Gastrointestinal dysfunction in the critically ill: a systematic scoping review and research agenda proposed by the Section of Metabolism, Endocrinology and Nutrition of the European Society of Intensive Care Medicine

Acute Pancreatitis: Diagnosis and Treatment

Acute pancreatitis is a common indication for hospital admission, increasing in incidence, including in children, pregnancy and the elderly. Moderately severe acute pancreatitis with fluid and/or necrotic collections causes substantial morbidity, and severe disease with persistent organ failure causes significant mortality. The diagnosis requires two of upper abdominal pain, amylase/lipase ≥ 3 ×upper limit of normal, and/or cross-sectional imaging findings. Gallstones and ethanol predominate while hypertriglyceridaemia and drugs are notable among many causes. Serum triglycerides, full blood count, renal and liver function tests, glucose, calcium, transabdominal ultrasound, and chest imaging are indicated, with abdominal cross-sectional imaging if there is diagnostic uncertainty. Subsequent imaging is undertaken to detect complications, for example, if C-reactive protein exceeds 150 mg/L, or rarer aetiologies. Pancreatic intracellular calcium overload, mitochondrial impairment, and inflammatory responses are critical in pathogenesis, targeted in current treatment trials, which are crucially important as there is no internationally licenced drug to treat acute pancreatitis and prevent complications. Initial priorities are intravenous fluid resuscitation, analgesia, and enteral nutrition, and when necessary, critical care and organ support, parenteral nutrition, antibiotics, pancreatic exocrine and endocrine replacement therapy; all may have adverse effects. Patients with local complications should be referred to specialist tertiary centres to guide further management, which may include drainage and/or necrosectomy. The impact of acute pancreatitis can be devastating, so prevention or reduction of the risk of recurrence and progression to chronic pancreatitis with an increased risk of pancreas cancer requires proactive management that should be long term for some patients.

Effect of supplemental parenteral nutrition on all-cause mortality in critically Ill adults: A meta-analysis and subgroup analysis

Objective

Several observational studies have demonstrated that increased nutritional delivery by supplemental parenteral nutrition (SPN) plus enteral nutrition (EN) reduces the rate of all-cause mortality in critically ill patients. Therefore, we aimed to compare and evaluate the effect of SPN plus EN on all-cause mortality in critically ill adults.

Methods

Randomized controlled trials were retrieved from PubMed, Embase, Google Scholar, Cochrane Library, and Sinomed (up to May 2021). Adults with severe illness treated with SPN plus EN or with EN alone were enrolled. The risk of bias was evaluated using the Newcastle-Ottawa scale, and a meta-analysis was conducted using Stata software. The primary outcome was all-cause mortality and was evaluated by pooled odds ratio (OR) with the fixed-effects model. Required information size was also calculated using trial sequential analysis.

Results

We identified 10 randomized controlled trials, with a total of 6,908 patients. No significant differences in rate of all-cause mortality (OR = 0.96, 95% CI: 0.84-1.09, P = 0.518), intensive care unit (ICU) mortality (OR = 0.90, 95% CI: 0.75-1.07, P = 0.229), and hospital mortality (OR = 0.95, 95% CI: 0.82-1.10, P = 0.482) were found between the SPN plus EN and EN alone groups. SPN plus EN support was associated with a significantly decreased risk of infection (OR = 0.83, 95% CI: 0.74-0.93, P = 0.001), although the duration of mechanical ventilation [standardized mean difference (SMD) = - 0.20], length of hospital stay (SMD = 0.12), and ICU stay (SMD = - 0.57) were similar between the two groups (all P > 0.05). Meta-regression analyses showed no significant correlations between all-cause mortality and baseline clinical factors, including patients' age, the Acute Physiology and Chronic Health Evaluation II (APACHE II) score, time of SPN initiation, and follow-up duration (all P > 0.05). Subgroup analysis showed that SPN plus EN support was associated with a trend toward decreased rate of all-cause mortality in studies with follow-up < 30 days (OR = 0.61, 95% CI: 0.36-1.02, P = 0.058). Trial sequence analysis showed that the required information size for all-cause mortality was 16,972, and the cumulative Z-curve indicated no significant differences in the risk of all-cause mortality between the two groups (P > 0.05).

Conclusion

SPN plus EN support can significantly reduce the risk of infection, although it has no significant effect on all-cause mortality among critically ill patients. More studies are warranted to confirm these findings.

Effect of melatonin on electrical impedance and biomarkers of damage in a gastric ischemia/reperfusion model

The damage to the gastrointestinal mucosa induced by ischemia/reperfusion (I/R) is closely related to high mortality in critically ill patients, which is attributable, in part, to the lack of an early method of diagnosis to show the degree of ischemia-induced injury in this type of patients. Electrical Impedance Spectroscopy (EIS) has been shown to be a tool to early diagnose gastric mucosal damage induced by ischemia. A therapeutic alternative to reduce this type of injury is melatonin (MT), which has gastroprotective effects in I/R models. In this work, the effect of treatment with MT on the electrical properties of gastric tissue, biomarkers of inflammatory (iNOS and COX-2), proliferation, and apoptotic process under I/R conditions in male Wistar rats was evaluated through EIS, histological and immunohistochemical analysis. Treatment with MT prevents gastric mucosa damage, causing a decrease in gastric impedance parameters related to the inflammatory process and cellular damage. This suggests that EIS could be used as a tool to diagnose and monitor the evolution of gastric mucosal injury, as well as in the recovery process in critically ill patients.

