Role of the microbiome, probiotics, and 'dysbiosis therapy' in critical illness.

Purpose of reviewLoss of 'health-promoting' microbes and overgrowth of pathogenic bacteria (dysbiosis) in ICU is believed to contribute to nosocomial infections, sepsis, and organ failure (multiple organ dysfunction syndrome). This review discusses new understanding of ICU dysbiosis, new data for probiotics and fecal transplantation in ICU, and new data characterizing the ICU microbiome.Recent findingsICU dysbiosis results from many factors, including ubiquitous antibiotic use and overuse. Despite advances in antibiotic therapy, infections and mortality from often multidrug-resistant organisms (i.e., Clostridium difficile) are increasing. This raises the question of whether restoration of a healthy microbiome via probiotics or other 'dysbiosis therapies' would be an optimal alternative, or parallel treatment option, to antibiotics. Recent clinical data demonstrate probiotics can reduce ICU infections and probiotics or fecal microbial transplant (FMT) can treat Clostridium difficile. This contributes to recommendations that probiotics should be considered to prevent infection in ICU. Unfortunately, significant clinical variability limits the strength of current recommendations and further large clinical trials of probiotics and FMT are needed. Before larger trials of 'dysbiosis therapy' can be thoughtfully undertaken, further characterization of ICU dysbiosis is needed. To addressing this, we conducted an initial analysis demonstrating a rapid and marked change from a 'healthy' microbiome to an often pathogen-dominant microbiota (dysbiosis) in a broad ICU population.SummaryA growing body of evidence suggests critical illness and ubiquitous antibiotic use leads to ICU dysbiosis that is associated with increased ICU infection, sepsis, and multiple organ dysfunction syndrome. Probiotics and FMT show promise as ICU therapies for infection. We hope future-targeted therapies using microbiome signatures can be developed to correct 'illness-promoting' dysbiosis to restore a healthy microbiome post-ICU to improve patient outcomes

Hospital Change to Mixed Lipid Emulsion From Soybean Oil-Based Lipid Emulsion for Parenteral Nutrition in Hospitalized and Critically Ill Adults Improves Outcomes: A Pre-Post-Comparative Study

INTRODUCTION: Early data suggest use of a mixed lipid emulsion (LE) with a soybean oil reduction strategy in parenteral nutrition (PN) may improve clinical outcomes. Duke University Hospital made a full switch to a Soybean oil/MCT/Olive/Fish Oil lipid (4-OLE) from pure soybean oil-based LE (Intralipid, Baxter Inc) in May 2017. Since 4-OLE has limited evidence related to its effects on clinical outcome parameters in US hospitals, evidence for clinical benefits of switching to 4-OLE is needed. Therefore, we examined the clinical utility of a hospital-wide switch to 4-OLE and its effect on patient outcomes. METHODS: We conducted a single-center retrospective cohort study among adult patients (\u3e 18 years) requiring PN from 2016 to 2019. Our primary exposure was treatment period (1-year pre-4-OLE switch versus 2-year post). We used multivariable regression models to examine our primary outcomes, the association of treatment period with hospital length of stay (LOS), and secondary outcomes liver function, infections, and ICU LOS. Analyses were stratified into critically ill and entire adult cohort. RESULTS: We identified 1200 adults hospitalized patients. 28% of PN patients (n = 341) were treated pre-4-OLE switch and 72% post-4-OLE (n = 859). In the adult cohort, 4-OLE was associated with shorter hospital LOS (IRR 0.97, 95% CI 0.95-0.99, p = 0.039). The ICU cohort included 447 subjects, of which 25% (n = 110) were treated pre-4-OLE switch and 75% (n = 337) were post-switch. ICU patients receiving 4-OLE were associated with shorter hospital LOS (IRR 0.91, 95% CI 0.87-0.93, p \u3c 0.0001), as well as a shorter ICU LOS (IRR 0.90, 95% CI 0.82-0.99, p = 0.036). 4-OLE ICU patients also had a significantly lower delta total bilirubin (- 1.6, 95% CI - 2.8 to - 0.2, p = 0.021) and reduced urinary tract infection (UTI) rates (OR 0.50, 95% CI 0.26-0.96, p = 0.038). There were no associations in AST, ALT, or total bilirubin in ICU and all adult patients. CONCLUSION: 4-OLE was successfully implemented and reduced soybean oil LE exposure in a large academic hospital setting. The introduction of 4-OLE was associated with reduced LOS, UTI rates, and mitigated hepatic dysfunction in critically ill patients. Overall, these findings prove a switch to a soybean oil-LE sparing strategy using 4-OLE is feasible and safe and is associated with improved clinical outcomes in adult PN patients

