Selenium supplementation in critically ill patients: a systematic review and meta-analysis

Efficacy and safety of selenium or vitamin E administration alone or in combination in ICU patients: A systematic review and meta-analysis

BACKGROUND

Micronutrient administration that contributes to antioxidant defense has been extensively studied in critically ill patients, but consensus remains elusive. Selenium and vitamin E are two important micronutrients that have synergistic antioxidant effects. This meta-analysis aimed to assess the effect of selenium or vitamin E administration alone and the combination of both on clinical outcomes in patients hospitalized in the ICU.

METHODS

After electronic searches on PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), SinoMed, VIP database and Wanfang data, initially 1767 papers were found, and 30 interventional studies were included in this analysis. We assessed the risk-difference between treatment and control (standard treatment) groups by pooling available data on length of stay (ICU length of stay and hospital length of stay), mortality (ICU mortality, hospital mortality, 28-day mortality, 6-month mortality and all-cause mortality), duration of mechanical ventilation, adverse events and new infections.

RESULTS

By analyzing the included studies, we found no significant effect of selenium administration alone on mortality, mechanical ventilation duration, or adverse events in ICU patients. However, after excluding studies with high heterogeneity, the meta-analysis showed that selenium alone reduced the length of hospital stay (MD: -1.38; 95% CI: -2.52, -0.23; I-square: 0%). Vitamin E administration alone had no significant effect on mortality, duration of mechanical ventilation, or adverse events in ICU patients. However, after excluding studies with high heterogeneity, the meta-analysis showed that vitamin E alone could reduce the length of ICU stay (MD: -1.27; 95% CI: -1.86, -0.67; I-square: 16%). Combined administration of selenium and vitamin E had no significant effect on primary outcomes in ICU patients.

CONCLUSIONS

Selenium administration alone may shorten the length of hospital stay, while vitamin E alone may reduce the length of ICU stay. The putative synergistic beneficial effect of combined administration of selenium and vitamin E in ICU patients has not been observed, but more clinical studies are pending to confirm it further.

Randomized Clinical Trial of Antioxidant Therapy Patients with Septic Shock and Organ Dysfunction in the ICU: SOFA Score Reduction by Improvement of the Enzymatic and Non-Enzymatic Antioxidant System

BACKGROUND AND AIM

Here, we assess the effect of adjuvant antioxidant therapies in septic shock patients with organ dysfunction and their effect on the enzymatic and non-enzymatic antioxidant systems.

METHODS

Randomized clinical trial run between 2018 and 2022. One hundred and thirty-one patients with septic shock were included in five groups with 25, 27, 24, 26 and 29 patients each. Group 1 received vitamin C (Vit C), Group 2 vitamin E (Vit E), Group 3 n-acetylcysteine (NAC), Group 4 melatonin (MT) and group 5 no treatment. All antioxidants were administered orally or through a nasogastric tube for 5 days as an adjuvant to standard therapy.

RESULTS

All patients had multiple organ failure (MOF) and low Vit C levels. Vit C therapy decreased CRP, PCT and NO₃^-/NO₂^- but increased Vit C levels. The SOFA score decreased with MT in 75%, Vit C 63% and NAC 50% vs. controls 33% (p = 0.0001, p = 0.03 and p = 0.001 respectively). MT diminished lipid peroxidation (LPO) (p = 0.01) and improved total antioxidant capacity (TAC) (p = 0.04). Vit E increased thiol levels (p = 0.02) and tended to decrease LPO (p = 0.06). Selenium levels were decreased in the control group (p = 0.04).

CONCLUSIONS

Antioxidants used as an adjuvant therapy in the standard treatment of septic shock decrease MOF and oxidative stress markers. They increase the TAC and thiols, and maintain selenium levels.

Combination of Phycocyanin, Zinc, and Selenium Improves Survival Rate and Inflammation in the Lipopolysaccharide-Galactosamine Mouse Model

Sepsis is related to systemic inflammation and oxidative stress, the primary causes of death in intensive care units. Severe functional abnormalities in numerous organs can arise due to sepsis, with acute lung damage being the most common and significant morbidity. Spirulina, blue-green algae with high protein, vitamins, phycocyanin, and antioxidant content, shows anti-inflammatory properties by decreasing the release of cytokines. In addition, zinc (Zn) and selenium (Se) act as an antioxidant by inhibiting the oxidation of macromolecules, as well as the inhibition of the inflammatory response. The current study aimed to examine the combined properties of Zn, Se, and phycocyanin oligopeptides (ZnSePO) against lipopolysaccharide-D-galactosamine (LPS-GalN)-induced septic lung injury through survival rate, inflammatory, and histopathological changes in Balb/c mice. A total of 30 mice were allocated into three groups: normal control, LPS-GalN (100 ng of LPS plus 8 mg of D-galactosamine), LPS-GalN + ZnSePO (ZnPic, 52.5 µg/mL; SeMet, 0.02 µg/mL; and phycocyanin oligopeptide (PO), 2.00 mg/mL; at 1 h before the injection of LPS-GalN). Lung tissue from mice revealed noticeable inflammatory reactions and typical interstitial fibrosis after the LPS-GalN challenge. LPS-GalN-induced increased mortality rate and levels of IL-1, IL-6, IL-10, TGF-β, TNF-α, and NF-κB in lung tissue. Moreover, treatment of septic mice LPS-GalN + ZnSePO reduced mortality rates and inflammatory responses. ZnSePO considerably influenced tissue cytokine levels, contributing to its capacity to minimize acute lung injury (ALI) and pulmonary inflammation and prevent pulmonary edema formation in LPS-GalN-injected mice. In conclusion, ZnSePO treatment enhanced the survival rate of endotoxemia mice via improving inflammation and oxidative stress, indicating a possible therapeutic effect for patients with septic infections.

The effect of selenium therapy in critically ill patients: an umbrella review of systematic reviews and meta-analysis of randomized controlled trials

BACKGROUND

Selenium is an essential nutrient with antioxidant, anti-inflammatory, and immuno-regulatory properties. Studies have displayed that in critically ill patients, selenium supplementation may be a potentially promising adjunctive therapy.

OBJECTIVE

We aimed to present an overview of the effects of selenium supplementation in adult critically ill patients based on published systematic reviews and meta-analyses (SRMAs) of randomized controlled trials (RCTs).

METHODS

A literature search in three electronic databases, PubMed, Scopus, and Web of Science, was performed to find eligible SRMAs until July 2022. For each outcome, the risk ratios (RRs) or mean differences (MDs) and 95% confidence intervals (CIs) were recalculated using either random or fixed effect models. The methodological quality and quality of evidence of the SRMAs were assessed by applying "A Measurement Tool to Assess Systematic Reviews" (AMSTAR2) and Grading of Recommendations Assessment, Development, and Evaluation(GRADE) tools, respectively.

RESULTS

We included 17 meta-analyses containing 24 RCTs based on inclusion criteria. Selenium supplementation can reduce the incidence of mortality (RR: 0.83, 95% CI 0.71, 0.98, P = 0.024) and incidence of acute renal failure (RR: 0.67, 95% CI 0.46, 0.98, P: 0.038) significantly; however, the certainty of evidence was low. Moreover, with moderate to very low certainty of evidence, no significant effects were found for risk of infection (RR: 0.92, 95% CI 0.80, 1.05, P: 0.207), pneumonia (RR: 1.11, 95% CI 0.72, 1.72, P: 0.675), as well as the length of ICU (MD: 0.15, 95% CI - 1.75, 2.05, P: 0.876) and hospital stay (MD: - 0.51, 95% CI - 3.74, 2.72, P: 0.757) and days on ventilation (MD: - 0.98, 95% CI - 2.93, 0.98, P: 0.329).

CONCLUSIONS

With low quality of evidence, the use of selenium supplementation could improve the risk of mortality and acute renal failure, but not other outcomes in critically ill patients.

Nutrients in prevention, treatment, and management of viral infections; special focus on Coronavirus

BACKGROUND

The coronavirus disease 2019 (COVID-19) is a pandemic caused by coronavirus with mild to severe respiratory symptoms. This paper aimed to investigate the effect of nutrients on the immune system and their possible roles in the prevention, treatment, and management of COVID-19 in adults.

METHODS

This Systematic review was designed based on the guideline of the Preferred Reporting for Systematic Reviews (PRISMA). The articles that focussed on nutrition, immune system, viral infection, and coronaviruses were collected by searching databases for both published papers and accepted manuscripts from 1990 to 2020. Irrelevant papers and articles without English abstract were excluded from the review process.

RESULTS

Some nutrients are actively involved in the proper functioning and strengthening of the human immune system against viral infections including dietary protein, omega-3 fatty acids, vitamin A, vitamin D, vitamin E, vitamin B₁, vitamin B₆, vitamin B₁₂, vitamin C, iron, zinc, and selenium. Few studies were done on the effect of dietary components on prevention of COVID-19, but supplementation with these nutrients may be effective in improving the health status of patients with viral infections.

CONCLUSION

Following a balanced diet and supplementation with proper nutrients may play a vital role in prevention, treatment, and management of COVID-19. However, further clinical trials are needed to confirm these findings and presenting the strong recommendations against this pandemic.

