Early Renal Microcirculatory Perfusion Patterns in Sepsis: Associations with SA-AKI Trajectories in the Emergency Department.

BackgroundSepsis is a life-threatening response to an infection, often complicated by sepsis-associated acute kidney injury (SA-AKI). Early recognition of SA-AKI is critical but challenged by the limited sensitivity of existing diagnostic markers. MicroRNAs (miRNAs), which regulate key SA-AKI pathways, have shown diagnostic promise, yet their clinical utility in early SA-AKI recognition remains unexplored. Moreover, validation in relevant clinical settings and populations remains limited. Therefore, this study aims to explore the potential of miRNAs for early recognition of SA-AKI at emergency department (ED) presentation, and explore the generalizability of findings by including a cohort of intensive care urine (ICU) patients with more advanced disease.MethodsWe conducted a post-hoc analysis of prospectively collected data from patients admitted to the ED and ICU. We performed a thorough literature review to select twelve miRNAs, previously implicated in kidney injury and sepsis or SA-AKI. MiRNAs were extracted from plasma and quantified using qPCR with and normalization to the global mean. We measured plasma levels of selected miRNAs upon ED arrival in 193 acutely ill patients (no infection, n = 65; sepsis, n = 67; SA-AKI, n = 61), and 47 critically ill patients (sepsis, n = 18; SA-AKI, n = 29). Statistical analyses included logistic and Cox regression adjusted for clinical variables, with correlations assessed between miRNA levels and disease severity markers. Diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis.ResultsMiR-21-5p (OR 2.28, 95% CI [1.40–3.73]; p < 0.01) and miR-16-5p (OR 0.74, 95% CI [0.59–0.93]; p = 0.01) levels were associated with SA-AKI at ED presentation. Furthermore, miR-21-5p was independently associated with 30-day mortality after adjusting for age, illness severity, and comorbidities (adjusted OR 2.30, 95% CI [1.38–3.86]; p < 0.01). Similarly, in the ICU cohort with more advanced sepsis, miR-21-5p was associated with SA-AKI (OR 3.48, 95% CI [1.27–9.53]; P = 0.02), achieving an AUC of 0.74 (95% CI [0.58–0.89]), although it was not associated with 30-day mortality in this cohort.ConclusionWe selected twelve miRNAs through literature review associated with kidney injury, sepsis or SA-AKI. Of these, only miR-21-5p was associated with SA-AKI and predicted 30-day mortality upon ED admission. This analysis effectively serves as a negative validation for most literature-derived miRNAs, challenging their clinical applicability identification of SA-AKI both at early presentation and in more advanced stages.Trial registrationThis study is embedded in the Acutelines data-biobank (www.acutelines.nl), registered in Clinicaltrials.gov (NCT04615065, November 3rd 2020) and the The Biobank Intensive Care Groningen registered in Clinicaltrials.gov (NCT04502511, August 6th 2020).

Sepsis is a life-threatening response to an infection, often complicated by sepsis-associated acute kidney injury (SA-AKI). Early recognition of SA-AKI is critical but challenged by the limited sensitivity of existing diagnostic markers. MicroRNAs (miRNAs), which regulate key SA-AKI pathways, have shown diagnostic promise, yet their clinical utility in early SA-AKI recognition remains unexplored. Moreover, validation in relevant clinical settings and populations remains limited. Therefore, this study aims to explore the potential of miRNAs for early recognition of SA-AKI at emergency department (ED) presentation, and explore the generalizability of findings by including a cohort of intensive care urine (ICU) patients with more advanced disease. We conducted a post-hoc analysis of prospectively collected data from patients admitted to the ED and ICU. We performed a thorough literature review to select twelve miRNAs, previously implicated in kidney injury and sepsis or SA-AKI. MiRNAs were extracted from plasma and quantified using qPCR with and normalization to the global mean. We measured plasma levels of selected miRNAs upon ED arrival in 193 acutely ill patients (no infection, n = 65; sepsis, n = 67; SA-AKI, n = 61), and 47 critically ill patients (sepsis, n = 18; SA-AKI, n = 29). Statistical analyses included logistic and Cox regression adjusted for clinical variables, with correlations assessed between miRNA levels and disease severity markers. Diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis. MiR-21-5p (OR 2.28, 95% CI [1.40-3.73]; p < 0.01) and miR-16-5p (OR 0.74, 95% CI [0.59-0.93]; p = 0.01) levels were associated with SA-AKI at ED presentation. Furthermore, miR-21-5p was independently associated with 30-day mortality after adjusting for age, illness severity, and comorbidities (adjusted OR 2.30, 95% CI [1.38-3.86]; p < 0.01). Similarly, in the ICU cohort with more advanced sepsis, miR-21-5p was associated with SA-AKI (OR 3.48, 95% CI [1.27-9.53]; P = 0.02), achieving an AUC of 0.74 (95% CI [0.58-0.89]), although it was not associated with 30-day mortality in this cohort. We selected twelve miRNAs through literature review associated with kidney injury, sepsis or SA-AKI. Of these, only miR-21-5p was associated with SA-AKI and predicted 30-day mortality upon ED admission. This analysis effectively serves as a negative validation for most literature-derived miRNAs, challenging their clinical applicability identification of SA-AKI both at early presentation and in more advanced stages. This study is embedded in the Acutelines data-biobank (www.acutelines.nl), registered in Clinicaltrials.gov (NCT04615065, November 3rd 2020) and the The Biobank Intensive Care Groningen registered in Clinicaltrials.gov (NCT04502511, August 6th 2020).

