Update on antioxidant micronutrients in the critically ill

The Effect of Parenteral Selenium Therapy on Serum Concentration of Inflammatory Mediators: a Systematic Review and Dose-Response Meta-Analysis of Randomized Clinical Trials

Selenium can protect against inflammation through its incorporation in selenoenzymes; therefore, in this study, we assessed the effect of parenteral selenium on C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) through a systematic review and meta-analysis on randomized controlled trials (RCTs). A systematic search was performed in the databases, including PubMed, Scopus, Cochrane, clinicaltrials.gov, and ISI Web of Science, up to October 2022, with no limitation in study location or publication time. We calculated the effect size by the mean change from baseline in serum concentration of selected inflammatory mediators and their standard deviations. DerSimonian and Laird random effects model was used to estimate the heterogeneity and summary of the overall effects. Included studies in this systematic review and meta-analysis were 10 and 8 RCTs, respectively. Our results revealed parenteral selenium significantly decreased serum IL-6 (Weighted Mean Difference (WMD) = -3.85 pg/ml; 95% confidence interval (CI) = -7.37, -0.34 pg/ml; p = 0.032) but did not significantly change serum levels of CRP (WMD = 4.58 mg/L; 95% CI = -6.11, 15.27 mg/L; P = 0.401) compared to the comparison groups. According to our results, parenteral selenium supplementation might reduce serum levels of inflammatory mediators.

Zinc levels of patients with a moderate to severe COVID-19 infection at hospital admission and after 4th days of ward hospitalization and their clinical outcome

BACKGROUND

Previous studies associate the disturbance of the Zinc (Zn) status with the severity of the disease and the inflammatory process in the critically ill patient. This decrease in Zn concentrations is an indicator of poor prognosis. Our aim was to evaluate Zn levels at admission and after four days, and to study if lower Zn levels at those days were related to a worse clinical outcome.

MATERIAL AND METHODS

Observational cohort study at a tertiary Hospital. Recruitment period: 09/04/2020-04/24/2021. Clinical information on hypertension, diabetes mellitus (DM), chronic obstructive pulmonary disease (COPD), or bronchial asthma was collected. Obesity was defined as BMI ≥ 30 Kg/m2. Blood extraction was performed at admission and after 4 days. Zn was measured by atomic absorption using a flame method. Worse clinical outcome was defined as death during admission, intensive critical care unit admission or receiving supplemental oxygen through noninvasive or invasive ventilator care.

RESULTS

129 subjects were invited to participate but only 100 subjects completed the survey. According to ROC curve [AUC= 0.63 (95% CI 0.60-0.66)], Zn < 79 μg/dL showed the best performance to detect a worse outcome (Sn=0.85; Sp=0.36). Patients with Zn < 79 μg/dL were older (70 vs 61 y; p = 0.002) with no differences by sex. Most patients presented with fever, dysthermic symptoms and cough, without differences between groups. Pre-existing comorbid conditions did not differ significantly between groups. Less obese subjects were found in the Zn < 79 μg/dL group (21.4 vs 43.3%, p = 0.025). In the univariate analysis, Zn < 79 μg/dL at hospital admission was related to a worse outcome (p = 0.044), but after adjusting for age, C-reactive protein, and obesity there was no difference, but a tendency towards a worse prognosis [OR 2.20 (0.63-7.70), p = 0.215]. Zn levels increased in both groups after 4 days (66.6 vs 73.1 μg/dL at admission, and 72.2 vs 80.5 μg/dL at 4th day), with ns. difference (p = 0.214).

CONCLUSION

Zn < 79 μg/dL at admission for a moderate to severe COVID-19 infection could be related to a worse outcome, although after adjustment for age, C-reactive protein levels and obesity, this Zn level threshold did not show statistically significant difference in the composite end point, but a tendency towards a worse prognosis. In addition, patients with the best clinical evolution showed higher serum Zn levels at 4th day after hospital admission than the patients with a worse prognosis.