Perioperative safety assessment of patients undergoing unilateral or bilateral hip replacements

Introduction

Due to the aging of the world population and the increase of obesity rate, it is expected that the number of joint replacement surgery will continue to increase in the next few years. This study evaluated the safety differences between unilateral and bilateral hip replacement surgeries.

Methods

The data for patients who underwent hip arthroplasty in 2021 and 2022 were examined. The data set included 68 patients who were grouped according to the type of hip replacement needed, sex, age, and body mass index. Total blood loss and operative time were the safety-related indicators used to compare the groups.

Results

Regardless of whether the unilateral replacement group was compared with the overall bilateral replacement group or separately with the staged and simultaneous bilateral replacement groups, simultaneous bilateral replacement surgeries were equally safe as the other types of hip replacements. The total blood loss and operative time for the simultaneous bilateral replacement group were not significantly different from those in the unilateral and staged bilateral replacement groups. For overweight patients, the operative time for simultaneous bilateral replacements was significantly shorter than that for unilateral replacements.

Conclusions

These findings suggest that for patients requiring bilateral hip replacements, the blood loss risk for patients undergoing simultaneous bilateral hip replacements was similar to that for patients undergoing either unilateral or staged bilateral hip replacements. Thus, simultaneous bilateral total hip replacement (THR) are safe and should be considered for candidate patients.

The influence of early selenium supplementation on trauma patients: A propensity-matched analysis

Introduction

Oxidative stress is involved in numerous inflammatory diseases, including trauma. Micronutrients, such as selenium (Se), which contribute to antioxidant defense, exhibit low plasma levels during critical illness. This study aimed to investigate the impact of early Se supplementation on trauma patients.

Materials and methods

A total of 6,891 trauma patients were registered at a single medical center from January 2018 to December 2021. Twenty trauma patients with Se supplemented according to the protocol were included in the study group. Subsequently, 1:5 propensity score matching (PSM) analysis was introduced. These patients received 100 mcg three times a day for 5 days. The primary outcome was overall survival (OS); the secondary outcomes were hospital/intensive care unit (ICU) length of stay (LOS), serologic change, ventilator dependence days, and ventilation profile.

Results

The hospital LOS (20.0 ± 10.0 vs. 37.4 ± 42.0 days, p = 0.026) and ICU LOS (6.8 ± 3.6 vs. 13.1 ± 12.6 days, p < 0.006) were significantly shorter in the study group. In terms of serology, improvement in neutrophil, liver function, and C-reactive protein (CRP) level change percentile indicated better outcomes in the study group as well as a better OS rate (100 vs. 83.7%, p = 0.042). Longer ventilator dependence was found to be an independent risk factor for mortality and pulmonary complications in 6,891 trauma patients [odds ratio (OR) = 1.262, 95% confidence interval (CI) = 1.039-1.532, p < 0.019 and OR = 1.178, 95% CI = 1.033-1.344, p = 0.015, respectively].

Conclusion

Early Se supplementation after trauma confers positive results in terms of decreasing overall ICU LOS/hospital LOS and mortality. Organ injury, particularly hepatic insults, and inflammatory status, also recovered better.

The effects of selenium supplementation on inflammatory markers in critically ill patients

Abstract

Low serum selenium (Se) levels have been shown in critical illness, which is associated with poor clinical outcomes and a higher mortality rate. Se plays an important role in inflammation and oxidative stress. Since the overproduction of inflammatory cytokines and increased oxidative stress is a major component of critical illnesses, its supplementation has been demonstrated to have promising effects on critically ill patients. This study aims to review the evidence regarding the effects of Se supplementation on inflammatory and oxidative markers in critically ill patients. The literature review highlights alterations of inflammatory markers, including procalcitonin, leukocyte count, albumin, prealbumin, C-reactive protein (CRP), inflammatory cytokines, and cholesterol following Se supplementation in critically ill patients. Besides, the antioxidant properties of Se due to its presence in the structure of several selenoenzymes have been reported.

Article highlights

Low serum Se level have been shown in critical illness, which is associated with poor clinical outcome and higher mortality rate.

Se plays an important role in inflammation and oxidative stress.

Se supplementation can have promising effects by alterations of inflammatory markers and its antioxidant properties for critically ill patients.

Association of COVID-19 mortality with serum selenium, zinc and copper: Six observational studies across Europe

Introduction

Certain trace elements are essential for life and affect immune system function, and their intake varies by region and population. Alterations in serum Se, Zn and Cu have been associated with COVID-19 mortality risk. We tested the hypothesis that a disease-specific decline occurs and correlates with mortality risk in different countries in Europe.

Methods

Serum samples from 551 COVID-19 patients (including 87 non-survivors) who had participated in observational studies in Europe (Belgium, France, Germany, Ireland, Italy, and Poland) were analyzed for trace elements by total reflection X-ray fluorescence. A subset (n=2069) of the European EPIC study served as reference. Analyses were performed blinded to clinical data in one analytical laboratory.

Results

Median levels of Se and Zn were lower than in EPIC, except for Zn in Italy. Non-survivors consistently had lower Se and Zn concentrations than survivors and displayed an elevated Cu/Zn ratio. Restricted cubic spline regression models revealed an inverse nonlinear association between Se or Zn and death, and a positive association between Cu/Zn ratio and death. With respect to patient age and sex, Se showed the highest predictive value for death (AUC=0.816), compared with Zn (0.782) or Cu (0.769).

Discussion

The data support the potential relevance of a decrease in serum Se and Zn for survival in COVID-19 across Europe. The observational study design cannot account for residual confounding and reverse causation, but supports the need for intervention trials in COVID-19 patients with severe Se and Zn deficiency to test the potential benefit of correcting their deficits for survival and convalescence.

Antioxidant, Anti-inflammatory, and Immunomodulatory Roles of Nonvitamin Antioxidants in Anti-SARS-CoV-2 Therapy

Viral pathologies encompass activation of pro-oxidative pathways and inflammatory burst. Alleviating overproduction of reactive oxygen species and cytokine storm in COVID-19 is essential to counteract the immunogenic damage in endothelium and alveolar membranes. Antioxidants alleviate oxidative stress, cytokine storm, hyperinflammation, and diminish the risk of organ failure. Direct antiviral roles imply: impact on viral spike protein, interference with the ACE2 receptor, inhibition of dipeptidyl peptidase 4, transmembrane protease serine 2 or furin, and impact on of helicase, papain-like protease, 3-chyomotrypsin like protease, and RNA-dependent RNA polymerase. Prooxidative environment favors conformational changes in the receptor binding domain, promoting the affinity of the spike protein for the host receptor. Viral pathologies imply a vicious cycle, oxidative stress promoting inflammatory responses, and vice versa. The same was noticed with respect to the relationship antioxidant impairment-viral replication. Timing, dosage, pro-oxidative activities, mutual influences, and interference with other antioxidants should be carefully regarded. Deficiency is linked to illness severity.

Rebalancing the unbalanced aged immune system - A special focus on zinc

Nowadays, aging is understood as a dynamic and multifaceted dysregulation process that spares almost no human organ or cell. The immune system being among the most affected, it has been shown predominantly that its integrity determines the tightrope walk between the difference of escaping or suffering from age-related diseases. Next to drug-based anti-aging strategies, micronutrient intervention may represent an emerging but less radical way to slow immune aging. While a sufficient supply of a variety of micronutrients is undeniably important, adequate intake of the trace element zinc appears to tower over others in terms of reaching old age. Inconveniently, zinc deficiency prevalence among the elderly is high, which in turn contributes to increased susceptibility to infection, decreased anti-tumor immunity as well as attenuated response to vaccination. Driven by this research, this review aims to provide a comprehensive and up-to-date overview of the various rebalancing capabilities of zinc in the unbalanced immune system of the elderly. This includes an in-depth and cell type-centered discussion on the role of zinc in immunosenescence and inflammaging. We further address upcoming translational aspects e.g. how zinc deficiency promotes the flourishing of certain pathogenic taxa of the gut microbiome and how zinc supply counteracts such alterations in a manner that may contribute to longevity. In the light of the ongoing COVID-19 pandemic, we also briefly review current knowledge on the interdependency between age, zinc status, and respiratory infections. Based on two concrete examples and considering the latest findings in the field we conclude our remarks by outlining tremendous parallels between suboptimal zinc status and accelerated aging on the one hand and an optimized zinc status and successful aging on the other hand.

Can selenium-enriched spirulina supplementation ameliorate sepsis outcomes in selenium-deficient animals?