The interaction between STING and NCOA4 exacerbates lethal sepsis by orchestrating ferroptosis and inflammatory responses in macrophages

The discovery of STING-related innate immunity has recently provided a deep mechanistic understanding of immunopathy. While the detrimental effects of STING during sepsis had been well documented, the exact mechanism by which STING causes lethal sepsis remains obscure. Through single-cell RNA sequence, genetic approaches, and mass spectrometry, we demonstrate that STING promotes sepsis-induced multiple organ injury by inducing macrophage ferroptosis in a cGAS- and interferon-independent manner. Mechanistically, Q237, E316, and S322 in the CBD domain of STING are critical binding sites for the interaction with the coiled-coil domain of NCOA4. Their interaction not only triggers ferritinophagy-mediated ferroptosis, but also maintains the stability of STING dimers leading to enhanced inflammatory response, and reduces the nuclear localization of NCOA4, which impairs the transcription factor coregulator function of NCOA4. Meanwhile, we identified HET0016 by high throughput screening, a selective 20-HETE synthase inhibitor, decreased STING-induced ferroptosis in peripheral blood mononuclear cells from patients with sepsis and mortality in septic mice model. Our findings uncover a novel mechanism by which the interaction between STING and NCOA4 regulates innate immune response and ferroptosis, which can be reversed by HET0016, providing mechanistic and promising targets insights into sepsis.

Intensive Care Management of the Cardiogenic Shock Patient

Optimal management of patients with cardiogenic shock requires a detailed and systematic assessment of all organ systems, balancing the risks and benefits of any investigation and intervention, while avoiding the complications of critical illness. Overall prognosis depends upon a number of factors, including that of the underlying cardiac disease and its potential reversibility, the severity of shock, the involvement of other organ systems, the age of the patient and comorbidities. As with all intensive care patients, the mainstay of management is supportive, up to and including implementation and management of a number of devices, including acute mechanical circulatory support. The assessment and management of these most critically ill patients therefore demands in-depth knowledge and skill relating to cardiac intensive care, extending well beyond standard intensive care or cardiology practice.

Efficacy and safety of ketone ester infusion to prevent muscle weakness in a mouse model of sepsis-induced critical illness

In septic mice, 3-hydroxybutyrate-sodium-salt has shown to partially prevent sepsis-induced muscle weakness. Although effective, the excessive sodium load was toxic. We here investigated whether ketone ester 3-hydroxybutyl-3-hydroxybutanoate (3HHB) was a safer alternative. In a mouse model of abdominal sepsis, the effects of increasing bolus doses of 3HHB enantiomers on mortality, morbidity and muscle force were investigated (n = 376). Next, plasma 3HB^- clearance after bolus d-3HHB was investigated (n = 27). Subsequently, in septic mice, the effect on mortality and muscle force of a continuous d,l-3HHB infusion was investigated (n = 72). In septic mice, as compared with placebo, muscle force was increased at 20 mmol/kg/day l-3HHB and at 40 mmol/kg/day d- and d,l-3HHB. However, severity of illness and mortality was increased by doubling the effective bolus doses. Bolus 3HHB caused a higher 3HB⁻ plasma peak and slower clearance with sepsis. Unlike bolus injections, continuous infusion of d,l-3HHB did not increase severity of illness or mortality, while remaining effective in improving muscle force. Treatment of septic mice with the ketone ester 3HHB partly prevented muscle weakness. Toxicity of 3HHB administered as bolus was completely avoided by continuous infusion of the same dose. Whether continuous infusion of ketone esters represents a promising intervention to also prevent ICU-acquired weakness in human patients should be investigated.

Novel insights in endocrine and metabolic pathways in sepsis and gaps for future research

Sepsis is defined as any life-threatening organ dysfunction caused by a dysregulated host response to infection. It remains an important cause of critical illness and has considerable short- and long-term morbidity and mortality. In the last decades, preclinical and clinical research has revealed a biphasic pattern in the (neuro-)endocrine responses to sepsis as to other forms of critical illness, contributing to development of severe metabolic alterations. Immediately after the critical illness-inducing insult, fasting- and stress-induced neuroendocrine and cellular responses evoke a catabolic state in order to provide energy substrates for vital tissues, and to concomitantly activate cellular repair pathways while energy-consuming anabolism is postponed. Large randomized controlled trials have shown that providing early full feeding in this acute phase induced harm and reversed some of the neuro-endocrine alterations, which suggested that the acute fasting- and stress-induced responses to critical illness are likely interlinked and benefical. However, it remains unclear whether, in the context of accepting virtual fasting in the acute phase of illness, metabolic alterations such as hyperglycemia are harmful or beneficial. When patients enter a prolonged phase of critical illness, a central suppression of most neuroendocrine axes follows. Prolonged fasting and central neuroendocrine suppression may no longer be beneficial. Although pilot studies have suggested benefit of fasting-mimicking diets and interventions that reactivate the central neuroendocrine suppression selectively in the prolonged phase of illness, further study is needed to investigate patient-oriented outcomes in larger randomized trials.

Management of gastrointestinal failure in the adult critical care setting

PURPOSE OF REVIEW

Gastrointestinal failure is a polymorphic syndrome with multiple causes. Managing the different situations from a practical, metabolic, and nutritional point of view is challenging, which the present review will try to address.