Thiamine pharmaconutrition in sepsis: Monotherapy, combined therapy, or neither? Current evidence on safety and efficacy

Sepsis is a life-threatening condition characterized by multiorgan dysfunction due to an exaggerated host response to infection associated with a homeostatic failure. In sepsis, different interventions, aimed at improving clinical outcomes, have been tested over the past decades. Among these most recent strategies, intravenous high-dose micronutrients (vitamins and/or trace elements) have been investigated. According to current knowledge, sepsis is characterized by low thiamine levels, which are associated with illness severity, hyperlactatemia, and poor clinical outcomes. However, caution is needed about the clinical interpretation of thiamine blood concentration in critically ill patients, and the inflammatory status, based on C-reactive protein levels, should always be measured. In sepsis, parenteral thiamine has been administered as monotherapy or in combination with vitamin C and corticosteroids. Nevertheless, most of those trials failed to report clinical benefits with high-dose thiamine. The purpose of this review is to summarize the biological properties of thiamine and to examine current knowledge regarding the safety and efficacy of high-dose thiamine as pharmaconutrition strategy when administering singly or in combination with other micronutrients in critically ill adult patients with sepsis or septic shock. Our examination of the most up-to-date evidence concludes that Recommended Daily Allowance supplementation is relatively safe for thiamine-deficient patients. However, current evidence does not support pharmaconutrition with high-dose thiamine as a single therapy or as combination therapy aimed at improving clinical outcomes in critically ill septic patients. The best nutrient combination still needs to be determined, based on the antioxidant micronutrient network and the multiple interactions among different vitamins and trace elements. In addition, a better understanding of the pharmacokinetic and pharmacodynamic profiles of intravenous thiamine is needed. Future well-designed and powered clinical trials are urgently warranted before any specific recommendations can be made regarding supplementation in the critical care setting.

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.

Association Between Low Zinc Levels and Severity of Acute Respiratory Distress Syndrome by New Coronavirus SARS-CoV-2

BACKGROUND

We verify the prevalence of low zinc levels among critically ill patients infected by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in the intensive care unit (ICU) who required invasive mechanical ventilation, as well as its association with severity of acute respiratory distress syndrome (ARDS).

METHODS

This is an observational study composed of patients admitted to the ICU. Demographics, anthropometric data for calculating body mass index (BMI), and laboratory data were obtained at admission: blood count, ferritin, arterial blood gas, serum zinc levels, and C-reactive protein. Also, arterial oxygen tension (PaO₂ ) divided by fractional inspired oxygen (FiO₂ ) was calculated by the first arterial blood gas after intubation. A diagnosis of severe ARDS was determined if the PaO₂ /FiO₂ ratio was ≤100 mm Hg. Low zinc levels were established if zinc levels were <70 μg/dL.

RESULTS

A total of 269 patients met inclusion criteria; 51.3% were men; median age was 74 (66-81) years; 91.1% (245 of 269) were elderly. The median BMI was 30.1 (24.7-32.1) kg/m² , with 59.9% (161 of 269) of patients having overweight and obesity. The prevalence of low zinc levels was 79.6% (214 of 269) and severe ARDS was 56.5% (152 of 269). There was an association of low zinc levels and severe ARDS (odds ratio [OR], 14.4; 95% CI, 6.2-33.5; P < .001), even after adjusting for baseline variables (OR, 15.4; 95% CI, 6.5-36.3; P < .001).

CONCLUSION

Critically ill patients infected by SARS-CoV-2 with severe ARDS have a high prevalence of low serum zinc levels.

Parenteral Provision of Micronutrients to Adult Patients: An Expert Consensus Paper

BACKGROUND

Micronutrients, an umbrella term used to collectively describe vitamins and trace elements, are essential components of nutrition. Those requiring alternative forms of nutrition support are dependent on the prescribed nutrition regimen for their micronutrient provision. The purpose of this paper is to assist clinicians to bridge the gap between the available guidelines' recommendations and their practical application in the provision of micronutrients via the parenteral route to adult patients.

METHODS

Based on the available evidenced-based literature and existing guidelines, a panel of multidisciplinary healthcare professionals with significant experience in the provision of parenteral nutrition (PN) and intravenous micronutrients developed this international consensus paper.

RESULTS

The paper addresses 14 clinically relevant questions regarding the importance and use of micronutrients in various clinical conditions. Practical orientation on how micronutrients should be prescribed, administered, and monitored is provided.

CONCLUSION

Micronutrients are a critical component to nutrition provision and PN provided without them pose a considerable risk to nutrition status. Obstacles to their daily provision-including voluntary omission, partial provision, and supply issues-must be overcome to allow safe and responsible nutrition practice.

