Immunonutrition in Critical Illness: What Is the Role?

Nutritional and metabolic modulation of inflammation in critically ill patients: a narrative review of rationale, evidence and grey areas

BACKGROUND

Inflammation is the hallmark of critical illness and triggers the neuro-endocrine stress response and an oxidative stress. Acute inflammation is initially essential for patient's survival. However, ongoing or exaggerated inflammation, due to persistent organ dysfunction, immune dysfunction or poor inflammation resolution, is associated to subsequent hypermetabolism and hypercatabolism that severely impact short and long-term functional status, autonomy, as well as health-related costs. Modulation of inflammation is thus tempting, with the goal to improve the short- and long-term outcomes of critically ill patients.

FINDINGS

Inflammation can be modulated by nutritional strategies (including the timing of enteral nutrition initiation, the provision of some specific macronutrients or micronutrients, the use of probiotics) and metabolic treatments. The most interesting strategies seem to be n-3 polyunsaturated fatty acids, vitamin D, antioxidant micronutrients and propranolol, given their safety, their accessibility for clinical use, and their benefits in clinical studies in the specific context of critical care. However, the optimal doses, timing and route of administration are still unknown for most of them. Furthermore, their use in the recovery phase is not well studied and defined.

CONCLUSION

The rationale to use strategies of inflammation modulation is obvious, based on critical illness pathophysiology and based on the increasingly described effects of some nutritional and pharmacological strategies. Regretfully, there isn't always substantial proof from clinical research regarding the positive impacts directly brought about by inflammation modulation. Some arguments come from studies performed in severe burn patients, but such results should be transposed to non-burn patients with caution. Further studies are needed to explore how the modulation of inflammation can improve the long-term outcomes after a critical illness.

A review of perioperative immune-modulating and metabolic-modulating nutrition strategies for bowel resection surgery

Focused perioperative nutrition strategies have proven benefits on the outcomes for patients undergoing major abdominal surgery. In this brief article, we will review these strategies and the evidence to support them with a focus on gastrointestinal anastomotic healing. We will elaborate the risks and benefits of enteral feeds, immune- and metabolic-modulating formulas, prebiotics and probiotics, and prehabilitation in preparation for surgery. Additionally, we will discuss the role of fish oils (eicosapentaenoic acid and docosahexaenoic acid) in the surgical patient and new data on specialized proresolving mediators in inflammation resolution. Finally, this article will consider the harmful impact surgical trauma has on the microbiome and the potential for perioperative dietary modulation to attenuate these negative effects.

Chemotherapy-Induced Changes in Plasma Amino Acids and Lipid Oxidation of Resected Patients with Colorectal Cancer: A Background for Future Studies

Previous studies have documented that FOLFOX and XELOX therapies negatively impact the metabolism of skeletal muscle and extra-muscle districts. This pilot study tested whether three-month FOLFOX or XELOX therapy produced changes in plasma amino acid levels (PAAL) (an estimation of whole-body amino acid metabolism) and in plasma levels of malondialdehyde (MDA), a marker of lipid hyper oxidation. Fourteen ambulatory, resected patients with colorectal cancer scheduled to receive FOLFOX (n = 9) or XELOX (n = 5) therapy, after overnight fasting, underwent peripheral venous blood sampling, to determine PAAL and MDA before, during, and at the end of three-month therapy. Fifteen healthy matched subjects (controls) only underwent measures of PAAL at baseline. The results showed changes in 87.5% of plasma essential amino acids (EAAs) and 38.4% of non-EAAs in patients treated with FOLFOX or XELOX. These changes in EAAs occurred in two opposite directions: EAAs decreased with FOLFOX and increased or did not decrease with XELOX (interactions: from p = 0.034 to p = 0.003). Baseline plasma MDA levels in both FOLFOX and XELOX patients were above the normal range of values, and increased, albeit not significantly, during therapy. In conclusion, three-month FOLFOX or XELOX therapy affected plasma EAAs differently but not the baseline MDA levels, which were already high.