The interplay between macro-microcirculatory dysfunction and sepsis associated acute kidney injury (SA-AKI) remains elusive. This study aimed to explore the association between hemodynamics and endothelial damage in SA-AKI by evaluating the combined predictive value of renal resistive index (RRI) and plasma syndecan-1. This prospective observational study enrolled 80 septic patients admitted to the general intensive care unit (ICU) of a tertiary hospital from May to December 2024. Plasma syndecan-1 levels were measured at admission, and RRI was assessed within 24 h of ICU admission. Univariate and multivariate logistic regression models were applied to identify independent risk factors of SA-AKI. Diagnostic performance was evaluated using receiver operating characteristic (ROC) curve analysis by calculating the area under the curve (AUC). Among 80 septic patients, 41(51.25%) developed AKI. Syndecan-1 levels were significantly higher in the AKI group [109.95 (73.67–221.40) vs.73.67 (54.59–109.95) ng/mL, p = 0.007], and RRI values were markedly elevated (0.69 ± 0.08 vs. 0.60 ± 0.06, p < 0.001) compared to non-AKI patients. Univariate analysis revealed syndecan-1 (OR = 2.68, 95%CI 1.29–5.59) and RRI (OR = 1.18, 95%CI 1.09–1.28) as predictors of AKI. In multivariate models adjusted for confounders, both plasma syndecan-1 (OR = 3.57, 95%CI 1.01–12.64, p = 0.048) and RRI (OR = 1.19, 95% CI 1.07–1.33, p = 0.002) retained significance. A predictive model using a combination of plasma syndecan-1 and RRI achieved superior diagnostic performance (AUC 0.859, sensitivity 87.8%, specificity 92.3%). In patients with SA-AKI, elevated plasma syndecan-1 and RRI were identified as independent risk factors. The combination of syndecan-1 and RRI can serve as synergistic biomarkers for the prediction of SA-AKI.

Acute kidney injury (AKI) is a critical complication of sepsis. There is a continuous need to identify and validate biomarkers for early detection. Serum and urinary biomarkers have been investigated, such as neutrophil gelatinase associated lipocalin (NGAL) and cystatin C (Cys C), but their reliability in the intensive care unit (ICU) remains unknown. Renal hemodynamics can be investigated by measuring the renal resistive index (RRI). This study aimed to compare the performance of RRI, serum NGAL (sNGAL), urinary NGAL (uNGAL), and serum Cys C levels as early predictors of the diagnosis and persistence of sepsis-associated AKI. A total of 166 adult patients with sepsis syndrome were enrolled immediately after ICU admission. Biomarkers were measured directly (T1) and on day 3 (T3). RRI was measured directly (T1) and 24 h later (T2). Patients were categorized (according to the occurrence and persistence of AKI within the first 7 days) into three groups: no AKI, transient AKI, and persistent AKI. The incidence rate of sepsis-associated AKI was 60.2%. Sixty-six patients were categorized as in the no AKI group, while another 61 were in transient AKI and only 39 were in persistent AKI. The RRI value (T1 ≥ 0.72) was the best tool for predicting AKI diagnosis (area under the receiver operating characteristic curve, AUROC = 0.905). Cys C (T1 ≥ 15.1 mg/l) was the best tool to predict the persistence of AKI (AUROC = 0.977). RRI (T1) was the best predictive tool for sepsis-associated AKI, while Cys C was the best predictor of its persistence and 28-day mortality.