Effects of High-Dose Selenium Supplementation on Oxidative Stress and Inflammatory Markers in Critically Ill Children After Gastrointestinal Surgery: A Randomized Clinical Trial

Background: Pediatric observational studies have indicated that most critically ill children have low serum selenium level, which is associated with the increased incidence of multiple organ failure and deteriorated clinical outcomes. Selenium plays a key role in the endogenous antioxidant defense mechanism and inflammatory pathways. Objectives: The present study aimed to assess the effects of high-dose selenium supplementation on the improvement of inflammatory and oxidative stress indices, as well as clinical outcomes, in pediatric patients with severe oxidative stress and inflammation following major gastrointestinal surgeries. Methods: This prospective, single-blind, randomized, parallel group superiority trial was conducted at the pediatric intensive care unit (PICU) of Akbar Pediatric Hospital in Mashhad, Iran in 2019. Patients were assigned to the supplementation (high-dose selenium: 20 µg/kg/d) and control groups (placebo with the recommended dietary allowance doses of selenium) using stratified blocks. Among 72 eligible critically ill children after gastrointestinal surgery, 66 patients completed the study. Inflammatory markers were measured and compared between the groups, including high-sensitivity C-reactive protein (hsCRP), interleukin 1 beta (IL-1β), prooxidant-antioxidant balance (PAB) assay, and clinical outcomes. Data analysis was performed in SPSS version 20 using the intention-to-treat approach. Results: Only 14 patients had optimal serum selenium concentrations before the surgery and PICU admission. At the end of the study, 90.6% of the patients (n = 29) in the intervention group and 100% (n = 34) of those in the placebo group had suboptimal serum selenium levels (< 50 ng/mL). Although supplementation with high-dose selenium decreased the inflammatory markers in the post-surgical critically ill children (-18 mg/mL and -37.5 pg/mL for hsCRP and IL-1β, respectively), the administered dose could not improve the serum glutathione peroxidase (GPx) concentrations as the selenium functional marker, as well as the PAB assay as the single test to assess the balance/imbalance of the oxidants and antioxidants simultaneously. Additionally, clinical outcomes such as infections, length of ICU stay, and 28-day mortality did not improve after the intervention. Conclusions: According to the results, high-dose selenium supplementation (20 µg/kg/d) in the post-surgical critically ill children could improve the serum inflammatory markers. However, the changes were suboptimal with no significant effects of the serum GPx concentrations, antioxidant defense system, and clinical outcomes.

Effects of magnesium, phosphate and zinc supplementation in ICU patients-Protocol for a systematic review

BACKGROUND

Depletion of the trace elements magnesium, phosphate and zinc is common in patients admitted to the intensive care unit (ICU). Observational studies have suggested worse outcome in patients with hypomagnesaemia, hypophosphataemia or hypozincaemia, but also inverse associations with worse outcome with too high serum levels. However, it is unclear whether data from randomised clinical trials (RCTs) confirm this. Accordingly, we plan to assess the balance between benefits and harms of supplementation as compared with placebo or no supplementation in adult ICU patients.

METHODS

We will conduct a systematic review of RCTs with meta-analysis and trial sequential analysis in accordance with the Cochrane Handbook for Systematic Reviews of Interventions, the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement and the Grading of Recommendation, Assessment, Development and Evaluation (GRADE) approach. We will assess the effects of any supplementation with magnesium, phosphate or zinc vs. placebo or no treatment in adult ICU patients. We will systematically search the Cochrane CENTRAL, Embase, PubMed, and for unpublished trials: ClinicalTrials.gov, the EU clinical Trials Register and the WHO International Clinical Trials Registry Platform. The primary outcomes will be days alive without mechanical ventilation and overall mortality. Secondary outcomes include use for mechanical ventilation, tachy-arrhythmias, use of vasopressors, length of hospital stay and use of renal replacement therapy.

DISCUSSION

The benefits and harms of supplementation therapy with magnesium, phosphate and zinc in general ICU patients are unknown. This outlined systematic review will provide data on the evidence, on which future recommendations for supplementation may be founded.