In intensive care units, sepsis is the first cause of death. In this pathology, inflammation and oxidative status play a crucial role in patient outcomes. Interestingly, 92% of septic patients exhibit low selenium plasma concentrations (a component of antioxidant enzymes). Moreover, Spirulina platensis, a blue-green algae, demonstrated anti-inflammatory effects. In this context, the main purpose of our study was to analyze the effect of a selenium-enriched spirulina after a selenium deficiency on sepsis outcome in rats. Sixty-four rats were fed 12 weeks with a selenium-deficient food. After 8 weeks, rats were supplemented (via drinking water) for 4 weeks with sodium selenite (Se), spirulina (Spi), or selenium-enriched spirulina (SeSp). Sepsis was then induced by cecal ligature and puncture, and survival duration was observed. The plasma selenium concentration was measured by ICPMS. Expression of GPx1 and GPx3 mRNA was measured by RT-PCR. Blood parameters (lactates and HCO3- concentrations, pH, PO2 , and PCO2 ) were analyzed at 0, 1, and 2 h as well as inflammatory cytokines (IL-6, TNF-α, IL-10). Sodium selenite and SeSP supplementations restored plasma selenium concentration prior to sepsis. The survival duration of SeSP septic rats was significantly lower than that of selenium-supplemented ones. Gpx1 mRNA was increased after a selenium-enriched spirulina supplementation while Gpx3 mRNA levels remained unchanged. Furthermore, sodium selenite prevented sepsis-induced acidosis. Our results show that on a basis of a Se deficiency, selenium-enriched spirulina supplementations significantly worsen sepsis outcome when compared to Se supplementation. Furthermore, Se supplementation but not selenium-enriched spirulina supplementation decreased inflammation and restored acid-base equilibrium after a sepsis induction.

The Role of Nutrition in COVID-19 Susceptibility and Severity of Disease: A Systematic Review

BACKGROUND

Many nutrients have powerful immunomodulatory actions with the potential to alter susceptibility to coronavirus disease 2019 (COVID-19) infection, progression to symptoms, likelihood of severe disease, and survival.

OBJECTIVE

The aim was to review the latest evidence on how malnutrition across all its forms (under- and overnutrition and micronutrient status) may influence both susceptibility to, and progression of, COVID-19.

METHODS

We synthesized information on 13 nutrition-related components and their potential interactions with COVID-19: overweight, obesity, and diabetes; protein-energy malnutrition; anemia; vitamins A, C, D, and E; PUFAs; iron; selenium; zinc; antioxidants; and nutritional support. For each section we provide: 1) a landscape review of pertinent material; 2) a systematic search of the literature in PubMed and EMBASE databases, including a wide range of preprint servers; and 3) a screen of 6 clinical trial registries. All original research was considered, without restriction to study design, and included if it covered: 1) severe acute respiratory syndrome coronavirus (CoV) 2 (SARS-CoV-2), Middle East respiratory syndrome CoV (MERS-CoV), or SARS-CoV viruses and 2) disease susceptibility or 3) disease progression, and 4) the nutritional component of interest. Searches took place between 16 May and 11 August 2020.

RESULTS

Across the 13 searches, 2732 articles from PubMed and EMBASE, 4164 articles from the preprint servers, and 433 trials were returned. In the final narrative synthesis, we include 22 published articles, 38 preprint articles, and 79 trials.

CONCLUSIONS

Currently there is limited evidence that high-dose supplements of micronutrients will either prevent severe disease or speed up recovery. However, results of clinical trials are eagerly awaited. Given the known impacts of all forms of malnutrition on the immune system, public health strategies to reduce micronutrient deficiencies and undernutrition remain of critical importance. Furthermore, there is strong evidence that prevention of obesity and type 2 diabetes will reduce the risk of serious COVID-19 outcomes. This review is registered at PROSPERO as CRD42020186194.

Daily parenteral selenium therapy in critically ill patients: An updated systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Patients hospitalized at the intensive care unit (ICU) are more prone to oxidative stress. Antioxidants such as selenium (Se) may have beneficial effects on outcomes in these patients. Studies and systematic reviews in this field have inconclusive results.

METHODS

An updated systematic search was done to find clinical trials published in PubMed, Cochrane's library, ISI web of Science, Scopus, and Ovid databases from January 1980 up to April 2020, to assess the effects of daily Se supplementation on patient's survival, hospital and ICU stay, duration of mechanical ventilation, infection, acute renal failure (ARF) occurrence and serum creatinine levels.

RESULTS

From 1394 papers found in the first step of the search, after deleting duplicate findings, 24 studies were included in this meta-analysis. Results of the pooled random-effect size analysis of 24 trials showed no remarkable effect of daily parenteral Se administration on patient's hospital and ICU stay, duration of mechanical ventilation, infectious complications, ARF, survival and serum creatinine levels (p > 0.05). The subgroup analysis showed that daily parenteral Se administration (in doses higher than 1000 μg/d) increased the length of ICU stay by 4.48-folds (95%CI: -0.5, 9.46, p = 0.07). Parenteral Se supplementation at the first and following dose of ≤1000 μg reduced the number of ARF at the hospitalized patients by 76% and 45%, respectively (p = 0.02, and p = 0.05).

CONCLUSIONS

High doses of Se increases days of ICU stay, but low doses decreases the number of ARF occurrence in ICU patients. More trials are needed to assess its effect on ARF occurrence.

The Association of Circulating Selenium Concentrations with Diabetes Mellitus

PURPOSE

The relationship between circulating selenium and diabetes mellitus (DM) remains inconsistent. Therefore, the relationship between circulating selenium and DM was investigated in the present study.

PATIENTS AND METHODS

All participants (aged ≥18 years) were included from the National Health and Nutrition Examination Survey (NHANES) 1999-2006. Selenium concentrations from the fasting serum samples were determined using inductively coupled mass spectrometry, then grouped into quartiles. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by using multivariate logistic regression analysis and the results were stratified by age and sex.

RESULTS

A total of 2,903 (61.9±13.7 years old) participants (49.3% males) were enrolled, and 580 (19.97%) of them had DM. The mean levels of selenium were 136.4±19.6 µg/L. Patients with DM (138.76±20.02 vs 135.88±19.44, P=0.002) had higher selenium levels compared to those without DM. The OR for DM was 1.12 (95% CI=1.01-1.24; P=0.0270) for each 10 µg/L increment in selenium, and subjects in the highest quartile of selenium levels (>147.00 uµg/L) had 2.82 (95% CI=1.55-5.11; P=0.0007) times higher risk of DM compared to the lowest quartile of selenium levels. Subgroup analysis showed that selenium was independently associated with DM only in female aged <65 years.

CONCLUSION

Circulating selenium levels were positively associated with the odds of DM, but difference in sex and age.

Intensity of renal replacement therapy and outcomes in critically ill patients with acute kidney injury: Critical appraisal of the dosing recommendations

The current care of critically ill patients with severe acute kidney injury requiring dialysis (AKI-D) is limited to supportive management in which renal replacement therapy (RRT) plays a central role. Renal replacement techniques are invasive bioincompatible procedures and are therefore associated with complications that may prove harmful to fragile patients. Inexperience with the standards and lacking or misinterpreted recommendations for the delivery of the RRT dose increases the risk of serious complications. Neither the optimal doses of intermittent or continuous RRTs nor the minimal or maximal effective doses are known. The Kidney Disease Improving Global outcomes (KDIGO) AKI guidelines for RRT dosing recommendations are inflexible, based on limited research, and may be at least partially outdated. High-intensity therapy may be associated with clinically relevant alterations in systemic and renal hemodynamics, profound electrolyte imbalances, the loss of nutrients or thermal energy, and underdosing of antimicrobial agents. However, higher doses of continuous renal replacement therapy (CRRT) may confer a survival benefit for certain subgroups of intensive care patients with severe AKI. Lower CRRT doses than the recommended adequate dosage may not lead to negative health outcomes, at least in Asian patients. Future research should evaluate the demand-capacity concept, recognizing that the delivery of the RRT dose is dynamic and should be modified in response to patient-related factors. There is a need for large-scale studies evaluating whether precision RRT dose modifications may improve patient-centered outcomes in subgroups of critically ill patients.

Nutrition in Sepsis: A Bench-to-Bedside Review

Nutrition therapy in sepsis is challenging and differs from the standard feeding approach in critically ill patients. The dysregulated host response caused by infection induces progressive physiologic alterations, which may limit metabolic capacity by impairing mitochondrial function. Hence, early artificial nutrition should be ramped-up and emphasis laid on the post-acute phase of critical illness. Caloric dosing is ideally guided by indirect calorimetry, and endogenous energy production should be considered. Proteins should initially be delivered at low volume and progressively increased to 1.3 g/kg/day following shock symptoms wane. Both the enteral and parenteral route can be (simultaneously) used to cover caloric and protein targets. Regarding pharmaconutrition, a low dose glutamine seems appropriate in patients receiving parenteral nutrition. Supplementing arginine or selenium is not recommended. High-dose vitamin C administration may offer substantial benefit, but actual evidence is too limited for advocating its routine use in sepsis. Omega-3 polyunsaturated fatty acids to modulate metabolic processes can be safely used, but non-inferiority to other intravenous lipid emulsions remains unproven in septic patients. Nutrition stewardship, defined as the whole of interventions to optimize nutritional approach and treatment, should be pursued in all septic patients but may be difficult to accomplish within a context of profoundly altered cellular metabolic processes and organ dysfunction caused by time-bound excessive inflammation and/or immune suppression. This review aims to provide an overview and practical recommendations of all aspects of nutritional therapy in the setting of sepsis.

