Enteral fish oil in critical illness: perspectives and systematic review

ESPEN practical and partially revised guideline: Clinical nutrition in the intensive care unit

Following the new ESPEN Standard Operating Procedures, the previous 2019 guideline to provide best medical nutritional therapy to critically ill patients has been shortened and partially revised. Following this update, we propose this publication as a practical guideline based on the published scientific guideline, but shortened and illustrated by flow charts. The main goal of this practical guideline is to increase understanding and allow the practitioner to implement the Nutrition in the ICU guidelines. All the items discussed in the previous guidelines are included as well as special conditions.

Neonatal Intensive Care Unit Mixed Lipid Emulsion Use Associated With Reduced Cholestasis at Discharge in Surgical Patients

INTRODUCTION

Parenteral nutrition associated cholestasis (PNAC) is a common morbidity in neonates requiring total parenteral nutrition (TPN). Previous studies in infants with intestinal failure have shown a benefit of mixed lipid emulsion (MLE) in reducing PNAC. It is not known whether this benefit extends to a general neonatal intensive care unit (NICU) population, where MLE is used on a selective basis. The objective of this study is to examine associations between MLE use and PNAC rate in the general NICU setting.

METHODS

This is a retrospective review of NICU patients who received TPN for 7 or more days. We compared patients born between 1/1/2014 and 12/31/2015 (pre-MLE) to patients born between 7/1/2017 and 12/31/2018 (post-MLE). Fisher's exact test and two-sample t-test were used to compare the two groups.

RESULTS

There were 353 patients in 2014-2015 and 271 patients in 2017-2018. Demographics were similar between the two groups, but there were more patients with congenital heart disease in the MLE era (P < 0.001). Mortality was similar (6.2% pre-MLE versus 6.3% post-MLE). There was no significant difference in PNAC rate between the pre-MLE (11.5%) and post-MLE (14.1%) patient cohorts (P = 0.342). Among patients receiving MLE (n = 38), 58% developed PNAC, while only 6.4% of the post-MLE cohort not receiving MLE developed PNAC. Of the patients coded with a surgical diagnosis, there was no significant difference in PNAC rates between pre-MLE and post-MLE groups. Discharge rates of PNAC did differ between pre-MLE surgical patients (13.0%) and post-MLE surgical patients (8.2%). In the subgroup of post-MLE surgical patients, PNAC rate differed significantly between those receiving MLE (43.5%) and not receiving MLE (15.4%). However, this difference was resolved by discharge (8.7% versus 7.7%).

CONCLUSIONS

There were no significant differences in PNAC rates between the pre-MLE and post-MLE cohorts. However, in surgical patients, MLE was associated with reduced PNAC at discharge, with levels equivalent to those seen in neonates receiving TPN for 7 or more days, despite having a higher starting rate of PNAC. Further studies are needed to determine whether the general NICU population may benefit from MLE or certain selective subpopulations like surgical patients.

Dietary Fish, Fish Nutrients, and Immune Function: A Review

Dietary habits have a major impact on the development and function of the immune system. This impact is mediated both by the intrinsic nutritional and biochemical qualities of the diet, and by its influence on the intestinal microbiota. Fish as a food is rich in compounds with immunoregulatory properties, among them omega-3 fatty acids, melatonin, tryptophan, taurine and polyamines. In addition, regular fish consumption favors the proliferation of beneficial members of the intestinal microbiota, like short-chain fatty acid-producing bacteria. By substituting arachidonic acid in the eicosanoid biosynthesis pathway, long-chain omega-3 fatty acids from fish change the type of prostaglandins, leukotrienes and thromboxanes being produced, resulting in anti-inflammatory properties. Further, they also are substrates for the production of specialized pro-resolving mediators (SPMs) (resolvins, protectins, and maresins), lipid compounds that constitute the physiological feedback signal to stop inflammation and give way to tissue reparation. Evidence from human observational and interventional studies shows that regular fish consumption is associated with reduced incidence of chronic inflammatory conditions like rheumatoid arthritis, and that continuous infusion of fish oil to tube-fed, critically ill patients may improve important outcomes in the ICU. There is also evidence from animal models showing that larger systemic concentrations of omega-3 fatty acids may counter the pathophysiological cascade that leads to psoriasis. The knowledge gained over the last few decades merits future exploration of the potential role of fish and its components in other conditions characterized by deregulated activation of immune cells and a cytokine storm like viral sepsis or COVID-19.