RECENT FINDINGS

Acute gastrointestinal injury (AGI) has been defined and has evolved into a concept of gastrointestinal dysfunction score (GIDS) built on the model of Sequential Organ Failure Assessment (SOFA) score, and ranging from 0 (no risk) to 4 (life threatening). But there is yet no specific, reliable and reproducible, biomarker linked to it. Evaluating the risk with the Nutrition Risk Screening (NRS) score is the first step whenever addressing nutrition therapy. Depending on the severity of the gastrointestinal failure and its clinical manifestations, nutritional management needs to be individualized but always including prevention of undernutrition and dehydration, and administration of target essential micronutrients. The use of fibers in enteral feeding solutions has gained acceptance and is even recommended based on microbiome findings. Parenteral nutrition whether alone or combined to enteral feeding is indicated whenever the intestine is unable to process the needs.

SUMMARY

The heterogeneity of gastrointestinal insufficiency precludes a uniform nutritional management of all critically ill patients but justifies its early detection and the implementation of individualized care.

Naloxegol to Prevent Constipation in ICU Adults Receiving Opioids: A Randomized Double-Blind Placebo-Controlled Pilot Trial

Background

Constipation is frequent in critically ill adults receiving opioids. Naloxegol (N), a peripherally acting mu-receptor antagonist (PAMORA), may reduce constipation. The objective of this trial was to evaluate the efficacy and safety of N to prevent constipation in ICU adults receiving opioids. Methods and Patients. In this single-center, double-blind, randomized trial, adults admitted to a medical ICU receiving IV opioids (≥100 mcg fentanyl/day), and not having any of 17 exclusion criteria, were randomized to N (25 mg) or placebo (P) daily randomized to receive N (25mg) or placebo (P) and docusate 100 mg twice daily until ICU discharge, 10 days, or diarrhea (≥3 spontaneous bowel movement (SBM)/24 hours) or a serious adverse event related to study medication. A 4-step laxative protocol was initiated when there was no SBM ≥3 days.

Results

Only 318 (20.6%) of the 1542 screened adults during the 1/17–10/19 enrolment period met all inclusion criteria. Of these, only 19/381 (4.9%) met all eligibility criteria. After 7 consent refusals, 12 patients were randomized. The study was stopped early due to enrolment futility. The N (n = 6) and P (n = 6) groups were similar. The time to first SBM (N 41.4 ± 31.7 vs. P 32.5 ± 25.4 hours, P = 0.56) was similar. The maximal daily abdominal pressure was significantly lower in the N group (N 10 ± 4 vs. P 13 ± 5, P = 0.002). The median (IQR) daily SOFA scores were higher in N (N 7 (4, 8) vs. P 4 (3, 5), P < 0.001). Laxative protocol use was similar (N 83.3% vs. P 66.6%; P = 0.51). Diarrhea prevalence was high but similar (N 66.6% vs. P 66.6%; P = 1.0). No patient experienced opioid withdrawal.

Conclusions

Important recruitment challenges exist for ICU trials evaluating the use of PAMORAs for constipation prevention. Despite being underpowered, our results suggest time to first SBM with naloxegol, if different than P, may be small. The effect of naloxegol on abdominal pressure, SOFA, and the interaction between the two requires further research.

Effects of Nalbuphine on Gastrointestinal Function in Post-Operative Critical Ill Patients Admitted to the ICU: A Multicenter Randomized Controlled Trial

Background

Gastrointestinal (GI) function can be a significant problem in critically ill patients and is associated with detrimental outcomes. The administration of opioids for pain reduction is thought to contribute to GI dysfunction. We tested whether nalbuphine, a mixed agonist/antagonist opioid modulator, can promote GI recovery in postoperative critical patients admitted to the intensive care unit (ICU) and compared it with fentanyl, a selective mu opioid receptor (MOR) agonist.

Methods

This is a multicenter, single-blind, randomized controlled trial to investigate whether nalbuphine improves the GI recovery in ICU patients after surgery, and compared it with fentanyl. The primary outcome was the time to first defecation. Secondary outcomes included the use of sedatives, enemas or laxatives, the acute gastrointestinal injury (AGI) grade, the incidence of vomiting, and the lengths of ICU and hospital stays.

Results

We randomized 436 patients, and a total of 369 patients were included in the modified intention-to-treat population (mITT) (185 to the nalbuphine group and 184 to the fentanyl group). The baseline demographic characteristics of the two groups were comparable after randomization. There was no significant difference in the time to defecation between the two groups [hazard ratio (HR) 0.94, 95% CI 0.74–1.19, p = 0.62]. There was no significant difference in the secondary outcomes between the two groups.

Conclusion

We found no evidence that nalbuphine administration can improve the GI function in postoperative critical patients admitted to the ICU compared with fentanyl. However, the CI was wide and we could not exclude the clinically important difference.

Enteral feeding, even when the gut does not feel very good?

PURPOSE OF REVIEW

To summarize knowledge on the gut function in relation to enteral nutrition.

RECENT FINDINGS

The gut is certainly suffering during critical illness but our understanding of the exact mechanisms involved is limited. Physicians at bedside are lacking tools to identify how well or bad the gut is doing and whether the gut is responding adequately to critical illness. Sensing nutrition as a signal is important for the gut and microbiome. Enteral nutrition has beneficial effects for the gut perfusion and function. However, early full enteral nutrition in patients with shock was associated with an increased number of rare but serious complications.

