WCN26-4500 DYNAMIC CHANGE IN RENAL RESISTIVE INDEX IN A PATIENT WITH HUMAN PARVOVIRUS B19 INDUCED GLOMERULONEPHRITIS

What do Doppler indices of renal perfusion tell us for the evaluation of renal disease?

BackgroundRenal resistive index (RRI) by Doppler ultrasound, reflects changes in both renal vascular and tubular-interstitial compartments and systemic vascular compliance related to physiological (age) and pathological conditions among which hypertension,...

Background: Chronic kidney disease (CKD) in cats often progresses silently, making early diagnosis challenging. Symmetric dimethylarginine (sSDMA) is a sensitive biomarker for early renal dysfunction, while the resistive index (RI), obtained via Doppler ultrasonography, reflects renal vascular resistance. Combining these tools may improve early CKD detection. This study aimed to evaluate the correlation of RI with sSDMA in asymptomatic cats. Materials, Methods & Results: A prospective, blinded cohort study assessed the correlation between renal RI and sSDMA in 101 clinically asymptomatic cats. Examinations were performed without sedation, with manual restraint, and approved by the Federal University of Paraná's Animal Ethics Committee. Triplex Doppler ultrasonography used a GE Logic 5 machine with a 7.5-12 MHz linear transducer. B-mode assessed renal morphology, followed by color and pulsed Doppler for vasculature and interlobar arteries. RI was automatically calculated from three waveforms per kidney. An RI ≥0.59 (left) or ≥0.54 (right) was considered elevated. Blood samples were collected from the jugular vein. Creatinine and sSDMA were measured at IDEXX Laboratories (São Paulo, Brazil) using liquid chromatography-mass spectrometry. Urine was collected via cystocentesis. sSDMA values ≥ 14 μg/dL were considered elevated. Cats were grouped by sSDMA levels. Statistical analysis used SPSS 21.0, with P < 0.05 set as significant. Reliable RI measurements were obtained in 91 cats; 10 were excluded due to poor waveform acquisition (e.g., patient movement, panting, poor corticomedullary definition). Mean RI was 0.61 ± 0.07 (left) and 0.62 ± 0.07 (right), with no significant difference. Increased RI was seen in 55.9% (47/84) of left kidneys and 86% (74/86) of right kidneys. Elevated sSDMA was detected in 14.9% (15/101) of cats. A statistically significant correlation was found between elevated RI in the right kidney and increased sSDMA (P = 0.001), but not the left (P = 0.246). Creatinine also positively correlated with elevated sSDMA (P = 0.022), supporting the link between renal hemodynamic changes and early biochemical markers. These results suggest RI, particularly in the right kidney, may be a useful non-invasive parameter for early CKD detection in cats, especially with sSDMA. Discussion: While renal ultrasonography is common in cats, few studies explore RI's diagnostic potential in asymptomatic animals. Doppler ultrasonography was feasible but sometimes limited by patient stress, obesity, and altered renal morphology, affecting waveform quality. No significant difference was found between right and left kidney RI values, though some cats showed inter-kidney discrepancies, possibly indicating unilateral disease. Mean RI values were normal but near early CKD values.The significant correlation between elevated RI in the right kidney and increased sSDMA was not observed in the left. The asymmetry is unclear, but extrarenal factors and comorbidities might influence both RI and sSDMA. Despite limitations, creatinine also correlated positively with sSDMA, supporting its reliability in early renal assessment. RI should not be a standalone CKD screening method but a complementary tool, especially with sSDMA. Bilateral assessment is recommended, and interpretation should be cautious with morphological abnormalities or poor patient cooperation. Overall, RI measurement is feasible in unsedated cats and may aid early detection of renal changes in subclinical disease. Keywords: feline, resistive index, doppler, kidney, SDMA.

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.