Selenium in Cardiac Surgery

Selenium (Se) is an essential trace element that plays a pivotal role in many of the body's regulatory and metabolic functions, especially during times of stress. After uptake, Se is incorporated into several Se-dependent proteins, which have potent anti-inflammatory and antioxidant capacities. Several observational clinical studies have demonstrated that Se deficiency can cause chronic cardiovascular diseases and aggravate organ dysfunction after cardiac surgery and that low levels of Se may be independently associated with the development of organ dysfunction after cardiac surgery. Based on these findings, several studies have investigated the effects of a perioperative Se supplementation strategy. Therefore, the present review describes in depth the pathophysiology and harmful stimuli during cardiac surgery, how Se may counteract these injuries, the different types of Se supplementation strategies that have been evaluated, and current evidence of its clinical significance.

Plasma Selenium and Cadmium Levels in Patients with Chronic Otitis Media in a Turkish Population and Their Relation to Inflammation Markers

Chronic otitis media (COM) is a multifactorial process, for which a clear etiology has not yet been established. The aims of the present study were to evaluate selenium (Se) and cadmium (Cd) levels in patients with COM and to analyze the correlation between Se and Cd with inflammation markers. The study population consisted of 88 participants: 45 healthy controls (group 1) and 43 patients with COM (group 2). Demographic data, Se, Cd, C-reactive protein (CRP), and white blood cell count (WBC) levels were all recorded. Se and Cd measurements were performed in a graphite furnace atomic absorption spectrophotometer (Perkin Elmer Analyst 800) using Zeeman background correction. The Se and Cd levels were compared between the groups and the correlation between Se and Cd with inflammation markers was analyzed. No statistically significant difference was determined between the groups in terms of demographic data (p > 0.05). CRP and WBC levels were significantly higher in group 2 than in group 1 (p < 0.05). Se levels were significantly lower in group 2 than in group 1, at 23.40 ± 12.08 μg/L vs. 37.31 ± 22.44 μg/L (p < 0.05). Cd levels were significantly higher in group 2 than in group 1, at 1.79 ± 1.63 μg/L vs. 0.68 ± 0.45 μg/L (p < 0.05). When all the cases were evaluated together, a statistically significant negative correlation was determined between Se and CRP (r = - 0.239, p = 0.013) and a positive correlation between Cd and CRP (r = 0.266, p = 0.006), WBC (r = 0.258, p = 0.008). Our results could propose that Se deficiency and Cd excess could play a crucial and additive role in the etiopathogenesis of COM. However, further investigations with larger numbers of patients are warranted to determine the exact role of these elements.

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.

Vitamin C Administration to the Critically Ill: A Systematic Review and Meta-Analysis

Vitamin C, an enzyme cofactor and antioxidant, could hasten the resolution of inflammation, oxidative stress, and microvascular dysfunction. While observational studies have demonstrated that critical illness is associated with low levels of vitamin C, randomized controlled trials (RCTs) of vitamin C, alone or in combination with other antioxidants, have yielded contradicting results. We searched MEDLINE, EMBASE, CINAHL, and the Cochrane Central Register of Controlled Trials (inception to December 2017) for RCTs comparing vitamin C, by enteral or parenteral routes, with placebo or none, in intensive care unit (ICU) patients. Two independent reviewers assessed study eligibility without language restrictions and abstracted data. Overall mortality was the primary outcome; secondary outcomes were incident infections, ICU length of stay (LOS), hospital LOS, and duration of mechanical ventilation (MV). We prespecified 5 subgroups hypothesized to benefit more from vitamin C. Eleven randomized trials were included. When 9 RCTs (n = 1322) reporting mortality were pooled, vitamin C was not associated with reduced risk of mortality (risk ratio [RR] 0.72, 95% confidence interval [CI]: 0.43-1.20, P = .21). No effect was found on infections, ICU or hospital LOS, or duration of MV. In multiple subgroup comparison, no statistically significant subgroup effects were observed. However, we did observe a tendency towards a mortality reduction (RR 0.21; 95% CI: 0.04-1.05; P = .06) when intravenous high-dose vitamin C monotherapy was administered. Current evidence does not support supplementing critically ill patients with vitamin C. A moderately large treatment effect may exist, but further studies, particularly of monotherapy administration, are warranted.

Inflammatory process of patients receiving parenteral nutrition is not exclusively responsible for low selenium and glutathione peroxidase levels

OBJECTIVE

The aim of this study was to verify if the selenium status of patients residing in locations with selenium-poor soil who receive parenteral nutrition (PN) without selenium supplementation is associated with the inflammatory process.