Expert Opinion on Benefits of Long-Chain Omega-3 Fatty Acids (DHA and EPA) in Aging and Clinical Nutrition

Life expectancy is increasing and so is the prevalence of age-related non-communicable diseases (NCDs). Consequently, older people and patients present with multi-morbidities and more complex needs, putting significant pressure on healthcare systems. Effective nutrition interventions could be an important tool to address patient needs, improve clinical outcomes and reduce healthcare costs. Inflammation plays a central role in NCDs, so targeting it is relevant to disease prevention and treatment. The long-chain omega-3 polyunsaturated fatty acids (omega-3 LCPUFAs) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are known to reduce inflammation and promote its resolution, suggesting a beneficial role in various therapeutic areas. An expert group reviewed the data on omega-3 LCPUFAs in specific patient populations and medical conditions. Evidence for benefits in cognitive health, age- and disease-related decline in muscle mass, cancer treatment, surgical patients and critical illness was identified. Use of DHA and EPA in some conditions is already included in some relevant guidelines. However, it is important to note that data on the effects of omega-3 LCPUFAs are still inconsistent in many areas (e.g., cognitive decline) due to a range of factors that vary amongst the trials performed to date; these factors include dose, timing and duration; baseline omega-3 LCPUFA status; and intake of other nutrients. Well-designed intervention studies are required to optimize the effects of DHA and EPA in specific patient populations and to develop more personalized strategies for their use.

Muscle Mass Loss in the Older Critically Ill Population: Potential Therapeutic Strategies

Skeletal muscle plays a critical role in everyday life, and its age-associated reduction has severe health consequences. The pre-existing presence of sarcopenia, combined with anabolic resistance, protein undernutrition, and the pro-catabolic/anti-anabolic milieu induced by aging and exacerbated in critical care, may accelerate the rate at which skeletal muscle is lost in patients with critical illness. Advancements in intensive care unit (ICU)-care provision have drastically improved survival rates; therefore, attention can be redirected toward other significant issues affecting ICU patients (e.g., length of stay, days on ventilation, nosocomial disease development, etc.). Thus, strategies targeting muscle mass and function losses within an ICU setting are essential to improve patient-related outcomes. Notably, loading exercise and protein provision are the most compelling. Many older ICU patients seldom meet the recommended protein intake, and loading exercise is difficult to conduct in the ICU. Nevertheless, the incorporation of physical therapy (PT), neuromuscular electrical stimulation, and early mobilization strategies may be beneficial. Furthermore, a number of nutrition practices within the ICU have been shown to improve patient-related outcomes ((e.g., feeding strategy [i.e., oral, early enteral, or parenteral]), be hypocaloric (∼70%-80% energy requirements), and increase protein provision (∼1.2-2.5 g/kg/d)). The aim of this brief review is to discuss the dysregulation of muscle mass maintenance in an older ICU population and highlight the potential benefits of strategic nutrition practice, specifically protein, and PT within the ICU. Finally, we provide some general guidelines that may serve to counteract muscle mass loss in patients with critical illness.

ESPEN guideline on clinical nutrition in the intensive care unit

Following the new ESPEN Standard Operating Procedures, the previous guidelines to provide best medical nutritional therapy to critically ill patients have been updated. These guidelines define who are the patients at risk, how to assess nutritional status of an ICU patient, how to define the amount of energy to provide, the route to choose and how to adapt according to various clinical conditions. When to start and how to progress in the administration of adequate provision of nutrients is also described. The best determination of amount and nature of carbohydrates, fat and protein are suggested. Special attention is given to glutamine and omega-3 fatty acids. Particular conditions frequently observed in intensive care such as patients with dysphagia, frail patients, multiple trauma patients, abdominal surgery, sepsis, and obesity are discussed to guide the practitioner toward the best evidence based therapy. Monitoring of this nutritional therapy is discussed in a separate document.