Introduction The furosemide stress test (FST) predicts the severity and the need for renal replacement therapy (RRT) in patients with sepsis-associated acute kidney injury(S-AKI). The renal resistive index (RRI) indicates renal vascular resistance. Objectives The primary objective was to find the correlation between FST and RRI in S-AKI. The secondary objectives were to evaluate the role of FST and RRI on the progression of S-AKI. Methods A total of 154 consenting adult patients with S-AKI were administered FST. Renal echography was performed within the first 12 hours of admission, and RRI was calculated. The patients were grouped either into progressors or non-progressors to AKI-KDIGO stage 3. Results Of the patients who had RRI at Day 1 less than 0.73, 60% recovered, 34.3% needed RRT, and 35.5% died, whereas in those who had RRI at Day 1 greater than 0.73, only 22% recovered, 46.6% required RRT, and 51.6% died. RRI value of 0.73 predicted the need for RRT with a sensitivity of 35.1%, specificity of 80.4% and accuracy of 69.1%. The highest number of patients of KDIGO stage 3 (50%), followed by stage 2 (28.1%) and stage 1 (21.9%), presented technical difficulties in measuring the RRI. Conclusion FST is an economical and easily administered test to assess renal tubular function and can predict the occurrence and progression of S-AKI. RRI is a modest marker for predicting the need for RRT or persistent AKI.

This study aimed to explore the significance of renal Doppler ultrasound in evaluating systemic and renal perfusion in sepsis patients before and after fluid resuscitation. Forty sepsis patients admitted to the Department of Intensive Medicine and intensive care unit (ICU) of the Fourth Hospital of Hebei Medical University from June 2014 to December 2014 were enrolled in this study, and 35 patients were included in the final analysis. These patients were divided into positive and negative fluid responsiveness groups. They were also divided into an acute kidney injury (AKI) group and a non-AKI group according to changes in creatinine and urine volume. The correlations of the changes in hemodynamics before and after fluid resuscitation in each group with the changes in renal resistance index (RRI) and renal blood flow (RBF) grades were evaluated. Before and after fluid resuscitation, the heart rate (HR), blood creatinine (Cre), and lactate (Lac) levels of all patients, including the patients in the positive fluid responsiveness group decreased, and the stroke volume (SV) and central venous pressure (CVP) increased. Only HR decreased in the negative fluid responsiveness group. In the AKI group, HR, Cre, and Lac decreased, while in the non-AKI group, HR decreased, but CVP and SV increased. There were differences between HR, Lac, and change rate of Lac (Lac%) after fluid resuscitation for the positive and negative fluid responsiveness groups. There was no statistical difference between the RRI values of each group before and after fluid resuscitation. The RRI values of the AKI group were higher than those of the non-AKI group, while the AKI group's RBF grades were lower than those of the non-AKI group. The change rate of RRI (RRI%) was higher in the AKI group than in the non-AKI group. Except for the negative fluid responsiveness group, the RBF grade of each group increased. The approach of RBF classification based on Doppler ultrasound can be used to evaluate the systemic and renal perfusion of patients with severe sepsis before and after fluid resuscitation, while the RRI value cannot be used for evaluation. However, the RRI value can be used as a dynamic index for the evaluation of renal perfusion in patients with AKI.

To examine the effect of extracorporeal shock wave lithotripsy (ESWL) on renal perfusion before and after treatment, by assessing renal resistive index (RI) using colour Doppler ultrasonography (CDUS), magnetic resonance perfusion imaging (MRPI), radionuclide renography and big-endothelin-1 values (Big-ET-1). In 69 normotensive patients the RI was measured before, 1, 3, 6 and 24 h after ESWL using CDUS. The RI values, measured in interlobar/arcuate arteries, were correlated with the findings on MRPI, done before and within 24 h after ESWL. In addition, renal plasma flow (RPF, assessed on radionuclide renography) and Big-ET-1 levels (a potent vasoconstrictor peptide), served as a control for evaluating renal perfusion. The patients were stratified in three age groups, i.e. <or=39, 40-59 and >or=60 years, with 23 patients in each group. The mean (sd) RI increased significantly in the treated kidneys, from 0.64 (0.05) before to 0.72 (0.08) after ESWL (P = 0.001). Only in patients aged >or=60 years did the RI continue to increase over the 24 h. MRPI showed a decrease of renal blood flow (RBF) in all age groups, but most significantly in those aged >or=60 years. The radionuclide renography and big-ET-1 levels changed significantly only in the oldest group. The best correlation was between RI and RBF changes detected by MRPI. ESWL obviously causes disturbances of renal perfusion, particularly in elderly patients (>or=60 years). Measurement of RI with Doppler techniques might provide useful information for the clinical diagnosis of renal damage.