Extreme Dysbiosis of the Microbiome in Critical Illness.

Critical illness is hypothesized to associate with loss of "health-promoting" commensal microbes and overgrowth of pathogenic bacteria (dysbiosis). This dysbiosis is believed to increase susceptibility to nosocomial infections, sepsis, and organ failure. A trial with prospective monitoring of the intensive care unit (ICU) patient microbiome using culture-independent techniques to confirm and characterize this dysbiosis is thus urgently needed. Characterizing ICU patient microbiome changes may provide first steps toward the development of diagnostic and therapeutic interventions using microbiome signatures. To characterize the ICU patient microbiome, we collected fecal, oral, and skin samples from 115 mixed ICU patients across four centers in the United States and Canada. Samples were collected at two time points: within 48 h of ICU admission, and at ICU discharge or on ICU day 10. Sample collection and processing were performed according to Earth Microbiome Project protocols. We applied SourceTracker to assess the source composition of ICU patient samples by using Qiita, including samples from the American Gut Project (AGP), mammalian corpse decomposition samples, childhood (Global Gut study), and house surfaces. Our results demonstrate that critical illness leads to significant and rapid dysbiosis. Many taxons significantly depleted from ICU patients versus AGP healthy controls are key "health-promoting" organisms, and overgrowth of known pathogens was frequent. Source compositions of ICU patient samples are largely uncharacteristic of the expected community type. Between time points and within a patient, the source composition changed dramatically. Our initial results show great promise for microbiome signatures as diagnostic markers and guides to therapeutic interventions in the ICU to repopulate the normal, "health-promoting" microbiome and thereby improve patient outcomes. IMPORTANCE Critical illness may be associated with the loss of normal, "health promoting" bacteria, allowing overgrowth of disease-promoting pathogenic bacteria (dysbiosis), which, in turn, makes patients susceptible to hospital-acquired infections, sepsis, and organ failure. This has significant world health implications, because sepsis is becoming a leading cause of death worldwide, and hospital-acquired infections contribute to significant illness and increased costs. Thus, a trial that monitors the ICU patient microbiome to confirm and characterize this hypothesis is urgently needed. Our study analyzed the microbiomes of 115 critically ill subjects and demonstrated rapid dysbiosis from unexpected environmental sources after ICU admission. These data may provide the first steps toward defining targeted therapies that correct potentially "illness-promoting" dysbiosis with probiotics or with targeted, multimicrobe synthetic "stool pills" that restore a healthy microbiome in the ICU setting to improve patient outcomes

Early propranolol treatment induces lung heme-oxygenase-1, attenuates metabolic dysfunction, and improves survival following experimental sepsis

