Gastrointestinal ultrasound in the critically ill: A narrative review and a proposal for a protocol.

Critically ill patients are at risk of presenting with gastrointestinal dysfunction at intensive care unit admission or during their stay. However, identifying gastrointestinal dysfunction is difficult because clinical evaluation is frequently nonspecific and validated biomarkers are lacking. In this context, ultrasound of the digestive tract may help to identify gastrointestinal dysfunction. In this narrative review, we summarize available evidence and propose a protocol for assessment of the gastrointestinal tract with ultrasound. First, we report available evidence from use of four available protocols: the gastrointestinal and urinary tract sonography protocol, the acute gastrointestinal injury ultrasound score, the transabdominal gastrointestinal ultrasound protocol, and the Lai protocol, each addressing somewhat different aspects. Outputs from these protocols have been associated with clinical scores of gastrointestinal failure, feeding intolerance, and 28-day mortality. Second, we describe the potential pitfalls of using ultrasound in the critically ill, such as obesity, abdominal dressings, or the presence of intraluminal gas. Third, we suggest perspectives of ultrasound in monitoring the response to enteral nutrition and for early identification of nonocclusive mesenteric ischemia. Fourth, we propose a structured protocol for gastrointestinal ultrasound describing all the different structures that should be evaluated and provide detailed guidance for a clockwise abdominal examination. In conclusion, the use of a specific and structured protocol might help to identify patients presenting with gastrointestinal dysfunction, guide nutrition, and allow the proposal of pathophysiological hypotheses (complications of enteral nutrition, intra-abdominal infection, bowel ischemia, etc.). The benefit of using a structured protocol requires further investigation.

Preferences for albumin use in adult intensive care unit patients with shock: An international survey.

INTRODUCTION: Use of albumin is suggested for some patients with shock, but preferences for its use may vary among intensive care unit (ICU) physicians. METHODS: We conducted an international online survey of ICU physicians with 20 questions about their use of albumin and their opinion towards a randomised trial among adults with shock comparing the use versus no use of albumin. RESULTS: A total of 1248 respondents participated, with a mean response rate of 37%, ranging from 18% to 75% across 21 countries. Respondents mainly worked in mixed ICUs and 92% were specialists in intensive care medicine. The reported use of albumin in general shock varied as 18% reported 'almost never', 22% 'rarely', 34% 'occasionally', 22% 'frequently' and 4% 'almost always' using albumin. In septic shock, 19% reported 'almost never', 22% 'rarely', 29% 'occasionally', 22% 'frequently' and 7% 'almost always' using albumin. Physicians' preferences were more consistent for haemorrhagic- and cardiogenic shock, with more than 45% reporting 'almost never' using albumin. While the reported use of albumin for other purposes than resuscitation was infrequent (40%-85% reported 'almost never' for five other indications), the most frequent other indications were low serum albumin levels and improvement of the efficacy of diuretics. Most respondents (93%) would randomise adult ICU patients with shock to a trial of albumin versus no albumin. CONCLUSIONS: In this international survey, the reported preferences for the use of albumin in adult ICU patients with shock varied considerably among surveyed ICU physicians. The support for a future randomised trial was high.

Prospective multicenter study to validate the gastrointestinal dysfunction score (GIDS) in intensive care patients: Study protocol for Part A of the international GUTPHOS study.

