Fish oil in critical illness: mechanisms and clinical applications

The role of fatty acid metabolism in acute lung injury: a special focus on immunometabolism

Reputable evidence from multiple studies suggests that excessive and uncontrolled inflammation plays an indispensable role in mediating, amplifying, and protracting acute lung injury (ALI). Traditionally, immunity and energy metabolism are regarded as separate functions regulated by distinct mechanisms, but recently, more and more evidence show that immunity and energy metabolism exhibit a strong interaction which has given rise to an emerging field of immunometabolism. Mammalian lungs are organs with active fatty acid metabolism, however, during ALI, inflammation and oxidative stress lead to a series metabolic reprogramming such as impaired fatty acid oxidation, increased expression of proteins involved in fatty acid uptake and transport, enhanced synthesis of fatty acids, and accumulation of lipid droplets. In addition, obesity represents a significant risk factor for ALI/ARDS. Thus, we have further elucidated the mechanisms of obesity exacerbating ALI from the perspective of fatty acid metabolism. To sum up, this paper presents a systematical review of the relationship between extensive fatty acid metabolic pathways and acute lung injury and summarizes recent advances in understanding the involvement of fatty acid metabolism-related pathways in ALI. We hold an optimistic believe that targeting fatty acid metabolism pathway is a promising lung protection strategy, but the specific regulatory mechanisms are way too complex, necessitating further extensive and in-depth investigations in future studies.

Nutrition in critically ill children with acute kidney injury on continuous kidney replacement therapy: a 2023 executive summary

OBJECTIVES

Nutrition plays a vital role in the outcome of critical illness in children, particularly those with acute kidney injury. Currently, there are no established guidelines for children with acute kidney injury treated with continuous kidney replacement therapy. Our objective was to create clinical practice points for nutritional assessment and management in critically ill children with acute kidney injury receiving continuous kidney replacement therapy.

METHODS

An electronic search using PubMed and an inclusive academic library search (including MEDLINE, Cochrane, and Embase databases) was conducted to find relevant English-language articles on nutrition therapy for children (<18 y of age) receiving continuous kidney replacement therapy.

RESULTS

The existing literature was reviewed by our work group, comprising pediatric nephrologists and experts in nutrition. The modified Delphi method was then used to develop a total of 45 clinical practice points. The best methods for nutritional assessment are discussed. Indirect calorimetry is the most reliable method of predicting resting energy expenditure in children on continuous kidney replacement therapy. Schofield equations can be used when indirect calorimetry is not available. The non-intentional calories contributed by continuous kidney replacement therapy should also be accounted for during caloric dosing. Protein supplementation should be increased to account for the proteins, peptides, and amino acids lost with continuous kidney replacement therapy.

CONCLUSIONS

Clinical practice points are provided on nutrition assessment, determining energy needs, and nutrient intake in children with acute kidney injury and on continuous kidney replacement therapy based on the existing literature and expert opinions of a multidisciplinary panel.

Nutrition in Critically Ill Children with AKI on Continuous RRT: Consensus Recommendations

BACKGROUND

Nutrition plays a vital role in the outcome of critically ill children, particularly those with AKI. Currently, there are no established guidelines for children with AKI treated with continuous RRT (CRRT). A thorough understanding of the metabolic changes and nutritional challenges in AKI and CRRT is required. Our objective was to create clinical practice points for nutritional assessment and management in critically ill children with AKI receiving CRRT.

METHODS

PubMed, MEDLINE, Cochrane, and Embase databases were searched for articles related to the topic. Expertise of the authors and a consensus of the workgroup were additional sources of data in the article. Available articles on nutrition therapy in pediatric patients receiving CRRT through January 2023.

RESULTS

On the basis of the literature review, the current evidence base was examined by a panel of experts in pediatric nephrology and nutrition. The panel used the literature review as well as their expertise to formulate clinical practice points. The modified Delphi method was used to identify and refine clinical practice points.

CONCLUSIONS

Forty-four clinical practice points are provided on nutrition assessment, determining energy needs, and nutrient intake in children with AKI and on CRRT on the basis of the existing literature and expert opinions of a multidisciplinary panel.

Does inclusion of bioactive n-3 PUFAs in parenteral nutrition benefit postoperative patients undergoing liver surgery? A systematic review and meta-analysis of randomised control trials

OBJECTIVES

This meta-analysis aims to evaluate the effect of n-3 polyunsaturated fatty acids (PUFAs) as a part of parenteral nutrition in patients undergoing liver surgery.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, the Cochrane Central Register of Controlled Trials, Springer link, Web of Science, China National Knowledge Infrastructure and VIP Database.

