Why Wonder Why?

This essay describes how a physician’s encounter with a patient with repeated intensive care unit admissions illuminated the value of wonder in clinical care and medical education.

Enteral nutrition in septic shock: a call for a paradigm shift

PURPOSE OF REVIEW

The purpose of this review is to identify contemporary evidence evaluating enteral nutrition in patients with septic shock, outline risk factors for enteral feeding intolerance (EFI), describe the conundrum of initiating enteral nutrition in patients with septic shock, appraise current EFI definitions, and identify bedside monitors for guiding enteral nutrition therapy.

RECENT FINDINGS

The NUTRIREA-2 and NUTRIREA-3 trial results have better informed the dose of enteral nutrition in critically ill patients with circulatory shock. In both trials, patients with predominant septic shock randomized to receive early standard-dose nutrition had more gastrointestinal complications. Compared to other contemporary RCTs that included patients with circulatory shock, patients in the NUTRIREA-2 and NUTRIREA-3 trials had higher bowel ischemia rates, were sicker, and received full-dose enteral nutrition while receiving high baseline dose of vasopressor. These findings suggest severity of illness, vasopressor dose, and enteral nutrition dose impact outcomes.

SUMMARY

The provision of early enteral nutrition preserves gut barrier functions; however, these benefits are counterbalanced by potential complications of introducing luminal nutrients into a hypo-perfused gut, including bowel ischemia. Findings from the NUTRIREA2 and NUTRIREA-3 trials substantiate a 'less is more' enteral nutrition dose strategy during the early acute phase of critical illness. In the absence of bedside tools to guide the initiation and advancement of enteral nutrition in patients with septic shock, the benefit of introducing enteral nutrition on preserving gut barrier function must be weighed against the risk of harm by considering dose of vasopressor, dose of enteral nutrition, and severity of illness.

Factors influencing diagnostic accuracy among intensive care unit clinicians - an observational study

OBJECTIVES

Diagnostic errors are a source of morbidity and mortality in intensive care unit (ICU) patients. However, contextual factors influencing clinicians' diagnostic performance have not been studied in authentic ICU settings. We sought to determine the accuracy of ICU clinicians' diagnostic impressions and to characterize how various contextual factors, including self-reported stress levels and perceptions about the patient's prognosis and complexity, impact diagnostic accuracy. We also explored diagnostic calibration, i.e. the balance of accuracy and confidence, among ICU clinicians.

METHODS

We conducted an observational cohort study in an academic medical ICU. Between June and August 2019, we interviewed ICU clinicians during routine care about their patients' diagnoses, their confidence, and other contextual factors. Subsequently, using adjudicated final diagnoses as the reference standard, two investigators independently rated clinicians' diagnostic accuracy and on each patient on a given day ("patient-day") using 5-point Likert scales. We conducted analyses using both restrictive and conservative definitions of clinicians' accuracy based on the two reviewers' ratings of accuracy.

RESULTS

We reviewed clinicians' responses for 464 unique patient-days, which included 255 total patients. Attending physicians had the greatest diagnostic accuracy (77-90 %, rated as three or higher on 5-point Likert scale) followed by the team's primary fellow (73-88 %). Attending physician and fellows were also least affected by contextual factors. Diagnostic calibration was greatest among ICU fellows.

CONCLUSIONS

Additional studies are needed to better understand how contextual factors influence different clinicians' diagnostic reasoning in the ICU.

The impact of higher protein dosing on outcomes in critically ill patients with acute kidney injury: a post hoc analysis of the EFFORT protein trial

BACKGROUND

Based on low-quality evidence, current nutrition guidelines recommend the delivery of high-dose protein in critically ill patients. The EFFORT Protein trial showed that higher protein dose is not associated with improved outcomes, whereas the effects in critically ill patients who developed acute kidney injury (AKI) need further evaluation. The overall aim is to evaluate the effects of high-dose protein in critically ill patients who developed different stages of AKI.

METHODS

In this post hoc analysis of the EFFORT Protein trial, we investigated the effect of high versus usual protein dose (≥ 2.2 vs. ≤ 1.2 g/kg body weight/day) on time-to-discharge alive from the hospital (TTDA) and 60-day mortality and in different subgroups in critically ill patients with AKI as defined by the Kidney Disease Improving Global Outcomes (KDIGO) criteria within 7 days of ICU admission. The associations of protein dose with incidence and duration of kidney replacement therapy (KRT) were also investigated.

RESULTS

Of the 1329 randomized patients, 312 developed AKI and were included in this analysis (163 in the high and 149 in the usual protein dose group). High protein was associated with a slower time-to-discharge alive from the hospital (TTDA) (hazard ratio 0.5, 95% CI 0.4-0.8) and higher 60-day mortality (relative risk 1.4 (95% CI 1.1-1.8). Effect modification was not statistically significant for any subgroup, and no subgroups suggested a beneficial effect of higher protein, although the harmful effect of higher protein target appeared to disappear in patients who received kidney replacement therapy (KRT). Protein dose was not significantly associated with the incidence of AKI and KRT or duration of KRT.