INTRODUCTION: Pharmacological agents that block beta-adrenergic receptors have been associated with improved outcome in burn injury. It has been hypothesized that injuries leading to a hypermetabolic state, such as septic shock, may also benefit from beta-blockade; however, outcome data in experimental models have been contradictory. Thus, we investigated the effect of beta-blockade with propranolol on survival, hemodynamics, lung heat shock protein (HSP) expression, metabolism and inflammatory markers in a rat cecal ligation and puncture (CLP) model of sepsis. METHODS: Sprague-Dawley rats receiving either repeated doses (30 minutes pre-CLP and every 8 hours for 24 hours postoperatively) of propranolol or control (normal saline), underwent CLP and were monitored for survival. Additionally, lung and blood samples were collected at 6 and 24 hours for analysis. Animals also underwent monitoring to evaluate global hemodynamics. RESULTS: Seven days following CLP, propranolol improved survival versus control (P < 0.01). Heart rates in the propranolol-treated rats were approximately 23% lower than control rats (P < 0.05) over the first 24 hours, but the mean arterial blood pressure was not different between groups. Metabolic analysis of lung tissue demonstrated an increase in lung ATP/ADP ratio and NAD+ content and a decreased ratio of polyunsaturated fatty acids to monounsaturated fatty acids (PUFA/MUFA). Cytokine analysis of the inflammatory cytokine tumor necrosis factor alpha (TNF-alpha) demonstrated decreased expression of TNF-alpha in both lung and plasma at 24 hours post CLP induced sepsis. Finally, propranolol led to a significant increase in lung hemeoxygenase-1 expression, a key cellular protective heat shock protein (HSP) in the lung. Other lung HSP expression was unchanged. CONCLUSIONS: These results suggest that propranolol treatment may decrease mortality during sepsis potentially via a combination of improving metabolism, suppressing aspects of the inflammatory response and enhancing tissue protection

Feasibility of a Novel Augmented 6-Minute Incremental Step Test:A Simplified Cardiorespiratory Fitness Assessment Tool

Background: The cardiopulmonary exercise test (CPET) is considered a gold standard in assessing cardiorespiratory fitness (CRF) but has limited accessibility due to competency requirements and cost. Incorporating portable sensor devices into a simple bedside test of CRF could improve diagnostic and prognostic value. Objectives: The authors sought to evaluate the association of an augmented 6-minute incremental step test (6MIST) with standard CPET. Methods: We enrolled patients undergoing clinically indicated supine cycle ergometry CPET with invasive hemodynamics (iCPET) for the same-day 6MIST. CRF-related variables were simultaneously recorded using a signal morphology-based impedance cardiograph (PhysioFlow Enduro) and a portable metabolic analyzer (VO2 Master Pro) during incremental pace stationary stepping. The correlation between CPET and hemodynamic parameters from both tests was assessed using the intraclass correlation coefficient (ICC). Results: Fifteen patients (mean age 60 ± 14 years, 40% female, 27% Black) were included. All patients who agreed to undergo 6MIST completed the study without any test-related adverse events. We observed good to excellent correlation between iCPET- and 6MIST-measured CPET parameters: peak heart rate (ICC = 0.60; 95% CI: 0.15-0.85), absolute peak O2 consumption (VO2) (ICC = 0.77; 95% CI: 0.44-0.92), relative peak VO2 (ICC = 0.64; 95% CI: 0.20-0.86), maximum ventilation (ICC = 0.59; 95% CI: 0.13-0.84), O2 pulse (ICC = 0.71; 95% CI: 0.33-0.89), and cardiorespiratory optimal point (ICC = 0.82; 95% CI: 0.52-0.94). No significant correlation was determined between iCPET and 6MIST in measuring cardiac index at rest (ICC = 0.19; 95% CI: −0.34 to 0.63) or at peak exercise (ICC = 0.36; 95% CI: −0.17 to 0.73). Conclusions: We demonstrate the feasibility of a novel augmented 6MIST with wearable devices for simultaneous CPET and hemodynamic assessment. 6MIST-measured CPET parameters were strongly correlated with the iCPET-derived measurements. Additional studies are needed to confirm the validity of the 6MIST compared to standard upright CPET.</p

Prognostic significance of muscle fasciculations in critically Ill COVID-19 patients under mechanical ventilation

