Micronutrients early in critical illness, selective or generous, enteral or intravenous?

Micronutrients as therapy in critical illness

PURPOSE OF REVIEW

Recent large-scale randomized controlled trials (RCTs) challenged current beliefs about the potential role of micronutrients to attenuate the inflammatory response and improve clinical outcomes of critically ill patients. The purpose of this narrative review is to provide an overview and critical discussion about most recent clinical trials, which evaluated the clinical significance of a vitamin C, vitamin D, or selenium administration in critically ill patients.

RECENT FINDINGS

None of the most recent large-scale RCTs could demonstrate any clinical benefits for a micronutrient administration in ICU patients, whereas a recent RCT indicated harmful effects, if high dose vitamin C was administered in septic patients. Following meta-analyses could not confirm harmful effects for high dose vitamin C in general critically ill patients and indicated benefits in the subgroup of general ICU patients with higher mortality risk. For vitamin D, the most recent large-scale RCT could not demonstrate clinical benefits for critically ill patients, whereas another large-scale RCT is still ongoing. The aggregated and meta-analyzed evidence highlighted a potential role for intravenous vitamin D administration, which encourages further research. In high-risk cardiac surgery patients, a perioperative application of high-dose selenium was unable to improve patients' outcome. The observed increase of selenium levels in the patients' blood did not translate into an increase of antioxidative or anti-inflammatory enzymes, which illuminates the urgent need for more research to identify potential confounding factors.

SUMMARY

Current data received from most recent large-scale RCTs could not demonstrate clinically meaningful effects of an intervention with either vitamin C, vitamin D, or selenium in critically ill patients. More attention is needed to carefully identify potential confounding factors and to better evaluate the role of timing, duration, and combined strategies.

Relationship of blood thiamine pyrophosphate to plasma phosphate and the response to enteral nutrition plus co-administration of intravenous thiamine during critical illness

BACKGROUND

Hypovitamin B1 occurs frequently during critical illness but is challenging to predict or rapidly diagnose. The aim of this study was to evaluate whether plasma phosphate concentrations predict hypovitamin B1, enteral nutrition prevents hypovitamin B1 and intravenous thiamine supplementation achieves supraphysiological concentrations in critically ill patients.

METHODS

Thirty-two enterally fed critically ill patients, with a plasma phosphate concentration ≤0.65 mmol/L, formed a nested cohort within a larger randomised clinical trial. Patients were assigned to receive intravenous thiamine (200 mg) twice daily, and controls were not administered intravenous thiamine. Thiamine pyrophosphate concentrations were measured at four time points (pre- and post-infusion and 4- and 6-h post-infusion) on days 1 and 3 in those allocated to thiamine and once in the control group.

RESULTS

Baseline thiamine pyrophosphate concentrations were similar (intervention 88 [67, 93] vs. control 89 [62, 110] nmol/L, p = 0.49). Eight (25%) patients had hypovitamin B1 (intervention 3 vs. control 5), with two patients in the control group remaining insufficient at day 3. There was no association between baseline phosphate and thiamine pyrophosphate concentrations. Intravenous thiamine achieved supraphysiological concentrations 6 h post first infusion, with concentrations increasing to day 3. In the control group, thiamine pyrophosphate concentrations were not statistically different between baseline and day 3 (mean change: 8.6 [-6.0, 23.1] nmol/L, p = 0.25).

CONCLUSIONS

Phosphate concentrations did not predict hypovitamin B1, which was observed in 25% of the participants. Enteral nutrition alone prevented the development of new hypovitamin B1. Administration of a single 200-mg dose of intravenous thiamine achieved supraphysiological concentrations of thiamine pyrophosphate, with repeated dosing sustaining this effect.

Nutrition after severe burn injury

PURPOSE OF REVIEW

Severe burn injury causes significant metabolic changes and demands that make nutritional support particularly important. Feeding the severe burn patient is a real challenge in regard to the specific needs and the clinical constraints. This review aims to challenge the existing recommendations in the light of the few recently published data on nutritional support in burn patients.

RECENT FINDINGS

Some key macro- and micro-nutrients have been recently studied in severe burn patients. Repletion, complementation or supplementation of omega-3 fatty acids, vitamin C, vitamin D, antioxidant micronutrients may be promising from a physiologic perspective, but evidence of benefits on hard outcomes is still weak due to the studies' design. On the contrary, the anticipated positive effects of glutamine on the time to discharge, mortality and bacteremias have been disproved in the largest randomized controlled trial investigating glutamine supplementation in burns. An individualized approach in term of nutrients quantity and quality may proof highly valuable and needs to be validated in adequate trials. The combination of nutrition and physical exercises is another studied strategy that could improve muscle outcomes.

SUMMARY

Due to the low number of clinical trials focused on severe burn injury, most often including limited number of patients, developing new evidence-based guidelines is challenging. More high-quality trials are needed to improve the existing recommendations in the very next future.

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.