BACKGROUND: While gastrointestinal (GI) dysfunction is commonly encountered among critically ill patients, a uniform prospectively validated scoring system is lacking. The present study aims to validate the recently developed Gastrointestinal Dysfunction Score (GIDS) in a multicenter, prospective cohort of consecutive adult patients admitted to intensive care units (ICU). METHODS: GUTPHOS is a prospective, multicenter, non-interventional cohort study in which at least 1400 consecutive adult patients (age ≥18 years) admitted to the ICU will be monitored daily for abdominal signs and symptoms of GI dysfunction. The previously developed GIDS constructed from these signs and symptoms will be tested in relation to mortality and duration of ICU dependency and parenteral nutrition (PN) dependency. Between January and June 2024, each participating clinical site will include 50-120 consecutive patients over an eight-week period. Study data will be collected in three phases: baseline data upon ICU admission, daily observations throughout a maximum of 7 days in ICU or until discharge, and a follow-up period of 90 days. The primary outcomes are 28- and 90-day all-cause mortality. Secondary outcomes include ICU and hospital mortality, ICU and hospital length of stay, days alive and free of ICU by day 28 and day 90, days alive and free of hospital by day 28 and day 90, and days alive and free of organ support and PN dependency by day 28. DISCUSSION: The GUTPHOS study will be the first worldwide, multicenter, prospective, observational cohort study to validate the GIDS in adult patients admitted to ICUs against 28- and 90-day mortality. The availability of a validated tool will allow its use in interventional studies that are currently hindered by the lack of a validated measurement tool for GI dysfunction. CLINICAL TRIAL REGISTRY: NCT05909722.

Biomarkers In Prediction of Acute Mesenteric Ischaemia: a prospective multicentre study (BIPAMI study): a study protocol.

BACKGROUND: Acute mesenteric ischaemia (AMI) is a life-threatening disease where early diagnosis is critical to avoid morbidity and mortality from extensive irreversible bowel necrosis. Appropriate prediction of presence of bowel necrosis is currently not available but would help to choose the optimal method of treatment. The study aims to identify combinations of biomarkers that can reliably identify AMI and distinguish between potentially reversible and irreversible bowel ischaemia. METHODS: This is a prospective multicentre study. Adult patients with clinical suspicion of AMI (n = 250) will be included. Blood will be sampled on admission, at and after interventions, or during the first 48 h of suspicion of AMI if no intervention undertaken. Samples will be collected and the following serum or plasma biomarkers measured at Tartu University Hospital laboratory: intestinal fatty acid-binding protein (I-FABP), alpha-glutathione S-transferase (Alpha- GST), interleukin 6 (IL-6), procalcitonin (PCT), ischaemia-modified albumin (IMA), D-lactate, D-dimer, signal peptide-CUB-EGF domain-containing protein 1 (SCUBE-1) and lipopolysaccharide-binding protein (LBP). Additionally, more common laboratory markers will be measured in routine clinical practice at study sites. Diagnosis of AMI will be confirmed by computed tomography angiography, surgery, endoscopy or autopsy. Student's t or Wilcoxon rank tests will be used for comparisons between transmural vs. suspected (but not confirmed) AMI (comparison A), confirmed AMI of any stage vs suspected AMI (comparison B) and non-transmural AMI vs transmural AMI (comparison C). Optimal cut-off values for each comparison will be identified based on the AUROC analysis and likelihood ratios calculated. Positive likelihood ratio > 10 (> 5) and negative likelihood ratio < 0.1 (< 0.2) indicate high (moderate) diagnostic accuracy, respectively. All biomarkers with at least moderate accuracy will be entered as binary covariates (using the best cutoffs) into the multivariable stepwise regression analysis to identify the best combination of biomarkers for all comparisons separately. The best models for each comparison will be used to construct a practical score to distinguish between no AMI, non-transmural AMI and transmural AMI. DISCUSSION: As a result of this study, we aim to propose a score including set of biomarkers that can be used for diagnosis and decision-making in patients with suspected AMI. TRIAL REGISTRATION: NCT06212921 (Registration Date 19-01-2024).

Nutrition in the intensive care unit: from the acute phase to beyond.