Redox-Active Selenium in Health and Disease: A Conceptual Review

Although it is generally accepted that selenium (Se) is important for life, it is not well known which forms of organic and/or inorganic Se compound are the most biologically active. In nature Se exists mostly in two forms, namely as selenite with fourvalent and selenate with sixvalent cations, from which all other inorganic and organic species are derived. Despite a small difference in their electronic structure, these two inorganic parent compounds differ significantly in their redox properties. Hence, only selenite can act as an oxidant, particularly in the reaction with free and/or protein- bound sulhydryl (SH) groups. For example, selenite was shown to inhibit the hydroxyl radicalinduced reduction and scrambled reoxidation of disulfides in human fibrinogen thus preventing the formation of highly hydrophobic polymer, termed parafibrin. Such a polymer, when deposited within peripheral and/or cerebral circulation, may cause irreversible damage resulting in the development of cardiovascular, neurological and other degenerative diseases. In addition, parafibrin deposited around tumor cells produces a protease-resistant coat protecting them against immune recognition and elimination. On the other hand, parafibrin generated by Ebola's protein disulfide isomerase can form a hydrophobic 'spike' that facilitates virus attachment and entry to the host cell. In view of these specific properties of selenite this compound is a potential candidate as an inexpensive and readily available food supplement in the prevention and/or treatment of cardiovascular, neoplastic, neurological and infectious diseases.

A meta-analysis of randomized controlled trials: Efficacy of selenium treatment for sepsis

BACKGROUND

To understand the clinical outcomes of selenium therapy in patients with sepsis syndrome, we conducted a meta-analysis of randomized controlled trials (RCT).

METHODS

A total of 13 RCTs comparing selenium and placebo for patients with sepsis were reviewed systematically.

RESULTS

However, we could not detect the association of selenium treatment with a decreased mortality at different time course (relative risk [RR] [95% confidence interval, CI]: 0.94 [0.82-1.06] at day 28; 0.73 [0.36-1.47] at day 90; 1.16 [0.78-1.71] at 6 months; respectively). Selenium supplementation did not show favorable efficacy in the incidence of renal failure, secondary infection or duration of mechanical ventilation (RR [95% CI]: 0.65 [0.41-1.03]; 0.96 [0.87-1.06]; standard mean difference [SMD] [95% CI]: 0.17 [-0.30-0.63]; respectively). Interestingly, we found that selenium therapy was benefit for sepsis patients with reduced duration of vasopressor therapy, staying time in intensive care unit and hospital, and incidence of ventilator-associated pneumonia (SMD [95% CI]: -0.75 [-1.37 to -0.13]; -0.15 [CI: -0.25 to -0.04]; -1.22 [-2.44 to -0.01]; RR [95% CI]: 0.61 [0.42-0.89]; respectively).

CONCLUSION

Based on our findings, intravenous selenium supplementation could not be suggested for routine use.

Multiple Micronutrient Plasma Level Changes Are Related to Oxidative Stress Intensity in Critically Ill Children

OBJECTIVES

Micronutrient supplementation in critically ill adults remains controversial. In the pediatric setting, the impact of oxidative stress on the overall micronutrient status has been poorly explored, due to the limited number of studies and to confounding factors (i.e., malnutrition or extra losses). In order to better understand this phenomenon, we aim to describe micronutrient status, focusing on seven micronutrients, in well-nourished critically ill children presenting with severe oxidative stress.

DESIGN

Prospective, transversal, observational, single-center study.

SETTING

PICU, and anesthesiology department, Lyon, France.

PATIENTS

Three groups of patients were clinically defined: severe oxidative stress PICU group (at least two organ dysfunctions), moderate oxidative stress PICU group (single organ dysfunction), and healthy control group (prior to elective surgery); oxidative stress intensity was controlled by measuring plasma levels of glutathione peroxidase and glutathione. Children presenting any former condition leading to micronutrient deficiency were excluded (malnutrition, external losses).

INTERVENTIONS

Plasma levels of selenium, zinc, copper, vitamin A, vitamin E, vitamin C, and β-carotene were measured in PICU oxidative stress conditions and compared with those of healthy children.

MEASUREMENTS AND MAIN RESULTS

Two hundred one patients were enrolled (51, 48, and 102 in severe, moderate, and healthy control groups, respectively). Median age was 7.1 years (interquartile range, 2.1-13.8 yr). There was a significant trend (p < 0.02) toward plasma level decrease of six micronutrients (selenium, zinc, copper, vitamin E, vitamin C, and β-carotene) while oxidative stress intensity increased. Biological markers of oxidative stress (glutathione peroxidase and glutathione) were in accordance with the clinical definition of the three groups.

CONCLUSIONS

A multiple micronutrient deficiency or redistribution occurs in critically ill children presenting with severe oxidative stress. These findings will help to better identify children who might benefit from micronutrient supplementation and to design adapted supplementation trials in this particular setting.

Gut-origin sepsis in the critically ill patient: pathophysiology and treatment

INTRODUCTION

Gut permeability is increased in critically ill patients, and associated with the development of the systemic inflammatory response syndrome and multiple organ dysfunction syndrome (MODS). The pathogenetic link(s) and potential therapies are an area of intense research over the last decades.

METHODS

We thoroughly reviewed the literature on gut-origin sepsis and MODS in critically ill patients, with emphasis on the implicated pathophysiological mechanisms and therapeutic interventions.

FINDINGS

Intestinal barrier failure leading to systemic bacterial translocation associated with MODS was the predominant pathophysiological theory for several years. However, clinical studies with critically ill patients failed to provide the evidence of systemic spread of gut-derived bacteria and/or their products as a cause of MODS. Newer experimental data highlight the role of the mesenteric lymph as a carrier of gut-derived danger-associated molecular patterns (DAMPs) to the lung and the systemic circulation. These substances are recognized by pattern recognition receptor-bearing cells in diverse tissues and promote proinflammatory pathways and the development MODS. Therefore, the gut becomes a pivotal proinflammatory organ, driving the systemic inflammatory response through DAMPs release in mesenteric lymph, without the need for systemic bacterial translocation.

CONCLUSIONS

There is an emerging need for application of sensitive non-invasive and easily measured biomarkers of early intestinal injury (e.g., citrulline, intestinal fatty acid protein, and zonulin) in our everyday clinical practice, guiding the early pharmacological intervention in critically ill patients to restore or prevent intestinal injury and improve their outcomes.

Antioxidant reserve of the lungs and ventilator-associated pneumonia: A clinical trial of high dose selenium in critically ill patients

PURPOSE

To evaluate the effect of supplemental selenium administration on the incidence of ventilator-associated pneumonia (VAP) in critically ill patients.

METHODS

Ninety-nine mechanically ventilated patients were randomized to receive either selenium or isotonic saline infusion for 10days. The primary endpoint was serum glutathione peroxidase-3 (GPX-3) activity and secondary endpoints were development of VAP or death, ICU stay and vasopressor requirement. Serum concentrations of selenium and GPX-3 were measured on Day-1, Day-4 and Day-10. Chi Square and log-rank analyses were used for statistical analyses and odds ratios were calculated.

RESULTS

Serum selenium and GPX-3 activity levels increased steadily in the treatment group within 10days (P<0.025), while they remained unchanged in the placebo group. The incidence of VAP was 19.4/1000days of mechanical ventilation in the placebo group while it was 15.8/1000 ventilated days in the treatment group (P=0.250). The risk of VAP or death was similar between the treatments and placebo groups.

CONCLUSION

Despite increasing the antioxidant activity, selenium supplementation did not affect the incidence of VAP in critically ill patients. The risk of developing VAP or death within 30days of ICU admission remained the same in the treatment and the controls.

Synthesis and antioxidant properties of Lycium barbarum polysaccharides capped selenium nanoparticles using tea extract

Selenium nanoparticles (SeNPs) have attracted increasing interest over the last decades because of their activities on redox balance in human body. However, the SeNPs tend to aggregate into large clusters, resulting in lower bioactivity, bioavailability and biocompatibility. Surface-capping agents on SeNPs play crucial roles in its stabilization and biological activity. Here, a green synthesis method for the preparation of Lycium barbarum polysaccharides capped SeNPs using green tea extracts as reductants under mild conditions, at room temperature, is reported. The structure, size, morphology and thermal behaviour were analyzed by various characterization techniques. The functionalized nanoparticles demonstrated high antioxidant activity, including DPPH and ABTS free radical scavenging. Moreover, the SeNPs significantly protected the H₂O₂-induced PC-12 cell death. Taken together, these results evidence the possible application of these SeNPs as antioxidants food supplement or ingredient and neuroprotective agent.

Trace elements in patients on continuous renal replacement therapy

PURPOSE

Intensive care patients with acute kidney injury (AKI), treated with continuous renal replacement therapy (CRRT) are at great risk for disturbances in plasma levels of trace elements due to the underlying illness, AKI, and dialysis. This study was performed to increase our knowledge regarding eight different trace elements during CRRT.

METHODS

Thirty one stable patients with AKI, treated with CRRT, were included in the study. Blood, plasma and effluent samples were taken at the start of the study and 36 ± 12 h later. A group of 48 healthy volunteers were included as controls and exposed to one fasting blood sample. Samples were analysed for trace elements (Cr, Cu, Mn, Co, Zn, Rb, Mo, Se) and standard blood chemistry.

RESULTS

Blood and plasma levels of selenium and rubidium were significantly reduced while the levels of chromium, cobalt, and molybdenum were significantly increased in the study group vs. healthy volunteers. There was an uptake of chromium, manganese, and zinc. Molybdenum mass balance was around zero. For selenium, copper, and rubidium there were a marked loss.

