Role of Resistive Index to Differentiate between Prerenal Acute Kidney Injury and Acute Tubular Necrosis.

Acute kidney injury (AKI) a life threatening condition, one of the most dreadful disease with a broad etiological profile, a challenging problem in our community and specially in critically ill patients and also associated with high morbidity and mortality. Accurate and rapid diagnosis of the cause of AKI is particularly important for selecting appropriate therapy. Measurement of renal indices is commonly used to differentiate prerenal AKI from ATN, often cannot be used and also may not be accurate in many conditions. As renal biopsy is gold standard but this invasive procedure may not be feasible in critically ill patients. Therefore, this cross sectional study was conducted among patients with AKI at Department of Nephrology in Dhaka Medical College Hospital, Bangladesh from November 2017 to June 2019, to assess the ability of Resistive index (RI) to differentiate prerenal AKI and ATN. Mean age were 39.45±10.96 years, with male 65.0%. Among all, 19.0% of AKI patients were found to be sepsis followed by acute watery diarrhea (17.5%), when all causes of hypovolemia were combined, hypovolemia constituted the most prevalent cause. According to renal indices 47.0% patients had prerenal AKI and 53.0%, ATN. On the basis of RI, about 45.0% patients were as a case of prerenal AKI with mean RI 0.63±0.07 and 55.0% were ATN with Mean RI 0.77±0.71. But, type of AKI based on clinical diagnosis was considered as standard and were 46.0% prerenal AKI and 54.0% patients ATN. When compared with clinical diagnosis, RI was found to be more correlated with clinical diagnosis with p<0.001 than renal indices. RI had 91.89% sensitivity and 95.35% specificity to differentiate prerenal AKI and ATN. On the other hand, renal indices had low sensitivity (62.16%) and specificity (65.12%). Moreover, a statistically significant difference were noted between type of AKI diagnosed by RI and by renal indices (p<0.05). So, RI derived from Doppler ultrasound is superior to renal indices and can be used as a useful differentiating tool.