Exploring the impact of arginine-supplemented immunonutrition on length of stay in the intensive care unit: A retrospective cross-sectional analysis

BACKGROUND

Arginine-supplemented enteral immunonutrition has been designed to optimize outcomes in critical care patients. Existing formulas may be isocaloric and isoproteic, yet differ in L-arginine content, energy distribution, and in source and amount of many other specialized ingredients. The individual contributions of each may be difficult to pinpoint; however, all cumulate in the body's response to illness and injury. The study objective was to compare health outcomes between different immunonutrition formulas.

METHODS

Real-world data from October 2015 -February 2019 in the PINC AI™ Healthcare Database (formerly the Premier Healthcare Database) was reviewed for patients with an intensive care unit (ICU) stay and ≥3 days exclusive use of either higher L-arginine formula (HAF), or lower L-arginine formula (LAF). Multivariable generalized linear model regression was used to check associations between formulas and ICU length of stay.

RESULTS

3,284 patients (74.5% surgical) were included from 21 hospitals, with 2,525 receiving HAF and 759 LAF. Inpatient mortality (19.4%) and surgical site infections (6.2%) were similar across groups. Median hospital stay of 17 days (IQR: 16) did not differ by immunonutrition formula. Median ICU stay was shorter for patients receiving HAF compared to LAF (10 vs 12 days; P<0.001). After adjusting for demographics, visit, severity of illness, and other clinical characteristics, associated regression-adjusted ICU length of stay for patients in the HAF group was 11% shorter [0.89 (95% CI: 0.84, 0.94; P<0.001)] compared to patients in the LAF group. Estimated adjusted mean ICU length of stay was 9.4 days (95% CI: 8.9, 10.0 days) for the HAF group compared to 10.6 days (95% CI: 9.9, 11.3 days) for the LAF group (P<0.001).

CONCLUSIONS

Despite formulas being isocaloric and isoproteic, HAF use was associated with significantly reduced ICU length of stay, compared to LAF. Higher arginine immunonutrition formula may play a role in improving health outcomes in primarily surgical critically ill patients.

Modifications of lung microbiota structure in traumatic brain injury ventilated patients according to time and enteral feeding formulas: a prospective randomized study

BACKGROUND

Specialized diets enriched with immune nutrients could be an important supplement in patients (pts) with acute traumatic brain injury (TBI). Omega-3 and arginine may interact with immune response and microbiota. No data are available about the role of the specialized diets in modulating the lung microbiota, and little is known about the influence of lung microbiota structure in development of ventilator-associated pneumonia (VAP) in TBI pts. The aims of this study are to evaluate the impact of specific nutrients on the lung microbiota and the variation of lung microbiota in TBI pts developing VAP.

METHODS

A cohort of 31 TBI pts requiring mechanical ventilation in ICU was randomized for treatment with specialized (16pts) or standard nutrition (15pts). Alpha and beta diversity of lung microbiota were analyzed from bronco Alveolar Lavage (BAL) samples collected at admission and 7 days post-ICU admission in both groups. A further analysis was carried out on the same samples retrospectively grouped in VAP or no VAP pts.

RESULTS

None developed VAP in the first week. Thereafter, ten out of thirty-one pts developed VAP. The BAL microbiota on VAP group showed significant differences in beta diversity and Staphylococcus and Acinetobacter Genera were high. The specialized nutrition had influence on beta diversity that reached statistical significance only in Bray-Curtis distance.

CONCLUSION

Our data suggest that TBI patients who developed VAP during ICU stay have different structures of BAL microbiota either at admission and at 7 days post-ICU admission, while no correlation has been observed between different enteral formulas and microbiota composition in terms of richness and evenness. These findings suggest that targeting the lung microbiota may be a promising approach for preventing infections in critically ill patients.

