Renal Arterial Resistive Index Versus Novel Biomarkers for Early Prediction of Sepsis Associated-acute Kidney Injury

Populations at high risk of Sepsis-Associated Acute Kidney Injury (SA-AKI) have been identified. Sources of sepsis, in particular, bloodstream infection, abdominal and genitourinary sepsis, and infective endocarditis, are associated with a higher likelihood of developing AKI. Similar to the poor outcome of patients with sepsis, delayed administration of appropriate antimicrobial therapy was shown to be an independent predictor of the development of AKI. Incremental delays in antimicrobial delivery after the onset of hypotension showed a direct relationship with the development of AKI. The need for sensitive, simple and time-applicable biomarker to predict AKI development after renal insult is urgent. Serum creatinine (sCr) and urea are used routinely for the diagnosis of AKI. However, these parameters are not accurate for the diagnosis of AKI. Cystatin C. (CysC) is suggested to be a good biomarker because of its constant rate of production, almost filtered by glomeruli (99%), has no significant protein binding and not secreted by renal tubule. Neutrophil gelatinase-associated lipocalin (NGAL) is recently identified and extensively investigated as a most promising early marker of AKI. Urinary NGAL is not only effective in detection of AKI but also its degree of expression might distinguish among AKI, prerenal azotemia and chronic kidney disease, and it is detectable before the accumulation of serum creatinine. Ultrasonography (US) is used routinely to assess renal morphology. Renal Resistive Index (RRI) is a non-invasive Doppler-measured parameter that is directly correlated with intra-renal arterial resistance. RRI is defined as \[(peak systolic velocity - end diastolic velocity)/ peak systolic velocity\]. It theoretically ranges from 0 to 1 and it is normally lower than 0.7 with age differences. RRI calculation was found to be useful as an early indicator of the vascular resistance changes and in the determination of the optimal systemic hemodynamics required for