Fig. 2

Continuous hemoglobin drop thresholds for multi-mini-datasets with preoperative hemoglobin. The whole dataset was divided into multiple mini-datasets. Every mini-dataset had a preoperative hemoglobin span equaled to 3 g/L. (for instance, 100 g/L -103 g/L, 101 g/L -104 g/L,102 g/L -105 g/L …… from 90 to 160 g/L). The threshold for every mini-dataset was calculated and presented as black dots. A linear regression line was plotted, shaded areas represent 95% confidence intervals. With the preoperative hemoglobin level decrease, the thresholds decrease dramatically accordingly. AKI: acute kidney injury