Recent randomized controlled trials (RCTs) have shown no benefit but  dose-dependent harm by early full nutritional support in critically ill patients. Lack of benefit may be explained by anabolic resistance, suppression of cellular repair processes, and aggravation of hyperglycemia and insulin needs. Also early high amino acid doses did not provide benefit, but instead associated with harm in patients with organ dysfunctions. However, most studies focused on nutritional interventions initiated during the first days after intensive care unit admission. Although the intervention window of some RCTs extended into the post-acute phase of critical illness, no large RCTs studied nutritional interventions initiated beyond the first week. Hence, clear evidence-based guidance on when and how to initiate and advance nutrition is lacking. Prolonged underfeeding will come at a price as there is no validated metabolic monitor that indicates readiness for medical nutrition therapy, and an adequate response to nutrition, which likely varies between patients. Also micronutrient status cannot be assessed reliably, as inflammation can cause redistribution, so that plasma micronutrient concentrations are not necessarily reflective of total body stores. Moreover, high doses of individual micronutrients have not proven beneficial. Accordingly, current evidence provides clear guidance on which nutritional strategies to avoid, but the ideal nutritional regimen for individual patients remains unclear. In this narrative review, we summarize the findings of recent studies, discuss possible mechanisms explaining the results, point out pitfalls in interpretation of RCTs and their effect on clinical practice, and formulate suggestions for future research.

Incidence, diagnosis, management and outcome of acute mesenteric ischaemia: a prospective, multicentre observational study (AMESI Study).

BACKGROUND: The aim of this multicentre prospective observational study was to identify the incidence, patient characteristics, diagnostic pathway, management and outcome of acute mesenteric ischaemia (AMI). METHODS: All adult patients with clinical suspicion of AMI admitted or transferred to 32 participating hospitals from 06.06.2022 to 05.04.2023 were included. Participants who were subsequently shown not to have AMI or had localized intestinal gangrene due to strangulating bowel obstruction had only baseline and outcome data collected. RESULTS: AMI occurred in 0.038% of adult admissions in participating acute care hospitals worldwide. From a total of 705 included patients, 418 patients had confirmed AMI. In 69% AMI was the primary reason for admission, while in 31% AMI occurred after having been admitted with another diagnosis. Median time from onset of symptoms to hospital admission in patients admitted due to AMI was 24 h (interquartile range 9-48h) and time from admission to diagnosis was 6h (1-12 h). Occlusive arterial AMI was diagnosed in 231 (55.3%), venous in 73 (17.5%), non-occlusive (NOMI) in 55 (13.2%), other type in 11 (2.6%) and the subtype could not be classified in 48 (11.5%) patients. Surgery was the initial management in 242 (58%) patients, of which 59 (24.4%) underwent revascularization. Endovascular revascularization alone was carried out in 54 (13%), conservative treatment in 76 (18%) and palliative care in 46 (11%) patients. From patients with occlusive arterial AMI, revascularization was undertaken in 104 (45%), with 40 (38%) of them in one site admitting selected patients. Overall in-hospital and 90-day mortality of AMI was 49% and 53.3%, respectively, and among subtypes was lowest for venous AMI (13.7% and 16.4%) and highest for NOMI (72.7% and 74.5%). There was a high variability between participating sites for most variables studied. CONCLUSIONS: The overall incidence of AMI and AMI subtypes varies worldwide, and case ascertainment is challenging. Pre-hospital delay in presentation was greater than delays after arriving at hospital. Surgery without revascularization was the most common management approach. Nearly half of the patients with AMI died during their index hospitalization. Together, these findings suggest a need for greater awareness of AMI, and better guidance in diagnosis and management. TRIAL REGISTRATION: NCT05218863 (registered 19.01.2022).

Diagnostic accuracy of biomarkers to detect acute mesenteric ischaemia in adult patients: a systematic review and meta-analysis.