SUMMARY

Whenever synthesizing knowledge in physiology and available evidence in critically ill, we suggest that enteral nutrition has beneficial effects but may turn harmful if provided too aggressively. Contraindications to enteral nutrition are listed in recent guidelines. For patients with gastrointestinal dysfunction but without these contraindications, we suggest considering early enteral nutrition as a signal to the gut and to the body rather than an energy and protein provision. With this rationale, we think that low dose of enteral nutrition could and probably should be provided also when the gut does not feel very good. Understanding the feedback from the gut in response to enteral nutrition would be important, however, monitoring tools are currently limited to clinical assessment only.

Association of Gastric Antrum Echodensity and Acute Gastrointestinal Injury in Critically Ill Patients

(1) Background: Acute muscle inflammation leads to increased sonographic echodensity. We developed a technique to characterize the echodensity of the gastric antrum wall and assess its feasibility in evaluating the severity of acute gastrointestinal injury (AGI); (2) Methods: The B-mode images of the gastric antrum of each enrolled patient were obtained daily by point-of-care ultrasound (POCUS). The 50th percentile, 85th percentile, and mean value of the grayscale distribution according to histogram analysis (ED50, ED85, and EDmean, respectively) were used to characterize the gastric antrum echodensity. Consistency and correlation analyses were performed to evaluate the feasibility and reproducibility of gastric antrum echodensity measurement. The association of gastric antrum echodensity with the severity of AGI and its ability to predict feeding intolerance (FI) were analyzed; (3) Results: In total, 206 POCUS images of 43 patients were analyzed. The gastric antrum echodensity measurements had sufficient intra- and inter-investigator reliabilities (intraclass correlation coefficient >0.9 for all parameters). The ED50 showed a significant upward trend as AGI severity increased, as well as ED85 and EDmean (p for trend <0.001, respectively). Patients who experienced FI had a higher ED50 (67.8 vs. 56.1, p = 0.02), ED85 (85.6 vs. 71.2, p = 0.01), and EDmean (70.3 vs. 57.6, p = 0.01) upon enteral feeding initiation; (4) Conclusions: Measurement of gastric antrum echodensity was technically feasible and reproducible in ventilated patients. Increased gastric antrum echodensity was associated with greater severity of AGI. Patients with higher gastric antrum echodensity upon enteral nutrition initiation via a nasogastric tube were more likely to develop FI.

Integrin αEβ7 is involved in the intestinal barrier injury of sepsis

Background: IL-9-producing CD4(+) T (Th9) cell was related to acute intestinal barrier injury in sepsis. Integrin αEβ7 was an important lymphocyte homing receptor on the surface of intestinal Th9 cells. However, the roles of αEβ7 in the intestinal injury caused by Th9 cells were not clear in sepsis.

Methods: To investigate the roles of αEβ7 in the intestinal injury caused by Th9 cells in sepsis model, the Th9 cells percentages, αEβ7, E-cadherin, IL-9, and D-lactate levels in both serum and intestinal tissue were measured. The intestinal histopathology, epithelium apoptosis, and mucosal permeability measurement were also performed. The survival rate of septic rats was recorded daily for 14 days.

Results: Rats were assigned to four cohorts: control cohort, sepsis cohort, sepsis+αEβ7i (αEβ7 inhibition) cohort, and sepsis+αEβ7e (αEβ7 overexpression) cohort. The Th9 cells percentages, αEβ7, IL-9, and D-lactate levels of the sepsis cohort were significantly higher than those of the control cohort. The levels of these variables were also elevated progressively in the sepsis+αEβ7i cohort, sepsis cohort, and sepsis+αEβ7e cohort. The E-cadherin levels were decreased progressively in the control cohort, sepsis+αEβ7i cohort, sepsis cohort, and sepsis+αEβ7e cohort. Moreover, αEβ7 overexpression could decrease the 14-day survival rate. The findings of histopathology staining, apoptosis detection, and intestinal permeability test also confirmed that the barrier injury was deteriorated or relieved by elevating or decreasing the αEβ7 expression levels, respectively.

Conclusions: Integrin αEβ7 was closely associated with the intestinal barrier injury caused by Th9 lymphocytes in sepsis.

When is parenteral nutrition indicated?

The indications and contraindications of parenteral nutrition (PN) are discussed in view of recent clinical findings. For decades, PN has been restricted to patients unable to tolerate enteral nutrition (EN) intake owing to the perceived risk of severe side-effects. The evolution of the PN substrate composition and delivery of nutrition via all-in-one bags has dramatically improved the application prospects of PN. Recent studies show similar complication rates of nutrition therapy administered through enteral and intravenous routes. Therefore, indications of PN have, based on evidence, extended beyond complete gastrointestinal (GI) failure to include conditions such as insufficient EN generating persistent negative energy balance and insufficient protein intakes, malabsorption, or specific needs that are impossible to cover with EN feeds.

A guide to enteral nutrition in intensive care units: 10 expert tips for the daily practice

The preferential use of the oral/enteral route in critically ill patients over gut rest is uniformly recommended and applied. This article provides practical guidance on enteral nutrition in compliance with recent American and European guidelines. Low-dose enteral nutrition can be safely started within 48 h after admission, even during treatment with small or moderate doses of vasopressor agents. A percutaneous access should be used when enteral nutrition is anticipated for ≥ 4 weeks. Energy delivery should not be calculated to match energy expenditure before day 4–7, and the use of energy-dense formulas can be restricted to cases of inability to tolerate full-volume isocaloric enteral nutrition or to patients who require fluid restriction. Low-dose protein (max 0.8 g/kg/day) can be provided during the early phase of critical illness, while a protein target of > 1.2 g/kg/day could be considered during the rehabilitation phase. The occurrence of refeeding syndrome should be assessed by daily measurement of plasma phosphate, and a phosphate drop of 30% should be managed by reduction of enteral feeding rate and high-dose thiamine. Vomiting and increased gastric residual volume may indicate gastric intolerance, while sudden abdominal pain, distension, gastrointestinal paralysis, or rising abdominal pressure may indicate lower gastrointestinal intolerance.

