BackgroundCritical illness is characterized by a loss of commensal flora and an overgrowth of potentially pathogenic bacteria, leading to a high susceptibility to nosocomial infections. Probiotics are living non-pathogenic microorganisms, which may protect the gut barrier, attenuate pathogen overgrowth, decrease bacterial translocation and prevent infection. The purpose of this updated systematic review is to evaluate the overall efficacy of probiotics and synbiotic mixtures on clinical outcomes in critical illness.MethodsComputerized databases from 1980 to 2016 were searched. Randomized controlled trials (RCT) evaluating clinical outcomes associated with probiotic therapy as a single strategy or in combination with prebiotic fiber (synbiotics). Overall number of new infections was the primary outcome; secondary outcomes included mortality, ICU and hospital length of stay (LOS), and diarrhea. Subgroup analyses were performed to elucidate the role of other key factors such as probiotic type and patient mortality risk on the effect of probiotics on outcomes.ResultsThirty trials that enrolled 2972 patients were identified for analysis. Probiotics were associated with a significant reduction in infections (risk ratio 0.80, 95 % confidence interval (CI) 0.68, 0.95, P = 0.009; heterogeneity I2 = 36 %, P = 0.09). Further, a significant reduction in the incidence of ventilator-associated pneumonia (VAP) was found (risk ratio 0.74, 95 % CI 0.61, 0. 90, P = 0.002; I2 = 19 %). No effect on mortality, LOS or diarrhea was observed. Subgroup analysis indicated that the greatest improvement in the outcome of infections was in critically ill patients receiving probiotics alone versus synbiotic mixtures, although limited synbiotic trial data currently exists.ConclusionProbiotics show promise in reducing infections, including VAP in critical illness. Currently, clinical heterogeneity and potential publication bias reduce strong clinical recommendations and indicate further high quality clinical trials are needed to conclusively prove these benefits.

The trace element selenium is of high importance for many of the body’s regulatory and metabolic functions. Balanced selenium levels are essential, whereas dysregulation can cause harm. A rapidly increasing number of studies characterizes the wide range of selenium dependent functions in the human body and elucidates the complex and multiple physiological and pathophysiological interactions of selenium and selenoproteins. For the majority of selenium dependent enzymes, several biological functions have already been identified, like regulation of the inflammatory response, antioxidant properties and the proliferation/differentiation of immune cells. Although the potential role of selenium in the development and progression of cardiovascular disease has been investigated for decades, both observational and interventional studies of selenium supplementation remain inconclusive and are considered in this review. This review covers current knowledge of the role of selenium and selenoproteins in the human body and its functional role in the cardiovascular system. The relationships between selenium intake/status and various health outcomes, in particular cardiomyopathy, myocardial ischemia/infarction and reperfusion injury are reviewed. We describe, in depth, selenium as a biomarker in coronary heart disease and highlight the significance of selenium supplementation for patients undergoing cardiac surgery.

IntroductionCritical illness is characterized by oxidative stress, which is a major promoter of systemic inflammation and organ failure due to excessive free radical production, depletion of antioxidant defenses, or both. We hypothesized that exogenous supplementation of trace elements and vitamins could restore antioxidant status, improving clinical outcomes.MethodsWe searched computerized databases, reference lists of pertinent articles and personal files from 1980 to 2011. We included randomized controlled trials (RCTs) conducted in critically ill adult patients that evaluated relevant clinical outcomes with antioxidant micronutrients (vitamins and trace elements) supplementation versus placebo.ResultsA total of 21 RCTs met inclusion criteria. When the results of these studies were statistically aggregated (n = 20), combined antioxidants were associated with a significant reduction in mortality (risk ratio (RR) = 0.82, 95% confidence interval (CI) 0.72 to 0.93, P = 0.002); a significant reduction in duration of mechanical ventilation (weighed mean difference in days = -0.67, 95% CI -1.22 to -0.13, P = 0.02); a trend towards a reduction in infections (RR= 0.88, 95% CI 0.76 to 1.02, P = 0.08); and no overall effect on ICU or hospital length of stay (LOS). Furthermore, antioxidants were associated with a significant reduction in overall mortality among patients with higher risk of death (>10% mortality in control group) (RR 0.79, 95% CI 0.68 to 0.92, P = 0.003) whereas there was no significant effect observed for trials of patients with a lower mortality in the control group (RR = 1.14, 95% 0.72 to 1.82, P = 0.57). Trials using more than 500 μg per day of selenium showed a trend towards a lower mortality (RR = 0.80, 95% CI 0.63 to 1.02, P = 0.07) whereas trials using doses lower than 500 μg had no effect on mortality (RR 0.94, 95% CI 0.67 to 1.33, P = 0.75).ConclusionsSupplementation with high dose trace elements and vitamins may improve outcomes of critically ill patients, particularly those at high risk of death.