BACKGROUND: Acute mesenteric ischaemia (AMI) is a disease with different pathophysiological mechanisms, leading to a life-threatening condition that is difficult to diagnose based solely on clinical signs. Despite widely acknowledged need for biomarkers in diagnosis of AMI, a broad systematic review on all studied biomarkers in different types of AMI is currently lacking. The aim of this study was to estimate the diagnostic accuracy of all potential biomarkers of AMI studied in humans. METHODS: A systematic literature search in PubMed, The Cochrane Library, Web of Science and Scopus was conducted in December 2022. Studies assessing potential biomarkers of AMI in (at least 10) adult patients and reporting their diagnostic accuracy were included. Meta-analyses of biomarkers' sensitivity, specificity, and positive and negative likelihood ratios were conducted. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed, and the study quality was assessed with the QUADAS-2 tool. RESULTS: Seventy-five studies including a total of 9914 patients assessed 18 different biomarkers in serum/plasma and one in urine (each reported in at least two studies), which were included in meta-analyses. None of the biomarkers reached a conclusive level for accurate prediction. The best predictive value overall (all studies with any type and stage of AMI pooled) was observed for Ischaemia-modified albumin (2 studies, sensitivity 94.7 and specificity 90.5), interleukin-6 (n = 4, 96.3 and 82.6), procalcitonin (n = 6, 80.1 and 86.7), and intestinal fatty acid-binding protein (I-FABP) measured in serum (n = 16, 73.9 and 90.5) or in urine (n = 4, 87.9 and 78.9). In assessment of transmural mesenteric ischaemia, urinary I-FABP (n = 2, 92.3 and 85.2) and D-dimer (n = 3, 87.6 and 83.6) showed moderate predictive value. Overall risk of bias was high, mainly because of selected study populations and unclear timings of the biomarker measurements after onset of symptoms. Combinations of biomarkers were rarely studied, not allowing meta-analyses. CONCLUSIONS: None of the studied biomarkers had sufficient sensitivity and specificity to diagnose AMI, although some biomarkers showed moderate predictive accuracy. Future studies should focus on timing of measurements of biomarkers, distinguishing between early stage and transmural necrosis, and between different types of AMI. Additionally, studies on combinations of biomarkers are warranted. PROSPERO registration: CRD42022379341.

Intravenous vitamin C therapy in adult patients with sepsis: A rapid practice guideline.

BACKGROUND: This Rapid Practice Guideline provides an evidence-based recommendation to address the question: in adults with sepsis or septic shock, should we recommend using or not using intravenous vitamin C therapy? METHODS: The panel included 21 experts from 16 countries and used a strict policy for potential financial and intellectual conflicts of interest. Methodological support was provided by the Guidelines in Intensive Care, Development, and Evaluation (GUIDE) group. Based on an updated systematic review, and the grading of recommendations, assessment, development, and evaluation approach, we evaluated the certainty of evidence and developed recommendations using the evidence-to-decision framework. We conducted an electronic vote, requiring >80% agreement among the panel for a recommendation to be adopted. RESULTS: At longest follow-up, 90 days, intravenous vitamin C probably does not substantially impact (relative risk 1.05, 95% confidence interval [CI] 0.94 to 1.17; absolute risk difference 1.8%, 95% CI -2.2 to 6.2; 6 trials, n = 2148, moderate certainty). Effects of vitamin C on mortality at earlier timepoints was of low or very low certainty due to risk of bias of the included studies and significant heterogeneity between study results. Few adverse events were reported with the use of vitamin C. The panel did not identify any major differences in other outcomes, including duration of mechanical ventilation, ventilator free days, hospital or intensive care unit length of stay, acute kidney injury, need for renal replacement therapy. Vitamin C may result in a slight reduction in duration of vasopressor support (MD -18.9 h, 95% CI -26.5 to -11.4; 21 trials, n = 2661, low certainty); but may not reduce sequential organ failure assessment scores (MD -0.69, 95% CI -1.55 to 0.71; 24 trials, n = 4002, low certainty). The panel judged the undesirable consequences of using IV vitamin C to probably outweigh the desirable consequences, and therefore issued a conditional recommendation against using IV vitamin C therapy in sepsis. CONCLUSIONS: The panel suggests against use of intravenous vitamin C in adult patients with sepsis, beyond that of standard nutritional supplementation. Small and single center trials on this topic should be discouraged.

How to avoid harm with feeding critically ill patients: a synthesis of viewpoints of a basic scientist, dietitian and intensivist.