[Immunomodulation by nutritional intervention in critically ill patients]

Critically ill patients often suffer from a complex and severe immunological dysfunction. The differentiation and function of human immune cells are fundamentally controlled through metabolic processes. New concepts of immunonutrition therefore try to use enteral and parenteral nutrition to positively impact on the immune function of intensive care unit patients. This review article concisely presents the currently available evidence on the commonly used isolated supplements (anti-oxidative substances, amino acids, essential fatty acids) and difficulties related to their clinical use. The second part presents new and more comprehensive concepts of immunonutrition to influence the intestinal microbiome and to modulate the macronutrient composition. Immunonutrition of critically ill patients bears enormous potential and could become a valuable clinical tool for modulation of the immunometabolism of intensive care unit patients.

The interplay between hypovitaminosis D and the immune dysfunction in the arteriovenous thrombotic complications of the sever coronavirus disease 2019 (COVID-19) infection

Thromboembolic complications including cerebrovascular accidents, pulmonary embolism, myocardial infarction, deep vein thrombosis and disseminating intravascular coagulopathy are serious encounters in sever coronavirus disease 2019 (COVID-19) infected patients. This worsens the prognosis and may lead to death or life long morbidities. The laboratory finding of the disturbed haemostasias and the hyperinflammatory response are almost invariably present in COVID-19 patients. Multiple treatment modalities are utilized by the healthcare professionals to overcome the cytokine storm, oxidative stress, endothelial dysfunction, and coagulopathy in these patients. The combined actions of vitamin D (VitD) as a steroid hormone with anti-inflammatory, immunomodulatory, and antithrombotic properties increase the potential of the possible involvement of hypovitaminosis D in the thromboembolic complications of COVID-19 infection, and stimulated researchers and physicians to administer VitD therapy to prevent the infection and/or overcome the disease complications. The current review highlighted the immunomodulatory, anti-inflammatory, antioxidative and hemostatic functions of VitD and its interrelation with the renin-angiotensin-aldosterone system (RAAS) pathway and the complement system. Additionally, the association of VitD deficiency with the incidence and progression of COVID-19 infection and the associated cytokine storm, oxidative stress, hypercoagulability, and endothelial dysfunction were emphasized. Normalizing VitD levels by daily low dose therapy in patients with hypovitaminosis D below (25 nmol/l) is essential for a balanced immune response and maintaining the health of the pulmonary epithelium. It protects against upper respiratory tract infections and decreases the complications of COVID-19 infections. Understanding the role of VitD and its associated molecules in the protection against the coagulopathy, vasculopathy, inflammation, oxidative stress and endothelial dysfunction in COVID-19 infection could lead to new therapeutic strategies to prevent, treat, and limit the complications of this deadly virus infection.

Enteral nutrition product formulations: A review of available products and indications for use

When oral nutrition is not feasible, enteral nutrition (EN) therapy is often considered the preferred route of nutrition support to meet the nutrient needs of individuals with a functional gastrointestinal tract across multiple levels of care (critical care, acute care, and home care). Enteral formulations have progressively evolved over the last 50 years from the simple blending of hospital food thin enough to run through a feeding tube, to the development of commercial standard formulas, followed by specialized formulas with immune-modulating and disease-specific qualities, to the most recent shift to food-based or blenderized EN composed of natural, whole foods with perceived health benefits. With the vast number of enteral formulations on the market, clinicians may be overwhelmed trying to determine proven vs theoretical benefits. This review is intended to explore differences in enteral formulations, identify implications for clinical practice, and review evidenced-based clinical guidelines to assist clinicians in enteral formula selection.

Application strategy and effect analysis of nutritional support nursing for critically ill patients in intensive care units