PurposeHyperthermic intraperitoneal chemotherapy (HIPEC) is accompanied with an increased risk of acute kidney injury (AKI). Whether AKI is induced by chemotoxicity or hyperthermia-related changes in renal perfusion remains controversial. The influence of HIPEC on renal perfusion has not been evaluated in patients yet.MethodsRenal blood perfusion was assessed in ten patients treated with HIPEC by intraoperative renal Doppler pulse-wave ultrasound. Ultrasound (US) examinations were performed pre-, intra-, and postoperative with analyses of time-velocity curves. Patient demographics, surgical details, and data regarding renal function were recorded perioperatively. For evaluation of renal Doppler US to predict AKI, patients were divided in two groups with (AKI +) and without (AKI −) kidney injury.ResultsThroughout HIPEC perfusion, neither significant nor consistent changes in renal perfusion could be observed. Postoperative AKI occurred in 6 of 10 participating patients. Intraoperative renal resistive index (RRI) values > 0.8 were observed in one patient developing stage 3 AKI according KDIGO criteria. At 30 min in perfusion, RRI values were significantly higher in AKI + patients.ConclusionAKI is a common and frequent complication after HIPEC, but underlying pathophysiology remains elusive. High intraoperative RRI values may indicate an increased risk of postoperative AKI. Present data challenges the relevance of hyperthermia-derived hypothesis of renal hypoperfusion with prerenal injury during HIPEC. More attention should be drawn towards chemotoxic-induced hypothesis of HIPEC-induced AKI and caution applying regimens containing nephrotoxic agents in patients. Further confirmatory and complementary studies on renal perfusion as well as pharmacokinetic HIPEC studies are required.

In humans, renal endothelial function is assessed by the vasoconstrictive response to L-NG-monomethyl arginine (L-NMMA). We hypothesized that Doppler sonographic measurements of the renal resistive index in response to inhibition of nitric oxide synthase offer a new methodological approach for testing renal endothelial function. Forty-one patients without nephropathy were included. Para-aminohippurate and inulin clearance were performed under basal conditions and during L-NMMA infusion. In parallel, renal resistive index was assessed by Doppler sonography, and central blood pressure was determined. Following nitric oxide synthase inhibition, renal resistive index increased significantly, and 29% of our patients developed Doppler sonographic diastolic zero flow. Renal plasma flow decreased in response to L-NMMA, and conversely, renal vascular resistance increased. There was no correlation of renal vascular resistance and renal resistive index at baseline and during nitric oxide synthase inhibition. Changes in renal resistive index were not related to changes in renal perfusion or renal vascular resistance. Renal resistive index correlated with central pulse pressure at baseline and during L-NMMA infusion, whereas renal vascular resistance did not correlate with central pulse pressure. Our data do not support the hypothesis that renal resistive index is a tool to test renal endothelial function in humans and should not be used interchangeably with renal vascular resistance.

