for those committee members attending the conference). A formal conflict of interest policy was developed at the onset of the process and enforced throughout. The entire guidelines process was conducted independent of any industry funding. A stand-alone meeting was held for all subgroup heads, co- and vice-chairs, and selected individuals. Teleconferences and electronic-based discussion among subgroups and among the entire committee served as an integral part of the development.

METHODS

The authors were advised to follow the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to guide assessment of quality of evidence from high (A) to very low (D) and to determine the strength of recommendations as strong (1) or weak (2). The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasized. Recommendations were classified into three groups: (1) those directly targeting severe sepsis; (2) those targeting general care of the critically ill patient and considered high priority in severe sepsis; and (3) pediatric considerations.

RESULTS

Key recommendations and suggestions, listed by category, include: early quantitative resuscitation of the septic patient during the first 6 h after recognition (1C); blood cultures before antibiotic therapy (1C); imaging studies performed promptly to confirm a potential source of infection (UG); administration of broad-spectrum antimicrobials therapy within 1 h of the recognition of septic shock (1B) and severe sepsis without septic shock (1C) as the goal of therapy; reassessment of antimicrobial therapy daily for de-escalation, when appropriate (1B); infection source control with attention to the balance of risks and benefits of the chosen method within 12 h of diagnosis (1C); initial fluid resuscitation with crystalloid (1B) and consideration of the addition of albumin in patients who continue to require substantial amounts of crystalloid to maintain adequate mean arterial pressure (2C) and the avoidance of hetastarch formulations (1B); initial fluid challenge in patients with sepsis-induced tissue hypoperfusion and suspicion of hypovolemia to achieve a minimum of 30 mL/kg of crystalloids (more rapid administration and greater amounts of fluid may be needed in some patients (1C); fluid challenge technique continued as long as hemodynamic improvement is based on either dynamic or static variables (UG); norepinephrine as the first-choice vasopressor to maintain mean arterial pressure ≥65 mmHg (1B); epinephrine when an additional agent is needed to maintain adequate blood pressure (2B); vasopressin (0.03 U/min) can be added to norepinephrine to either raise mean arterial pressure to target or to decrease norepinephrine dose but should not be used as the initial vasopressor (UG); dopamine is not recommended except in highly selected circumstances (2C); dobutamine infusion administered or added to vasopressor in the presence of (a) myocardial dysfunction as suggested by elevated cardiac filling pressures and low cardiac output, or (b) ongoing signs of hypoperfusion despite achieving adequate intravascular volume and adequate mean arterial pressure (1C); avoiding use of intravenous hydrocortisone in adult septic shock patients if adequate fluid resuscitation and vasopressor therapy are able to restore hemodynamic stability (2C); hemoglobin target of 7-9 g/dL in the absence of tissue hypoperfusion, ischemic coronary artery disease, or acute hemorrhage (1B); low tidal volume (1A) and limitation of inspiratory plateau pressure (1B) for acute respiratory distress syndrome (ARDS); application of at least a minimal amount of positive end-expiratory pressure (PEEP) in ARDS (1B); higher rather than lower level of PEEP for patients with sepsis-induced moderate or severe ARDS (2C); recruitment maneuvers in sepsis patients with severe refractory hypoxemia due to ARDS (2C); prone positioning in sepsis-induced ARDS patients with a PaO (2)/FiO (2) ratio of ≤100 mm Hg in facilities that have experience with such practices (2C); head-of-bed elevation in mechanically ventilated patients unless contraindicated (1B); a conservative fluid strategy for patients with established ARDS who do not have evidence of tissue hypoperfusion (1C); protocols for weaning and sedation (1A); minimizing use of either intermittent bolus sedation or continuous infusion sedation targeting specific titration endpoints (1B); avoidance of neuromuscular blockers if possible in the septic patient without ARDS (1C); a short course of neuromuscular blocker (no longer than 48 h) for patients with early ARDS and a PaO (2)/FI O (2) <150 mm Hg (2C); a protocolized approach to blood glucose management commencing insulin dosing when two consecutive blood glucose levels are >180 mg/dL, targeting an upper blood glucose ≤180 mg/dL (1A); equivalency of continuous veno-venous hemofiltration or intermittent hemodialysis (2B); prophylaxis for deep vein thrombosis (1B); use of stress ulcer prophylaxis to prevent upper gastrointestinal bleeding in patients with bleeding risk factors (1B); oral or enteral (if necessary) feedings, as tolerated, rather than either complete fasting or provision of only intravenous glucose within the first 48 h after a diagnosis of severe sepsis/septic shock (2C); and addressing goals of care, including treatment plans and end-of-life planning (as appropriate) (1B), as early as feasible, but within 72 h of intensive care unit admission (2C). Recommendations specific to pediatric severe sepsis include: therapy with face mask oxygen, high flow nasal cannula oxygen, or nasopharyngeal continuous PEEP in the presence of respiratory distress and hypoxemia (2C), use of physical examination therapeutic endpoints such as capillary refill (2C); for septic shock associated with hypovolemia, the use of crystalloids or albumin to deliver a bolus of 20 mL/kg of crystalloids (or albumin equivalent) over 5-10 min (2C); more common use of inotropes and vasodilators for low cardiac output septic shock associated with elevated systemic vascular resistance (2C); and use of hydrocortisone only in children with suspected or proven "absolute"' adrenal insufficiency (2C).