CONCLUSIONS

In critically ill patients with AKI, high protein may be associated with worse outcomes in all AKI stages. Recommendation of higher protein dosing in AKI patients should be carefully re-evaluated to avoid potential harmful effects especially in patients who were not treated with KRT.

TRIAL REGISTRATION

This study is registered at ClinicalTrials.gov (NCT03160547) on May 17th 2017.

Nutrition dose in the early acute phase of critical illness: Finding the sweet spot and heeding the lessons from the NUTRIREA trials

The landmark NUTRIREA-2 and NUTRIREA-3 trials compared the route and dose of nutrition, respectively, in critically ill patients with circulatory shock. The results of both trials support a "less-is-more" paradigm shift in the early acute phase of critical illness. In this review, the authors outline and appraise the results of the NUTRIREA-2 and NUTRIREA-3 trials, introduce the concept of identifying the "sweet spot" for nutrition dose based on severity of illness/nutrition risk and nutrition dose, and identify the unintended consequences of delivering full-dose nutrition in sicker critically ill patients during the early acute phase of critical illness.

The Efficacy of Glutamine Supplementation in Severe Adult Burn Patients: A Systematic Review With Trial Sequential Meta-Analysis

OBJECTIVES

Evidence supporting glutamine supplementation in severe adult burn patients has created a state of uncertainty due to the variability in the treatment effect reported across small and large randomized controlled trials (RCTs). We aimed to systematically review the effect of glutamine supplementation on mortality in severe adult burn patients.

DATA SOURCES

MEDLINE, Embase, CINAHL, and Cochrane Central were searched from inception to February 10, 2023.

STUDY SELECTION

RCTs evaluating the effect of enteral or IV glutamine supplementation alone in severe adult burn patients were included.

DATA EXTRACTION

Two reviewers independently extracted data on study characteristics, burn injury characteristics, description of the intervention between groups, adverse events, and clinical outcomes.

DATA SYNTHESIS

Random effects meta-analyses were performed to estimate the pooled risk ratio (RR). Trial sequential analyses (TSA) for mortality and infectious complications were performed. Ten RCTs (1,577 patients) were included. We observed no significant effect of glutamine supplementation on overall mortality (RR, 0.65, 95% CI, 0.33-1.28; p = 0.21), infectious complications (RR, 0.83; 95% CI, 0.63-1.09; p = 0.18), or other secondary outcomes. In subgroup analyses, we observed no significant effects based on administration route or burn severity. We did observe a significant subgroup effect between single and multicenter RCTs in which glutamine significantly reduced mortality and infectious complications in singe-center RCTs but not in multicenter RCTs. However, TSA showed that the pooled results of single-center RCTs were type 1 errors and further trials would be futile.

CONCLUSIONS

Glutamine supplementation, regardless of administration, does not appear to improve clinical outcomes in severely adult burned patients.

Benefits and harm of probiotics and synbiotics in adult critically ill patients. A systematic review and meta-analysis of randomized controlled trials with trial sequential analysis

BACKGROUND & AIMS

Several systematic reviews and meta-analyses of randomized controlled trials concluded that probiotics administration in critically ill patients was safe and associated with reduced rates of ventilator-associated pneumonia and diarrhea. However, a recent large multicenter trial found probiotics administration, compared to placebo, was not efficacious and increased adverse events. An updated meta-analysis that controls for type-1 and -2 errors using trial sequential analysis, with a detailed account of adverse events associated with probiotic administration, is warranted to confirm the safety and efficacy of probiotic use in critically ill patients.

METHODS

RCTs that compared probiotics or synbiotics to usual care or placebo and reported clinical and diarrheal outcomes were searched in 4 electronic databases from inception to March 8, 2022 without language restriction. Four reviewers independently extracted data and assessed the study qualities using the Critical Care Nutrition (CCN) Methodological Quality Scoring System. Random-effect meta-analysis and trial sequential analysis (TSA) were used to synthesize the results. The primary outcome was ventilator-associated pneumonia (VAP). The main subgroup analysis compared the effects of higher versus lower quality studies (based on median CCN score).

RESULTS

Seventy-five studies with 71 unique trials (n = 8551) were included. In the overall analysis, probiotics significantly reduced VAP incidence (risk ratio [RR] 0.70, 95% confidence interval [CI] 0.56-0.88; I² = 65%; 16 studies). However, such benefits were demonstrated only in lower (RR 0.47, 95% CI 0.32, 0.69; I² = 44%; 7 studies) but not higher quality studies (RR 0.89, 95% CI 0.73, 1.08; I² = 43%; 9 studies), with significant test for subgroup differences (p = 0.004). Additionally, TSA showed that the VAP benefits of probiotics in the overall and subgroup analyses were type-1 errors. In higher quality trials, TSA found that future trials are unlikely to demonstrate any benefits of probiotics on infectious complications and diarrhea. Probiotics had higher adverse events than control (pooled risk difference: 0.01, 95% CI 0.01, 0.02; I² = 0%; 22 studies).