Selenocompounds and Sepsis-Redox Bypass Hypothesis: Part B-Selenocompounds in the Management of Early Sepsis

Significance: Endothelial barrier damage, which is in part caused by excess production of reactive oxygen, halogen and nitrogen species (ROHNS), especially peroxynitrite (ONOO^-), is a major event in early sepsis and, with leukocyte hyperactivation, part of the generalized dysregulated immune response to infection, which may even become a complex maladaptive state. Selenoenzymes have major antioxidant functions. Their synthesis is related to the need to limit deleterious oxidant redox cycling by small selenocompounds, which may be of therapeutic cytotoxic interest. Plasma selenoprotein-P is crucial for selenium transport from the liver to the tissues and for antioxidant endothelial protection, especially against ONOO^-. Above micromolar concentrations, sodium selenite (Na₂SeO₃) becomes cytotoxic, with a lower cytotoxicity threshold in activated cells, which has led to cancer research. Recent Advances: Plasma selenium (<2% of total body selenium) is mainly contained in selenoprotein-P, and concentrations decrease rapidly in the early phase of sepsis, because of increased selenoprotein-P binding and downregulation of hepatic synthesis and excretion. At low concentrations, Na₂SeO₃ acts as a selenium donor, favoring selenoprotein-P synthesis in physiology, but probably not in the acute phase of sepsis. Critical Issues: The cytotoxic effects of Na₂SeO₃ against hyperactivated leukocytes, especially the most immature forms that liberate ROHNS, may be beneficial, but they may also be harmful for activated endothelial cells. Endothelial protection against ROHNS by selenoprotein-P may reduce Na₂SeO₃ toxicity, which is increased in sepsis. Future Direction: The combination of selenoprotein-P for endothelial protection and the cytotoxic effects of Na₂SeO₃ against hyperactivated leukocytes may be a promising intervention for early sepsis. Antioxid. Redox Signal. 37, 998-1029.

Delayed increase of plasma selenoproteins and absence of side effect induced by infusion of pharmacological dose of sodium selenite in septic shock: Secondary analysis of a multicenter, randomized controlled trial

BACKGROUND

In sepsis, neutrophil respiratory bursts participate in endothelium damage, the first step to multiple organ failure. In plasma two antioxidant selenoenzymes, which protect the endothelium, decrease: selenoprotein-P, and to a lesser extent glutathione peroxidase (GPX3). Sodium selenite (Na₂SeO₃) is a Se donor, but also an oxidant chemotherapy drug depending on its concentration. In a previous published study, Na₂SeO₃ continuous infusion in septic shock patients at a pharmacological dose of 4 mg¹ Se/day on day-1, followed by a high nutritional dose of 1 mg Se/day during 9 days, showed no beneficial effect on weaning of catecholamine nor on survival. In this ancillary study, we report clinical and biological effects of such continuous infusion of Na₂SeO_3. METHODS: This was a multicenter, placebo-controlled, double-blind study on 60 patients. Na₂SeO₃ or placebo in continuous infusion as described above. Evolution with time of plasma Se, selenoprotein-P, GPX3, Organ dysfunction (sequential organ failure assessment SOFA scores, including PaO2/FiO2, for respiratory failure, and plasma lactate) and quality of life at 6 months (by SF36 scores) were analyzed using two-way (time, treatment) non-parametric repeated-measures analysis of variance (Friedman test).

MAIN RESULTS

At baseline, plasma Se was about a quarter of reference values. From baseline to day-4 plasma Se, selenoprotein-P and GPX3 significantly increased by 3.9, 2.7 and 1.8 respectively in the Na₂SeO₃ group as compared with placebo and remained elevated by 2.3, 2.7 and 2.1 at day-14 respectively (p < 0.001). Na₂SeO₃ did not affect global and organ by organ SOFA Scores and plasma lactate concentration at day-1 and later up to day-14. The evolution of PaO2/FiO2 until day-14 was similar in the two groups. Quality of life in the surviving patients at 6 months was similar between the two groups.

CONCLUSION

Continuous infusion of Na₂SeO₃ at 4 mg Se at day-1 seems to have neither beneficial nor toxic effect at day-1 or later and induces a late increase of selenoprotein-P at day-4. Preclinical studies are required to confirm the use of Na₂SeO₃ as a cytotoxic drug against neutrophils and protection of the endothelium by selenoprotein-P.