We investigate nutritional support and nursing status of critical patients in intensive care units (ICUs) to understand the latest nutritional support guidelines' implementation by clinical medical staff; identify problems in nutritional support and nursing for these patients, analyze causes, and present suggestions; and provide a clinical/theoretical bases to improve nutritional support implementation and nursing strategies for them. Clinical case information of 304 critically ill ICU patients admitted from July 2017 to July 2021 was analyzed. They were divided into the experimental (nutritional support) and control (no nutritional support) groups to compare their laboratory indicators, 28-day case fatality rate, and infection incidence. Least significant difference was used for postanalysis of statistically significant items to obtain pairwise comparisons. Nutrition support strategies for ICU patients are consistent with guidelines but have an implementation gap. No statistically significant differences were found in hemoglobin (HB), total serum protein (TP), serum albumin (ALB), transferrin (TF), prealbumin (PA), and total lymphocyte count (TLC) in experimental group patients compared with the control group within 24 hours (before nutritional support, P > .05). No statistically significant differences were also found in HB, TP, TLC, and ALB between the enteral nutrition + parenteral nutrition (EN + PN), total EN (TEN), total PN (TPN), and control groups on admission day 7 (after nutritional support, P > .05), while statistically significant differences existed between PA and TF (P < .05). TF of patients supported by TEN was higher (statistically significant difference, P < .05). PA in patients receiving TEN and EN + PN support was higher than in control group patients (statistically significant difference, P < .05). Compared with the control group, in experimental group patients, infection incidence was significantly lower (40.2% vs 62.9%, P < .05); incidence of complications was lower, but not statistically significant (40.2% vs 57.1%, P > .05); and 28-day mortalities were significantly lower (26.7% vs 45.7%, P < .05). Nutritional support can reduce hospitalization complications and 28-day mortality in critical patients, but its implementation must be standardized. Especially for patients with gastrointestinal dysfunction, personalized/standardized nutrition strategies and nursing procedures are needed when PN support is applied, and training of clinical medical staff should be strengthened to improve nutrition support's efficiency.

Disease-Related Malnutrition and Enteral Nutrition

There are many misconceptions surrounding the diagnosing and treatment of malnutrition and around feeding people with enteral nutrition (EN). Often the decisions made by clinicians are made from anecdote or guidelines that may be out of date or supported by low-quality evidence. In this article, we will discuss different aspects of diagnosing malnutrition and delve deeper into the science and evidence behind certain recommendations. Our goal is to better equip the reader with the most current data-supported recommendation, such as indications, contraindications, complications of EN, tube and ostomy complications, types and use of specialized enteral formulas, and home management.

Healthcare Resource Utilization and Cost Comparisons of High-Protein Enteral Nutrition Formulas Used in Critically Ill Patients

Background: High-protein enteral nutrition is advised for patients who are critically ill. Options include immunonutrition formulas of various compositions and standard high-protein formulas (StdHP). Additional research is needed on the health economic value of immunonutrition in a broad cohort of severely ill hospitalized patients. Objective: The study goal was to compare healthcare resource utilization (HCRU) and cost between immunonutrition and StdHP using real-world evidence from a large US administrative database. Methods: A retrospective cohort study was designed using the PINC AI™ Healthcare Database from 2015 to 2019. IMPACT® Peptide 1.5 (IP) was compared with Pivot® 1.5 (PC), and StdHP formulas. Inclusion criteria comprised patients age 18+ with at least 1 day's stay in the intensive care unit (ICU) and at least 3 out of 5 consecutive days of enteral nutrition. Pairwise comparisons of demographics, clinical characteristics, HCRU, and costs were conducted between groups. Multivariable regression was used to assess total hospital cost per day associated with enteral nutrition cohort. Results: A total of 5752 patients were identified across 27 hospitals. Overall, a median 7 days of enteral nutrition was received over a 16-day hospital and 10-day ICU stay. Median total and daily hospital costs were lower for IP vs PC ($71 196 vs $80 696, P<.001) and ($4208 vs $4373, P=.019), with each higher than StdHP. However, after controlling for covariates such as mortality risk, surgery, and discharge disposition, average total hospital cost per day associated with IP use was 24% lower than PC, and 12% lower than StdHP (P<.001). Readmissions within 30 days were less frequent for patients receiving IP compared with PC (P<.02) and StdHP (P<.001). Discussion: Choice of high-protein enteral nutrition for patients in the ICU has implications for HCRU and daily hospital costs. Considering these correlations is important when comparing formula ingredients and per unit costs. Among the enteral nutrition products studied, IP emerged as the most cost-saving option, with lower adjusted hospital cost per day than PC or StdHP. Conclusions: Using a select immunonutrition formula for critically ill patients may provide overall cost savings for the healthcare system.