ELIGIBILITY CRITERIA

We included randomised controlled trials (RCTs) and evaluated the outcomes of liver function, inflammatory reaction, the influence of certain markers of the immune system, and specific clinical indexes for patients undergoing liver surgery and receiving parenteral nutrition with n-3 PUFAs.

DATA EXTRACTION AND SYNTHESIS

The Cochrane Collaboration's tool was used to assess the risk of bias for each study. Findings were summarised in Grades of Recommendation, Assessment, Development and Evaluation evidence profiles and synthesised qualitatively.

RESULTS

Eight RCTs, including 748 patients (trial: 374; control: 374), were included in the meta-analysis. Compared with patients in the control group, the patients in the n-3 PUFA group who underwent liver surgery had significantly lower aspartate aminotransferase (mean difference, MD -42.72 (95% CI -71.91 to -13.52); p=0.004), alanine aminotransferase (MD -38.90 (95% CI -65.44 to -12.37); p=0.004), white cell count (MD -0.93 (95% CI -1.60 to -0.26); p=0.007) and IL-6 (MD -11.37 (95% CI -14.62 to -8.13); p<0.00001) levels and a higher albumin level (MD 0.42 (95% CI 0.26 to 0.57); p<0.00001). They also had fewer infection complications (OR 0.44 (95% CI 0.28 to 0.68); p=0.0003) and a shorter duration of hospital stay (MD -2.17 (95% CI -3.04 to -1.3); p<0.00001) than the controls. However, there were no significant differences in terms of total bilirubin, TNF-α, IL-2, IgA, IgG, IgM and CD3, biliary leakage and mortality between the two groups.

CONCLUSIONS

We found that n-3 PUFAs can benefit patients undergoing liver surgery by improving liver function and certain clinical indexes and decreasing related inflammation factors. However, there are limited RCTs on the application of n-3 PUFAs for patients undergoing liver surgery. Further evidence of the benefit of n-3 PUFAs in these patients warrants further exploration.

Effect of Omega-3 fatty acids supplementation on serum level of C-reactive protein in patients with COVID-19: a systematic review and meta-analysis of randomized controlled trials

Background

Omega-3 may alleviate the severity of coronavirus disease 2019 (COVID-19) by reducing the C-reactive protein (CRP) level, a marker for systemic inflammation. Because the scientific evidence indicating such a role is inconsistent, we aimed to evaluate the effect of Omega-3 on CRP change and CRP level in patients with COVID-19.

Methods

We conducted a comprehensive search on four databases (PubMed, Web of Science, EMBASE, and Scopus). We included all RCTs comparing Omega-3 with a control group regarding their effect on the CRP levels in patients with COVID-19. We used version two of the Cochrane risk of bias assessment tool to appraise the included studies. We extracted data to an online data extraction sheet. The primary outcomes were CRP change from baseline and CRP serum levels.

Results

We included four randomized controlled trials (RCTs) with 274 patients in this study. The overall effect estimate favored Omega-3 over the control group in terms of CRP change from baseline (mean difference (MD) =− 2.53, 95% confidence interval (CI): − 4.40, − 0.66) and CRP serum levels at the end of the study (MD =− 6.24, 95% CI: − 11.93, − 0.54).

Conclusion

Omega-3 showed promising effects on systemic inflammation by reducing CRP levels in COVID-19 patients. Based on this finding, we recommend Omega-3 for COVID-19 patients for its anti-inflammatory actions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03604-3.

Omega-3 polyunsaturated fatty acids supplementation improve clinical symptoms in patients with Covid-19: A randomised clinical trial

AIMS

We hypothesised that omega-3 fatty acids would be an appropriate adjunct therapy for alleviating the inflammatory response and clinical manifestation in hospitalised patients with Covid-19 disease.

METHODS

This was a single-blind randomised controlled trial in Amir-Alam hospital in Tehran. Thirty adult men and women diagnosed with Covid-19 were allocated to either control group (receiving Hydroxychloroquine) or intervention group (receiving Hydroxychloroquine plus 2 grams of Docosahexaenoic acid [DHA] + Eicosapentaenoic acid [EPA]) for 2 weeks. Primary outcome of the intervention including C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) as well as clinical symptoms including body pain, fatigue, appetite and olfactory and secondary outcomes including liver enzymes were determined at the baseline and after omega-3 supplementation. Clinical signs were measured using self-reported questionnaires. There were commercial kits for determination of CRP and liver enzymes concentrations in the serum of patients. For determination of ESR automated haematology analyser was applied. The study of "Comparison of the effectiveness of omega-3 and Hydroxychloroquine on Inflammatory factors, liver enzymes and clinical symptoms in diabetic Covid-19 patients" was registered in Iranian Registry of Clinical Trials (IRCT) with ID number: IRCT20200511047399N1.

