[The value of renal resistance index and urine oxygen pressure for prediction of acute kidney injury in patients with septic shock]

Objective: To explore the value of renal resistance index (RI) and urine oxygen pressure for early prediction of acute kidney injury (AKI) in patients with septic shock. Methods: Patients with septic shock were enrolled from August 2018 to November 2018 in intensive care unit (ICU) at Peking Union Medical College Hospital. Subjects' general information and AKI characteristics were assessed. Area under the receiver operating characteristic (ROC) curve was used to analyze the predictive value of RI, urine oxygen pressure, or combination of RI on the occurrence of AKI. Results: A total of 72 septic shock patients were enrolled including 29 patients with AKI and 43 without. Logistic regression analysis of AKI risk factors found that RI (OR=1.139, 95%CI 1.029-1.261, P=0.012) and urine oxygen pressure (OR=0.957, 95%CI 0.923-0.991, P=0.014) at admission were independent risk factors for AKI in patients with septic shock. The sensitivity and specificity of dual RI and urine oxygen pressure in predicting AKI were 65.5% and 76.7% respectively (AUC_ROC 0.772, Youden index 0.423). We selected the cut-off value of RI as 0.70,and urine oxygen pressure as 48 mmHg (1 mmHg=0.133 kPa). According to this two cut-off values patients were divided into four groups, those with RI≥0.70 and urine oxygen pressure≤48 mmHg showed the highest incidence of AKI (75%). There was no statistically difference in 28-day survival rate between the four groups (P=0.197). Conclusion: High RI and low urine oxygen pressure are independent risk factors for the development of AKI in patients with septic shock. The predictive cut-off values are 0.70 for RI and 48 mmHg for urine oxygen pressure. Combination of RI and urine oxygen pressure has a practical predictive value for AKI in patients with septic shock.