The Effect of Enteral Immunonutrition in the Intensive Care Unit: Does It Impact on Outcomes?

Background: The present research aimed to evaluate the effect on outcomes of immunonutrition (IMN) enteral formulas during the intensive care unit (ICU) stay. Methods: A multicenter prospective observational study was performed. Patient characteristics, disease severity, nutritional status, type of nutritional therapy and outcomes, and laboratory parameters were collected in a database. Statistical differences were analyzed according to the administration of IMN or other types of enteral formulas. Results: In total, 406 patients were included in the analysis, of whom 15.02% (61) received IMN. Univariate analysis showed that patients treated with IMN formulas received higher mean caloric and protein intake, and better 28-day survival (85.2% vs. 73.3%; p = 0.014. Unadjusted Hazard Ratio (HR): 0.15; 95% CI (Confidence Interval): 0.06−0.36; p < 0.001). Once adjusted for confounding factors, multivariate analysis showed a lower need for vasopressor support (OR: 0.49; 95% CI: 0.26−0.91; p = 0.023) and continuous renal replacement therapies (OR: 0.13; 95% CI: 0.01−0.65; p = 0.049) in those patients who received IMN formulas, independently of the severity of the disease. IMN use was also associated with higher protein intake during the administration of nutritional therapy (OR: 6.23; 95% CI: 2.59−15.54; p < 0.001), regardless of the type of patient. No differences were found in the laboratory parameters, except for a trend toward lower triglyceride levels (HR: 0.97; 95% CI: 0.95−0.99; p = 0.045). Conclusion: The use of IMN formulas may be associated with better outcomes (i.e., lower need for vasopressors and continuous renal replacement), together with a trend toward higher protein enteral delivery during the ICU stay. These findings may ultimately be related to their modulating effect on the inflammatory response in the critically ill. NCT Registry: 03634943.

Medium-Chain Triglyceride (MCT) Content of Adult Enteral Tube Feeding Formulas and Clinical Outcomes. A Systematic Review

Available data on the effect of lipid composition of enteral formulas on clinical outcomes are controversial. The present systematic review was performed in order to verify whether the presence of specific lipidic substrates, namely medium-chain triglycerides (MCT), in enteral tube feeding formulas is associated to measurable clinical benefits in patients receiving enteral nutrition in different clinical settings, including home enteral nutrition (HEN). The results of this systematic review highlight a lack of robust evidence supporting the use of specific types of lipids in standard or disease-specific formulas. Evidence exists, however, that MCT-containing formulas are safe and well-tolerated. Further, well-designed, adequately powered, randomized controlled trials would be needed in order to assess the superiority of MCT- containing enteral formulas over other standard or disease-specific commercially available enteral products.

Research Status and Progress of Nutritional Support Therapy for Ovarian Cancer

Ovarian cancer is one of the most fatal gynecological cancers. For most ovarian cancer patients, nutritional risk or malnutrition may accompany them for life. Regular nutritional risk screening, timely nutritional assessment and necessary nutritional treatment play an extremely important role in the process of comprehensive treatment of ovarian cancer. The nutritional status and influence of ovarian cancer patients, preoperative screening and assessment of nutritional risk, preoperative and postoperative nutritional treatment indicate that nutritional treatment of ovarian cancer is one of the key factors in the treatment of cancer. We have summarized the status and progress of nutritional support therapy for ovarian cancer. We are aimed to improve the understanding of the impact of nutritional support therapy for ovarian cancer and to guide the clinical work.

How to Increase Muscle Mass in Critically Ill Patients: Lessons Learned from Athletes and Bodybuilders

PURPOSE OF REVIEW

Decades of research on nutrition and exercise on athletes and bodybuilders has yielded various strategies to promote anabolism and improve muscle health and growth. We reviewed these interventions in the context of muscle loss in critically ill patients.