Fish oil and depression: The skinny on fats

Depression is the leading cause of disability worldwide, and even though many forms of therapy exist, about one third of patients treated with conventional antidepressants do not experience a response. For these reasons, new approaches to treat depression, including fish oil, are being investigated. Fish oil is known to have many beneficial side effects, and clinical trials demonstrate that supplementation with fish oil is beneficial in the management of depression. Fish oil contains omega-3 polyunsaturated fatty acids (PUFA), and there are several mechanisms by which PUFAs are thought to induce an antidepressant effect, including anti-inflammatory action and direct effects on membrane properties. This review will analyze and evaluate the clinical trials surrounding fish oil use in the treatment of depression, and will also review the likely sites of action of PUFAs at the cell membrane with special attention being placed on lipid rafts and G-proteins.

Remodelling of primary human CD4+ T cell plasma membrane order by n-3 PUFA

Cell membrane fatty acids influence fundamental properties of the plasma membrane, including membrane fluidity, protein functionality, and lipid raft signalling. Evidence suggests that dietary n-3 PUFA may target the plasma membrane of immune cells by altering plasma membrane lipid dynamics, thereby regulating the attenuation of immune cell activation and suppression of inflammation. As lipid-based immunotherapy might be a promising new clinical strategy for the treatment of inflammatory disorders, we conducted in vitro and in vivo experiments to examine the effects of n-3 PUFA on CD4+ T cell membrane order, mitochondrial bioenergetics and lymphoproliferation. n-3 PUFA were incorporated into human primary CD4+ T cells phospholipids in vitro in a dose-dependent manner, resulting in a reduction in whole cell membrane order, oxidative phosphorylation and proliferation. At higher doses, n-3 PUFA induced unique phase separation in T cell-derived giant plasma membrane vesicles. Similarly, in a short-term human pilot study, supplementation of fish oil (4 g n-3 PUFA/d) for 6 weeks in healthy subjects significantly elevated EPA (20 : 5n-3) levels in CD4+ T cell membrane phospholipids, and reduced membrane lipid order. These results demonstrate that the dynamic reshaping of human CD4+ T cell plasma membrane organisation by n-3 PUFA may modulate down-stream clonal expansion.

Lipids in the intensive care unit: Recommendations from the ESPEN Expert Group

This article summarizes the presentations given at an ESPEN Workshop on "Lipids in the ICU" held in Tel Aviv, Israel in November 2014 and subsequent discussions and updates. Lipids are an important component of enteral and parenteral nutrition support and provide essential fatty acids, a concentrated source of calories and building blocks for cell membranes. Whilst linoleic acid-rich vegetable oil-based enteral and parenteral nutrition is still widely used, newer lipid components such as medium-chain triglycerides and olive oil are safe and well tolerated. Fish oil (FO)-enriched enteral and parenteral nutrition appears to be well tolerated and confers additional clinical benefits, particularly in surgical patients, due to its anti-inflammatory and immune-modulating effects. Whilst the evidence base is not conclusive, there appears to be a potential for FO-enriched nutrition, particularly administered peri-operatively, to reduce the rate of complications and intensive care unit (ICU) and hospital stay in surgical ICU patients. The evidence for FO-enriched nutrition in non-surgical ICU patients is less clear regarding its clinical benefits and additional, well-designed large-scale clinical trials need to be conducted in this area. The ESPEN Expert Group supports the use of olive oil and FO in nutrition support in surgical and non-surgical ICU patients but considers that further research is required to provide a more robust evidence base.

Lipid metabolism in critical illness

PURPOSE OF REVIEW

This article describes recent findings regarding lipid metabolism in critical illness as well as in lipid therapy.

RECENT FINDINGS

In critical illness, in the presence of a decrease in lipid absorption, adipose tissue lipolysis raises triglyceride levels. High-density lipoprotein and low-density lipoprotein are decreased because of impairment of lecithin-cholesterol acyltransferase, mainly in sepsis. In septic patients, lipid profile may be a predictor of survival. Nonsurvivors have lower levels of high-density lipoprotein and low-density lipoprotein. In metabolomic studies, most of the changes from baseline in septic patients were related to lipid metabolism. Lysophosphatidylcholine was also significantly lower in nonsurviving septic patients.

SUMMARY

Lipid profile results are too often neglected by the clinician despite increasing knowledge in the modifications related to septic state as well as the importance of these values in the prognosis of the critically ill. Lipid administration (enterally or parenterally) should be guided by better knowledge of the lipid metabolism of the patient.