The intensivist's assessment of gastrointestinal function: A pilot study

Gastrointestinal dysfunction/failure (GDF) is a common cause of concern in critically ill patients. Although the gut plays an important role in the genesis of organ failure, its exclusion from organ severity scoring systems has made it challenging for intensivists to score it sufficiently at the bedside. We aimed to survey intensive care specialists about their perceptions, attitudes, and approaches towards the assessment of the gut in Australia and New Zealand intensive care units (ICUs). An electronic (online) questionnaire was used to survey intensive care specialists from the Australia and New Zealand Intensive Care Society (ANZICS). The survey comprised 10 questions focused on four key areas: (i) the extent of the problem with GDF in ICUs, (ii) the use and reliability of the current gut scoring tools, (iii) personal approaches and practices associated with GDF assessment, and (4) potential value of a novel GDF scoring system and its incorporation into an organ severity score. Our results showed that GDF was a significant concern amongst ICUs in Australia and New Zealand intensivists (84%; 66/79), with a small number of participants (14%; 3/79) using a gut scoring tool in their ICUs. Despite this, we have no established objective scoring tool for its assessment. The survey highlighted the need for developing a novel scoring tool to assess the gut was considered important amongst majority of the intensivists (92%; 72/78), which would prove useful in clinical practice and potentially lead to incorporation into an organ severity score in the future.

The effect of opioids on gastrointestinal function in the ICU

Gastrointestinal (GI) dysfunction is common in the critical care setting and is highly associated with clinical outcomes. Opioids increase the risk for GI dysfunction and are frequently prescribed to reduce pain in critically ill patients. However, the role of opioids in GI function remains uncertain in the ICU. This review aims to describe the effect of opioids on GI motility, their potential risk of increasing infection and the treatment of GI dysmotility with opioid antagonists in the ICU setting.

Avoiding Misdiagnosis of Abdominal Vascular Catastrophes

Abdominal vascular emergencies are an uncommon entity in emergency medicine, but when they present, they are often catastrophic. These time-sensitive and life-threatening diagnoses are often hidden in nonspecific complaints such as nausea, vomiting, or flank pain, so the emergency physician must remain diligent and consider these in the differential diagnoses. The following is an overview of the more common of these abdominal vascular emergencies, in the hope that they help the Emergency Physician avoid the misdiagnosis and subsequent vascular catastrophe that would follow.

Nutrition in the Intensive Care Unit-A Narrative Review

Background: While consent exists, that nutritional status has prognostic impact in the critically ill, the optimal feeding strategy has been a matter of debate. Methods: Narrative review of the recent evidence and international guideline recommendations focusing on basic principles of nutrition in the ICU and the treatment of specific patient groups. Covered topics are: the importance and diagnosis of malnutrition in the ICU, the optimal timing and route of nutrition, energy and protein requirements, the supplementation of specific nutrients, as well as monitoring and complications of a Medical Nutrition Therapy (MNT). Furthermore, this review summarizes the available evidence to optimize the MNT of patients grouped by primarily affected organ system. Results: Due to the considerable heterogeneity of the critically ill, MNT should be carefully adapted to the individual patient with special focus on phase of critical illness, metabolic tolerance, leading symptoms, and comorbidities. Conclusion: MNT in the ICU is complex and requiring an interdisciplinary approach and frequent reevaluation. The impact of personalized and disease-specific MNT on patient-centered clinical outcomes remains to be elucidated.

Effects of permissive hypocaloric vs standard enteral feeding on gastrointestinal function and outcomes in sepsis

BACKGROUND

Intestinal mucosal barrier injury and gastrointestinal dysfunction are important causes of sepsis. However, few studies have investigated the effects of enteral underfeeding on gastrointestinal function in sepsis. Moreover, no consensus on goal enteral caloric intake has been reached in sepsis.

AIM

To investigate the effects of different goal caloric requirements of enteral nutrition on the gastrointestinal function and outcomes in the acute phase of sepsis.

METHODS

Patients were randomly assigned to receive 30% (defined as group A), 60% (group B), or 100% (group C) of goal caloric requirements of enteral nutrition in this prospective pilot clinical trial. The acute gastrointestinal injury (AGI) grades, incidence of feeding intolerance (FI), daily caloric intake, nutritional and inflammatory markers, and biomarkers of mucosal barrier function were collected during the first 7 d of enteral feeding. The clinical severity and outcome variables were also recorded.

RESULTS

A total of 54 septic patients were enrolled. The days to goal calorie of group C (2.55 ± 0.82) were significantly longer than those of group A (3.50 ± 1.51; P = 0.046) or B (4.85 ± 1.68; P < 0.001). The FI incidence of group C (16.5%) was higher than that of group A (5.0%) or B (8.7%) (P = 0.009). No difference in the incidence of FI symptoms was found between groups A and B. The serum levels of barrier function biomarkers of group B were significantly lower than those of group A (P < 0.05) on the 7th day of feeding. The prealbumin and IL-6 levels of group A were lower than those of group B (P < 0.05) on the 7^th day of feeding. No significant differences in the clinical outcome variables or 28-d mortality were found among the three groups.