CONCLUSION

High-quality RCTs did not support a beneficial effect of probiotics on clinical or diarrheal outcomes in critically ill patients. Given the lack of benefits and the increased incidence of adverse events, probiotics should not be routinely administered to critically ill patients.

PROSPERO REGISTRATION

CRD42022302278.

Current practices in medical nutrition therapy in the cardiac surgical critical care setting - an international multicenter observational study

BACKGROUND

Cardiac surgery patients with prolonged stay in the intensive care unit (ICU) are at high-risk for acquired malnutrition. Medical nutrition therapy practices in cardiac surgery patients are unknown. The objective of this study is to describe current nutrition practices in critically ill cardiac surgery patients worldwide.

METHODS

We conducted a prospective observational study in 13 international ICUs involving mechanically ventilated cardiac surgery patients with an ICU stay of at least 72 hours. Collected data included calorie and protein prescription, type and time to initiation of nutrition, and actual quantity of energy and protein delivered (maximum: 12 days).

RESULTS

Among 237 enrolled patients, enteral nutrition (EN) was started, on average, 45 hours after ICU admission (range 0-277 hours; site average 53 [range 10-79 hours]). EN was prescribed in 187 (79%) patients and combined EN and parenteral nutrition (PN) in 33 (14%). Overall, patients received 44.2% (0.0-117.2%) of prescribed calories and 39.7% (0.0-122.8%) of prescribed protein. At a site level, the average nutritional adequacy was 47.5% (30.5-78.6%) for calories and 43.6% (21.7-76.6%) for protein received from all nutritional sources.

CONCLUSION

Critically ill cardiac surgery patients with prolonged ICU stay experience significant delays in starting EN and receive low levels of calories and protein. There exists tremendous variability in site performance, whereas achieving optimal nutrition performance is doable.

VIDEO ABSTRACT

A video abstract (Video S1) is provided with the supplementary materials. This article is protected by copyright. All rights reserved.

Intravenous vitamin C monotherapy in critically ill patients: a systematic review and meta-analysis of randomized controlled trials with trial sequential analysis

BACKGROUND

A recent landmark randomized controlled trial (RCT) in septic patients demonstrated an increased risk of death and persistent organ dysfunction with intravenous Vitamin C (IVVC) monotherapy, which represents a disparate result from previous systematic reviews and meta-analyses (SRMA). We performed an updated SRMA of IVVC monotherapy to summarize and explore heterogeneity across current trials and conduct trial sequential analysis (TSA) to guard against type-I or type-II statistical errors.

METHODS

RCTs evaluating IVVC in adult critically ill patients were included. Four databases were searched from inception to 22 June 2022 without language restrictions. The primary outcome was overall mortality. Random effect meta-analysis was performed to estimate the pooled risk ratio. TSA for mortality was performed using the DerSimonian-Laird random effect model, alpha 5%, beta 10%, and relative risk reduction (RRR) of 30%, 25%, and 20%.

RESULTS

We included 16 RCTs (n = 2130). IVVC monotherapy is associated with significant reduction in overall mortality [risk ratio (RR) 0.73, 95% confidence interval (CI) 0.60-0.89; p = 0.002; I² = 42%]. This finding is supported by TSA using RRR of 30% and 25%, and sensitivity analysis using fixed-effect meta-analysis. However, the certainty of our mortality finding was rated low using GRADE due to the serious risk of bias and inconsistency. In a priori subgroup analyses, we found no differences between single vs multicenter, higher (≥ 10,000 mg/day) vs lower dose and sepsis vs non-sepsis trials. Post-hoc, we found no differences in subgroup analysis of earlier (< 24 h) vs delayed treatment, longer (> 4 days) vs shorter treatment duration, and low vs other risk of bias studies. IVVC may have the greatest benefit in trials that enrolled patients above (i.e., > 37.5%; RR 0.65, 95% CI 0.54-0.79) vs below (i.e., ≤ 37.5%; RR 0.89, 95% CI 0.68-1.16) median control group mortality (test for subgroup differences: p = 0.06), and TSA supported this.

CONCLUSIONS

IVVC monotherapy may be associated with mortality benefits in critically ill patients, particularly in patients with a high risk of dying. Given the low certainty of evidence, this potentially life-saving therapy warrants further studies to identify the optimal timing, dosage, treatment duration, and patient population that will benefit most from IVVC monotherapy. PROSPERO Registration ID: CRD42022323880. Registered 7th May 2022.

Nutrition for the high-risk surgical patient, when they need it most: Question and answer session

Patients requiring complex or extensive surgery are often at high risk for perioperative and postoperative nutrition risk. Despite published guidelines, providing adequate nutrition to these patients continues to remain a clinical challenge. Using the case of a patient with preoperative nutrition risk who will need to undergo timely cancer resectional surgery, speakers presenting at the American Society for Parenteral and Enteral Nutrition 2022 Preconference discussed novel strategies to assess for nutrition risk, enhanced recovery after surgery, and preoperative and postoperative nutrition management in these often complex surgical patients.

