The Combined Application Value of Renal Resistance Index and Renal Venous Impedance Index in Predicting Acute Kidney Injury After Cardiac Surgery

Statistical analyses were performed using SPSS software (version 25.0, IBM Corp, Armonk, NY, USA).Normally distributed continuous data were expressed as mean ± standard deviation. Intergroup mean comparisons employed the independent samples t-test. For non-normally distributed quantitative data, median and interquartile range were used, assessed via the Mann-Whitney U test. Categorical data were presented as percentages (%), evaluated using the chi-square test. Logistic regression analysed the correlation between RRI and VII with AKI occurrence. Predictive performance was evaluated using ROC curves, p