Ultrasonographic measurement of the respiratory variation in the inferior vena cava diameter is predictive of fluid responsiveness in critically ill patients: systematic review and meta-analysis.

Respiratory variation in the inferior vena cava (ΔIVC) has been extensively studied with respect to its value in predicting fluid responsiveness, but the results are conflicting. This systematic review was aimed at investigating the diagnostic accuracy of ΔIVC in predicting fluid responsiveness. Databases including Medline, Embase, Scopus and Web of Knowledge were searched from inception to May 2013. Studies exploring the diagnostic performance of ΔIVC in predicting fluid responsiveness were included. To allow for more between- and within-study variance, a hierarchical summary receiver operating characteristic model was used to pool the results. Subgroup analyses were performed for patients on mechanical ventilation, spontaneously breathing patients and those challenged with colloids and crystalloids. A total of 8 studies involving 235 patients were eligible for analysis. Cutoff values of ΔIVC varied across studies, ranging from 12% to 40%. The pooled sensitivity and specificity in the overall population were 0.76 (95% confidence interval [CI]: 0.61-0.86) and 0.86 (95% CI: 0.69-0.95), respectively. The pooled diagnostic odds ratio (DOR) was 20.2 (95% CI: 6.1-67.1). The diagnostic performance of ΔIVC appeared to be better in patients on mechanical ventilation than in spontaneously breathing patients (DOR: 30.8 vs. 13.2). The pooled area under the receiver operating characteristic curve was 0.84 (95% CI: 0.79-0.89). Our study indicates that ΔIVC measured with point-of-care ultrasonography is of great value in predicting fluid responsiveness, particularly in patients on controlled mechanical ventilation and those resuscitated with colloids.