Introduction: The COVID-19 pandemic brought unprecedented challenges to healthcare systems worldwide, particularly the often challenging physical recovery from critical illness. Among the myriad complications faced by these patients, ICU-acquired weakness (ICU-AW) stands out due to its significant impact on patient outcomes. ICU-AW, characterized by skeletal muscle atrophy and weakness, is linked to critical illness polyneuropathy (CIN), myopathy (CIM), and muscle atrophy. Notably, fasciculations, or involuntary muscle twitches, have been observed in patients with ICU-AW, suggesting altered muscle fiber excitability. This study aimed to describe the pattern of fasciculations in critically ill mechanically ventilated COVID-19 patients, assess clinical features associated with fasciculations, and evaluate their prognostic significance. Methods: The study enrolled patients admitted to the Intensive Care Unit (ICU) with COVID-19 infection requiring intubation and mechanical ventilation. Quadriceps muscles were assessed using muscle skeletal (MSK) ultrasound and Phase Angle (PhA) through multifrequency segmental bioelectrical impedance analysis (MFBIA) every 72 h. PhA is considered a marker of cell membrane integrity and function, with lower PhA values indicating reduced skeletal muscle quality and increased risk of sarcopenia. Fasciculations were classified based on their appearance and frequency. Results: A total of 35 intubated patients were studied, with 15 patients (43%) displaying scattered fasciculations exclusively in the vastus intermedius muscles. Upon admission, the study found no significant difference in PhA between the fasciculation and non-fasciculation groups. However, PhA decreased significantly from admission to discharge ICU only in the fasciculation group. Patients with fasciculations exhibited higher mortality rates, though not statistically significant, and this correlated with prolonged ICU and hospital lengths of stay. Discussion: This study is the first to report scattered fasciculations in the vastus intermedius muscles of multiple patients with SARS-CoV-2 infection identified with MSK ultrasound. The findings suggest that the combination of impaired muscle cellular function (PhA) and the onset of fasciculations could serve as a potential biomarker of adverse outcomes and ICU-related muscle dysfunction and muscle loss

Diagnosing Sarcopenia with AI-Aided Ultrasound (DINOSAUR)—A Pilot Study

Background: Sarcopenia has been recognized as a determining factor in surgical outcomes and is associated with an increased risk of postoperative complications and readmission. Diagnosis is currently based on clinical guidelines, which includes assessment of skeletal muscle mass but not quality. Ultrasound has been proposed as a useful point-of-care diagnostic tool to assess muscle quality, but no validated cut-offs for sarcopenia have been reported. Using novel automated artificial intelligence (AI) software to interpret ultrasound images may assist in mitigating the operator-dependent nature of the modality. Our study aims to evaluate the fidelity of AI-aided ultrasound as a reliable and reproducible modality to assess muscle quality and diagnose sarcopenia in surgical patients. Methods: Thirty-six adult participants from an outpatient clinic were recruited for this prospective cohort study. Sarcopenia was diagnosed according to Asian Working Group for Sarcopenia (AWGS) 2019 guidelines. Ultrasonography of the rectus femoris muscle was performed, and images were analyzed by an AI software (MuscleSound® (Version 5.69.0)) to derive muscle parameters including intramuscular adipose tissue (IMAT) as a proxy of muscle quality. A receiver operative characteristic (ROC) curve was used to assess the predictive capability of IMAT and its derivatives, with area under the curve (AUC) as a measure of overall diagnostic accuracy. To evaluate consistency between ultrasound users of different experience, intra- and inter-rater reliability of muscle ultrasound parameters was analyzed in a separate cohort using intraclass correlation coefficients (ICC) and Bland–Altman plots. Results:The median age was 69.5 years (range: 26–87), and the prevalence of sarcopenia in the cohort was 30.6%. The ROC curve plotted with IMAT index (IMAT% divided by muscle area) yielded an AUC of 0.727 (95% CI: 0.551–0.904). An optimal cut-off point of 4.827%/cm2 for IMAT index was determined with a Youden’s Index of 0.498. We also demonstrated that IMAT index has excellent intra-rater reliability (ICC = 0.938, CI: 0.905–0.961) and good inter-rater reliability (ICC = 0.776, CI: 0.627–0.866). In Bland–Altman plots, the limits of agreement were from −1.489 to 1.566 and −2.107 to 4.562, respectively. Discussion: IMAT index obtained via ultrasound has the potential to act as a point-of-care evaluation for sarcopenia screening and diagnosis, with good intra- and inter-rater reliability. The proposed IMAT index cut-off maximizes sensitivity for case finding, supporting its use as an easily implementable point-of-care test in the community for sarcopenia screening. Further research incorporating other ultrasound parameters of muscle quality may provide the basis for a more robust diagnostic tool to help predict surgical risk and outcomes.</p