Insights Into Thiamine Supplementation in Patients With Septic Shock

Septic shock is associated with unacceptably high mortality rates, mainly in developing countries. New adjunctive therapies have been explored to reduce global mortality related to sepsis. Considering that metabolic changes, mitochondrial dysfunction and increased oxidative stress are specific disorders within the path of septic shock, several micronutrients that could act in cellular homeostasis have been studied in recent decades. Thiamine, also known as vitamin B1, plays critical roles in several biological processes, including the metabolism of glucose, synthesis of nucleic acids and reduction of oxidative stress. Thiamine deficiency could affect up to 70% of critically ill patients, and thiamine supplementation appears to increase lactate clearance and decrease the vasopressor dose. However, there is no evident improvement in the survival of septic patients. Other micronutrients such as vitamin C and D, selenium and zinc have been tested in the same context but have not been shown to improve the outcomes of these patients. Some problems related to the neutrality of these clinical trials are the study design, doses, route, timing, length of intervention and the choice of endpoints. Recently, the concept that multi-micronutrient administration may be better than single-micronutrient administration has gained strength. In general, clinical trials consider the administration of a single micronutrient as a drug. However, the antioxidant defense is a complex system of endogenous agents in which micronutrients act as cofactors, and the physiological interactions between micronutrients are little discussed. In this context, the association of thiamine, vitamin C and corticoids was tested as an adjunctive therapy in septic shock resulting in a significant decrease in mortality. However, after these initial results, no other study conducted with this combination could reproduce those benefits. In addition, the use of low-dose corticosteroids is recommended in patients with septic shock who do not respond to vasopressors, which can affect the action of thiamine. Therefore, given the excellent safety profile, good biologic rationale and promising clinical studies, this review aims to discuss the mechanisms behind and the evidence for single or combined thiamine supplementation improving the prognosis of patients with septic shock.

Course and Survival of COVID-19 Patients with Comorbidities in Relation to the Trace Element Status at Hospital Admission

Selenium (Se) and zinc (Zn) are essential trace elements needed for appropriate immune system responses, cell signalling and anti-viral defence. A cross-sectional observational study was conducted at two hospitals in Ghent, Belgium, to investigate whether Se and/or Zn deficiency upon hospital admission correlates to disease severity and mortality risk in COVID-19 patients with or without co-morbidities. Trace element concentrations along with additional biomarkers were determined in serum or plasma and associated to disease severity and outcome. An insufficient Se and/or Zn status upon hospital admission was associated with a higher mortality rate and a more severe disease course in the entire study group, especially in the senior population. In comparison to healthy European adults, the patients displayed strongly depressed total Se (mean ± SD: 59.2 ± 20.6 vs. 84.4 ± 23.4 µg L⁻¹) and SELENOP (mean ± SD: 2.2 ± 1.9 vs. 4.3 ± 1.0 mg L⁻¹) concentrations at hospital admission. Particularly strong associations were observed for death risk of cancer, diabetes and chronic cardiac disease patients with low Se status, and of diabetes and obese patients with Zn deficiency. A composite biomarker based on serum or plasma Se, SELENOP and Zn at hospital admission proved to be a reliable tool to predict severe COVID-19 course and death, or mild disease course. We conclude that trace element assessment at hospital admission may contribute to a better stratification of patients with COVID-19 and other similar infectious diseases, support clinical care, therapeutic interventions and adjuvant supplementation needs, and may prove of particular relevance for patients with relevant comorbidities.

A multicenter randomized clinical trial of pharmacological vitamin B1 administration to critically ill patients who develop hypophosphatemia during enteral nutrition (The THIAMINE 4 HYPOPHOSPHATEMIA trial)

BACKGROUND

Hypophosphatemia may be a useful biomarker to identify thiamine deficiency in critically ill enterally-fed patients. The objective was to determine whether intravenous thiamine affects blood lactate, biochemical and clinical outcomes in this group.

METHOD

This randomized clinical trial was conducted across 5 Intensive Care Units. Ninety critically ill adult patients with a serum phosphate ≤0.65 mmol/L within 72 h of commencing enteral nutrition were randomized to intravenous thiamine (200 mg every 12 h for up to 14 doses) or usual care (control). The primary outcome was blood lactate over time and data are median [IQR] unless specified.

RESULTS

Baseline variables were well balanced (thiamine: lactate 1.2 [1.0, 1.6] mmol/L, phosphate 0.56 [0.44, 0.64] mmol/L vs. control: lactate 1.0 [0.8, 1.3], phosphate 0.54 [0.44, 0.61]). Patients randomized to the intervention received a median of 11 [7.5, 13.5] doses for a total of 2200 [1500, 2700] mg of thiamine. Blood lactate over the entire 7 days of treatment was similar between groups (mean difference = -0.1 (95 % CI -0.2 to 0.1) mmol/L; P = 0.55). The percentage change from lactate pre-randomization to T = 24 h was not statistically different (thiamine: -32 (-39, -26) vs. control: -24 (-31, -16) percent, P = 0.09). Clinical outcomes were not statistically different (days of vasopressor administration: thiamine 2 [1, 4] vs. control 2 [0, 5.5] days; P = 0.37, and deaths 9 (21 %) vs. 5 (11 %); P = 0.25).

CONCLUSIONS

In critically ill enterally-fed patients who developed hypophosphatemia, intravenous thiamine did not cause measurable differences in blood lactate or clinical outcomes.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry (ACTRN12619000121167).