The optimal feeding strategy in critically ill patients is a matter of debate, with current guidelines recommending different strategies regarding energy and protein targets. Several recent trials have added to the debate and question our previous understanding of the provision of nutrition during critical illness. This narrative review aims to provide a summary of interpretation of recent evidence from the view of basic scientist, critical care dietitian and intensivist, resulting in joined suggestions for both clinical practice and future research. In the most recent randomised controlled trial (RCT), patients receiving 6 versus 25 kcal/kg/day by any route achieved readiness for ICU discharge earlier and had fewer GI complications. A second showed that high protein dosage may be harmful in patients with baseline acute kidney injury and more severe illness. Lastly, a prospective observational study using propensity score matched analysis suggested that early full feeding, especially enteral, compared to delayed feeding is associated with a higher 28-day mortality. Viewpoints from all three professionals point to the agreement that early full feeding is likely harmful, whereas important questions regarding the mechanisms of harm as well as on timing and optimal dose of nutrition for individual patients remain unanswered and warrant future studies. For now, we suggest giving low dose of energy and protein during the first few days in the ICU and apply individualised approach based on assumed metabolic state according to the trajectory of illness thereafter. At the same time, we encourage research to develop better tools to monitor metabolism and the nutritional needs for the individual patient accurately and continuously.

Gastrointestinal function in critically ill patients.

PURPOSE OF REVIEW: To summarize recent evidence regarding the diagnosis of acute gastrointestinal dysfunction and enteral feeding intolerance, and relationship of these to development of multiple organ dysfunction syndrome, during critical illness. RECENT FINDINGS: Novel gastric feeding tubes that attenuate gastroesophageal regurgitation or facilitate continuous monitoring of gastric motility have been developed. The definition of enteral feeding intolerance remains controversial, which may be resolved using a consensus process. A novel scoring system for gastrointestinal dysfunction (GIDS - GastroIntestinal Dysfunction Score) was recently developed but it is not yet validated or tested to evaluate the effect of any interventions. Studies of biomarkers to identify gastrointestinal dysfunction have yet to yield a suitable biomarker for daily clinical use. SUMMARY: The assessment of gastrointestinal function in critically ill patients continues to rely on complex daily clinical assessment. Scoring systems, consensus definitions and novel technology appear the most promising tools and interventions to improve patient care.

Current practice of gastric residual volume measurements and related outcomes of critically ill patients: A secondary analysis of the intestinal-specific organ function assessment study.

BACKGROUND: Gastric residual volume (GRV) measurement to detect gastrointestinal (GI) dysfunction is a common diagnostic procedures in critical care, albeit still not well standardized being operator-, patient-, and tube-dependent. Our aim was to describe current practice of GRV measurements and its association with clinical outcomes in critically ill patients. METHODS: This was a secondary analysis of an international prospective observational cohort study (intestinal-specific organ function assessment). Eligibility criteria were defined as ≥1 GRV measurement during the 7-day study period. Data collection included GRV measurement practices, tube diameters and volumes, symptoms of GI dysfunction, and clinical outcomes. The primary aim was to describe current practices of GRV measurements, and the secondary aim was to test the association of high (>200 ml) vs. low GRV with symptoms of GI dysfunction and clinical outcomes using generalized linear regression and survival models. RESULTS: Two hundred fifty-eight patients with 2422 GRV measurements on 875 study days were analyzed. GRV was mainly measured via passive drainage twice daily using large diameter tubes. There was no significant association between tube size or measurement technique and high GRV. High GRV occurred in 34% of patients and was associated with other GI symptoms and with increased disease severity but not with 28-day or 90-day mortality, intensive care unit-free and ventilator-free days. CONCLUSION: There was substantial variability of GRV measurement techniques, but this had no impact on the amount of GRV. High GRV was not associated with mortality or ventilator-free days but may serve as a marker of GI dysfunction and disease severity.

Management of acute mesenteric ischaemia: Results of a worldwide survey.

