Importance of the early increase in intestinal permeability in critically ill patients

Probiotic Supplementation Prevents the Development of Ventilator-Associated Pneumonia for Mechanically Ventilated ICU Patients: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials

Background

Ventilator-associated pneumonia (VAP) is one of the common critical complications of nosocomial infection (NI) in invasive mechanically ventilated intensive care unit (ICU) patients. The efficacy of total parenteral nutrition (TPN), enteral nutrition and/or adjuvant peripheral parenteral nutrition (EPN) supplemented with or without probiotic, prebiotic, and synbiotic therapies in preventing VAP among these patients has been questioned. We aimed to systematically and comprehensively summarize all available studies to generate the best evidence of VAP prevention for invasive mechanically ventilated ICU patients.

Methods

Randomized controlled trials (RCTs) for the administration of TPN, EPN, probiotics-supplemented EPN, prebiotics-supplemented EPN, and synbiotics-supplemented EPN for VAP prevention in invasive mechanically ventilated ICU patients were systematically retrieved from four electronic databases. The incidence of VAP was the primary outcome and was determined by the random-effects model of a Bayesian framework. The secondary outcomes were NI, ICU and hospital mortality, ICU and hospital length of stay, and mechanical ventilation duration. The registration number of Prospero is CRD42020195773.

Results

A total of 8339 patients from 31 RCTs were finally included in network meta-analysis. The primary outcome showed that probiotic-supplemented EPN had a higher correlation with the alleviation of VAP than EPN in critically invasive mechanically ventilated patients (odds ratio [OR] 0.75; 95% credible intervals [CrI] 0.58–0.95). Subgroup analyses showed that probiotic-supplemented EPN prevented VAP in trauma patients (OR 0.30; 95% CrI 0.13–0.83), mixed probiotic strain therapy was more effective in preventing VAP than EPN therapy (OR 0.55; 95% CrI 0.31–0.97), and low-dose probiotic therapy (less than 10¹⁰ CFU per day) was more associated with lowered incidence of VAP than EPN therapy (OR 0.16; 95% CrI 0.04–0.64). Secondary outcomes indicated that synbiotic-supplemented EPN therapy was more significantly related to decreased incidence of NI than EPN therapy (OR 0.34; 95% CrI 0.11–0.85). Prebiotic-supplemented EPN administration was the most effective in preventing diarrhea (OR 0.05; 95% CrI 0.00–0.71).

Conclusion

Probiotic supplementation shows promise in reducing the incidence of VAP in critically invasive mechanically ventilated patients. Currently, low quality of evidence reduces strong clinical recommendations. Further high-quality RCTs are needed to conclusively prove these findings.

Systamatic Review Registration

[https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020195773], identifier [CRD42020195773].

Semi-Solid Nutrients for Prevention of Enteral Tube Feeding-Related Complications in Japanese Population: A Systematic Review and Meta-Analysis

The aim of this systematic review was to assess the best available evidence on semi-solid nutrients for prevention of complications associated with enteral tube feeding (ETF). PubMed (MEDLINE), EMBASE, Cochrane Central Register of Controlled Trial, Ichushi-web, and World Health Organization International Clinical Trials Registry Platform databases were searched for relevant articles. Randomized controlled trials (RCTs), cluster RCTs, and crossover trials comparing the effects of semi-solid nutrients with those of control interventions in patients on ETF were included in the review. The primary outcome was development of gastroesophageal reflux (GER). Eight RCTs and five crossover trials involving 889 study participants in total were examined via meta-analysis. The meta-analysis showed that semi-solid nutrients significantly decreased the risk of GER (risk ratio 0.39; 95% confidence interval (CI) 0.21 to 0.73) and the GER index (mean difference −2.93; 95% CI −5.18 to −0.68). Dwell time in the stomach was significantly shortened (standardized mean difference (SMD) −0.50; 95% CI −0.99 to −0.02), as was care time defined as the time needed to prepare and administer the nutrient solution (SMD −8.02; 95% CI −10.94 to −5.10). Semi-solid nutrients significantly decrease the risk of GER and the dwell time in the stomach in adult patients.