CONCLUSIONS

The low levels of selenium and rubidium in blood and plasma from CRRT patients, together with the loss via CRRT effluent, raises the possibility of the need for selenium supplementation in this group of patients, despite the unchanged levels during the short study period. Further investigations on the effect of additional administration of trace elements to CRRT patients would be of interest.

Niacin and Selenium Attenuate Sepsis-Induced Lung Injury by Up-Regulating Nuclear Factor Erythroid 2-Related Factor 2 Signaling

OBJECTIVES

To determine whether the combination therapy of niacin and selenium attenuates lung injury and improves survival during sepsis in rats and whether its benefits are associated with the activation of the glutathione redox cycle and up-regulation of nuclear factor erythroid 2-related factor 2.

DESIGN

Prospective laboratory study.

SETTING

University laboratory.

SUBJECTS

Human lung microvascular endothelial cells and male Sprague-Dawley rats (n = 291).

INTERVENTION

In lipopolysaccharide-exposed cells, the dose-related effects of niacin and selenium were assessed, and the therapeutic effects of the combination therapy of niacin (0.9 mM) and selenium (1.5 μM) were evaluated. The role of nuclear factor erythroid 2-related factor 2 was determined using nuclear factor erythroid 2-related factor 2 knockdown cells. In endotoxemic and cecal ligation and puncture with antibiotics rats, the therapeutic effects of the posttreatments of clinically relevant doses of niacin (360 mg/kg) and selenium (60 μg/kg) were evaluated.

MEASUREMENTS AND MAIN RESULTS

Combination therapy reduced the hydrogen peroxide level via the synergistic activation of the glutathione redox cycle, which involves niacin-induced increases in glutathione reductase activity, and reduced the glutathione level and a selenium-induced increase in glutathione peroxidase activity. Combination therapy contributed to the up-regulation of nuclear factor erythroid 2-related factor 2, enhancement of glutathione synthesis, and down-regulation of nuclear factor κB signaling, but nuclear factor erythroid 2-related factor 2 knockdown inhibited the enhancement of glutathione synthesis and down-regulation of the nuclear factor κB pathway. The therapeutic effects of combination therapy on endotoxemic rats were consistent with those on lipopolysaccharide-exposed cells. In addition, the posttreatment of combination therapy attenuated lung injury and improved survival in endotoxemic and cecal ligation and puncture with antibiotics rats. However, individual therapies of niacin or selenium failed to achieve these benefits.

CONCLUSIONS

The combination therapy of niacin and selenium attenuated lung injury and improved survival during sepsis. Its therapeutic benefits were associated with the synergistic activation of the glutathione redox cycle, reduction of hydrogen peroxide level, and up-regulation of nuclear factor erythroid 2-related factor 2.

Effect of high-dose sodium selenite in cardiac surgery patients: A randomized controlled bi-center trial

BACKGROUND & AIMS

Cardiac surgery is accompanied by oxidative stress and systemic inflammatory response, which may be associated with organ dysfunction and increased mortality. Selenium and selenoenzymes are important constituents of anti-oxidative defense. We hypothesized that high-dose sodium selenite supplementation can attenuate the postoperative inflammation and might, therefore, improve clinical outcome.

METHODS

Randomized, placebo-controlled, double-blinded, bi-center study on 411 adult patients undergoing elective cardiac surgery. Patients received an intravenous bolus of 4000 μg selenium (in the form of sodium selenite) or placebo after induction of anesthesia and 1000 μg/d selenium or placebo during their intensive care unit (ICU) stay. Primary outcome measure was the Sequential Organ Failure Assessment (SOFA) score on the second postoperative day. Secondary endpoints included the change in perioperative selenium levels, change of inflammatory and cardiac markers, use of vasoactive medication, incidence of acute kidney injury, ICU and hospital length of stay, and mortality.

RESULTS

The perioperative administration of high-dose sodium selenite prevented the postoperative drop of blood and serum selenium levels, reduced the number of patients depending on postoperative vasoactive support but failed to reduce the postoperative SOFA score and its related organ-specific scores compared to placebo. Except for an increase of postoperative procalcitonin and bilirubin levels in the sodium selenite group, other inflammatory markers, organ function variables and clinical endpoints remained unchanged.

CONCLUSIONS

The perioperative administration of high-dose sodium selenite in cardiac surgery patients prevented the postoperative fall of blood selenium levels and reduced the need for postoperative vasoactive support by a yet unknown mechanism.

TRIAL REGISTRATION

Registered under ClinicalTrials.gov Identifier no. NCT01141556.

Treatment with Myo-Inositol and Selenium Ensures Euthyroidism in Patients with Autoimmune Thyroiditis

Clinical evidences have highlighted the efficacy of myo-inositol and selenium in the treatment of autoimmune thyroiditis. Aim of this study was to further analyze the role of myo-inositol plus selenium (Myo-Ins-Se) in restoring a normal thyroid function of Hashimoto's patients with subclinical hypothyroidism. Eighty-six patients with Hashimoto's thyroiditis having thyroid-stimulating hormone (TSH) levels between 3 and 6 mIU/L, elevated serum antithyroid peroxidase (TPOAb) and/or antithyroglobulin (TgAb), and normal free thyroxine (fT4) and free triiodothyronine (fT3) levels were enrolled in the study: one hyperthyroid subject with TSH about 0.14 μU/ml was included in this trial as a single case. Patients were assigned to receive Myo-Ins-Se. TSH, TPOAb, and TgAb levels were significantly decreased in patients treated with combined Myo-Ins-Se after 6 months of treatment. In addition, a significant fT3 and fT4 increase, along with an amelioration of their quality of life, was observed. Remarkably, TSH values of the hyperthyroid patient increased from 0.14 μU/ml up to 1.02 μU/ml, showing a complete restoration of TSH values at a normal range. In conclusion, the administration of Myo-Ins-Se is significantly effective in decreasing TSH, TPOAb, and TgAb levels, as well as enhancing thyroid hormones and personal wellbeing, therefore restoring euthyroidism in patients diagnosed with autoimmune thyroiditis.

Role of divalent metals in infectious disease susceptibility and outcome

BACKGROUND

Divalent metals play important roles in maintaining metabolism and cellular growth of both eukaryotic hosts and invading microbes. Both metal deficiency and overload can result in abnormal cellular function or damage. Given its central role in host-pathogen interactions, subtle alterations of divalent metal homeostasis can occur in the course of infectious diseases which aim, from the host perspective, either to reduce the availability of respective metals to microbes or to use toxic metal accumulation to eliminate pathogens.

AIMS

To provide the reader with background information and clinical data on divalent metal homeostasis in host-pathogen interactions, how this affects the course of infectious disease and whether correction of metal disturbances has shown benefit in infections.

SOURCES

An in-depth analysis of PubMed articles related to the topic of this review published in English between 1970 and 2016 was performed.

CONTENT

From the microbial perspective, divalent metals are essential for growth and pathogenicity and to mount effective protection against antimicrobial host responses, including toxic radical formation. Microbes have evolved multiple strategies to control their access to divalent metals. From the clinical perspective, alterations of divalent metal levels may result in increased or decreased susceptibility to infection and often occur in response to infections. However, keeping in mind the strategies underlying such alterations, for which the term 'nutritional immunity' was coined, the uncritical correction of such divalent metal imbalances may cause harm to patients. This review addresses the role of the divalent metals iron, selenium, zinc, manganese and copper in infectious diseases from a mechanistic and clinical perspective.

IMPLICATIONS

We point out areas of research needed to expand our limited knowledge, hoping to improve the clinical management of patients with infections and to identify promising new targets for treatment by modulation of host or microbe divalent metal metabolism.

High-dose intravenous selenium does not improve clinical outcomes in the critically ill: a systematic review and meta-analysis

Background

Selenium (Se) is an essential trace element with antioxidant, anti-inflammatory, and immunomodulatory effects. So far, several randomized clinical trials (RCTs) have demonstrated that parenteral Se may improve clinical outcomes in intensive care unit (ICU) patients. Since publication of our previous systematic review and meta-analysis on antioxidants in the ICU, reports of several trials have been published, including the largest RCT on Se therapy. The purpose of the present systematic review was to update our previous data on intravenous (IV) Se in the critically ill.

Methods

We searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials. We included RCTs with parallel groups comparing parenteral Se as single or combined therapy with placebo. Potential trials were evaluated according to specific eligibility criteria, and two reviewers abstracted data from original trials in duplicate independently. Overall mortality was the primary outcome; secondary outcomes were infections, ICU length of stay (LOS), hospital LOS, ventilator days, and new renal dysfunction.

Results

A total of 21 RCTs met our inclusion criteria. When the data from these trials were aggregated, IV Se had no effect on mortality (risk ratio [RR] 0.98, 95 % CI 0.90–1.08, P = 0.72, heterogeneity I² = 0 %). In addition, when the results of ten trials in which researchers reported on infections were statistically aggregated, there was no significant treatment effect of parenteral Se (RR 0.95, 95 % CI 0.88–1.02, P = 0.15, I² = 0 %). There was no positive or negative effect of Se therapy on ICU and hospital LOS, renal function, or ventilator days.

Conclusions

In critically ill patients, IV Se as monotherapy does not improve clinical outcomes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1529-5) contains supplementary material, which is available to authorized users.

