US Duplex Doppler Kidneys Retroperitoneal Renovascular causes of AKI/CKD are rare; renal artery stenosis was found in 1.5% of cases with AKI even when not the cause of AKI [4]. In an older series of intensive care patients, AKI was attributed to renal artery thrombosis, stenosis, or trauma in 1% [17]. The diagnosis of significant renal artery stenosis can be made by obtaining angle- corrected measurements of the peak systolic velocities in the aorta and main renal arteries. Using a cutoff value of 285 cm/s achieved sensitivity, specificity, and overall accuracy of 67%, 90%, and 81%, respectively, for >60% stenosis [32]. In a smaller series, using a cutoff value of 180 cm/s, the sensitivity and specificity of US were 85% and 84%, respectively, for >60% stenosis [18]. Renal artery duplex Doppler studies may be appropriate in selected patients with a high clinical suspicion of renal artery stenosis. RI has been studied in patients with AKI as a means to detect intrarenal vasoconstriction and differentiate renal from prerenal AKI. An elevated RI has been reported to be an early predictor of early or persistent postoperative AKI after cardiac or hip surgery [33,34], or persistent AKI in critically ill patients [35], and is associated with intensive care unit mortality [36]. An elevated RI can predict progression to CKD [37]. However, an elevated intrarenal RI is not specific to the cause of AKI, as RI depends on multiple physiologic and pathologic factors; including vascular compliance, age, atherosclerosis, renal damage, hypertension, heart rate, as well as intrinsic renal disease [33,37]. Serial RI measurement is largely a research tool at this time. Variant 4: Renal failure. Neurogenic bladder. Initial imaging.
Renal Failure. US Duplex Doppler Kidneys Retroperitoneal Renovascular causes of AKI/CKD are rare; renal artery stenosis was found in 1.5% of cases with AKI even when not the cause of AKI [4]. In an older series of intensive care patients, AKI was attributed to renal artery thrombosis, stenosis, or trauma in 1% [17]. The diagnosis of significant renal artery stenosis can be made by obtaining angle- corrected measurements of the peak systolic velocities in the aorta and main renal arteries. Using a cutoff value of 285 cm/s achieved sensitivity, specificity, and overall accuracy of 67%, 90%, and 81%, respectively, for >60% stenosis [32]. In a smaller series, using a cutoff value of 180 cm/s, the sensitivity and specificity of US were 85% and 84%, respectively, for >60% stenosis [18]. Renal artery duplex Doppler studies may be appropriate in selected patients with a high clinical suspicion of renal artery stenosis. RI has been studied in patients with AKI as a means to detect intrarenal vasoconstriction and differentiate renal from prerenal AKI. An elevated RI has been reported to be an early predictor of early or persistent postoperative AKI after cardiac or hip surgery [33,34], or persistent AKI in critically ill patients [35], and is associated with intensive care unit mortality [36]. An elevated RI can predict progression to CKD [37]. However, an elevated intrarenal RI is not specific to the cause of AKI, as RI depends on multiple physiologic and pathologic factors; including vascular compliance, age, atherosclerosis, renal damage, hypertension, heart rate, as well as intrinsic renal disease [33,37]. Serial RI measurement is largely a research tool at this time. Variant 4: Renal failure. Neurogenic bladder. Initial imaging.