Enteral Nutrition in the Mechanically Ventilated Patient

Mechanically ventilated patients are unable to take food orally and therefore are dependent on enteral nutrition for provision of both energy and protein requirements. Enteral nutrition is supportive therapy and may impact patient outcomes in the intensive care unit. Early enteral nutrition has been shown to decrease complications and hospital length of stay and improve the prognosis at discharge. Nutrition support is unique for patients on mechanical ventilation and, as recently published literature shows, should be tailored to the individuals' underlying pathology. This review will discuss the most current literature and recommendations for enteral nutrition in patients receiving mechanical ventilation.

Stimulation of the endogenous incretin glucose-dependent insulinotropic peptide by enteral dextrose improves glucose homeostasis and inflammation in murine endotoxemia

Loss of glucose homeostasis during sepsis is associated with increased organ dysfunction and higher mortality. Novel therapeutic strategies to promote euglycemia in sepsis are needed. We have previously shown that early low-level intravenous (IV) dextrose suppresses pancreatic insulin secretion and induces insulin resistance in septic mice, resulting in profound hyperglycemia and worsened systemic inflammation. In this study, we hypothesized that administration of low-level dextrose via the enteral route would stimulate intestinal incretin hormone production, potentiate insulin secretion in a glucose-dependent manner, and thereby improve glycemic control in the acute phase of sepsis. We administered IV or enteral dextrose to 10-week-old male C57BL/6J mice exposed to bacterial endotoxin and measured incretin hormone release, glucose disposal, and proinflammatory cytokine production. Compared with IV administration, enteral dextrose increased circulating levels of the incretin hormone glucose-dependent insulinotropic peptide (GIP) associated with increased insulin release and insulin sensitivity, improved mean arterial pressure, and decreased proinflammatory cytokines in endotoxemic mice. Exogenous GIP rescued glucose metabolism, improved blood pressure, and increased insulin release in endotoxemic mice receiving IV dextrose, whereas pharmacologic inhibition of GIP signaling abrogated the beneficial effects of enteral dextrose. Thus, stimulation of endogenous GIP secretion by early enteral dextrose maintains glucose homeostasis and attenuates the systemic inflammatory response in endotoxemic mice and may provide a therapeutic target for improving glycemic control and clinical outcomes in patients with sepsis.

Epithelial tight junctions in intestinal inflammation

The epithelium in inflamed intestinal segments of patients with Crohn's disease is characterized by a reduction of tight junction strands, strand breaks, and alterations of tight junction protein content and composition. In ulcerative colitis, epithelial leaks appear early due to micro-erosions resulting from upregulated epithelial apoptosis and in addition to a prominent increase of claudin-2. Th1-cytokine effects by interferon-gamma in combination with TNFalpha are important for epithelial damage in Crohn's disease, while interleukin-13 (IL-13) is the key effector cytokine in ulcerative colitis stimulating apoptosis and upregulation of claudin-2 expression. Focal lesions caused by apoptotic epithelial cells contribute to barrier disturbance in IBD by their own conductivity and by confluence toward apoptotic foci or erosions. Another type of intestinal barrier defect can arise from alpha-hemolysin harboring E. coli strains among the physiological flora, which can gain pathologic relevance in combination with proinflammatory cytokines under inflammatory conditions. On the other hand, intestinal barrier impairment can also result from transcellular antigen translocation via an initial endocytotic uptake into early endosomes, and this is intensified by proinflammatory cytokines as interferon-gamma and may thus play a relevant role in the onset of IBD. Taken together, barrier defects contribute to diarrhea by a leak flux mechanism (e.g., in IBD) and can cause mucosal inflammation by luminal antigen uptake. Immune regulation of epithelial functions by cytokines may cause barrier dysfunction not only by tight junction impairments but also by apoptotic leaks, transcytotic mechanisms, and mucosal gross lesions.