RESULTS

In comparison to control group, patients receiving omega-3 indicated favourable changes in all clinical symptoms except for olfactory (P < .001 for body pain and fatigue, P = .03 for appetite and P = .21 for olfactory). Reducing effects of omega-3 supplementation compared with control group were also observed in the levels of ESR and CRP after treatment (P < .001 for CRP and P = .02 for ESR). However, no between group differences in the liver enzymes serum concentrations were observed after supplementation (P > .05).

CONCLUSION

Current observations are very promising and indicate that supplementation with moderate dosages of omega-3 fatty acids may be beneficial in the management of inflammation-mediated clinical symptoms in Covid-19 patients.

Parenteral nutrition with fish oil-based lipid emulsion reduces the risk of cholestasis in preterm infants

OBJECTIVE

Preterm infants receive long-term parenteral nutrition (PN) for gastrointestinal immaturity. This study aimed to determine if mixed lipid emulsions containing fish oil decrease the incidence of PN-associated cholestasis by reducing oxidative stress and providing an anti-inflammatory effect.

METHODS

This retrospective cohort study enrolled 399 very low birth weight premature infants (gestational age ≤32 weeks) between January 2009 and November 2017 at a single neonatal intensive care unit. Preterm infants received total PN with either mixed lipid emulsion including fish oil (SMOFlipid®, n = 195) or soybean oil-based lipid emulsion (Lipovenoes®, n = 204) for at least 7 days. We compared the outcomes of PN-associated cholestasis, comorbidities, and mortality between the groups.

RESULTS

The incidence of PN-associated cholestasis was significantly lower in the SMOFlipid group than in the Lipovenoes group. The duration to full feeding days was significantly shorter in the SMOFlipid group compared with the Lipovenoes group. Relevant complications, such as severe retinopathy of prematurity and bronchopulmonary dysplasia, were also significantly reduced in the SMOFlipid group compared with the Lipovenoes group.

CONCLUSION

In premature infants, PN with fish oil-based lipid emulsions is associated with a lower incidence of PN-associated cholestasis compared with soybean oil-based lipid emulsions.

Potential benefits and risks of omega-3 fatty acids supplementation to patients with COVID-19

Studies have shown that infection, excessive coagulation, cytokine storm, leukopenia, lymphopenia, hypoxemia and oxidative stress have also been observed in critically ill Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) patients in addition to the onset symptoms. There are still no approved drugs or vaccines. Dietary supplements could possibly improve the patient's recovery. Omega-3 fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), present an anti-inflammatory effect that could ameliorate some patients need for intensive care unit (ICU) admission. EPA and DHA replace arachidonic acid (ARA) in the phospholipid membranes. When oxidized by enzymes, EPA and DHA contribute to the synthesis of less inflammatory eicosanoids and specialized pro-resolving lipid mediators (SPMs), such as resolvins, maresins and protectins. This reduces inflammation. In contrast, some studies have reported that EPA and DHA can make cell membranes more susceptible to non-enzymatic oxidation mediated by reactive oxygen species, leading to the formation of potentially toxic oxidation products and increasing the oxidative stress. Although the inflammatory resolution improved by EPA and DHA could contribute to the recovery of patients infected with SARS-CoV-2, Omega-3 fatty acids supplementation cannot be recommended before randomized and controlled trials are carried out.

The Underappreciated Role of Low Muscle Mass in the Management of Malnutrition

Preserving muscle is not only crucial for maintaining proper physical movement, but also for its many metabolic and homeostatic roles. Low muscle mass has been shown to adversely affect health outcomes in a variety of disease states (eg, chronic obstructive pulmonary disease, cancer, cardiovascular disease) and leads to an increased risk for readmission and mortality in hospitalized patients. Low muscle mass is now included in the most recent diagnostic criteria for malnutrition. Current management strategies for malnutrition may not prioritize the maintenance and restoration of muscle mass. This likely reflects the challenge of identifying and measuring this body composition compartment in clinical practice and the lack of awareness by health care professionals of the importance that muscle plays in patient health outcomes. As such, we provide a review of current approaches and make recommendations for managing low muscle mass and preventing muscle loss in clinical practice. Recommendations to assist the clinician in the optimal management of patients at risk of low muscle mass include the following: (1) place muscle mass at the core of nutritional assessment and management strategies; (2) identify and assess low muscle mass; (3) develop a management pathway for patients at risk of low muscle mass; (4) optimize nutrition to focus on muscle mass gain versus weight gain alone; and (5) promote exercise and/or rehabilitation therapy to help maintain and build muscle mass. The need to raise awareness of the importance of screening and managing 'at risk' patients so it becomes routine is imperative for change to occur. Health systems need to drive clinicians to treat patients with this focused approach, and the economic benefits need to be communicated to payers. Lastly, further focused research in the area of managing patients with low muscle mass is warranted.