Acute kidney injury is one of the most frequent and prognostically relevant complications in cardiogenic shock. The purpose of this study was to evaluate the potential effect of the Impella® pump on hemodynamics and renal organ perfusion in patients with myocardial infarction complicating cardiogenic shock. Between January 2020 and February 2022 patients with infarct-related cardiogenic shock supported with the Impella® pump were included in this single-center prospective short-term study. Changes in hemodynamics on different levels of Impella® support were documented with invasive pulmonal arterial catheter. As far as renal function is concerned, renal perfusion was assessed by determining the renal resistive index (RRI) using Doppler sonography. A total of 50 patients were included in the analysis. The increase in the Impella® output by a mean of 1.0 L/min improved the cardiac index (2.7 ± 0.86 to 3.3 ± 1.1 p &lt; 0.001) and increased central venous oxygen saturation (62.6 ± 11.8% to 67.4 ± 10.5% p &lt; 0.001). On the other side, the systemic vascular resistance (1035 ± 514 N·s/m5 to 902 ± 371 N·s/m5p = 0.012) and the RRI were significantly reduced (0.736 ± 0.07 to 0.62 ± 0.07 p &lt; 0.001). Furthermore, in the overall cohort, a baseline RRI ≥ 0.8 was associated with a higher frequency of renal replacement therapy (71% vs. 39% p = 0.04), whereas the consequent reduction of the RRI below 0.7 during Impella® support improved the glomerular filtration rate (GFR) during hospital stay (15 ± 3 days; 53 ± 16 mL/min to 83 ± 16 mL/min p = 0.04). Impella® support in patients with cardiogenic shock seems to improve hemodynamics and renal organ perfusion. The RRI, a well-known parameter for the early detection of acute kidney injury, can be directly influenced by the Impella® flow rate. Thus, a targeted control of the RRI by the Impella® pump could mediate renal organ protection.

Aim: The doppler-based renal resistive index is a recently proposed technique for measuring changes in renal perfusion and predicting acute kidney damage. The purpose of this study was to look at the influence of stone density on the renal resistive index (RI) after extracorporeal shock wave lithotripsy (ESWL) in patients with non-obstructed kidney stones.Material and Method: Between May 2020 and July 2021, 48 consecutive patients with unilateral renal calculi of ≤ 20 mm were treated with ESWL monotherapy. The patients' non-contrast computed tomography (NCCT) images were processed and grouped into two groups using Hounsfield units (HU) (Group 1, n=27, ≤ 1000 HU; Group 2, n=21, &amp;gt; 1000 HU). The same radiologist performed Doppler ultrasonography on all cases before, one hour, and one week following ESWL. Measurement of the RI taken in the remote region (at least 20 mm from the stones). Patient age, gender, BMI, stone laterality, stone size, and stone position were investigated as potential predictors.Results: The average stone size for Group 1 was 11.7±3.3 mm and 12.1±2.8 mm for Group 2. The mean RI values before ESWL for Group 1 and Group 2 were 0.54 and 0.53, respectively. On comparing the pre-treatment data with the 1 hour after ESWL, a statistically significant increase was recorded in the RI value for both groups. However, there was no significant difference in RI values between groups 1 and 2 1 hour and 1 week following lithotripsy therapy. After one week, the mean RI returned to pretreatment levels, according to a follow-up doppler investigation. There was no association between stone density and RI (p &amp;gt; 0.05). Conclusion: High stone densities detected with NCCT were not associated with a significant change in RI. Post-ESWL therapy alterations are present and reversible one week after the treatment.

ObjectivesThe performance of renal resistance index (RRI) in predicting persistent sepsis-associated acute kidney injury (S-AKI) remains debatable, and the value of urinary C–C motif chemokine ligand 14 (CCL14) in predicting persistent S-AKI has not been validated yet. Therefore, we aimed to determine the applicability of a urinary biomarker CCL14 for the early detection of persistent S-AKI. Furthermore, the use of RRI obtained from renal Doppler ultrasonography was applied to differentiate transient from persistent S-AKI. Finally, we aimed to evaluate the use of these techniques in predicting different subtypes of S-AKI.MethodsThis prospective observational study was conducted at the internal medicine intensive care unit (ICU) of a university hospital. The RRI was determined within 12 h of ICU admission and the urinary CCL14 was evaluated at T0, T6, T12, and T24. The reversibility of renal dysfunction was assessed within 48 h. The receiver operating characteristic curves were then plotted to assess the diagnostic efficacy of the RRI and urinary CCL14 in predicting persistent S-AKI.ResultsOut of 48 patients, 23 developed persistent S-AKI upon admission. The RRI was higher in the persistent S-AKI group (P = 0.02) and the RRI ≥ 0.679 could predict persistent S-AKI with an area under the receiver operating characteristic curve of 0.79 (95% CI 0.65–0.93), a sensitivity of 91.30% (95% CI 70–98%), and a specificity of 65.20% (95% CI 43–83%). Urinary CCL14 was not significantly different between the two groups at the tested period, showing poor diagnostic performance at T0, T6, T12, and T24, with areas under the receiver operating characteristic curves of 0.56 (95% CI 0.38–0.73), 0.62 (95% CI 0.46–0.79), 0.52 (95% CI 0.35–0.68), and 0.60 (95% CI 0.43–0.77), respectively.ConclusionsThe RRI obtained from renal Doppler ultrasound is extremely effective in predicting persistent S-AKI in critically ill patients, and urinary CCL14 could not distinguish between transient and persistent S-AKIs.