BackgroundHyperdynamic circulatory state in liver cirrhosis is characterized by increased splanchnic blood flow and renal vasoconstriction. AimTo evaluate the relationship between renal resistive indices (RI) and HCV liver cirrhosis severity and RI value in predicting 6month survival of those patients. Also we aimed to assess the effect of midodrine on RI. Patients and methods120 patients with HCV liver cirrhosis and 40 healthy controls were enrolled in the study. INR, total bilirubin, albumin, creatinine and sodium were measured in all patients. Both patients and controls underwent abdominal ultrasound with duplex Doppler examination of the kidneys with RI calculated. Patients were followed for 6months. Surviving patients with highest risk underwent renal duplex with RI calculation (RI2). They then received oral midodrine at a dose of 7.5mg three times daily for 3months with revaluation of RI (RI3). Results57 (47.5%) patients had high RI (RI>0.7) while 63 (52.5%) patients had normal RI. Patients had significantly higher RI than healthy controls (P<0.001). There was a significant positive correlation between RI and MELD, MELD-Na, and Child class (r=0.859, r=0.769, rho=0.56 respectively and P<0.001). Patients with RI>0.73 are at higher risk of death within 6months (P<0.001). Administration of midodrine resulted in no significant difference in RI in the 37 surviving patients with baseline RI>0.73 (P=0.1605). ConclusionRI is strongly correlated with liver cirrhosis severity and had comparable prognostic value with MELD score. Midodrine had no significant effect on RI in high risk patients.

BackgroundAcute kidney injury (AKI) complicates shock. Diagnosis is based on rising creatinine, a late phenomenon. Intrarenal vasoconstriction occurs earlier. Measuring flow resistance in the renal circulation, Renal Resistive Index (RRI), could become part of vital organ function assessment using Doppler ultrasound. Our aim was to determine whether RRI on ICU admission is an early predictor and discriminator of AKI developed within the first week.MethodsIn this prospective cohort of mixed ICU patients with and without shock, RRI was measured <24-h of admission. Besides routine variables, sublingual microcirculation and bioelectrical impedance were measured. AKI was defined by the Kidney Disease Improving Global Outcomes criteria. Uni- and multivariate regression and Receiver Operating Characteristics curve analyses were performed.ResultsNinety-nine patients were included, median age 67 years (IQR 59–75), APACHE III score 67 (IQR 53–89). Forty-nine patients (49%) developed AKI within the first week. AKI patients had a higher RRI on admission than those without: 0.71 (0.69–0.73) vs. 0.65 (0.63–0.68), p = 0.001. The difference was significant for AKI stage 2: RRI = 0.72 (0.65–0.80) and 3: RRI = 0.74 (0.67–0.81), but not for AKI stage 1: RRI = 0.67 (0.61–0.74). On univariate analysis, RRI significantly predicted AKI 2–3: OR 1.012 (1.006–1.019); Area Under the Curve (AUC) of RRI for AKI 2–3 was 0.72 (0.61–0.83), optimal cut-off 0.74, sensitivity 53% and specificity 87%. On multivariate analysis, RRI remained significant, independent of APACHE III and fluid balance; adjusted OR: 1.008 (1.000–1.016).ConclusionsHigh RRI on ICU admission was a significant predictor for development of AKI stage 2–3 during the first week. High RRI can be used as an early warning signal RRI, because of its high specificity. A combined score including RRI, APACHE III and fluid balance improved AKI prediction, suggesting that vasoconstriction or poor vascular compliance, severity of disease and positive fluid balance independently contribute to AKI development.Trial registrationClinicalTrials.gov NCT02558166.

Preoperative Renal Resistive Index Predicts Risk of Acute Kidney Injury in Patients Undergoing Cardiac Surgery

High renal resistive index (RI) is observed in diabetes and is associated with poor patient survival, but whether it is primarily due to renal vascular resistance or systemic vascular alterations is unclear. The respective impact of kidney transplant from diabetic donors or to diabetic recipients on RI would shed some light on this issue. The objective of the study was to analyze the impact of donor and recipient diabetes on RI in order to understand the respective impact of the kidney and the vascular environment. The authors conducted a retrospective study in 1827 renal transplant recipients who received a kidney between 1985 and 2017, and had Doppler measurements at 3months after transplant. Donor and recipient characteristics at the time of transplant and at 3months were reviewed. Both donor diabetes and recipient diabetes were associated with RI in univariate analysis, but only recipient diabetes remained significantly associated in stepwise multivariate analyses (effect estimate on RI: +0.03±0.005, P<0.001). These findings were confirmed when RI was expressed as a binary variable using a cutoff of 0.75 (OR=2.50 [1.77, 3.54], P<0.001). Other determinants of RI were recipient characteristics (age, sex, systolic and diastolic blood pressure, and duration of dialysis). Donor characteristics were not associated with RI. Our results suggest that high RI observed in diabetic recipients shortly after transplant is primarily due to the new vascular environment, rather than to characteristics of the transplanted kidney. Therefore, RI reflects systemic rather than intra-renal changes.

