Fig. 2

HSROC curve of the ΔScvO₂ for defining fluid responsiveness. The area under the hierarchical summary receiver operating curve was 0.86 (95% CI 0.83–0.89). The size of the circles indicates the weight of each individual study. The summary point (maroon solid square) represents the average sensitivity and specificity estimates from the study results, and its corresponding 95% confidence region (orange dashed line) is illustrated. The 95% prediction region represents the confidence region for a forecast of true sensitivity and specificity in a future study. HSROC hierarchical summary receiver operating characteristic; ΔScvO₂ variation in central venous oxygen saturation during the fluid challenge