Serum selenium levels in patients with respiratory diseases: a prospective observational study

BACKGROUND

Serum selenium levels are lower in critically ill patients as compared with healthy controls. However, there is no data about the difference in serum selenium levels depending on the severity of lung diseases. We aimed to identify the factors associated with low serum selenium levels in critically ill patients with respiratory diseases.

METHODS

A prospective study was performed in 83 patients with respiratory diseases who had admitted to the intensive care unit (ICU) and general wards. We obtained systemic inflammatory markers, nutritional indicators and prognostic factors as the explanatory variables for the outcome of low serum selenium levels.

RESULTS

Serum selenium levels on admission were lower by 28% in the ICU group as compared with the general ward group (70.0±26.4 and 97.9±20.8 ng/mL, respectively, P<0.001). Low serum selenium levels had a correlation with malnutrition represented by decreases in levels of lymphocyte (R(2)=0.107, P=0.005) and albumin (R(2)=0.174, P<0.001). In addition, low serum selenium levels were associated with an increase in baseline C-reactive protein (CRP) (R(2)=0.059, P=0.041) and APACHE II scores (R(2)=0.209, P<0.001). Lower albumin levels (P=0.032) and higher APACHE II scores (P=0.046) showed a significant correlation with lower serum selenium levels on multivariate analysis.

CONCLUSIONS

Low serum selenium levels in patients with respiratory diseases have a significant correlation with poor nutritional status and prognosis on admission.

Metabolic resuscitation in sepsis: a necessary step beyond the hemodynamic?

Despite the advances made in monitoring and treatment of sepsis and septic shock, many septic patients ultimately develop multiple organ dysfunction (MODS) and die, suggesting that other players are involved in the pathophysiology of this syndrome. Mitochondrial dysfunction occurs early in sepsis and has a central role in MODS development. MODS severity and recovery of mitochondrial function have been associated with survival. In recent clinical and experimental investigations, mitochondrion-target therapy for sepsis and septic shock has been suggested to reduce MODS severity and mortality. This intervention, which might be named "metabolic resuscitation", would lead to improved mitochondrial activity afforded by pharmacological and nutritional agents. Of particular interest in this therapeutic strategy is thiamine, a water-soluble vitamin that plays an essential role in cellular energy metabolism. Critical illness associated with hypermetabolic states may predispose susceptible individuals to the development of thiamine deficiency, which is not usually identified by clinicians as a source of lactic acidosis. The protective effects of thiamine on mitochondrial function may justify supplementation in septic patients at risk of deficiency. Perspectives of supplementation with other micronutrients (ascorbic acid, tocopherol, selenium and zinc) and potential metabolic resuscitators [coenzyme Q10 (CoQ10), cytochrome oxidase (CytOx), L-carnitine, melatonin] to target sepsis-induced mitochondrial dysfunction are also emerging. Metabolic resuscitation may probably be a safe and effective strategy in the treatment of septic shock in the future. However, until then, preliminary investigations should be replicated in further researches for confirmation. Better identification of groups of patients presumed to benefit clinically by a certain intervention directed to "mitochondrial resuscitation" are expected to increase driven by genomics and metabolomics.

Effects of Low-dose Selenium on the Inflammatory Response in Coronary Artery Bypass Graft Surgery: A Clinical Trial

Background

Coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB) triggers an inflammatory reaction, leading to the development of myocardial damage and dysfunction. It is suggested that selenium (Se), an essential trace element, has a protective role against oxidative stress. Decreased intraoperative Se levels might be an independent predictive factor for postoperative multiorgan failure. In spite of its proposed advantages, however, the optimal timing and dosage are not well known.

Objectives

To determine whether 600 µg of intravenous Se administration before induction of anesthesia for CABG surgery could attenuate inflammatory reactions in an Iranian population.

Methods

This randomized triple-blind clinical trial took place in the department of cardiac surgery of an academic hospital affiliated with Guilan University of Medical Sciences (GUMS) from May 2015 to September 2015. Eighty-eight eligible patients scheduled for elective on-pump CABG surgery were divided into two groups using randomized fixed quadripartite blocks. They received either an intravenous bolus of 600 µg Se before induction of anesthesia, or normal saline as a placebo. We had four measurement time-points: just before induction of anesthesia (T0), immediately after the end of CPB (T1), 24 hours after surgery (T2), and 48 hours after surgery (T3). Interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP) serum levels were measured using the enzyme-linked immunosorbent assay (ELISA).

Results

Data from a total of 81 patients were analyzed: group S (n = 41) and group C (n = 40). There was no significant difference between the two groups with regard to baseline characteristics. In both groups, CPB caused markedly increased IL-6, TNF-α, and CRP plasma concentrations compared with baseline (P = 0.0001). However, the pattern of changes was not significantly different between group S (P = 0.068) and group C (P = 0.26). The IL-6 and TNF-α change trends were significant in each group (P=0.0001). However, comparing the two groups showed no significant difference. With regard to IL-6, there was no significant difference between the two groups at the time-points of T1 (P = 0.34), T2 (P = 0.17), and T3 (P = 0.056), and the same was found for TNF-α at T1 (P = 0.34), T2 (P = 0.17), and T3 (P = 0.056). With regard to CRP, the trend of the changes was significant in each group (P = 0.0001). However, comparing two groups showed a borderline significant difference between them at T1 (P = 0.039), but not at T2 (P = 0.075) or T3 (P = 0.11).

Conclusions

This study revealed that the administration of 600 μg of intravenous Se immediately before induction of anesthesia was safe, but when compared to a placebo, no predominant clinical effects or modifications in the systemic inflammatory response induced by on-pump CABG were observed.

Low preoperative selenium is associated with post-operative atrial fibrillation in patients having intermediate-risk coronary artery surgery

BACKGROUND/OBJECTIVES

Post-operative atrial fibrillation (POAF) is a frequent complication of cardiac surgery. Oxidative stress and reduced antioxidant function have major roles in its development. Selenium is a key to normal antioxidant function, and levels are often low before cardiac surgery. This study investigated whether low preoperative selenium levels were associated with POAF in cardiac surgical patients.

SUBJECTS/METHODS

Using the Society of Thoracic Surgeons (STS) Mortality risk score, 50 patients having primary coronary artery bypass grafts (CABG) surgery were divided into two groups: (i) low-risk group (STS ⩽0.5%; n=26) and (ii) intermediate-risk group (STS ⩾2.0%; n=24). Plasma levels of selenium, glutathione peroxidase (GPx) and malondialdehyde (MDA) were measured in all patients at anaesthetic induction, after aortic cross-clamp removal, 3 h post cardiopulmonary bypass and on post-operative days 1 and 5. Multiple logistic regression was used to assess whether selenium levels were associated with POAF development.

RESULTS

Seventeen patients developed POAF (14 patients in the intermediate-risk group and 3 patients in the low-risk group). Preoperative selenium was lower in patients who developed POAF compared with those with normal sinus rhythm (0.73±0.16 vs 0.89±0.13 μmol/l, P=0.005), and this was independently associated with POAF (PR 0.32; 95% confidence credible interval (95%cI) 0.06-0.85, P=0.016). Regardless of POAF, preoperative selenium was lower in the intermediate-risk patients than in the low-risk patients (0.77±0.15 vs 0.89±0.14 μmol/l; P=0.004).

CONCLUSIONS

Intermediate-risk patients with low preoperative selenium levels may be at a greater risk of developing POAF following CABG. This raises the question of whether selenium supplementation in select cardiac surgical patients may reduce their POAF risk.

Radioiodine-induced oxidative stress in patients with differentiated thyroid carcinoma and effect of supplementation with vitamins C and E and selenium (antioxidants)

OBJECTIVE

The objective of this study, in addition to confirming that therapy with 131I causes oxidative stress, was to evaluate the effect of supplementation with vitamins C and E and selenium on this phenomenon by measuring plasma 8-epi-PGF2a, a marker of lipid peroxidation.

SUBJECTS AND METHODS

Forty patients with thyroid cancer submitted to thyroidectomy, who received 3.7 GBq 131I after levothyroxine withdrawal, were selected; 20 patients did not receive (control group) and 20 patients received (intervention group) daily supplementation consisting of 2000 mg vitamin C, 1000 mg vitamin E and 400 µg selenium for 21 days before 131I. Plasma 8-epi-PGF2a was measured immediately before and 2 and 7 days after 131I.

RESULTS

A significant increase in plasma 8-epi-PGF2a after 131I was observed in the two groups. The concentrations of 8-epi-PGF2α were significantly higher in the control group before and 2 and 7 days after 131I. The percentage of patients with elevated 8-epi-PGF2α was also significantly higher in the control group before and after 131I. Furthermore, the increase (percent) in 8-epi-PGF2α was significantly greater in the control group (average of 112.3% versus 56.3%). Only two patients (10%) reported side effects during supplementation.

CONCLUSIONS

Ablation with 131I causes oxidative stress which can be minimized by the use of antioxidants.

Micronutrient and amino acid losses in acute renal replacement therapy

PURPOSE OF REVIEW

A wide range of renal replacement therapies is now available to support patients with acute kidney injury. These treatments utilize diffusion, convection or a combination of these mechanisms to remove metabolic waste products from the bloodstream. It is inevitable that physiologically important substances including micronutrients will also be removed. Here we review current knowledge of the extent of micronutrient loss, how it varies between treatment modalities and its clinical significance.