Preconditioning rats with three lipid emulsions prior to acute lung injury affects cytokine production and cell apoptosis in the lung and liver

BACKGROUND

Critically ill patients are at higher risk having acute lung injury (ALI) and more often in need of parenteral nutrition. We sought to study whether preconditioning with representative of lipid emulsions for one week could benefit rats from ALI.

METHODS

Using a lipopolysaccharide (LPS)-induced ALI rat model and techniques such as polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining.

RESULTS

PGE₂ production in the serum was highest in the LPS group, followed with Intralipid group, and the PGE₂ level of these two groups was significantly (P < 0.05) higher than the rest. Intralipid conditioning caused significantly less production of LTB₄ than the LPS, Clinoleic, or Omegaven group. In contrast to Intralipid, rats pretreated with Clinoleic or Omegaven significantly decreased their production of inflammatory mediators (IL-1 β, IL-6 and TNF-α), had less apoptosis in the lung tissues, and Omegaven greatly improved liver function upon lipopolysaccharide (LPS) challenge.

CONCLUSIONS

In an ALI setting, preconditioning with Omegaven or Clinoleic was better than Intralipid in decreasing the intensity of the cytokine storm and apoptosis caused by LPS challenge, and Omegaven in addition had the potential to improve liver function. The results from the present study set a basis for further investigation of the molecular mechanisms of ALI, including the up- and downstream pathways of proinflammatory factor production, in search of (small) molecules intervening with the pathogenesis of ALI in order to translate relevant research findings into clinical benefit for patients with ALI. The use of Omegaven or Clinoleic, particularly in patients with ALI, is still characterized by uncertainty due to a lack of relevant studies. Future investigations must specifically focus on the route of administration and mode of application (enteral vs. parenteral/bolus vs. continuous), determining an optimal dose of Omegaven or Clinoleic, and the defining the best timepoint(s) for administration. Critically ill patients are at higher risk having acute lung injury (ALI) and more often in need of parenteral nutrition. The effect of lipid emulsion via parenteral nutrition on liver function was first time evaluated in rats in an ALI setting. The comparison of three forms of lipid emulsion in a rat model of acute lung injury was first time studied. The fish oil-based lipid emulsion decrease in PGE 2 and increase in LTB 4 was first time reported.

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).

Efficacy of a long-term home parenteral nutrition regimen containing fish oil-derived n-3 polyunsaturated fatty acids: a single-centre, randomized, double blind study

Background

Data on the use of lipid emulsions containing fish-oil (FO) derived n-3 polyunsaturated fatty acids (n-3 PUFAs) in addition to medium- and long-chain triglycerides (MCT/LCT) for long-term home parenteral nutrition (HPN) are limited. This study aimed to compare HPN regimens containing either MCT/LCT/FO-derived n-3 PUFAs (test group) or MCT/LCT (control group) with respect to efficacy and safety during 8 weeks of HPN using a non-inferiority trial design with change of body mass index (BMI) as primary endpoint.

Methods

This prospective, randomized, double-blind study was conducted at the Charité, Berlin, Germany, from 02/2008 until 01/2014. Adult patients (n = 42; aged 18 to 80 years) requiring HPN for at least 8 weeks were randomly assigned to the test or control group. Assessments included weight, height, physical examination (cardiovascular system, abdomen, respiratory tract, liver, spleen, kidney, urine tract, skin, mucous membrane, neurology, psyche, musculoskeletal system, lymph nodes), bio impedance analysis, calorimetry, blood samplings (haematology, biochemistry, fatty acid analysis) and quality of life questionnaire.

Results

BMI increased in both groups with 8 weeks of HPN (ΔBMI_{(test group)} = 1.3 ± 1.1 kg/m²; ΔBMI_{(control group)} = 0.6 ± 0.9 kg/m²) demonstrating non-inferiority of the test regimen regarding nutritional efficacy. Assessment of secondary efficacy endpoints revealed that after 8 weeks of HPN with the test regimen, the proportion of n-3 PUFAs in serum, platelet and red blood cell phospholipids significantly increased, while the proportion of n-6 PUFAs decreased. The fatty acid pattern in the control group remained mostly stable. No statistically significant differences were detected between groups regarding inflammatory markers or quality of life. Laboratory parameters reflecting the safety endpoints liver function, bone metabolism, renal function, metabolic activity, lipid metabolism, coagulation and haematology were stable in both groups and no group differences were detected regarding (serious) adverse events.