CONCLUSIONS

Strong agreement existed among a large cohort of international experts regarding many level 1 recommendations for the best care of patients with severe sepsis. Although a significant number of aspects of care have relatively weak support, evidence-based recommendations regarding the acute management of sepsis and septic shock are the foundation of improved outcomes for this important group of critically ill patients.

Perioperative arginine-supplemented nutrition in malnourished patients with head and neck cancer improves long-term survival

BACKGROUND

Plasma arginine concentrations are lower in patients with cancer, which indicates that arginine metabolism may be disturbed in these patients. Arginine supplementation has been associated with positive effects on antitumor mechanisms and has been shown to reduce tumor growth and to prolong survival. Furthermore, the prognosis of patients with head and neck cancer remains disappointing. Insufficient intake frequently leads to malnutrition, which contributes to high morbidity and mortality rates.

OBJECTIVE

The aim of this study was to assess the long-term effects of perioperative arginine supplementation in severely malnourished patients with head and neck cancer.

DESIGN

In this double-blind, randomized, controlled trial, we randomly assigned 32 severely malnourished patients with head and neck cancer to receive 1) standard perioperative enteral nutrition (n = 15) or 2) arginine-supplemented perioperative enteral nutrition (n = 17). The primary outcome was long-term (≥10 y) survival. Secondary outcomes included the long-term appearance of locoregional recurrence, distant metastases, and second primary tumors.

RESULTS

No significant differences in baseline characteristics were observed between groups. The group receiving arginine-enriched nutrition had a significantly better overall survival (P = 0.019) and better disease-specific survival (P = 0.022). Furthermore, the arginine-supplemented group had a significantly better locoregional recurrence-free survival (P = 0.027). No significant difference in the occurrence of distant metastases or occurrence of a second primary tumor was observed between the groups.

CONCLUSION

Perioperative arginine-enriched enteral nutrition significantly improved the long-term overall survival and long-term disease-specific survival in malnourished patients with head and neck cancer.

Effects of long-term continuous use of immune-enhancing enteral formula on nutritional and immunologic status in non-surgical patients

OBJECTIVE

Although the perioperative use of immune-enhancing enteral formula (IEEF) effectively reduces the rate of infectious complications, whether chronic use of IEEF is beneficial is unknown. A prospective randomized clinical trial was performed to examine the safety and effectiveness of long-term IEEF on nutritional and immunologic status in non-surgical patients receiving total enteral nutrition through the gastrostomy access route.

METHODS

A total of 30 patients were randomly assigned to two groups in which they received total enteral nutrition, an IEEF (n = 15) or a regular polymeric enteral formula (control group; n = 15) for 12 wk. Nutritional and immunologic variables were periodically examined.

RESULTS

Serum concentrations of insulin-like growth factor-I increased significantly for the IEEF group throughout the study. Although serum concentrations of dihomo-gamma-linoleic acid decreased significantly in the IEEF group, serum concentrations of eicosapentaenoic acid and docosahexaenoic acid increased significantly, as did concentrations of serum arginine and ornithine. The CD4/CD8 ratio and natural killer cell activity also increased for the IEEF group, but the differences were not significant. The B-cell fraction increased and the T-cell fraction of peripheral lymphocytes decreased for the IEEF group. Neither infectious nor non-infectious complications occurred during the study period in either group, except for a significant increase in serum urea nitrogen and uric acid concentrations for the IEEF group.

CONCLUSION

Long-term use of IEEF is safe in non-surgical patients and results in a significant increase in serum insulin-like growth factor-I concentrations in association with increased humoral immunity.