RECENT FINDINGS

For critically ill patients, ensuring optimum protein intake is important, potentially using a whey-containing source and supplemented with vitamin D and leucine. Agents like hydroxyl β-methylbutyrate and creatine can be used to promote muscle synthesis. Polyunsaturated fatty acids stimulate muscle production as well as have anti-inflammatory properties that may be useful in critical illness. Adjuncts like oxandralone promote anabolism. Resistance training has shown mixed results in the ICU setting but needs to be explored further with specific outcomes. Critically ill patients suffer from severe proteolysis during hospitalization as well as persistent inflammation, immunosuppression, and catabolism syndrome after discharge. High protein supplementation, ergogenic aids, anti-inflammatories, and anabolic adjuncts have shown potential in alleviating muscle loss and should be used in intensive care units to optimize patient recovery.

Immunonutrition effects on coping with COVID-19

COVID-19 implications are still a threat to global health. In the face of this pandemic, food and nutrition are key issues that can boost the immune system. The bioactivity of functional foods and nutrients (probiotics, prebiotics, water- and fat-soluble vitamins, minerals, flavonoids, glutamine, arginine, nucleotides, and PUFAs) contributes to immune system modulation, which establishes the status of nutrients as a factor of immune competence. These foods can contribute, especially during a pandemic, to the minimization of complications of SARS-CoV-2 infection. Therefore, it is important to support the nutritional strategies for strengthening the immune status, associated with good eating habits, as a way to confront COVID-19.

Preoperative serum cholinesterase levels as a risk factor of postoperative complications for the elderly undergoing emergency surgery

PURPOSES

An accurate assessment of preoperative malnutrition in the elderly is critically important to predicting postoperative complications. The aim of this study is to evaluate the predictive value of the preoperative serum cholinesterase levels as a risk factor for postoperative complications in the elderly who have undergone emergency surgery.

METHODS

The study comprised 60 elderly patients who had undergone emergency major gastroenterological surgery. We retrospectively investigated the relationship between the preoperative serum cholinesterase levels and postoperative complications (Clavien-Dindo classification ≥ II). Univariate and multivariate analyses were performed to evaluate the risk factors for postoperative complications.

RESULTS

Thirty-three patients (55%) developed postoperative complications. According to the univariate analysis, hemoglobin (P = 0.018), albumin (P = 0.0036), cholinesterase (P < 0.001), C-reactive protein (P = 0.043), prognostic nutritional index (P = 0.0050), the Physiologic and Operative Severity Score for the enUmeration of Mortality and Morbidity (P < 0.001) and operation time (P = 0.042) were identified to be risk factors for postoperative complications. According to the multivariate analysis, low preoperative serum cholinesterase levels were found to be an independent risk factor for postoperative complications (P = 0.029). In the extremely elderly (80-95 years), the cholinesterase-low group had a higher complication rate compared to the cholinesterase-high group (77.8 vs 43.8%, P = 0.028).

CONCLUSION

The preoperative serum cholinesterase levels may be a risk factor for postoperative complications in elderly patients after emergency surgery, thus suggesting the significance of cholinesterase in evaluating the nutritional status.

Nutrition in the Neurocritical Care Unit: a New Frontier

PURPOSE OF REVIEW

This review presents the most current recommendations for providing nutrition to the neurocritical care population. This includes updates on initiation of feeding, immunonutrition, and metabolic substrates including ketogenic diet, cerebral microdialysis (CMD) monitoring, and the microbiome.

RECENT FINDINGS

Little evidence exists to support differences in feeding practices among the neurocritical care population. New areas of interest with limited data include use of immunonutrition, pre/probiotics for microbiome manipulation, ketogenic diet, and use of CMD catheters for substrate utilization monitoring.