Conclusions

The HPN regimen prepared with MCT/LCT/FO-derived n-3 PUFAs was at least as efficient in maintaining or even improving nutritional status during HPN as the control MCT/LCT regimen. Administration of FO-derived n-3 PUFAs for 8 weeks altered the fatty acid pattern of serum, platelet and red blood cell phospholipids. Both regimens were safe and well tolerated.

Trial registration

www.clinicaltrials.gov, registration number: NCT00530738.

Electronic supplementary material

The online version of this article (10.1186/s12937-018-0419-x) contains supplementary material, which is available to authorized users.

Effect of ω-3 polyunsaturated fatty acid-supplemented parenteral nutrition on inflammatory and immune function in postoperative patients with gastrointestinal malignancy: A meta-analysis of randomized control trials in China

BACKGROUND

There are no consensus regarding the efficacy of omega-3polyunsaturated fatty acids (PUFAs) on inflammatory and immune function in postoperative patients with gastrointestinal malignancy.

METHODS

The literatures published randomized control trials (RCT) were searched in PubMed, Embase, Scopus, Cochrane Library, CNKI, Weipu, and Wanfang Databases. The immune efficacy outcomes of ω-3 polyunsaturated fatty acid-supplemented parenteral nutrition in patients with gastrointestinal malignancy were compared.

RESULTS

Sixteen RCTs involving 1008 patients (506 in the omega-3 group, 502 in the control group) were enrolled into the analysis. The results of meta-analysis: the cell immunity: The proportions of CD3, CD4, CD4/CD8 in the omega-3 group were significantly higher than those in the control group (CD3: WMD = 4.48; 95% CI, 3.34-5.62; P < .00001; I = 0%; CD4: WMD = 5.55; 95% CI, 4.75-6.34; P < .00001; I = 0%; CD4/CD8: WMD = .28; 95% CI, 0.13-0.44; P = .0004; I = 81%). In the humoral immunity: The levels of IgA, IgM and IgG in the omega-3 group were significantly higher than those in the control group (IgA: WMD = 0.31; 95% CI, 0.25-0.37; P < .00001; I = 0%; IgM: WMD = 0.12; 95% CI, 0.06-1.81; P < .00001; I = 0%; IgG: WMD = 1.19; 95% CI, 0.80-1.58; P < .00001; I = 0%). The count of lymphocyte in the omega-3 group was significantly higher than that in the control group (WMD = 0.22; 95% CI, 0.12-0.33; P < .0001; I = 40%). In the postoperative inflammatory cytokine: The levels of interleukin-6, tumor necrosis factor (TNF)-α and C-reactive protein in the omega-3 group were significantly lower than those in the control group (IL-6: WMD = -3.09; 95% CI, -3.91 to 2.27; P < .00001; I = 45%; TNF-α: WMD = -1.65; 95% CI, -2.05 to 1.25; P < .00001; I = 28%; CRP: WMD = -4.28; 95% CI, -5.26 to 3.30; P < .00001; I = 37%). The rate of postoperative infective complications in the omega-3 group was significantly lower than that in the control group (OR = 0.36; 95% CI, 0.20-0.66; P = .0008; I = 0%).

CONCLUSION

This meta-kanalysis confirmed that early intervention with Omega -3 fatty acid emulsion in gastrointestinal cancer can not only improve the postoperative indicators of immune function, reduce inflammatory reaction, and improve the postoperative curative effect but also improve the immune suppression induced by conventional PN or tumor. Therefore, postoperative patients with gastrointestinal cancer should add omega-3 unsaturated fatty acids in their PN formula. Further high-quality RCTs are needed to verify its efficacy.