Renal resistive index (RI) calculated using renal Doppler ultrasonography (RDU) has recently been considered a clinically important indicator of renal outcome, survival, and systemic arteriosclerotic disorders. However, the cause of RI elevation remains unclear. The present study was an effort to first, identify the factors related to RI elevation, and second, understand the effect of renin-angiotensin system inhibitors (RAS-Is) on renal RI elevation. We carried out this single-center case-control study among 100 CKD patients, recruited from outpatients who underwent RDU more than twice, at least a year apart. The rate of renal RI change per year (dRIpy) was chosen as the dependent variable: [(last examined renal RI-initial examined renal RI)/(initial examined renal RI × period of observation) × 100 (%/year)]. We examined the association between dRIpy and other clinical and biological data. Among 100 CKD patients, the average serum creatinine and eGFR were 1.76 ± 0.84mg/dL and 37.0 ± 18.2ml/min/1.73m2, respectively. The average dRIpy in all patients was 1.8 ± 1.4%/year. The linear multiple regression demonstrated that dRIpy was positively associated with the presence of diabetes mellitus (DM) and high low-density lipoprotein cholesterol (LDL) levels, and negatively with eGFR and RAS-I use. This study demonstrated that the elevation of RI was related to DM, eGFR, high LDL, and the use of RAS-Is. In particular, RAS-Is could contribute towards suppressing the elevation of RI in CKD patients and towards preventing the development of renal failure in CKD patients.

Doppler ultrasonography is one of the tools that started to use recently in human and veterinary medicine for this purpose. Currently, there are many studies to investigate methods of earlier diagnosis of prognosis of renal and hepatic diseases. However there is stil no consensus among researchers about the normal values. To our knowledge no systematical research exits revealing the normal values of Kangal breed dogs. Our purpose in this research is to determine the normal renal and hepatic doppler values of Kangal breed. For this purpose, 30 Turkish Kangal dogs and 20 healty dogs from several breeds were included to the study. The mean value of renal resistive index (RI) and pulsative index (PI) were 0,65±0,04 and 1.13±0,05 for Turkish Kangal dogs; 0,64±0,08 and 1.12±0,05 for different breed dogs. For the hepatic RI and PI values 0,65±0,04 and, 1.16±0,03 for Turkish Kangal dogs; 0.63±0,04 and 1.15±0.04 for different breed dogs respectively. The hepatic and renal PI and RI values of Kangal dogs were found to be compatible with other breeds.