SUMMARY

Acute neurologic injury incites a cascade of adrenergic and neuroendocrine events resulting in a pro-inflammatory and hypercatabolic state, which is associated with an increase in morbidity and mortality. Nutritional support provides substrates to mitigate the damaging effects of hypermetabolism. Despite this practice, studies on feeding delivery outcomes remain inconsistent. Guidelines suggest use of early enteral nutrition using standard polymeric formulas. Population heterogeneity, variability in interventions, complexities of the metabolic and inflammatory responses, and paucity of nutrition research in patients requiring neurocritical care have led to controversies in the field. It is imperative that more pragmatic and reproducible research be conducted to better understand underlying pathophysiology and develop interventions that may improve outcomes.

Link between Viral Infections, Immune System, Inflammation and Diet

The strong spread of COVID-19 and the significant number of deaths associated with it could be related to improper lifestyles, which lead to a low-grade inflammation (LGI) that not only increases the risk of chronic diseases, but also the risk of facing complications relating to infections and a greater susceptibility to infections themselves. Recently, scientific research has widely demonstrated that the microbiota plays a fundamental role in modulating metabolic responses in the immune system. There is, in fact, a two-way interaction between lifestyle, infection, and immunity. The immune response is compromised if nutrition is unbalanced or insufficient, because diet affects the intestinal flora predisposing people to infections and, at the same time, the nutritional state can be aggravated by the immune response itself to the infection. We evaluate the link between balanced diet, the efficiency of the immune system, and microbiota with the aim of providing some practical advice for individuals, with special attention to the elderly. A correct lifestyle that follows the Mediterranean model, which is especially rich in plant-based foods along with the use of extra-virgin olive oil, are the basis of preventing LGI and other chronic pathologies, directly influencing the intestinal microbiota and consequently the immune response.

Potential immunomodulatory effects of vitamin D in the prevention of severe coronavirus disease 2019: An ally for Latin America (Review)

Currently, the world is under a pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for coronavirus disease 2019 (COVID-19). This disease is characterized by a respiratory syndrome that can progress to an acute respiratory distress syndrome. To date, limited effective therapies are available for the prevention or treatment of COVID-19; therefore, it is necessary to propose novel treatment options with immunomodulatory effects. Vitamin D serves functions in bone health and has been recently reported to exert protective effects against respiratory infections. Observational studies have demonstrated an association between vitamin D deficiency and a poor prognosis of COVID-19; this is alarming as vitamin D deficiency is a global health problem. In Latin America, the prevalence of vitamin D deficiency is unknown, and currently, this region is in the top 10 according to the number of confirmed COVID-19 cases. Supplementation with vitamin D may be a useful adjunctive treatment for the prevention of COVID-19 complications. The present review provides an overview of the current knowledge of the potential immunomodulatory effects of vitamin D in the prevention of COVID-19 and sets out vitamin D recommendations for the Latin American population.

Persistent inflammation, immunosuppression and catabolism syndrome (PICS) in critically ill children is associated with clinical outcomes: a prospective longitudinal study

BACKGROUND

Persistent inflammation, immunosuppression and catabolism syndrome (PICS) has been described in critically ill adults and may contribute to unfavourable outcomes. The present study aimed to describe and characterise PICS in critically ill children (PICS-ped) and to verify its association with clinical outcomes.

METHODS

A prospective longitudinal study was conducted in a paediatric intensive care unit (PICU) with children aged between 3 months and 15 years. PICS-ped, based on adult definition, was described. PICS-ped was defined as PICU length of stay >14 days; C-reactive protein > 10.0 mg L^-1 ; lymphocytes <25%; and any reduction of mid-upper arm circumference Z-score. Clinical, demographic, nutritional status, nutrition therapy parameters and clinical outcomes were assessed. Statistical analysis comprised Mann-Whitney and Fisher's chi-squared tests, as well as logistic and Cox regression. P < 0.05 was considered statistically significant.

RESULTS

In total, 153 children were included, with a median age of 51.7 months (interquartile range 15.6-123.4 months), and 60.8% male. The mortality rate was 10.5%. The prevalence of PICS-ped was 4.6%. Days using vasoactive drugs and days using antibiotics were associated with PICS-ped. PICS-ped was associated with mortality in crude (odds ratio = 6.67; P = 0.013) and adjusted analysis (odds ratio = 7.14; P = 0.017). PICS-ped was also associated with PICU and hospital length of stay, as well as duration of mechanical ventilation. Similar results were found in a subset of critically ill children who required mechanical ventilation for more than 48 h.