Combination of aspirin with essential fatty acids is superior to aspirin alone to prevent or ameliorate sepsis or ARDS

It has been suggested that aspirin may be of benefit in treating sepsis and ARDS in view of its ability to block cyclo-oxygenase-1 (COX-1) and COX-2 activities; inhibit nuclear factor kappa B (NF-κB); enhance the production of endothelial nitric oxide (eNO) and lipoxin A4 (LXA4). Our previous studies revealed that plasma phospholipid content of arachidonic acid (AA) and eicosapentaenoic acid (EPA) is low in patients with sepsis. This implies that beneficial actions of aspirin in sepsis and ARDS is unlikely to be obtained in view of deficiency of AA and EPA, the precursors of LXA4 and resolvins respectively that are potent anti-inflammatory compounds and enhancers of eNO generation. In view of this, I propose that a combination of aspirin and AA and EPA (and possibly, docosahexaenoic acid, DHA) is likely to be superior in the management of sepsis and ARDS compared to aspirin alone. This suggestion is supported by the recent observation that trauma patients with uncomplicated recoveries had higher resolvin pathway gene expression and lower gene expression ratios of leukotriene: resolvin pathways.

Parenteral Nutrition and Infection Risk in the Intensive Care Unit: A Practical Guide for the Bedside Clinician

The safety of parenteral nutrition (PN) administration in critically ill patients has been the subject of much controversy. Historically, PN administration has been associated with an increased risk of bacterial and fungal infections, leading to significant morbidity and mortality. Much of the data showing increased infectious complications compared with either no nutrition or enteral nutrition was derived from early studies conducted in the 1980s-2000s. Poor glucose control and hyperalimentation are confounding factors in many early studies, making it difficult to determine the true PN infection risks. While PN studies conducted during the past 10 years have failed to show the same infection rates, these risks continue to be cited as dogma. Potential reasons for such discordant results include improved glycemic control, avoidance of overfeeding, and improved sterility and central venous catheter care. Understanding the true infectious risk of PN administration in the intensive care unit is necessary to optimize patient care, as inappropriately withholding such nutrition is potentially deleterious. This review is meant to serve as a practical guide to the bedside clinician who is evaluating the risks and benefits of initiating PN in a critically ill patient. Each component of PN will be evaluated based on risk of infection, and the potential ways to mitigate risks will be discussed.

Nonpulmonary treatments for pediatric acute respiratory distress syndrome: proceedings from the Pediatric Acute Lung Injury Consensus Conference

OBJECTIVE

To describe the recommendations from the Pediatric Acute Lung Injury Consensus Conference on nonpulmonary treatments in pediatric acute respiratory distress syndrome.

DESIGN

Consensus conference of experts in pediatric acute lung injury.

METHODS

A panel of 27 experts met over the course of 2 years to develop a taxonomy to define pediatric acute respiratory distress syndrome and to make recommendations regarding treatment and research priorities. The nonpulmonary subgroup comprised three experts. When published data were lacking, a modified Delphi approach emphasizing strong professional agreement was utilized.

RESULTS

The Pediatric Acute Lung Injury Consensus Conference experts developed and voted on a total of 151 recommendations addressing the topics related to pediatric acute respiratory distress syndrome, 30 of which related to nonpulmonary treatment. All 30 recommendations had strong agreement. Patients with pediatric acute respiratory distress syndrome should receive 1) minimal yet effective targeted sedation to facilitate mechanical ventilation; 2) neuromuscular blockade, if sedation alone is inadequate to achieve effective mechanical ventilation; 3) a nutrition plan to facilitate their recovery, maintain their growth, and meet their metabolic needs; 4) goal-directed fluid management to maintain adequate intravascular volume, end-organ perfusion, and optimal delivery of oxygen; and 5) goal-directed RBC transfusion to maintain adequate oxygen delivery. Future clinical trials in pediatric acute respiratory distress syndrome should report sedation, neuromuscular blockade, nutrition, fluid management, and transfusion exposures to allow comparison across studies.

CONCLUSIONS

The Consensus Conference developed pediatric-specific definitions for pediatric acute respiratory distress syndrome and recommendations regarding treatment and future research priorities. These recommendations for nonpulmonary treatment in pediatric acute respiratory distress syndrome are intended to promote optimization and consistency of care for patients with pediatric acute respiratory distress syndrome and identify areas of uncertainty requiring further investigation.

Parenteral fish oil lipid emulsions in the critically ill: a systematic review and meta-analysis

INTRODUCTION

ω-3 Polyunsaturated fatty acids contained in fish oils (FO) possess major anti-inflammatory, antioxidant, and immunologic properties that could be beneficial during critical illness. We hypothesized that parenteral FO-containing emulsions may improve clinical outcomes in the critically ill.

METHODS

We searched computerized databases from 1980-2012. We included randomized controlled trials (RCTs) conducted in critically ill adult patients that evaluated FO-containing emulsions, either in the context of parenteral nutrition (PN) or enteral nutrition (EN).