RECENT FINDINGS

Very few studies have specifically investigated micronutrient loss in renal replacement therapy for acute kidney injury. Recent data suggest that trace elements and amino acids are lost during intermittent dialysis, hybrid therapies such as sustained low-efficiency diafiltration and continuous therapies. Extent of micronutrient loss appears to vary with treatment type, with continuous convection-based treatments probably causing greatest losses.

SUMMARY

Patients with acute kidney injury are at high risk of disease-related malnutrition. The use of renal replacement therapy, although often essential for life support, results in loss of micronutrients into the filtrate or dialysate. Losses are probably greater with continuous convective treatments, but it is not yet known whether these losses are clinically significant or whether their replacement would improve patient outcomes.

The effect of parenteral selenium on outcomes of mechanically ventilated patients following sepsis: a prospective randomized clinical trial

Background

Sepsis and septic shock is characterized by oxidative stress that mainly promotes systemic inflammation and organ failure due to excessive free radical production and depletion of antioxidant defenses. Therefore, we investigated the effect of selenium administration on antioxidant status, levels of cytokines and clinical outcomes.

Methodology

This study was a prospective randomized control trial (RCT) whereby patients received selenium as sodium selenite (2 mg IV bolus followed by 1.5 mg continuous infusion for 14 days) plus standard therapy. The control group received standard therapy without selenium. The primary endpoint was 28-day mortality. The changes in the mean levels of glutathione peroxidase (GPX) activity, IL-6, IL-8 and IL-10, the incidence of ventilator-associated pneumonia (VAP) and other secondary endpoints were also recorded. VAP was broken down into early VAP and late VAP to see the clinical significance of each. We also recorded any adverse outcomes from selenium infusion.

Results

Over 24-month period, 54 patients were recruited and randomized and an intention to treat (ITT) principle was applied (selenium, n = 29; control, n = 25) in the final analysis. There was no statistically significant difference between the two groups in 28-day mortality although it was lower in the selenium group compared with the control group: 9 (31 %) in the selenium versus 10 (40 %) in the control groups (p = 0.49). At day 0, GPX activity was 0.185 ± 0.3 versus 0.19 ± 0.3 U/mL (p = 0.9), day 3, GPX activity was 0.52 ± 0.5 versus 0.17 ± 0.2 U/mL (p = 0.02), at day 7 it was 0.55 ± 0.5 versus 0.24 ± 0.3 U/mL (p = 0.032), at day 10 it was 0.62 ± 0.7 versus 0.33 ± 0.4 U/mL (p = 0.048) and at day 14 it was 1.1 ± 1 versus 0.89 ± 1 U/mL (p = 0.70) for the selenium versus control groups, respectively. However, there were no significant differences between the mean plasma levels of all the three inflammatory cytokines at any point in time between the two groups. There was a significant reduction in occurrence of VAP in the selenium group compared with the control group (55.2 versus 84 %, p = 0.023), respectively.

Conclusion

High-dose selenium administration within the time frame of early goal-directed therapy was not resulted in reduction of 28-day mortality, but increased the activity of glutathione peroxidase with no effect on the levels of inflammatory cytokines at any point in time in mechanically ventilated septic patients. However, selenium supplementation in mechanically ventilated patients following sepsis was associated with reduced occurrence of VAP.

Trial registration: IRCT201212082887N4 at WHO Clinical Trial Registry, August 29, 2014

Plasma glutathione reductase activity and prognosis of septic shock

BACKGROUND

Our aim was to investigate whether plasma glutathione reductase (GR) activity is well correlated with the erythrocyte-reduced glutathione (GSH)/glutathione disulfide (GSSG) ratio and is associated with the mortality of septic shock.

MATERIALS AND METHODS

This study was conducted on male Sprague-Dawley rats and patients admitted to the intensive care unit with septic shock. To induce endotoxemia in rats, vehicle or lipopolysaccharide (LPS) at dosages of 5 or 10 mg/kg were injected into a tail vein. Animals were then euthanized 6 h post-LPS. Based on the 28-d mortality, the enrolled patients were divided into the survivors and nonsurvivors. We obtained blood samples from patients at admission (0 h) and 24 h after admission to the intensive care unit.

RESULTS

In endotoxemic rats, the erythrocyte GSH/GSSG ratio, erythrocyte GR activity, and plasma GR activity in the 10 mg/kg of LPS group were lower than those in the sham and 5 mg/kg of LPS groups. In patients with septic shock, decrease in plasma GR activity at 24 h was independently associated with an increase in 28-d mortality (odds ratio, 0.828; 95% confidence interval, 0.690-0.992, P = 0.041). Plasma GR activity was correlated with erythrocyte GR activity (Spearman ρ = 0.549, P < 0.001) and the erythrocyte GSH/GSSG ratio (rho = 0.367, P = 0.009) at 24 h.

CONCLUSIONS

Plasma GR activity was well correlated with erythrocyte GR activity and the erythrocyte GSH/GSSG ratio, and a decrease in plasma GR activity was associated with an increase in the mortality of septic shock patients.

Selenium supplementation for critically ill adults

BACKGROUND

Selenium is a trace mineral essential to health and has an important role in immunity, defence against tissue damage and thyroid function. Improving selenium status could help protect against overwhelming tissue damage and infection in critically ill adults. This Cochrane review was originally published in 2004 updated in 2007 and again 2015.

OBJECTIVES

The primary objective was to examine the effect of nutrition supplemented with selenium or ebselen on mortality in critically ill patients.The secondary objective was to examine the relationship between selenium or ebselen supplementation and number of infections, duration of mechanical ventilation, length of intensive care unit stay and length of hospital stay.

SEARCH METHODS

In this update, we searched the current issue of the Cochrane Central Register of Controlled Trials, the Cochrane Library (2014, Issue 5); MEDLINE (Ovid SP, to May 20, 2014), EMBASE (Ovid SP, to May 20, 2014), CAB, BIOSIS and CINAHL. We handsearched the reference lists of the newest reviews and cross-checked with our search in MEDLINE. We contacted the main authors of included studies to request any missed, unreported or ongoing studies. The latest search was performed up to 21 May 2014. The search is now from inception until 21 May 2014.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) irrespective of publication status, date of publication, blinding status, outcomes published or language. We contacted the trial investigators and authors in order to retrieve relevant and missing data.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and we resolved any disagreements by discussion. Our primary outcome measure was all-cause mortality. We performed several subgroup and sensitivity analyses to assess the effects of selenium in critically ill patients. We presented pooled estimates of the effects of intervention as risk ratios (RRs) with 95% confidence intervals (CIs). We assessed the risk of bias through assessment of trial methodological components and the risk of random error through trial sequential analysis.

MAIN RESULTS

We included six new RCTs in this review update. In total we included 16 RCTs (2084 participants) in this review. Most trials were at high risk of bias. The availability of outcome data was limited and trials involving selenium supplementation were, with the exception of one trial, small regarding sample size. Thus the results must be interpreted with caution.Thirteen trials of intravenous sodium selenite showed a statistically significant reduction in overall mortality (RR 0.82, 95% CI 0.72 to 0.93, 1391 participants, very low quality of evidence). However, the overall point estimate on mortality is primarily influenced by trials of high risk of bias. Meta-analysis of three trials of ebselen had a RR of 0.83 (95% CI 0.52 to 1.34, 693 participants, very low quality of evidence).Nine trials of intravenous sodium selenite were analysed for 28 days mortality with no statistically significant difference (RR 0.84, 95% CI 0.69 to 1.02, 1180 participants, very low quality of evidence) while three trials were analysed for 90 days mortality with similar findings (RR 0.96, 95% Cl 0.78 to 1.18, 614 participants, very low quality of evidence).Two trials of ebselen were analysed for 90 days mortality and were not found to yield any benefit (RR 0.72, 95% Cl 0.42 to 1.22, 588 participants, very low quality of evidence).For mortality among intensive care patients selenium supplementation failed to indicate any statistically significant advantage (RR 0.88, 95% CI 0.77 to 1.01, nine trials, 1168 participants, very low quality of evidence).Six trials of intravenous sodium selenite found no statistically significant difference for participants developing infection (RR 0.96, 95% CI 0.75 to 1.23, 934 patients, very low quality of evidence). Similarly, three trials of ebselen provided data for participants developing infections (pyrexia, respiratory infections or meningitis) with no obvious benefit (RR 0.60, 95% CI 0.36 to 1.02, 685 participants, very low quality of evidence).Our analyses showed no effect of selenium or ebselen on adverse events (Selenium: RR 1.03, 95% Cl 0.85 to 1.24; six trials, 925 participants ; Ebselen: RR 1.16, 95% CI 0.40 to 3.36; two trials, 588 participants, very low quality of evidence).No clear evidence emerged in favour of selenium supplementation for outcomes such as number of days on a ventilator (mean difference (MD) -0.86, 95% CI -4.39 to 2.67, four trials, 191 participants, very low quality of evidence), length of intensive care unit stay (MD 0.54, 95% CI -2.27 to 3.34, seven trials, 934 participants, very low quality of evidence) or length of hospital stay (MD -3.33, 95% Cl -5.22 to -1.44, five trials, 693 participants, very low quality of evidence).The quality of trial methodology was low. Due to high risk of bias in the included trials, results must be interpreted with caution.