Overview of oxidative stress and the role of micronutrients in critical illness

Inflammation and oxidative stress represent physiological response mechanisms to different types of stimuli and injury during critical illness. Its proper regulation is fundamental to cellular and organismal survival and are paramount to outcomes and recovery from critical illness. A proper maintenance of the delicate balance between inflammation, oxidative stress, and immune response is crucial for resolution from critical illness with important implications for patient outcome. The extent of inflammation and oxidative stress under normal conditions is limited by the antioxidant defense system of the human body, whereas the antioxidant capacity is commonly significantly compromised, and serum levels of micronutrients and vitamins significantly depleted in patients who are critically ill. Hence, the provision of antioxidants and anti-inflammatory nutrients may help to reduce the extent of oxidative stress and therefore improve clinical outcomes in patients who are critically ill. As existing evidence of the beneficial effects of antioxidant supplementation in patients who are critically ill is still unclear, actual findings about the most promising anti-inflammatory and antioxidative candidates selenium, vitamin C, zinc, and vitamin D will be discussed in this narrative review. The existing evidence provided so far demonstrates that several factors need to be considered to determine the efficacy of an antioxidant supplementation strategy in patients who are critically ill and indicates the need for adequately designed multicenter prospective randomized control trials to evaluate the clinical significance of different types and doses of micronutrients and vitamins in selected groups of patients with different types of critical illness.

Case presentation and panel discussion: Transitions in care

There is evidence that significant quality problems arise as patients transitions in care from one setting to another. Attention to nutrition during transitions of care is important to avoid complication. During the American Society for Parenteral and Enteral Nutrition 2022 preconference course, nutrition during transition of care from pediatric to adult care, from the intensive care unit to the hospital floors and from the hospital to home was addressed.

Case presentation and panel discussion: Micronutrient therapy in critical illness

Over the past decade, the use of supraphysiologic doses of micronutrients (also called metabolic resuscitation) in critically ill patients has gained significant attention. Building upon preclinical and observational human data, numerous randomized controlled trials have tested the impact of multiple micronutrients on various outcomes in critically ill patients. At the 2022 American Society for Parenteral and Enteral Nutrition Preconference Course, three world-renowned speakers delivered talks on the (1) overall role of micronutrients and, specifically, (2) selenium and vitamin C and (3) vitamin D and zinc in critically ill patients. Here, the case presentation and discussion from the postsession question and answer period are presented. The moderator for this session was Jose Pimiento, MD, and the speakers and panelists were Christian Stoppe, MD, Todd Rice, MD, and Daren Heyland, MD.

Medical nutrition therapy in patients receiving ECMO: Evidence-based guidance for clinical practice

Patients receiving extracorporeal membrane oxygenation (ECMO) inherit substantial disease-associated metabolic, endocrinologic, and immunologic modifications. Along with the technical components of ECMO, the aforementioned alterations may affect patients' needs and feasibility of adequate macronutrient and micronutrient supply and intake. Thus, patients receiving ECMO are at increased risk for iatrogenic malnutrition and require targeted individual medical nutrition therapy (MNT). However, specific recommendations for MNT in patients receiving ECMO are limited and, with some exceptions, based on an evidence base encompassing general patients who are critically ill. Consequently, clinician decision-making for MNT in patients receiving ECMO is unguided, which may further increase nutrition risk, culminating in iatrogenic malnutrition and ultimately affecting patient outcomes. The purpose of this article is to provide educational background and highlight specific points for MNT in adult patients receiving ECMO, which might serve as evidence-based guidance to develop institutional standard operating procedures and nutrition protocols for daily clinical practice.

History of scurvy and use of vitamin C in critical illness: A narrative review

In 1747, an important milestone in the history of clinical research was set, as the Scottish surgeon James Lind conducted the first randomized controlled trial. Lind was interested in scurvy, a severe vitamin C deficiency which caused the death of thousands of British seamen. He found that a dietary intervention with oranges and lemons, which are rich in vitamin C by nature, was effective to recover from scurvy. Because of its antioxidative properties and involvement in many biochemical processes, the essential micronutrient vitamin C plays a key role in the human biology. Moreover, the use of vitamin C in critical illness-a condition also resulting in death of thousands in the 21st century-has gained increasing interest, as it may restore vascular responsiveness to vasoactive agents, ameliorate microcirculatory blood flow, preserve endothelial barriers, augment bacterial defense, and prevent apoptosis. Because of its redox potential and powerful antioxidant capacity, vitamin C represents an inexpensive and safe antioxidant, with the potential to modify the inflammatory cascade and improve clinical outcomes of critically ill patients. This narrative review aims to update and provide an overview on the role of vitamin C in the human biology and in critically ill patients, and to summarize current evidence on the use of vitamin C in diverse populations of critically ill patients, in specific focusing on patients with sepsis and coronavirus disease 2019.