RESULTS

A total of 6 RCTs (n = 390 patients) were included; the mean methodological score of all trials was 10 (range, 6-13). When the results of these studies were aggregated, FO-containing emulsions were associated with a trend toward a reduction in mortality (risk ratio [RR], 0.71; 95% confidence interval [CI], 0.49-1.04; P = .08; heterogeneity I (2) = 0%) and a reduction in the duration of mechanical ventilation (weighted mean difference in days [WMD], -1.41; 95% CI, -3.43 to 0.61; P = .17). However, this strategy had no effect on infections (RR, 0.76; 95% CI, 0.42-1.36; P = .35) and intensive care unit length of stay (WMD, -0.46; 95% CI, -4.87 to 3.95; P = .84, heterogeneity I (2) = 75%).

CONCLUSION

FO-containing lipid emulsions may be able to decrease mortality and ventilation days in the critically ill. However, because of the paucity of clinical data, there is inadequate evidence to recommend the routine use of parenteral FO. Large, rigorously designed RCTs are required to elucidate the efficacy of parenteral FO in the critically ill.

Specialized nutritional support interventions in critically ill patients on renal replacement therapy

PURPOSE OF REVIEW

Optimal nutritional requirements and nutrient intake composition for patients with acute kidney injury remain a partially unresolved issue. Targeting nutritional support to the actual protein and energy needs improves the clinical outcome of critically ill patients, yet very few data are currently available on this topic in acute kidney injury. In this specific clinical condition the risk for underfeeding and overfeeding may be increased by factors interfering on nutrient need estimation, such as rapidly changing body weight due to fluid balance variations, nutrient losses and hidden calorie sources from renal replacement therapy. Moreover, as acute kidney injury is now considered a kidney-centered inflammatory syndrome, the renoprotective role of specific pharmaconutrients with anti-inflammatory properties remains to be fully defined. This review is aimed at discussing recently published results concerning quantitative and qualitative aspects of the nutritional approach to acute kidney injury in critically ill patients.

RECENT FINDINGS

Nutrient needs in patients with acute kidney injury can be difficult to estimate, and should be directly measured, especially in the ICU setting. In fact, recent findings suggest that hidden calorie sources not routinely taken into account - for example, calories from anticoagulants and replacement solutions for renal replacement therapy - could be quantitatively relevant in these patients. Moreover, recent experimental data indicate a possible role for some pharmaconutrients with anti-inflammatory effects (glutamine, and omega-3 fatty acids), in both the prevention of renal function worsening, and in the fostering of renal function recovery after an episode of acute kidney injury.

SUMMARY

Acute kidney injury includes a highly heterogeneous group of patients with widely varying nutrient needs and intakes. Nutritional requirements, in their quantitative and qualitative aspects, should be frequently assessed, individualized, and carefully integrated with renal replacement therapy, in order to avoid both underfeeding and overfeeding, as well as to exploit possible positive pharmacologic effects of specific nutrients.

Novel nutritional substrates in surgery

Pharmaco-nutrients have beneficial effects on protective and immunological mechanisms in patients undergoing surgery, which are important for recovery after injury and in combating infectious agents. The aim of this review article was to outline the potential of the administration of nutritional substrates to surgical patients and the underlying mechanisms that make them particularly important in peri-operative care. Surgery causes a stress response, which has catabolic effects on the body's substrate stores. The amino acid glutamine is a stimulating agent for immune cells. It activates protective mechanisms through its role as a precursor for antioxidants and it improves the barrier function of the gut. Arginine also enhances the function of the immune system, since it is the substrate for T-lymphocytes. Furthermore, n-3 PUFA stabilise surgery-induced hyper-inflammation. Taurine is another substrate that may counteract the negative effects of surgical injury on acid–base balance and osmotic balance. These pharmaco-nutrients rapidly become deficient under the influence of surgical stress. Supplementation of these nutrients in surgical patients may restore their protective and immune-enhancing actions and improve clinical outcome. Moreover, pre-operative fasting is still common practice in the Western world, although fasting has a negative effect on the patient's condition and the recovery after surgery. This may be counteracted by a simple intervention such as administering a carbohydrate-rich supplement just before surgery. In conclusion, there are various nutritional substrates that may be of great value in improving the condition of the surgical patient, which may be beneficial for post-operative recovery.