Use of n-3 PUFAs can decrease the mortality in patients with systemic inflammatory response syndrome: a systematic review and meta-analysis

BACKGROUND

There have been several meta-analyses evaluating the effect of n-3 polyunsaturated fatty acids (PUFAs) in critically ill patients, but of these, none focused on patients with systemic inflammatory response syndrome (SIRS). The objective of this meta-analysis was to evaluate the effect of omega-3 fatty acids (n-3 FAs) on this narrow subset.

METHODS

All relevant articles were searched on MEDLINE, EMBASE, SpringerLink, and the Cochrane Database of Systematic Reviews from 1990 to 2014. Meta-analyses were used to evaluate risk ratios and mean differences with 95% confidence intervals between the n-3 PUFA group and the control group. Subgroup analyses were conducted in terms of the route of fish oil.

RESULTS

Nine randomized controlled trials (RCTs) with 783 adult patients were included in this study. Compared with control groups, n-3 FA provision can significantly reduce the incidence of mortality (RR: 0.77 [0.60, 0.97]; P=0.03; I2=0%). Secondary outcomes showed no significant differences between groups except for shorter length of hospital stay (weighted mean difference: -10.56 [-19.76, -1.36], p<0.00001, I2=99%).

CONCLUSIONS

Overall, this meta-analysis from RCTs indicates that provision of n-3 PUFAs has a therapeutic effect on survival rate in patients with SIRS.

Parenteral fish oil-containing lipid emulsions may reverse parenteral nutrition-associated cholestasis in neonates: a systematic review and meta-analysis

BACKGROUND

Growing evidence indicates that fish oil-containing lipid emulsions have a beneficial effect on parenteral nutrition-associated cholestasis (PNAC) in adults; however, data are limited in neonates regarding the effect of fish oil on PNAC.

OBJECTIVE

We conducted a meta-analysis of studies that addressed the effect of fish oil-containing lipid emulsions on reversing and preventing PNAC.

METHODS

We searched PubMed, the EMBASE database, and the Cochrane Library for this systematic review and meta-analysis. The methodologic assessment of studies was performed with the Jadad scale and the Newcastle-Ottawa Scale. Comprehensive Met-Analysis version 2.0 was used for the statistical analysis. We performed a meta-analysis with the primary outcomes of reversal of PNAC and the occurrence of PNAC in newborn infants, including preterm infants, after parenteral administration of fish oil-containing lipid emulsions.

RESULTS

Of the 36 studies identified, 7 fulfilled the inclusion criteria and were used in this meta-analysis, including 3 studies with 93 participants in which reversal of PNAC was an outcome and 4 studies with 1012 participants on preventing PNAC. The use of fish oil-containing lipid emulsions was more likely to reverse PNAC (OR: 6.14; 95% CI: 2.27, 16.6; P < 0.01), but the use of fish oil-containing lipid emulsions did not have a significant effect on the development of PNAC (OR: 0.56; 95% CI: 0.28, 1.10; P = 0.09) compared with soybean-based or olive oil-based lipid emulsions.

CONCLUSIONS

The pooled data suggest that the use of fish oil-containing lipid emulsions is effective for reversing PNAC but cannot prevent PNAC in neonates who require prolonged parenteral nutritional support.

Enteral nutrition formula selection: current evidence and implications for practice

Many new enteral nutrition (EN) formulas have been created over the past several decades with a variety of intended uses. Although each is intended to promote improved outcomes, research is often unclear and, in many cases, conflicting. It is important to note that EN products are considered medical foods by the U.S. Food and Drug Administration and therefore do not have to complete premarket review or approval and are not regulated to the same extent as pharmaceuticals. While standard EN formulas are designed to meet the basic macro- and micronutrient requirements of individuals who cannot meet nutrition needs orally, specialty EN products have been developed to exhibit pharmacologic properties, such as immune-enhancing formulas containing arginine, glutamine, nucleotides, and ω-3 fatty acids. With the vast number of products available, rising costs of healthcare, and the drive toward evidence-based practice, it is imperative that clinicians carefully consider research regarding use of specialty formulas, paying close attention to the quality, patient population, clinical end points, and cost to patient and/or facility.