METHODS

This was a prospective cohort study with hospitalized patients who started PN. The analyzed biochemical tests were plasma selenium, glutathione peroxidase (GPx), C-reactive protein, prealbumin, albumin, creatinine, lymphocytes, total cholesterol, high-density lipoprotein, and triglycerides.

RESULTS

Seventy-seven patients with a mean age of 56.2 ± 15.7 y were studied. Most of them used PN as a result of clinical issues (70.1%) such as, gastric, renal, or hematologic neoplasia; gastrointestinal dysfunction; pancreatitis; sepsis; trauma without surgical needs; chylothorax; and fistula not related to surgical procedure. There were low levels of plasma selenium (98.7%) and GPx (60%) and elevated C-reactive protein (98.5%) in most cases. At the beginning of PN there was no correlation between selenium and laboratory tests (P > 0.05). At the second evaluation (seventh day of PN), there was a positive correlation of selenium levels with lymphocyte levels (r = 0.36; P = 0.04). After 2 wk of PN, there was a statistically significant correlation between selenium and GPx (r = 0.70; P = 0.02).

CONCLUSIONS

Very low values of selenium and GPx from the beginning of PN were identified. The correlation of selenium levels with GPx in only 14 d of PN, regardless of inflammation, may reflect a critical selenium status, mainly because the correlation was verified after the acute phase. Therefore it is important to emphasize that supplementation should be started from the beginning of PN, especially in regions with selenium-deficient soil.

Update on metabolism and nutrition therapy in critically ill burn patients

Major burn injury triggers severe oxidative stress, a systemic inflammatory response, and a persistent hypermetabolic and hypercatabolic state with secondary sarcopenia, multiorgan dysfunction, sepsis and an increased mortality risk. Calorie deficit, negative protein balance and antioxidant micronutrient deficiency after thermal injury have been associated to poor clinical outcomes. In this context, personalized nutrition therapy with early enteral feeding from the start of resuscitation are indicated. Over the last four decades, different nutritional and pharmacological interventions aimed at modulating the immune and metabolic responses have been evaluated. These strategies have been shown to be able to minimize acute malnutrition, as well as modulate the immunoinflammatory response, and improve relevant clinical outcomes in this patient population. The purpose of this updating review is to summarize the most current evidence on metabolic response and nutrition therapy in critically ill burn patients.

Influence of selenium supplementation on patients with inflammation: A pilot double blind randomized study

OBJECTIVE

The aim of the study was to analyze the effect of selenium supplementation on patients with inflammation receiving PN.

METHODS

This double-blind randomized study included 20 hospitalized patients experiencing an inflammatory process while being fed by PN, who were monitored in three stages: first 72 h (0), day 7 (1), and day 14 (2) of PN. The supplemented patients group (G+S) received 60 μg/d (0.75 μmol) of selenium as selenious acid which was added to the PN bag. The nonsupplemented group (G-S) did not receive selenium. The concentration range of 84 to 100 μg/L (1.07-1.27 μmol/L) was used as a reference of plasma selenium.

RESULTS

The study included 20 patients (8 G+S and 12 G-S) mainly diagnosed with cancer and/or sepsis. Most of them were hospitalized in the intensive care unit and were receiving PN for clinical reasons. Plasma selenium was greater in the G+S than in the G-S (P = 0.05) in two stages (0 and 1). Since the start of assessment, C-reactive protein (CRP) levels were elevated; however, there was no statistical difference in CRP values between groups (P > 0.05). There was no significant change of glutathione peroxidase over time or between groups (P > 0.05).

CONCLUSION

The selenium concentration was greater in the G+S than in the G-S, acting independently from CRP behavior. However, supplementation was not enough to reach the reference values.

Metabolism, Metabolomics, and Nutritional Support of Patients with Sepsis

Sepsis is characterized by profound changes in systemic and cellular metabolism that disrupt normal metabolic homeostasis. These metabolic changes can serve as biomarkers for disease severity. Lactate, a metabolite of anaerobic metabolism, is the most widely used ICU biomarker and it is incorporated into multiple management algorithms. Technological advances now make broader metabolic profiling possible, with early studies identifying metabolic changes associated with sepsis mortality. Finally, given the marked changes in metabolism in sepsis and the association of worse prognosis in patients with severe metabolic derangements, we summarize the seminal trials conducted to optimize nutrition in the ICU.

