Clinical study on the early predictive value of renal resistive index in acute kidney injury associated with severe acute pancreatitis

Objective To investigate the value of renal resistive index (RRI) in early predictor and discriminator of severe acute pancreatitis (SAP)-related acute kidney injury (AKI). Methods A retrospective observational study was conducted. SAP patients complicated with AKI (within 1 week of onset) and admitted to intensive care unit (ICU) of Ruijin Hospital Shanghai Jiaotong University School of Medicine from January 2016 to June 2019 were enrolled. The RRI within 24 hours admission was measured. Clinical data such as acute physiology and chronic health evaluation Ⅱ (APACHEⅡ), heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), intra-abdominal pressure (IAP), arterial blood lactate (Lac), oxygenation index (PaO2/FiO2), base excess (BE), serum creatinine (SCr), urine output, norepinephrine (NE) and RRI were collected. Within 24 hours and 7 days after ICU admission, patients were grouped according to AKI classification criteria of Kidney Disease: Improving Global Outcomes (KDIGO), and the differences of relevant parameters were statistically analyzed. Influence factors of AKI grading were screened by Logistic regression analysis. Pearson correlation analysis was used to analyze the correlation between RRI and other parameters. The predictive value of RRI for AKI classification was analyzed by receiver operating characteristic (ROC) curve. Results A total 57 patients were included, with an average age of (54.6±13.5) years old, and APACHEⅡscore of 21.8±5.6. Within 24 hours, the number of patients suffered from stage 1-3 AKI were 19 (33.3%), 18 (31.6%) and 20 (35.1%), respectively. On day 7, the number of patients suffered from stage 0-3 AKI were 21 (36.9%), 8 (14.0%), 9 (15.8%) and 19 (33.3%), respectively. The higher APACHEⅡ score, CVP, IAP, Lac, NE dosage and RRI were found in the group with higher AKI grades, especially in the group with stage 3 AKI on day 7. RRI of patients with stage 3 AKI was significantly higher than that of patients with stage 1 and 2 AKI within 24 hours (0.74±0.04 vs. 0.65±0.05, 0.68±0.05, both P 0.71, sensitivity was 71% and specificity was 83%. The correlation analysis showed that RRI was positively correlated to a certain extent with IAP and lactic acid (r1 = 0.49, r2 = 0.39, both P < 0.05). Conclusion High RRI on ICU admission was a significant predictor for development of severe AKI during the first week, and RRI can help predict the tendency of AKI in SAP. Key words: Severe acute pancreatitis; Acute kidney injury; Renal resistive index