CONCLUSION

Early moderate enteral underfeeding (60% of goal requirements) could improve the intestinal barrier function and nutritional and inflammatory status without increasing the incidence of FI symptoms in sepsis. However, further large-scale prospective clinical trials and animal studies are required to test our findings. Moreover, the effects of different protein intake on gastrointestinal function and outcomes should also be investigated in future work.

The correlation between gastric residual volumes and markers of gastric emptying: a post-hoc analysis of a randomized clinical trial

BACKGROUND

The correlation between gastric residual volumes (GRV) and markers of gastric emptying (GE) in critically ill patients is unclear. This is especially true for ICU surgical patients as they are underrepresented in previous studies.

METHODS

We conducted a post-hoc analysis of a multicenter trial that investigated the effectiveness of a promotility drug in increasing enteral nutrition intake. Pharmacokinetic markers of GE [3-O-methylglucose (3-OMG) and acetaminophen] were correlated with GRV measurements. High-GRV was defined as one episode of >400 mL or two consecutive episodes of >250 mL, and delayed GE was defined as <20^th percentile of the pharmacokinetic GE marker that had the strongest correlation with GE.

RESULTS

Out of 77 patients, 8 (10.4%) had high-GRV, and 15 (19.5%) had delayed GE. 3-OMG concentration at 60 mins had the strongest correlation with GRV (Rho: - 0.631), and high-GRV had low sensitivity (46.7%) but high specificity (98.4%) in discriminating delayed GE. The positive (87.5%) and negative (88.4%) predictive values were similar. There was a small sample of surgical patients (n = 14, 18.2%), and they had a significantly higher incidence of high-GRV (29% vs 6%, P: 0.032) and a trend towards delayed GE (36% vs 16%, p: 0.132) when compared to medical patients.

CONCLUSION

GRV reflects GE, and high-GRV is an acceptable surrogate marker of delayed GE. Based on our preliminary observation, surgical patients may have a higher risk of high-GRV and delayed GE. In summary, GRV should be monitored to determine if complex investigations or therapeutic interventions are warranted. This article is protected by copyright. All rights reserved.

Development of the Gastrointestinal Dysfunction Score (GIDS) for critically ill patients - A prospective multicenter observational study (iSOFA study)

BACKGROUND & AIMS

To develop a five grade score (0-4 points) for the assessment of gastrointestinal (GI) dysfunction in adult critically ill patients.

METHODS

This prospective multicenter observational study enrolled consecutive adult patients admitted to 11 intensive care units in nine countries. At all sites, daily clinical data with emphasis on GI clinical symptoms were collected and intra-abdominal pressure measured. In five out of 11 sites, the biomarkers citrulline and intestinal fatty acid-binding protein (I-FABP) were measured additionally. Cox models with time-dependent scores were used to analyze associations with 28- and 90-day mortality. The models were estimated with stratification for study center.

RESULTS

We included 540 patients (224 with biomarker measurements) with median age of 65 years (range 18-94), the Simplified Acute Physiology Score II score of 38 (interquartile range 26-53) points, and Sequential Organ Failure Assessment (SOFA) score of 6 (interquartile range 3-9) points at admission. Median ICU length of stay was 3 (interquartile range 1-6) days and 90-day mortality 18.9%. A new five grade Gastrointestinal Dysfunction Score (GIDS) was developed based on the rationale of the previously developed Acute GI Injury (AGI) grading. Citrulline and I-FABP did not prove their potential for scoring of GI dysfunction in critically ill. GIDS was independently associated with 28- and 90-day mortality when added to SOFA total score (HR 1.40; 95%CI 1.07-1.84 and HR 1.40; 95%CI 1.02-1.79, respectively) or to a model containing all SOFA subscores (HR 1.48; 95%CI 1.13-1.92 and HR 1.47; 95%CI 1.15-1.87, respectively), improving predictive power of SOFA score in all analyses.

CONCLUSIONS

The newly developed GIDS is additive to SOFA score in prediction of 28- and 90-day mortality. The clinical usefulness of this score should be validated prospectively.

TRIAL REGISTRATION

NCT02613000, retrospectively registered 24 November 2015.

Synbiotic Therapy Prevents Nosocomial Infection in Critically Ill Adult Patients: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials Based on a Bayesian Framework

Background: The efficacy of synbiotics, probiotics, prebiotics, enteral nutrition or adjuvant peripheral parenteral nutrition (EPN) and total parenteral nutrition (TPN) in preventing nosocomial infection (NI) in critically ill adults has been questioned. We conducted a systematic review and network meta-analysis (NMA) of randomized controlled trials (RCTs) to evaluate and rank the effectiveness of these therapies on NI amongst critically ill adults.

Methods: Four electronic databases were systematically searched up to June 30, 2019 for RCTs comparing the administration of probiotics, prebiotics, synbiotics, EPN and TPN in critically ill adults. The primary outcome was NI. The relative efficacy of all outcomes was determined by a Bayesian framework with random effects NMA. We estimated the odds ratio (OR) and mean difference (MD) and ranked the comparative effects of all regimens with the surface under the cumulative ranking probabilities. The study has been registered on PROSPERO (CRD42019147032).

