Objective: Fluid responsiveness is the ability to increase the cardiac output in response to a fluid challenge. Only about 50% of patients receiving fluid resuscitation for acute circulatory failure increase their stroke volume, but the other 50% may worsen their outcome. Therefore, predicting fluid responsiveness is needed. In this purpose, in recent years, the assessment of the inferior vena cava (IVC) through ultrasound (US) has become very popular. The aim of our work was to systematically review all the previously published studies assessing the accuracy of the diameter of IVC or its respiratory variations measured through US in predicting fluid responsiveness. Data Sources: We searched in the MEDLINE (PubMed), Embase, Web of Science databases for all relevant articles from inception to September 2017. Study Selection: Included articles specifically addressed the accuracy of IVC diameter or its respiratory variations assessed by US in predicting the fluid responsiveness in critically ill ventilated or not, adult or pediatric patients. Data Extraction: We included 26 studies that investigated the role of the caval index (IVC collapsibility or distensibility) and 5 studies on IVC diameter. Data Synthesis: We conducted a meta-analysis for caval index with 20 studies: The pooled area under the curve, logarithmic diagnostic odds ratio, sensitivity, and specificity were 0.71 (95% confidence interval [CI]: 0.46-0.83), 2.02 (95% CI: 1.29-2.89), 0.71 (95% CI: 0.62-0.80), and 0.75 (95% CI: 0.64-0.85), respectively. Conclusion: An extreme heterogeneity of included studies was highlighted. Ultrasound evaluation of the diameter of the IVC and its respiratory variations does not seem to be a reliable method to predict fluid responsiveness.

Community-acquired pneumonia (CAP) is one of the most widespread and severe infectious diseases worldwide. In the emergency department (ED), there is still a need for a rapid and accurate tool that can diagnose CAP. Lung ultrasound (LUS) is a recent tool that is increasingly being for this purpose. So far, the LUS has been evaluated on a wide range of patients, but not yet on the specific population in the ED through a meta-analysis. Our aim was to assess the accuracy of the LUS in diagnosing CAP in this setting through a systematic review and a meta-analysis. A systematic research of literature was carried out for all published studies comparing the diagnostic accuracy of the LUS against chest radiography or computerized tomography scan in patients older than 18 years of age with clinical criteria for CAP assessed in the ED. We extracted the descriptive and quantitative data from eligible studies, and calculated the pooled sensitivity, specificity, and diagnostic odds ratio. We defined the summary receiver operating characteristic curve. Our initial search strategy yielded 10 377 studies, of which 17 (0.2%) were eligible. These studies provided a combined sample size of 5108 participants. The general risk of bias of the considered studies was quite low, but some concerns were highlighted. The diagnostic odds ratio was around 181 (I ²: 27%). The pooled area under the curve, sensitivity, and specificity were, respectively, 97, 92, and 93%. The LUS was found to be an accurate tool in diagnosing CAP in adult patients in the ED. More methodologically rigorous trials are needed.