Early versus delayed enteral nutrition in mechanically ventilated patients with circulatory shock: a nested cohort analysis of an international multicenter, pragmatic clinical trial

Introduction

Real-world evidence on the timing and efficacy of enteral nutrition (EN) practices in intensive care unit (ICU) patients with circulatory shock is limited. We hypothesized early EN (EEN), as compared to delayed EN (DEN), is associated with improved clinical outcomes in mechanically ventilated (MV) patients with circulatory shock.

Methods

We analyzed a dataset from an international, multicenter, pragmatic randomized clinical trial (RCT) evaluating protein dose in ICU patients. Data were collected from ICU admission, and EEN was defined as initiating < 48 h from ICU admission and DEN > 48 h. We identified MV patients in circulatory shock to evaluate the association between the timing of EN initiation and clinical outcomes. The regression analysis model controlled for age, mNUTRIC score, APACHE II score, sepsis, and Site.

Results

We included 626 patients, from 52 ICUs in 14 countries. Median age was 60 years [18–93], 55% had septic shock, 99% received norepinephrine alone, 91% received EN alone, and 50.3% were randomized to a usual protein dose. Forty-two percent of EEN patients had persistent organ dysfunction syndrome plus death at day 28, compared to 53% in the DEN group (p = 0.04). EEN was associated with more ICU-free days (9.3 ± 9.2 vs. 5.7 ± 7.9, p = 0.0002), more days alive and free of vasopressors (7.1 ± 3.1 vs. 6.3 ± 3.2, p = 0.007), and shorter duration of MV among survivors (9.8 ± 10.9 vs. 13.8 ± 14.5, p = 0.0002). This trend was no longer observed in the adjusted analysis. There were no differences in ICU/60-day mortality or feeding intolerance rates between groups.

Conclusion

In MV patients with circulatory shock, EEN, as compared to DEN, was associated with improved clinical outcomes, but no longer when adjusting for illness severity. RCTs comparing the efficacy of EEN to DEN in MV patients with circulatory shock are warranted.

The Potential Role of Intravenous Vitamin C Monotherapy in Critical Illness

Vitamin C is an essential micronutrient with antioxidant properties and its use in critical illness has gained interest in recent years.¹ Four systematic reviews/meta-analyses (SRMAs) have been published in 2021 alone (see Table 1 summary).^2-5 These 4 SRMAs included between 8-43 randomized controlled trials evaluating vitamin C with or without thiamine and/or corticosteroids in general ICU patients and those with sepsis and septic shock. ^2-5 Fujii et al performed a network meta-analysis which is a method for comparing multiple treatments using both direct and indirect evidence across trials that included studies with vitamin C monotherapy or with thiamine and/or corticosteroids.⁹ This article is protected by copyright. All rights reserved.

Case presentation and panel discussion: Nutrition issues in cancer

Advances in treatment of malignancy including novel pharmacologic therapies and surgical interventions has led to significant improvement in survival. As cancer becomes a chronic disease, nutrition interventions play an increasingly important role in short- and long-term outcomes. The current manuscript presents a case of a 66-year-old male with new diagnosis of pancreatic cancer diagnosed incidentally in the setting of COVID-19. Expert panelists in the field of nutrition discuss optimal strategies for diagnosis of malnutrition along with preoperative, perioperative, and postoperative optimization of nutrition. This discussion focuses on the use of probiotics, immune-modulating nutrition, fish oil, specialized proresolving mediators, and use of enteral and parenteral nutrition support.

Enteral nutrition in septic shock: A pathophysiologic conundrum

Septic shock is a public health burden and defined as a subset of sepsis whereby abnormalities in microcirculatory and cellular metabolism manifest as acute circulatory failure. At the level of the gut, septic shock impairs epithelial barrier function (EBF), and the gut initiates proinflammatory responses contributing to multiple organ dysfunction syndrome. The timing and dose of enteral nutrition (EN) in septic shock remains a conundrum. On the one hand, early EN preserves EBF. On the other hand, serious gastrointestinal complications such as bowel necrosis may limit EN initiation in septic shock. We (1) describe the pathophysiologic conundrum septic shock poses for EN initiation, (2) outline guideline-based recommendations for EN in septic shock, (3) identify the role of parenteral nutrition in septic shock, and (4) identify and appraise postguideline literature on the timing, dose, and titration of EN in septic shock.

Case presentation and panel discussion: Cardiometabolic risk mitigation

The worldwide increase in the prevalence of obesity and adiposity-related comorbidities has required a novel approach to cardiometabolic risk mitigation focused on the key mechanistic drivers of disease. The current manuscript presents the case of a 74-year-old male with obesity complicated by coronary artery disease, hypertriglyceridemia, hypertension, nonalcoholic fatty liver disease, obstructive sleep apnea, and type 2 diabetes. Expert panelists discuss optimal diagnostic and treatment strategies focused on lifestyle modifications including dietary interventions such as the Mediterranean dietary pattern, medications that target multiple drivers of disease, as well as procedural options.