Plasma arginine correlations in trauma and sepsis

Arginine (ARG) is an amino acid (AA) with unique properties and with a key-role in the metabolic, immune and reparative response to trauma and sepsis. This study has been performed to characterize the correlations between plasma levels of ARG, of other AA and of multiple metabolic variables in trauma and sepsis. Two-hundred and sixty-three plasma amino-acidograms with a large series of additional biochemical and blood variables were obtained consecutively in 9 trauma patients who developed sepsis, undergoing total parenteral nutrition with dextrose, fat and a mixed AA solution containing 10.4% arginine. ARG was low soon after trauma, then it increased with increasing distance from trauma and with the development of sepsis. ARG was also directly related to the AA infusion rate (AAIR) and for any given AAIR, was lower after trauma than after the development of sepsis. ARG was also related directly to the plasma levels of most of the other AA, the best correlation being that with lysine (r(2) = 0.81, p < 0.001). These correlations were often shifted downwards (showing lower ARG for any given level of the other AA) in measurements performed after trauma, compared to those performed after development of sepsis; this effect was more pronounced for the correlations with branched chain AA. Correlations between ARG and non-AA variables were not particularly relevant. The best simultaneous correlates of ARG, among variables involved in plasma ARG availability, were citrulline level, AAIR and urinary 3-methylhistidine excretion (accounting for the effect of endogenous proteolysis) (multiple r(2) = 0.70, p < 0.001). Plasma ornithine (ORN), the AA more specifically linked to ARG metabolism, correlated with AAIR better than ARG and, for any given AAIR, was lower after trauma than after the development of sepsis. Correlations of ORN with other AA levels were poorer than those found for ARG, however ORN was directly related to white blood cell and platelet count, fibrinogen, transferrin, cholesterol and many AA clearances. These data show that changes in ARG in trauma and sepsis are correlated with changes in other AA and, within these correlations, reconfirm a tendency to lower ARG in trauma compared to sepsis. The strong correlation with lysine warrants a deeper assessment of the practical implications of interdependency between these two AA. The data also suggest that changes in plasma ORN in trauma and sepsis may reflect adequacy of AA substrate to support acute-phase and other synthetic processes.

Enteral and parenteral arginine supplementation to improve medical outcomes in hospitalized patients

The amino acid L-arginine has been administered as a single supplement to humans in an effort to improve the outcome of seriously ill patients. In normal individuals, markers of collagen biosynthesis have increased with daily oral doses ranging from 14 to 24.8 g of free arginine for 14 d. No clinical evidence of improved wound healing has been reported in the few patient studies performed to date. Administration of enteral, but not intravenous, arginine has been associated with markers of improved immune function in normal individuals and in some, but not all, patient groups studied. A single study in premature infants suggested that supplementation of L-arginine (261 mg . kg(-1) . d(-1)) administered by both the parenteral and enteral routes decreased the incidence of necrotizing enterocolitis. A single study demonstrated that oral arginine administration in conjunction with conventional chemotherapy for active tuberculosis to HIV- but not HIV+ individuals enhanced treatment responses. In both these area, larger multicenter investigations are needed. For a difference to be a difference it has to make a difference. Supplementation of only L-arginine does not to date universally show benefit, nor does it show harm. At this time there is no rationale for the routine supplementation of arginine alone to enhance recovery from serious illness. Because of the potential for harm, this amino acid should only be administered to critically ill patients in large doses under carefully monitored study conditions.

Nutritional papers in ICU patients: what lies between the lines?

The abundance of literature related to nutritional support reflects its recently recognised role in preventing metabolic complications and gut dysfunction during critical illness. However, some published studies lack relevance to critically ill patients, as a result of the selection of subjects and outcome variables, or flaws in the study design, as well as in the type, composition, timing, route of administration and amount of nutritional support given. This review will highlight these confounding factors by describing two imaginary (but typical) clinical trials and by analysing some studies published. The point at issue is that basic quality requirements, such as the formulation of a prospective hypothesis and the delineation of the effects of the reference treatment, are often lacking in many studies published. Data analysis was often found to be biased by the absence of statistical power calculation and intention-to-treat analysis. Globally, studies designed to assess the effects of nutritional support on the outcome of critically ill patients, rarely fulfil basic quality requirements and should therefore be interpreted cautiously. We suggest simple strategies or study design that will allow important questions to be answered by future clinical trials.