CONCLUSIONS

Children with PICS-ped required antibiotics or vasoactive drugs for a longer period. PICS-ped was associated with poor clinical outcomes in critically ill children. More studies are needed to properly define PICS-ped for this population.

Plasma Glutamine Levels in Relation to Intensive Care Unit Patient Outcome

Low and high plasma glutamine levels are associated with increased mortality. This study aimed to measure glutamine levels in critically ill patients admitted to the intensive care unit (ICU) , correlate the glutamine values with clinical outcomes, and identify proxy indicators of abnormal glutamine levels. Patients were enrolled from three ICUs in South Africa, provided they met the inclusion criteria. Clinical and biochemical data were collected. Plasma glutamine was categorized as low (<420 µmol/L), normal (420-700 µmol/L), or high (>700 µmol/L). Three hundred and thirty patients (median age 46.8 years, 56.4% male) were enrolled (median APACHE II score) 18.0 and SOFA) score 7.0). On admission, 58.5% had low (median 299.5 µmol/L) and 14.2% high (median 898.9 µmol/L) plasma glutamine levels. Patients with a diagnosis of polytrauma and sepsis on ICU admission presented with the lowest, and those with liver failure had the highest glutamine levels. Admission low plasma glutamine was associated with higher APACHE II scores (p = 0.003), SOFA scores (p = 0.003), C-reactive protein (CRP) values (p < 0.001), serum urea (p = 0.008), and serum creatinine (p = 0.023) and lower serum albumin (p < 0.001). Low plasma glutamine was also associated with requiring mechanical ventilation and receiving nutritional support. However, it was not significantly associated with length of stay or mortality. ROC curve analysis revealed a CRP threshold value of 87.9 mg/L to be indicative of low plasma glutamine levels (area under the curve (AUC) 0.7, p < 0.001). Fifty-nine percent of ICU patients had low plasma glutamine on admission, with significant differences found between diagnostic groupings. Markers of infection and disease severity were significant indicators of low plasma glutamine.

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.

Dietary Vitamin D3 Deficiency Increases Resistance to Leishmania (Leishmania) amazonensis Infection in Mice

The leishmaniases are a group of diseases caused by Leishmania parasites, which have different clinical manifestations. Leishmania (Leishmania) amazonensis is endemic in South America and causes cutaneous leishmaniasis (CL), which can evolve into a diffuse form, characterized by an anergic immune response. Since the leishmaniases mainly affect poor populations, it is important to understand the involvement of immunonutrition, how the immune system is modulated by dietary nutrients and the effect this has on Leishmania infection. Vitamin D3 (VitD) is an immunonutrient obtained from diet or endogenously synthesized, which suppresses Th1 and Th17 responses by favoring T helper (Th) 2 and regulatory T cell (Treg) generation. Based on these findings, this study aims to evaluate dietary VitD influence on L. (L.) amazonensis experimental infection in C57BL/6 and BALB/c mice. Thus, C57BL/6 and BALB/c VitD deficient (VDD) mice were generated through dietary VitD restriction 45 days prior to infection. Both strains of VDD mice showed a more controlled lesion development compared to mice on a regular diet (Ctrl). There were no differences in serum levels of anti-Leishmania IgG1 and IgG2a, but there was a decrease in IgE levels in BALB/c VDD mice. Although CD4⁺ T cell number was not changed, the CD4⁺ IFN-y⁺ T cell population was increased in both absolute number and percentage in C57BL/6 and BALB/c VDD mice compared to Ctrl mice. There was also no difference in IL-4 and IL-17 production, however, there was reduction of IL-10 production in VDD mice. Together, our data indicate that VitD contributes to murine cutaneous leishmaniasis susceptibility and that the Th1 cell population may be related to the resistance of VDD mice to L. (L.) amazonensis infection.