When Pandemics Collide: the Interplay of Obesity and COVID-19

PURPOSE OF REVIEW

The COVID-19 pandemic has been associated with significant morbidity and mortality worldwide. In addition to those with advanced age and co-morbidities such as heart disease or cancer, obese individuals have also had very high rates of hospitalization, critical illness, need for ventilator support, as well as mortality. A number of factors associated with obesity have led to devastating consequences as these two pandemics have interacted.

RECENT FINDINGS

Obese individuals through a combination of structural and cellular level changes have greater risk of ischemic heart disease, diabetes, cancer, and respiratory disease, which are themselves risk-factors for acquiring COVID-19 disease. These structural changes also result in increased intra-abdominal and intra-thoracic pressure as well as a restrictive lung physiology that leads to reduction in total lung capacity, functional residual capacity, and increase in airway hyper-reactivity. Adipose tissue is also impacted in obese individuals leading to local as well as systemic inflammation, which can contribute to increased release of free fatty acids and systemic insulin resistance. Additionally, angiotensin-converting enzyme 2 and dipeptidyl peptidase 4, which act as receptors for SARS-CoV-2 are also significantly increased in obese individuals. The present manuscript reviews these structural, immune, and molecular changes associated with obesity that make obese individuals more vulnerable to acquiring severe COVID-19 and more challenging to manage associated complications.

Fiber in the ICU: Should it Be a Regular Part of Feeding?

PURPOSE OF REVIEW

To highlight the controversy of fiber use in the current critical care nutrition guidelines; review the effect of fiber on the gut microbiota in the critically ill; and examine the data on fiber and outcomes in the intensive care setting.

RECENT FINDINGS

Fiber is increasingly recognized as a necessary component of colonic health and nutrition support. In critical illness there is a shift toward gut dysbiosis and immune dysregulation. Through fermentation and the generation of short-chain fatty acids, fiber has a role in maintaining intestinal homeostasis, immune function, and supporting commensal bacteria. In contrast to fermentable fiber, recent animal models suggest that non-fermentable fiber can also favorably alter intestinal homeostasis in a mechanism distinct from short chain fatty acids. In the critically ill, RCTs and meta-analyses suggest that soluble and mixed fiber supplemented enteral nutrition can reduce diarrhea and is well tolerated. Based on limited data, there may be benefits in reducing length of hospital stay, certain infections, and glucose metabolism. Nonetheless, the role of fiber enriched nutrition in critically ill patients is controversial as evident in the conflicting guidelines. Despite shortcomings in the literature, soluble and mixed fiber supplemented enteral nutrition is safe and beneficial in most hemodynamically stable intensive care patients. More research is necessary to determine optimal fiber composition.

The effect of higher versus lower protein delivery in critically ill patients: a systematic review and meta-analysis of randomized controlled trials

Background

The optimal protein dose in critical illness is unknown. We aim to conduct a systematic review of randomized controlled trials (RCTs) to compare the effect of higher versus lower protein delivery (with similar energy delivery between groups) on clinical and patient-centered outcomes in critically ill patients.

Methods

We searched MEDLINE, EMBASE, CENTRAL and CINAHL from database inception through April 1, 2021.We included RCTs of (1) adult (age ≥ 18) critically ill patients that (2) compared higher vs lower protein with (3) similar energy intake between groups, and (4) reported clinical and/or patient-centered outcomes. We excluded studies on immunonutrition. Two authors screened and conducted quality assessment independently and in duplicate. Random-effect meta-analyses were conducted to estimate the pooled risk ratio (dichotomized outcomes) or mean difference (continuous outcomes).

Results

Nineteen RCTs were included (n = 1731). Sixteen studies used primarily the enteral route to deliver protein. Intervention was started within 72 h of ICU admission in sixteen studies. The intervention lasted between 3 and 28 days. In 11 studies that reported weight-based nutrition delivery, the pooled mean protein and energy received in higher and lower protein groups were 1.31 ± 0.48 vs 0.90 ± 0.30 g/kg and 19.9 ± 6.9 versus 20.1 ± 7.1 kcal/kg, respectively. Higher vs lower protein did not significantly affect overall mortality [risk ratio 0.91, 95% confidence interval (CI) 0.75–1.10, p = 0.34] or other clinical or patient-centered outcomes. In 5 small studies, higher protein significantly attenuated muscle loss (MD −3.44% per week, 95% CI −4.99 to −1.90; p < 0.0001).

Conclusion

In critically ill patients, a higher daily protein delivery was not associated with any improvement in clinical or patient-centered outcomes. Larger, and more definitive RCTs are needed to confirm the effect of muscle loss attenuation associated with higher protein delivery.

PROSPERO registration number: CRD42021237530

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03693-4.

Enteral nutrition in circulatory shock: friend or foe?

PURPOSE OF REVIEW

Circulatory shock is associated with reduced splanchnic blood flow and impaired gut epithelial barrier function (EBF). Early enteral nutrition (EN) has been shown in animal models to preserve EBF. There are limited human data informing early EN in circulatory shock and critical care nutrition guidelines provide disparate recommendations regarding the optimal timing and dose. The purpose of this review is to describe the harms and benefits of early EN in circulatory shock by identifying and appraising recent human data.