Results: Fifty-five RCTs (7,119 patients) were identified. Primary outcome showed that synbiotics had the best effect in preventing NI than EPN (OR 0.37; 95% CrI 0.22–0.61), probiotics followed (OR 0.52; 95% CrI 0.34–0.77), whereas TPN significantly increased NI (OR 2.29; 95% CrI 1.48–3.67). Subgroup analysis showed that TPN significantly increased NI in intensive care unit (ICU) patients (OR 1.57; 95% CrI 1.01–2.56) and severe acute pancreatitis (SAP) patients (OR 3.93; 95% CrI 1.74–9.15). Secondary outcomes showed that synbiotics were more effective in preventing hospital-acquired pneumonia (HAP) (OR 0.34; 95% CrI 0.11–0.85), catheter-related bloodstream infection (OR 0.08; 95% CrI 0.01–0.80), urinary tract infection (OR 0.27; 95% CrI 0.08–0.71) and sepsis (OR 0.34; 95% CrI 0.16–0.70) than EPN. Amongst the treatments, probiotics were most effective for shortening the mechanical ventilation duration (MD −3.93; 95% CrI −7.98 to −0.02), prebiotics were most effective for preventing diarrhea (OR 0.24; 95% CrI 0.05–0.94) and TPN was the least effective in shortening hospital length of stay (MD 4.23; 95% CrI 0.97–7.33).

Conclusions: Amongst the five therapies, synbiotics not only prevented NI in critically ill adults but also demonstrated the best treatment results. By contrast, TPN did not prevent NI and ranked last, especially in ICU and SAP patients.

Take-Home Message: Nosocomial infection is a leading cause of mortality in critically ill patients in the ICU. However, the efficacy of synbiotics, probiotics, prebiotics, enteral nutrition or adjuvant peripheral parenteral nutrition and total parenteral nutrition in preventing nosocomial infection in critically ill adults has been questioned. The network meta-analysis provides evidence that amongst the five therapies, synbiotics not only prevented NI in critically ill adults but also demonstrated the best treatment results. By contrast, TPN did not prevent NI and ranked last, especially in ICU and SAP patients. The results of this study will provide a new scientific basis and a new idea for the debate on the efficacy of synbiotics and other treatments in the improvement of prognosis in critically ill adult patients.

Tweet: Synbiotic prevents nosocomial infection in critically ill adults, while total parenteral nutrition has the adverse curative.

Non-occlusive mesenteric ischemia: Diagnostic challenges and perspectives in the era of artificial intelligence

Acute mesenteric ischemia (AMI) is a severe condition associated with poor prognosis, ultimately leading to death due to multiorgan failure. Several mechanisms may lead to AMI, and non-occlusive mesenteric ischemia (NOMI) represents a particular form of AMI. NOMI is prevalent in intensive care units in critically ill patients. In NOMI management, promptness and accuracy of diagnosis are paramount to achieve decisive treatment, but the last decades have been marked by failure to improve NOMI prognosis, due to lack of tools to detect this condition. While real-life diagnostic management relies on a combination of physical examination, several biomarkers, imaging, and endoscopy to detect the possibility of several grades of NOMI, research studies only focus on a few elements at a time. In the era of artificial intelligence (AI), which can aggregate thousands of variables in complex longitudinal models, the prospect of achieving accurate diagnosis through machine-learning-based algorithms may be sought. In the following work, we bring you a state-of-the-art literature review regarding NOMI, its presentation, its mechanics, and the pitfalls of routine work-up diagnostic exams including biomarkers, imaging, and endoscopy, we raise the perspectives of new biomarker exams, and finally we discuss what AI may add to the field, after summarizing what this technique encompasses.

New insights into lipopolysaccharide inactivation mechanisms in sepsis

The complex pathophysiology of sepsis makes it a syndrome with limited therapeutic options and a high mortality rate. Gram-negative bacteria containing lipopolysaccharides (LPS) in their outer membrane correspond to the most common cause of sepsis. Since the gut is considered an important source of LPS, intestinal damage has been considered a cause and a consequence of sepsis. Although important in the maintenance of the intestinal epithelial cell homeostasis, the microbiota has been considered a source of LPS. Recent studies have started to shed light on how sepsis is triggered by dysbiosis, and an increased inflammatory state of the intestinal epithelial cells, expanding the understanding of the gut-liver axis in sepsis. Here, we review the gut-liver interaction in Gram-negative sepsis, exploring the mechanisms of LPS inactivation, including the recently described contribution of an isoform of the cholesteryl-ester transfer protein (CETPI). Although several key questions remain to be answered when the pathophysiology of sepsis is reviewed, new contributions coming to light exploring the way LPS might be inactivated in vivo, suggest that new applications might soon reach the clinical setting.

Metabolism of Proteins and Amino Acids in Critical Illness: From Physiological Alterations to Relevant Clinical Practice

The clinical impact of nutrition therapy in critically ill patients has been known for years, and relevant guidelines regarding nutrition therapy have emphasized the importance of proteins. During critical illness, such as sepsis or the state following major surgery, major trauma, or major burn injury, patients suffer from a high degree of stress/inflammation, and during this time, metabolism deviates from homeostasis. The increased degradation of endogenous proteins in response to stress hormones is among the most important events in the acute phase of critical illness. Currently published evidence suggests that adequate protein supplementation might improve the clinical outcomes of critically ill patients. The role of sufficient protein supplementation may even surpass that of caloric supplementation. In this review, we focus on relevant physiological alterations in critical illness, the effects of critical illness on protein metabolism, nutrition therapy in clinical practice, and the function of specific amino acids.