Emerging therapeutic targets of sepsis-associated acute kidney injury

Sepsis-associated acute kidney injury (SA-AKI) is linked to high morbidity and mortality. To date, singular approaches to target specific pathways known to contribute to the pathogenesis of SA-AKI have failed. Because of the complexity of the pathogenesis of SA-AKI, a reassessment necessitates integrative approaches to therapeutics of SA-AKI that include general supportive therapies such as the use of vasopressors, fluids, antimicrobials, and target-specific and time-dependent therapeutics. There has been recent progress in our understanding of the pathogenesis and treatment of SA-AKI including the temporal nature of proinflammatory and anti-inflammatory processes. In this review, we discuss the clinical and experimental basis of emerging therapeutic approaches that focus on targeting early proinflammatory and late anti-inflammatory processes, as well as therapeutics that may enhance cellular survival and recovery. Finally, we include ongoing clinical trials in sepsis.

Novel relationships between oxidative stress and angiogenesis-related factors in sepsis: New biomarkers and therapies

Sepsis is a systemic uncontrolled inflammatory response in the presence of an infection. It remains a major cause of morbidity and mortality in hospitalized patients. According to its severity, sepsis can progress to three different states: severe sepsis, septic shock, and multiple organ dysfunction syndrome, related to organ dysfunction and/or tissue hypoperfusion. Different processes underlie its pathophysiology; among them are oxidative stress, endothelial and mitochondrial dysfunction, and angiogenesis-related factors. However, no studies have integrated these elements in sepsis. The main difficulty in sepsis is its diagnosis. Currently, the potential of inflammatory biomarkers in septic patients remains weak. In this context, the research into new biomarkers is essential to aid with sepsis diagnosis and prognostication. Furthermore, even though the current management of severe forms of sepsis has been effective, morbimortality remains elevated. Therefore, it is essential to explore alternative approaches to therapy development. The aim of this review is to present an update of evidence supporting the role of oxidative stress and angiogenesis-related factors in the pathophysiology of the different forms of sepsis. It proposes a novel convergence between both elements in their role in the disease, and it will cover their utility as new diagnostic tools, predictors of outcome, and as novel therapeutic targets.

Metabolic and nutritional support of critically ill patients: consensus and controversies

The results of recent large-scale clinical trials have led us to review our understanding of the metabolic response to stress and the most appropriate means of managing nutrition in critically ill patients. This review presents an update in this field, identifying and discussing a number of areas for which consensus has been reached and others where controversy remains and presenting areas for future research. We discuss optimal calorie and protein intake, the incidence and management of re-feeding syndrome, the role of gastric residual volume monitoring, the place of supplemental parenteral nutrition when enteral feeding is deemed insufficient, the role of indirect calorimetry, and potential indications for several pharmaconutrients.

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.

Carnitine deficiency in chronic critical illness

PURPOSE OF REVIEW

New insight in mitochondrial physiology has highlighted the importance of mitochondrial dysfunction in the metabolic and neuroendocrine changes observed in patients presenting with chronic critical illness. This review highlights specifically the importance of carnitine status in this particular patient population and its impact on beta-oxidation and mitochondrial function.

RECENT FINDINGS

The main function of carnitine is long chain fatty acid esterification and transport through the mitochondrial membrane. Carnitine depletion should be suspected in critically ill patients with risk factors such as prolonged continuous renal replacement therapy or chronic parenteral nutrition, and evidence of beta-oxidation impairments such as inappropriate hypertriglyceridemia or hyperlactatemia. When fatty acid oxidation is impaired, acyl-CoAs accumulate and deplete the CoA intramitochondrial pool, hence causing a generalized mitochondrial dysfunction and multiorgan failure, with clinical consequences such as muscle weakness, rhabdomyolysis, cardiomyopathy, arrhythmia or sudden death. In such situations, carnitine plasma levels should be measured along with a complete assessment of plasma amino acid, plasma acylcarnitines and urinary organic acid analysis. Supplementation should be initiated if below normal levels (20 μmol/l) of carnitine are observed. In the absence of current guidelines, we recommend an initial supplementation of 0.5-1 g/day.

SUMMARY

Metabolic modifications associated with chronic critical illness are just being explored. Carnitine deficiency in critically ill patients is one aspect of these profound and complex changes associated with prolonged stay in ICU. It is readily measurable in the plasma and can easily be substituted if needed, although guidelines are currently missing.