RECENT FINDINGS

The cumulative risk of nonocclusive bowel ischemia and necrosis in patients with circulatory shock is no higher than 0.3% across observational and randomized controlled trial-level data, and whether the risk is increased by EN delivery remains uncertain. Observational data suggest that early EN in circulatory shock is associated with improved clinical outcomes but data from robust randomized controlled trials remain equivocal, so the optimal timing and dose remain unknown.

SUMMARY

Based on the best available data, initiating restrictive dose EN into the stomach after initial resuscitation in patients with circulatory shock does not appear to be harmful. In fact, early EN may preserve EBF and improve clinical outcomes.

Clinical Nutrition Research and the COVID-19 Pandemic: A Scoping Review of the ASPEN COVID-19 Task Force on Nutrition Research

The purpose of this scoping review by the American Society for Parenteral and Enteral Nutrition (ASPEN) Coronavirus Disease 2019 (COVID-19) Nutrition Task Force was to examine nutrition research applicable to the COVID-19 pandemic. The rapid pace of emerging scientific information has prompted this activity to discover research/knowledge gaps. This methodology adhered with recommendations from the Joanna Briggs Institute. There were 2301 citations imported. Of these, there were 439 articles fully abstracted, with 23 main topic areas identified across 24 article types and sourced across 61 countries and 51 specialties in 8 settings and among 14 populations. Epidemiological/mechanistic relationships between nutrition and COVID-19 were reviewed and results mapped to the Population, Intervention, Comparator, Outcome, and Time (PICO-T) questions. The aggregated data were analyzed by clinical stage: pre-COVID-19, acute COVID-19, and chronic/post-COVID-19. Research gaps were discovered for all PICO-T questions. Nutrition topics meriting urgent research included food insecurity/societal infrastructure and transcultural factors (pre-COVID-19); cardiometabolic-based chronic disease, pediatrics, nutrition support, and hospital infrastructure (acute COVID-19); registered dietitian nutritionist counseling (chronic/post-COVID-19); and malnutrition and management (all stages). The paucity of randomized controlled trials (RCTs) was particularly glaring. Knowledge gaps were discovered for PICO-T questions on pediatrics, micronutrients, bariatric surgery, and transcultural factors (pre-COVID-19); enteral nutrition, protein-energy requirements, and glycemic control with nutrition (acute COVID-19); and home enteral and parenteral nutrition support (chronic/post-COVID-19). In conclusion, multiple critical areas for urgent nutrition research were identified, particularly using RCT design, to improve nutrition care for patients before, during, and after COVID-19.

Safety, Tolerability, and Outcomes of Enteral Nutrition in Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation (ECMO) is a supportive care system for patients with respiratory or cardiac failure. Patients requiring ECMO are at risk for significant inflammation, prolonged hospitalization, and acquired malnutrition and sarcopenia. Societal guidelines recommend early enteral nutrition in critically ill patients; however, in this population, optimal timing and dose of nutrition remains unknown and fear of reduced splanchnic perfusion, delayed gastric emptying, and bowel ischemia poses a barrier to appropriate energy and protein intake. This narrative review intends to provide an overview of ECMO, highlight the rationale for nutrition support in this population, and review the safety, tolerability, and outcomes associated with enteral nutrition during ECMO.

Relevant Nutrition Therapy in COVID-19 and the Constraints on Its Delivery by a Unique Disease Process

Worldwide, as of July 2020, >13.2 million people have been infected by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. The spectrum of coronavirus disease 2019 (COVID-19) ranges from mild illness to critical illness in 5% of cases. The population infected with SARS-CoV-2 requiring an intensive care unit admission often requires nutrition therapy as part of supportive care. Although the various societal guidelines for critical care nutrition meet most needs for the patient with COVID-19, numerous factors, which impact the application of those guideline recommendations, need to be considered. Since the SARS-CoV-2 virus is highly contagious, several key principles should be considered when caring for all patients with COVID-19 to ensure the safety of all healthcare personnel involved. Management strategies should cluster care, making all attempts to bundle patient care to limit exposure. Healthcare providers should be protected, and the spread of SARS-CoV-2 should be limited by minimizing procedures and other interventions that lead to aerosolization, avoiding droplet exposure through hand hygiene and use of personal protective equipment (PPE). PPE should be preserved by decreasing the number of individuals providing direct patient care and by limiting the number of patient interactions. Enteral nutrition (EN) is tolerated by the majority of patients with COVID-19, but a relatively low threshold for conversion to parenteral nutrition should be maintained if increased exposure to the virus is required to continue EN. This article offers relevant and practical recommendations on how to optimize nutrition therapy in critically ill patients with COVID-19.

