Renal resistive index as a predictor of hemodialysis and mortality risk in septic patients developing acute kidney injury

Introduction Mechanisms of acute kidney injury (AKI) comprise renal hypoperfusion, intrarenal vasoconstriction, inflammation, oxidative stress, and nephrotoxicity. An important pathophysiological pathway includes intrarenal vasoconstriction and endothelial damage of the microvessel, leading to impaired macrovascular and microvascular flow, which further aggravates ischemia. Nowadays, Doppler ultrasound is rapidly gaining ground as a screening tool in critically ill patients. The performance of cardiac, lung, and abdominal ultrasound in patients after cardiac arrest, major operations, and during shock has become the standard policy. However, renal ultrasound, which could be easily incorporated in this screening, is not commonly performed. Aim To test the ability of renal resistive index (RRI) measurement by Doppler ultrasound to predict the development of AKI in septic patients and find a relation with the progression to persistent renal impairment and relation to outcome and mortality. Patients and methods A total of 40 septic patients with AKI were randomized and subjected to RRI measurements, on admission and after 48 h, and the patients were followed till hospital discharge to detect the correlation to outcome. Mortality risk assessment was measured by the APACHE III score. Results There was a statistically significant increase of RRI in cases with persistent AKI in comparison with cases with transient AKI (P<0.05). There was a statistically significant increase in APACHE III score in patients with high RI (P<0.005). Conclusion Renal Doppler RI may be a promising tool for predicting the risk of developing AKI in acutely ill septic patients and may help in predicting the reversibility of AKI. High RRI values in septic patients with AKI are independently related to ICU mortality and persistent renal dysfunction at discharge from ICU.