Nutritional immunomodulation in critically ill children with acute lung injury: feasibility and impact on circulating biomarkers

OBJECTIVE

Respiratory failure caused by acute lung injury or acute respiratory distress syndrome is associated with significant morbidity in children. Enteral nutrition enriched with eicosapentaenoic acid, γ-linolenic acid and antioxidants (eicosapentaenoic acid + γ-linolenic acid) can safely modulate plasma phospholipid fatty acid profiles, reduce inflammation, and improve clinical outcomes in adults. There is little information regarding the use of enteral eicosapentaenoic acid + γ-linolenic acid to modulate plasma phospholipid fatty acid profiles in children. We sought to determine if continuous feeding of enteral nutrition containing eicosapentaenoic acid, γ-linolenic acid, and antioxidants was feasible in critically ill children with acute lung injury or acute respiratory distress syndrome. We further evaluated the impact of such an approach on the alteration of plasma phospholipid fatty acid concentrations.

DESIGN

Prospective, blinded, randomized, controlled, multicenter trial.

SETTING

PICU.

PATIENTS

Twenty-six critically ill children (age 6.2 ± 0.9 yr, PaO2/FIO2 185 ± 15) with the diagnosis of acute lung injury or acute respiratory distress syndrome.

INTERVENTIONS

Mechanically ventilated children received either eicosapentaenoic acid + γ-linolenic acid or a standard pediatric enteral formula. Clinical, biochemical, plasma fatty acid, and safety data were assessed at baseline, study days 4 and 7.

MEASUREMENTS AND MAIN RESULTS

At baseline, there were no significant differences in the two study groups. Both groups met enteral feeding goals within 30 hrs and had similar caloric delivery. There were no differences in formula tolerance as measured by serum chemistries, liver and renal function, and hematology studies after 7 days of feeding either eicosapentaenoic acid + γ-linolenic acid or pediatric enteral formula. On study day 4 and 7, plasma phospholipid fatty acid profiles in the eicosapentaenoic acid + γ-linolenic acid group showed a significant increase in anti-inflammatory circulating markers.

CONCLUSIONS

Providing enteral nutrition with eicosapentaenoic acid + γ-linolenic acid to critically ill children with lung injury was feasible and caloric goals were met within 30 hrs. This feeding protocol effectively modulated plasma phospholipid fatty acid concentrations to reflect an anti-inflammatory profile. This study provides data to inform future outcome studies using enteral eicosapentaenoic acid + γ-linolenic acid in children with lung injury.

Nutritional pharmacology in surgery and critical care: 'you must unlearn what you have learned'

PURPOSE OF REVIEW

This review highlights the rapidly evolving field of 'pharmaconutrition' by discussing the mechanistic and clinical data for calorie delivery and nutrients shown to improve outcome in surgical and ICU care.

RECENT FINDINGS

International survey data reveals patients in acute care settings receive approximately 50% of calories/protein they are prescribed. This is, in part, due to the archaic practice of patients remaining nil per os postoperatively until return of bowel sounds. We also know certain nutrients serve as pharmacologic agents and improve clinically relevant outcomes. Thus, larger therapeutic doses of specific nutrients may be required to replace acute deficiencies brought on by specific injury states. Specifically, arginine can reduce postsurgical infection 40% as shown in over 30 trials of more than 3200 patients. Glutamine and fish oil have been shown to reduce mortality in general critical care and acute respiratory distress syndrome patients, respectively.

SUMMARY

We believe the future of surgical and ICU nutrition will involve administering specific pharmaconutrients as separate components, much like drugs are given. The current use of clinical pharmacology, molecular biology, and clinical research principles in the study of pharmaconutrients should yield answers on how to administer the right nutrients, in the right doses, at the right time in sick patients.

Beneficial effects of the n-3 long-chain polyunsaturated fatty acids in surgical patients: updating the evidence

The use of n-3 polyunsaturated fatty acids in surgical patients has risen by the fact that this may attenuate systemic and acute inflammatory responses secondary to surgical trauma through modulation of inflammatory mediators and cell membrane interactions. Moreover, the inclusion of n-3 fatty acids in clinical trials as part of the therapy in patients, who expect to undergo a surgical stress, suggests benefits on clinical progress. Therefore, the objective of this article is to review data from n-3 polyunsaturated fatty acid effects on biochemical parameters and on reduced length of hospitalization, number of infections, and mortality as main clinical outcomes in human surgical patients.

The optimal lipid formulation in enteral feeding in critical illness: clinical update and review of the literature

Suitable and timely early enteral nutrition is paramount to providing optimal patient care for the critically ill. Lipids serve many essential roles throughout the human body, and are important components of most enteral formulations. This paper reviews lipid structure, function, and optimal utility for this macronutrient in enteral feeds. The use of omega-3 fatty acids has become common in critical care formulations, and their clinical efficacy is outlined separately. Available evidence is reviewed, and future directions are discussed.