BACKGROUND: Acute mesenteric ischaemia (AMI) is a condition with high mortality. This survey assesses current attitudes and practices to manage AMI worldwide. METHODS: A questionnaire survey about the practices of diagnosing and managing AMI, endorsed by several specialist societies, was sent to different medical specialists and hospitals worldwide. Data from individual health care professionals and from medical teams were collected. RESULTS: We collected 493 individual forms from 71 countries and 94 team forms from 34 countries. Almost half of respondents were surgeons, and most of the responding teams (70%) were led by surgeons. Most of the respondents indicated that diagnosis of AMI is often delayed but rarely missed. Emergency revascularisation is often considered for patients with AMI but rarely in cases of transmural ischaemia (intestinal infarction). Responses from team hospitals with a dedicated special unit (14 team forms) indicated more aggressive revascularisation. Abdominopelvic CT-scan with intravenous contrast was suggested as the most useful diagnostic test, indicated by approximately 90% of respondents. Medical history and risk factors were thought to be more important in diagnosis of AMI without transmural ischaemia, whereas for intestinal infarction, plasma lactate concentrations and surgical exploration were considered more useful. In elderly patients, a palliative approach is often chosen over extensive bowel resection. There was a large variability in anticoagulant treatment, as well as in timing of surgery to restore bowel continuity. CONCLUSIONS: Delayed diagnosis of AMI is common despite wide availability of an adequate imaging modality, i.e. CT-scan. Large variability in treatment approaches exists, indicating the need for updated guidelines. Increased awareness and knowledge of AMI may improve current practice until more robust evidence becomes available. Adherence to the existing guidelines may help in improving differences in treatment and outcomes.

The need for biomarkers to determine response to enteral nutrition during and after critical illness: an update.

PURPOSE OF REVIEW: Biomarkers proposed to provide prognosis or to determine the response to enteral nutrition have been assessed in a number of experimental and clinical studies which are summarized in the current review. RECENT FINDINGS: There are several pathophysiological mechanisms identified which could provide biomarkers to determine response to enteral nutrition. Several biomarkers have been studied, most of them insufficiently and none of them has made its way to clinical practice. Available studies have mainly assessed a simple association of a biomarker with outcomes, but are less focused on dynamic changes in the biomarker levels. Importantly, studies on pathophysiology and clinical features of gastrointestinal dysfunction, including enteral feeding intolerance, are also needed to explore the mechanisms potentially providing specific biomarkers. Not only an association of the biomarker with any adverse outcome, but also a rationale for repeated assessment to assist in treatment decisions during the course of illness is warranted. SUMMARY: There is no biomarker currently available to reliably provide prognosis or determine the response to enteral nutrition in clinical practice, but identification of such a biomarker would be valuable to assist in clinical decision-making.

Epidemiology of Acute Mesenteric Ischemia: A Population-Based Investigation.

BACKGROUND: There is a lack of population-based studies on acute mesenteric ischemia (AMI). We have therefore performed a nationwide epidemiological study in Estonia, addressing incidence, demographics, interventions and mortality of AMI. METHODS: A retrospective population-based review was conducted of all adult cases of AMI accrued from the digital Estonian Health Insurance Fund and Causes of Death Registry for 2016-2020 based on international classification of diseases (ICD-10) diagnostic codes and procedure codes (NOMESCO). RESULTS: Overall, 577 cases of AMI were identified-an annual incidence of 8.7 per 100,000. The median age was 79 (range 32-104) and 57% were female. Predominating comorbidities included hypertensive disease (81%), atherosclerosis (67%), and atrial fibrillation (52%). The majority of cases (60%) were caused by superior mesenteric artery occlusion (thrombosis 54%, embolism 12%, and unclear 34%). Inferior mesenteric artery occlusion occurred in 7%, non-occlusive mesenteric ischemia in 7%, venous thrombosis in 4%, whereas the type remained unclear in 21% of cases. 40% of patients received intervention (revascularization and/or intestinal resection) and 13% active non-operative treatment. In 21% an exploratory laparotomy or laparoscopy revealed unsalvageable bowel prompting end-of-life care, which was the only management in a further 25% of cases. CONCLUSIONS: The population-based annual incidence of AMI in Estonia was 8.7 per 100,000 during the study period. The overall hospital mortality and 1 year mortality were 64% and 74%, respectively. In the 53% of patients who received active treatment hospital mortality was 32% and 1 year all-cause mortality was 51%. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT04867499.