Three Doppler-derived techniques have been proposed to assess renal perfusion at bedside: Doppler-based renal resistive index (RI) which has been extensively but imperfectly studied in assessing renal allograft status and changes in renal perfusion in critically ill patients and for predicting the reversibility of an acute kidney injury (AKI), semi-quantitative evaluation of renal perfusion using colour-Doppler which may be easier to perform and may give similar information than RI and contrast-enhanced sonography that may allow more precise renal and cortical perfusion assessment. These promising tools have several obvious advantages including their feasibility, non-invasiveness, repeatability and potential interest in assessing renal function or perfusion. However, several limits need to be taken into account with these techniques, and promising results remain associated with large areas of uncertainty. This editorial will describe more carefully advantages and limits of these techniques and will discuss their potential interest in assessing renal perfusion.Electronic supplementary materialThe online version of this article (doi:10.1186/s13089-015-0024-6) contains supplementary material, which is available to authorized users.

PurposeThe Acute Disease Quality Initiative (ADQI) Workgroup recently released a consensus definition of sepsis-associated acute kidney injury (SA-AKI), combining Sepsis-3 and Kidney Disease Improving Global Outcomes (KDIGO) AKI criteria. This study aims to describe the epidemiology of SA-AKI.MethodsThis is a retrospective cohort study carried out in 12 intensive care units (ICUs) from 2015 to 2021. We studied the incidence, patient characteristics, timing, trajectory, treatment, and associated outcomes of SA-AKI based on the ADQI definition.ResultsOut of 84,528 admissions, 13,451 met the SA-AKI criteria with its incidence peaking at 18% in 2021. SA-AKI patients were typically admitted from home via the emergency department (ED) with a median time to SA-AKI diagnosis of 1 day (interquartile range (IQR) 1–1) from ICU admission. At diagnosis, most SA-AKI patients (54%) had a stage 1 AKI, mostly due to the low urinary output (UO) criterion only (65%). Compared to diagnosis by creatinine alone, or by both UO and creatinine criteria, patients diagnosed by UO alone had lower renal replacement therapy (RRT) requirements (2.8% vs 18% vs 50%; p < 0.001), which was consistent across all stages of AKI. SA-AKI hospital mortality was 18% and SA-AKI was independently associated with increased mortality. In SA-AKI, diagnosis by low UO only, compared to creatinine alone or to both UO and creatinine criteria, carried an odds ratio of 0.34 (95% confidence interval (CI) 0.32–0.36) for mortality.ConclusionSA-AKI occurs in 1 in 6 ICU patients, is diagnosed on day 1 and carries significant morbidity and mortality risk with patients mostly admitted from home via the ED. However, most SA-AKI is stage 1 and mostly due to low UO, which carries much lower risk than diagnosis by other criteria.

Comparative sonographic examination of the renal resistance index (RRI) can provide evidence of renal artery stenosis. The extent to which the RRI is changed after stent graft implantation is not known. The aim of this study was to investigate the influence of stent graft implantation into non-diseased renal arteries during endovascular treatment of pararenal aortic aneurysms on the RRI. Sonographic examinations of the kidneys were conducted using a GE ultrasound system. The evaluation was performed according to the European Society for Vascular Surgery (ESVS) 2D standard criteria. RRI values were determined in consecutive patients on the day before and after stent graft implantation and compared for each kidney. A total of 32 consecutive patients (73.9 ± 8.2 years, 5 females, 27 males) were treated with a fenestrated or branched aortic stent graft including bridging stent graft implantations into both renal arteries and received pre- and postinterventional examinations. Sonomorphologically, the examined kidneys were inconspicuous. The arborisation of the renal perfusion was preserved pre- and post-implantation. The RRI did not differ (0.66 ± 0.06 versus 0.67 ± 0.07; p = ns). Successful stent graft implantation into non-stenosed renal arteries did not lead to a relevant change in RRI. Therefore, the RRI is a suitable tool for assessing renal perfusion after fenestrated or branched endovascular aortic therapy.