Nutrition Therapy in Critically Ill Patients With Coronavirus Disease 2019

In the midst of a coronavirus disease 2019 (COVID‐19) pandemic, a paucity of data precludes derivation of COVID‐19–specific recommendations for nutrition therapy. Until more data are available, focus must be centered on principles of critical care nutrition modified for the constraints of this disease process, ie, COVID‐19–relevant recommendations. Delivery of nutrition therapy must include strategies to reduce exposure and spread of disease by providing clustered care, adequate protection of healthcare providers, and preservation of personal protective equipment. Enteral nutrition (EN) should be initiated early after admission to the intensive care unit (ICU) using a standard isosmolar polymeric formula, starting at trophic doses and advancing as tolerated, while monitoring for gastrointestinal intolerance, hemodynamic instability, and metabolic derangements. Intragastric EN may be provided safely, even with use of prone‐positioning and extracorporeal membrane oxygenation. Clinicians should have a lower threshold for switching to parenteral nutrition in cases of intolerance, high risk of aspiration, or escalating vasopressor support. Although data extrapolated from experience in acute respiratory distress syndrome warrants use of fiber additives and probiotic organisms, the lack of benefit precludes a recommendation for micronutrient supplementation. Practices that increase exposure or contamination of equipment, such as monitoring gastric residual volumes, indirect calorimetry to calculate requirements, endoscopy or fluoroscopy to achieve enteral access, or transport out of the ICU for additional imaging, should be avoided. At all times, strategies for nutrition therapy need to be assessed on a risk/benefit basis, paying attention to risk for both the patient and the healthcare provider.

Impact of Enteral Feeding on Vasoactive Support in Septic Shock: A Retrospective Observational Study

BACKGROUND

Introducing enteral nutrition (EN) during hemodynamic instability may induce the splanchnic steal phenomenon, which may worsen systemic oxygen delivery and increase vasopressor dose. We aimed to determine the change in vasopressor dose in septic shock patients who received concomitant EN. We hypothesize that EN delivery is not associated with worsening hemodynamic instability, as defined by an increase in vasopressor dose ≥50% at 24 hours.

METHODS

This is a retrospective observational cohort study of adult patients with septic shock who were admitted to the intensive care unit from January 2015 to June 2015 and received EN. Vasopressor and EN parameters were collected at 6-hour intervals for the first 24 hours.

RESULTS

Data were available for 28 consecutive patients. The mean age was 60 years (SD = 18), and 54% were females. Norepinephrine (NE) was used in 100%. EN and vasopressor overlap totaled 36 hours (interquartile range [IQR], 27-69). Median NE dose when starting EN was 5.9 μg/min (IQR, 3.88). Median change in dose from 0 to 6 hours was 0.85 μg/min (95% CI, 0.681.06; P = 0.136), corresponding to a median increase of 14.5%. Total NE duration was 60.5 hours (IQR, 47.5-75.5). No serious complications occurred.

CONCLUSION

The median vasopressor dose did not increase by ≥50% during the first 24 hours of EN. This suggests early EN delivered during septic shock is not associated with worsening hemodynamic instability. Limitations include a small sample size and residual confounding. Prospective data are needed.

Safety and Outcomes of Early Enteral Nutrition in Circulatory Shock

Circulatory shock is one of the most common reasons for an intensive care unit admission, has been shown to impair gut barrier and immune functions, and promotes dysbiosis. The exact timing and dose of enteral nutrition (EN) in circulatory shock remains unclear. In fact, because of fear of complications such as nonocclusive mesenteric ischemia and bowel necrosis and splanchnic steal phenomenon, clinicians may hesitate to start EN in critically ill patients with circulatory shock. In this narrative review, we identify and appraise contemporary evidence evaluating the safety and outcomes of EN in circulatory shock.

Identifying High-Attenuating and Low-Attenuating Muscle Using Computerized Tomography and Exploring Its Impact on Physical Function and Muscle Strength in Obese Critically Ill Patients

BACKGROUND

Computed tomography (CT) methods to estimate sarcopenia in obesity do not differentiate high-attenuating from low-attenuating muscle. The primary purpose of this study was to determine agreement between a CT method using general workstation-derived total and high-attenuating psoas muscle cross-sectional area (CSA) and a commercially available segmentation software-derived value. Secondary purpose was to explore the relationship between quantity of high-attenuating muscle to physical functioning in a pilot cohort of obese medical intensive care unit (MICU) patients.

METHODS

We conducted a prospective observational cross-sectional study. CT images of obese MICU patients were reconstructed to calculate total psoas muscle, low-attenuating muscle, and high-attenuating muscle within the third lumbar psoas CSA using a CT method and commercial software. We performed blinded outcome measures of CSA, physical function, and muscle strength in 28 patients.

RESULTS

Concordance correlation coefficient for identifying total psoas muscle was 0.96 (95% confidence interval: 0.93-0.98, P-value < 0.0001) between CT method and commercial software. There was moderate correlation between modified Medical Research Council muscle strength scores and high-attenuating psoas muscle CSA (r = 0.47, P = 0.01) and lower extremity strength and high-attenuating psoas muscle CSA (r = 0.40, P = 0.04).

CONCLUSION

There was strong agreement between our CT method and a commercial software method to identify total psoas muscle CSA in obesity. Greater total high-attenuating psoas CSA moderately correlated with muscle strength. Additional studies using more objective markers of muscle strength validating these findings are needed.