AUTHORS' CONCLUSIONS

Despite publication of a number of trials, the current evidence to recommend supplementation of critically ill patients with selenium or ebselen remains disputed. Trials are required which overcome the methodological inadequacies of the reviewed studies, particularly in relation to sample size, design and outcomes.

Selenium: an element for life

This review aims to illustrate the importance of selenium (Se) for maintenance of overall health, especially for the thyroid, immunity, and homeostasis. Furthermore, it outlines the role of Se in reproduction and in virology and discusses the effects of Se supplementation in critical illness. The multifaceted aspects of this essential nutrient have attracted worldwide clinical and research interest in the last few decades. Se exerts its activity in the form of the aminoacid selenocysteine incorporated in selenoproteins. The impact of Se administration should be considered in relation to its apparent U shaped effects, i.e., exhibiting major advantages in Se-deficient individuals but specific health risks in those with Se excess. Addition of selenium to the administration of levothyroxine may be useful in patients with low Se intake and with mild-form or early-stage Hashimoto's thyroiditis (HT). Serum Se concentration (possibly also at tissue level) decreases in inflammatory conditions and may vary with the severity and duration of the inflammatory process. In such cases, the effect of Se supplementation seems to be useful and rational. Meanwhile, Se's ability to improve the activity of T cells and the cytotoxicity of natural killer cells could render it effective in viral disease. However, the evidence, and this should be stressed, is at present conflicting as to whether Se supplementation is of benefit in patients with HT, though there are indications that it is advantageous in cases of mild/moderate Graves' Orbitopathy. The role of Se in type 2 diabetes mellitus (T2DM) is ambiguous, driven by both Se intake and serum levels. The evidence that insulin and glycaemia influence the transport and activity of Se, via regulatory activity on selenoproteins, and that high serum Se may have a diabetogenic effect suggests a 'Janus-effect' of Se in T2DM. Though the evidence is not as yet clear-cut, the organic form (selenomethionine), due to its pharmacokinetics, is likely to be more advantageous in long-term prevention, and supplementation efforts, while the inorganic form (sodium selenite) has proven effective in an acute, e.g., sepsis, clinical setting. Recent data indicate that functional selenoprotein single-nucleotide polymorphisms (SNPs) may interfere with Se utilization and effectiveness.

Selenium prevents microparticle-induced endothelial inflammation in patients after cardiopulmonary resuscitation

Introduction

Microparticles are elevated in patients after successful cardiopulmonary resuscitation (CPR) and may play a role in the development of endothelial dysfunction seen in post-cardiac arrest syndrome (PCAS), a life threatening disease with high mortality. To identify mechanisms of endothelial activation and to develop novel approaches in the therapy of PCAS, the impact of selenium, a trace element with antioxidative properties, was characterized in endothelial dysfunction induced by microparticles of resuscitated patients. Additionally, course of plasma selenium levels was characterized in the first 72 hours post-CPR.

Methods

Endothelial cells were exposed to microparticles isolated of the peripheral blood of resuscitated patients, and leukocyte-endothelial interaction was measured by dynamic adhesion assay. Expression of adhesion molecules was assessed by immunoblotting and flow chamber. Blood samples were drawn 24, 48 and 72 hours after CPR for determination of plasma selenium levels in 77 resuscitated patients; these were compared to 50 healthy subjects and 50 patients with stable cardiac disease and correlated with severity of illness and outcome.

Results

Microparticles of resuscitated patients enhance monocyte-endothelial interaction by up-regulation of ICAM-1 and VCAM-1. Selenium administration diminished ICAM-1 and VCAM-1-mediated monocyte adhesion induced by microparticles of resuscitated patients, suggesting that selenium has anti-inflammatory effects after CPR. Lowered selenium plasma levels were observed in resuscitated patients compared to controls and selenium levels immediately and 24 hours after CPR, inversely correlated with clinical course and outcome after resuscitation.

Conclusions

Endothelial dysfunction is a pivotal feature of PCAS and is partly driven by microparticles of resuscitated patients. Administration of selenium exerted anti-inflammatory effects and prevented microparticle-mediated endothelial dysfunction. Decline of selenium was observed in plasma of patients after CPR and is a novel predictive marker of ICU mortality, suggesting selenium consumption promotes inflammation in PCAS.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-0774-3) contains supplementary material, which is available to authorized users.

Biomarkers in critically ill patients with systemic inflammatory response syndrome or sepsis supplemented with high-dose selenium

OBJECTIVE

Low levels of selenium (Se) and glutathione peroxidase (GSHPx), a key selenoenzyme, were documented in systemic inflammatory response syndrome (SIRS) and sepsis, both associated with high mortality. Se supplementation had mixed effects on outcome. We hypothesized that Se supplementation could have a different impact on biomarkers and 28-day mortality in patients with SIRS vs. sepsis.

METHODS

Adult patients with SIRS or sepsis were randomized to either high-dose (Se+, n = 75) or standard-dose (Se-, n = 75) Se supplementation. Plasma Se, whole blood GSHPx activity, C-reactive protein (CRP), procalcitonin (PCT), prealbumin, albumin and cholesterol levels were measured serially up to day 14.

RESULTS

There was no difference in mortality between Se- (24/75) vs. Se+ group (19/75; p = 0.367) or between SIRS and septic patients (8/26 vs. 35/124; p = 0.794). There was a trend to reduced mortality in SIRS patients in the Se+ vs. Se- group (p = 0.084). Plasma Se levels increased in the Se+ group only in patients with sepsis but not in patients with SIRS. Plasma Se levels correlated with GSHPx. In SIRS/Se+ group, Se correlated only with GSHPx. In SIRS/Se- group, Se correlated with cholesterol but not with other biomarkers. In sepsis patients, Se levels correlated with cholesterol, GSHPx and prealbumin. Cholesterol levels were higher in survivors in the Se- group.

CONCLUSIONS

Se levels correlated with GSHPx activity and other nutritional biomarkers with significant differences between SIRS and sepsis groups. High-dose Se supplementation did not affect mortality but a strong trend to decreased mortality in SIRS patients warrants further studies in this population.

Sulfur and selenium antioxidants: challenging radical scavenging mechanisms and developing structure-activity relationships based on metal binding

Because sulfur and selenium antioxidants can prevent oxidative damage, numerous animal and clinical trials have investigated the ability of these compounds to prevent the oxidative stress that is an underlying cause of cardiovascular disease, Alzheimer's disease, and cancer, among others. One of the most common sources of oxidative damage is metal-generated hydroxyl radical; however, very little research has focused on determining the metal-binding abilities and structural attributes that affect oxidative damage prevention by sulfur and selenium compounds. In this review, we describe our ongoing investigations into sulfur and selenium antioxidant prevention of iron- and copper-mediated oxidative DNA damage. We determined that many sulfur and selenium compounds inhibit Cu(I)-mediated DNA damage and that DNA damage prevention varies dramatically when Fe(II) is used in place of Cu(I) to generate hydroxyl radical. Oxidation potentials of the sulfur or selenium compounds do not correlate with their ability to prevent DNA damage, highlighting the importance of metal coordination rather than reactive oxygen species scavenging as an antioxidant mechanism. Additional gel electrophoresis, mass spectrometry, and UV-visible studies confirmed sulfur and selenium antioxidant binding to Cu(I) and Fe(II). Ultimately, our studies established that both the hydroxyl-radical-generating metal ion and the chemical environment of the sulfur or selenium significantly affect DNA damage prevention and that metal coordination is an essential mechanism for these antioxidants.

Pharmaconutrition with selenium in critically ill patients: what do we know?

Selenium is a component of selenoproteins with antioxidant, anti-inflammatory, and immunomodulatory properties. Systemic inflammatory response syndrome (SIRS), multiorgan dysfunction (MOD), and multiorgan failure (MOF) are associated with an early reduction in plasma selenium and glutathione peroxidase activity (GPx), and both parameters correlate inversely with the severity of illness and outcomes. Several randomized clinical trials (RCTs) evaluated selenium therapy as monotherapy or in antioxidant cocktails in intensive care unit (ICU) patient populations, and more recently several meta-analyses suggested benefits with selenium therapy in the most seriously ill patients. However, the largest RCT on pharmaconutrition with glutamine and antioxidants, the REducing Deaths due to Oxidative Stress (REDOXS) Study, was unable to find any improvement in clinical outcomes with antioxidants provided by the enteral and parenteral route and suggested harm in patients with renal dysfunction. Subsequently, the MetaPlus study demonstrated increased mortality in medical patients when provided extra glutamine and selenium enterally. The treatment effect of selenium may be dependent on the dose, the route of administration, and whether administered with other nutrients and the patient population studied. Currently, there are few small studies evaluating the pharmacokinetic profile of intravenous (IV) selenium in SIRS, and therefore more data are necessary, particularly in patients with MOD, including those with renal dysfunction. According to current knowledge, high-dose pentahydrate sodium selenite could be given as an IV bolus injection (1000-2000 µg), which causes transient pro-oxidant, cytotoxic, and anti-inflammatory effects, and then followed by a continuous infusion of 1000-1600 µg/d for up to 10-14 days. Nonetheless, the optimum dose and efficacy still remain controversial and need to be definitively established.