Postprandial rise of essential amino acids is impaired during critical illness and unrelated to small-intestinal function

Background

Postprandial rise of plasma essential amino acids (EAAs) determines the anabolic effect of dietary protein. Disturbed gastrointestinal function could impair the anabolic response in critically ill patients. Aim was to investigate the postprandial EAA response in critically ill patients and its relation to small‐intestinal function.

Methods

Twenty‐one mechanically ventilated patients and 9 healthy controls received a bolus containing 100 ml of a formula feed (Ensure) and 2 g of 3‐O‐Methyl‐d‐glucose (3‐OMG) via postpyloric feeding tube. Fasting and postprandial plasma concentrations of EAAs, 3‐OMG, total bile salts, and the gut‐released hormone fibroblast growth factor 19 (FGF19) were measured over a 4‐hour period. Changes over time and between groups were assessed with linear mixed‐effects analysis. Early (0–60 minutes) and total postprandial responses are summarized as the incremental area under the curve (iAUC).

Results

At baseline, fasting EAA levels were similar in both groups: 1181 (1055–1276) vs 1150 (1065–1334) μmol·L−1, P = .87. The early postprandial rise in EAA was not apparent in critically ill patients compared with healthy controls (iAUC₆₀, −4858 [−6859 to 2886] vs 5406 [3099–16,853] µmol·L⁻¹·60 minutes; P = .039). Impaired EAA response did not correlate with impaired 3‐OMG response (Spearman ρ 0.32, P = .09). There was a limited increase in total bile salts but no relevant FGF19 response in either group.

Conclusion

Postprandial rise of EAA is blunted in critically ill patients and unrelated to glucose absorption measured with 3‐OMG. Future studies should aim to delineate governing mechanisms of macronutrient malabsorption.

Protein absorption and kinetics in critical illness

PURPOSE OF REVIEW

Timing, dose, and route of protein feeding in critically ill patients treated in an ICU is controversial. This is because of conflicting outcomes observed in randomized controlled trials (RCTs). This inconsistency between RCTs may occur as the physiology of protein metabolism and protein handling in the critically ill is substantially different from the healthy with limited mechanistic data to inform design of RCTs. This review will outline the current knowledge and gaps in the understanding of protein absorption and kinetics during critical illness.

RECENT FINDINGS

Critically ill patients, both children and adults, lose muscle protein because of substantial increases in protein degradation with initially normal, and over time increasing, protein synthesis rates. Critically ill patients appear to retain the capacity to absorb dietary protein and to use it for building body protein; however, the extent and possible benefit of this needs to be elucidated. More sophisticated methods to study protein absorption and digestion have recently been described but these have yet to be used in the critically ill.

SUMMARY

Adequate understanding of protein absorption and kinetics during critical illness will help the design of better interventional studies in the future. Because of the complexity of measuring protein absorption and kinetics in the critically ill, very few investigations are executed. Recent data using isotope-labelled amino acids suggests that critically ill patients are able to absorb enteral protein and to synthesize new body protein. However, the magnitude of absorption and anabolism that occurs, and possible benefits for the patients need to be elucidated.

Enteral Nutrition Safety With Advanced Treatments: Extracorporeal Membrane Oxygenation, Prone Positioning, and Infusion of Neuromuscular Blockers

This review aims at assessing the safety and efficacy of enteral nutrition in critically ill patients receiving extracorporeal membrane oxygenation, prone positioning, and infusion of neuromuscular blockers. Existing data from randomized controlled trials demonstrate the survival benefit of early enteral nutrition in critically ill patients. Observational data have demonstrated that enteral nutrition in patients receiving extracorporeal membrane oxygenation, prone positioning, and infusion of neuromuscular blockers is generally safe. However, these patients are at increased risk for gastrointestinal complications from enteral nutrition because of critical illness-induced gastrointestinal dysfunction; associated shock; the concomitant use of vasopressor agents, sedatives, and narcotics; possibly mesenteric circulatory compromise; and regurgitation associated with prone positioning. Therefore, early enteral nutrition is generally recommended in these patients in the absence of severe gastrointestinal dysfunction or shock. To reduce the complications, early nutrition should be advanced gradually (trophic feeding or permissive underfeeding), the bed should be tilted to a maximum of 30°, and concentrated nutritional formulae and the use of prokinetics may be considered to treat enteral feeding intolerance. Physicians should be vigilant about monitoring for early signs of acute mesenteric ischemia, which should lead to holding enteral feeding. Parenteral nutrition may be utilized in patients who cannot receive enteral nutrition or are unable to reach their nutrition goals by the end of the first week.

Acute Intestinal Failure

Acute intestinal failure (AIF), "reduction of gut function below the minimum necessary for the absorption of macronutrients and/or water and electrolytes, requiring parenteral nutrition", is common, but very often neglected part of multiorgan dysfunction syndrome (MODS) in the critically ill patients. It is now increasingly being recognized as a cause of prolonged ICU and hospital stay and poor outcome. Multidisciplinary team approach, systematic approach to management with treatment of sepsis, early mobilization and enteral feeding with prokinetics if required, control of intra-abdominal pressure and surgical intervention, when mandated, can help treat AIF and improve patient outcomes. How to cite this article: Chandankhede SR, Kulkarni AP. Acute Intestinal Failure. Indian J Crit Care Med 2020;24(Suppl 4):S168-S174.