Background and Aims Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease and one of the most common causes of end-stage kidney disease (ESRD). The major ADPKD genes are PKD1 and PKD2, accounting for &amp;gt;90% of diagnosed families. The causal gene (PKD1&amp;gt;PKD2 or minor genes), type of PKD1 mutation, sex (male&amp;gt;female), environmental factors (obesity, salt intake), and total kidney volume (TKV), among others, are associated with severity and risk of progression to ESRD in ADPKD. TKV may be associated with intrarenal vascular involvement by kidney cysts. The best way to estimate TKV is by magnetic resonance imaging (MRI). Mutational analysis and MRI are expensive techniques, require expertise, and they are not always available in all centers. An increase in renal resistive index (RRI) assessed by ultrasonography (US) reflects intrarenal vascular involvement and has been related to a decrease in glomerular filtration rate (GFR) in other nephropathies. Gut microbiome has not been explored in ADPKD patients, but it has been demonstrated its relevance in other kidney diseases. Therefore, our aim was to explore the gut microbiome, and the RRI in ADPKD patients and to investigate their link with prognostic markers, such as causal gene, sex, obesity, and TKV. Method A cross-sectional observational study was performed including patients diagnosed with ADPKD. Relevant clinical, demographic, and analytical information were gathered for each participant. Mutational analysis was performed. TKV was measured by MRI. RRI was assessed by US. Gut microbiome profile was obtained by Shotgun. Results This study included 50 ADPKD patients with a median age of 44.5 years old (IR: 34.8–57.5). Men presented higher TKV compared to women (1786.8 vs 943, P = 0.007). TKV was positively correlated with RRI, and body mass index (BMI) and inversely correlated with GFR, and 1.25 dihydroxyvitamin D. BMI was positively correlated with hemoglobin and inversely correlated with 1.25 dihydroxyvitamin, and GFR. In the multivariate analysis, TKV, GFR, and sex were independent predictors of RRI, with statistical significance. The gut microbiome was compared between ADPKD patients according to GFR, using ANCOM-BC methodology adjusted by age, sex, and BMI. A statistically significant higher prevalence of species from the phylum Actinomycetota was observed in ADPKD patients with GFR≥60ml/min/1.73 m2, and a higher prevalence of species from the phylum Bacteroidota and Bacillota was found in ADPKD patients with GFR &amp;lt;60ml/min/1.73 m2. The taxonomic profiles when comparing between ADPKD patients with RRI &amp;lt;0.65 to ADPKD patients with RRI≥0.65 were distinct at species level, observing a predominance of Streptococcus genus in the group RRI ≥0.65. Analyzing RRI as a continuous variable, an increase in Streptococcus genus was confirmed while RRI rises. Moreover, higher RRI levels were associated to an increase in Pseudomonadota and Thermodesulfobacteriota and lower RRI levels were associated to an increase in Bacteroidota. Comparing taxonomic profiles in ADPKD patients according to the presence of PKD1 or PKD2 mutations, an increase in Actinomycetota, and Bacteroidota at phylum level, and Bacilalles, and Veionella at order level was observed in PKD1 group. Conclusion TKV, GFR, and sex are independent predictors of RRI in ADPKD, which implies a link between these factors and renal macro and microvascular involvement. Regarding the gut microbiome in our ADPKD patients, some specific taxa have been shown to be associated to well-stablished prognostic markers. Future studies may explore the role of these bacterial groups as potential biomarkers in ADPKD.

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.

Increased renal resistive index in type 2 diabetes: Clinical relevance, mechanisms and future directions

Objective: Cardiovascular diseases recognize ischemia as the main pathogenetic prime mover and represent the final step of morphofunctional vascular changes that develop over a long period of time, mostly asymptomatically. Recent studies detected the role of intrarenal hemodynamic changes as independent predictors of cardiovascular events in different populations. No data exist about the relationship between renal hemodynamics and coronary atherosclerotic damage. The purpose of our investigation is to study the relationship between intrarenal vascular changes and coronary atherosclerotic burden in hypertensive patients.Design and method: We enrolled 130 hypertensive subjects (30–80 years) who received indication for elective coronary angiography. Duplex ultrasound of intrarenal vasculature was performed to evaluate renal resistive index (RI), renal pulsatility index (PI) and renal acceleration time (AT). Subsequently, a coronary angiography was performed to assess atherosclerotic burden through Gensini Score (GS). Carotid intima-media thickness (cIMT) was also assessed as a model of vascular damage well related with renal parameters. The population was divided into quintiles based on the GS (I quintile: GS < 9; II quintile: GS>9 and <17; III quintile: GS>17 and <30.8; IV quintile: GS>30.8 and <44; V quintile: GS>44). Statistical analysis was also performed in the population divided in 2 groups: 1) subjects with mild coronary disease (GS<30); 2) subjects with severe coronary disease (GS>30). Results: Subjects in higher quintiles had greater values of PI, RI and lower values of AT compared to the ones in lower quintiles. The correlation between GS and PI, RI or AT was not statistically significant at the univariate analysis in overall population, whereas GS, IR and IP were significantly associated with cIMT (all p < 0.01). IP and IR, but not AT, were associated to GS in the group with GS<30, whereas did not correlate in subjects with GS>30. These correlations held after adjustment for multiple confounders. Conclusions: Renal vascular changes are not significantly related to coronary atherosclerotic burden in all hypertensive patients. Nevertheless, within the complex mathematical relationship between PI (or RI) and GS (Figure 1), the relationship becomes linear and significant in patients with mild coronary disease.

The renal resistive index (RI) value of 0.73 has been proposed as the upper limit in normal adult dogs. In humans, changes in RI with age are associated with plasma renin activity. There are relatively few equivalent reference data for dogs. We obtained reference RI data from 22 clinically healthy dogs <4 months of age and 33 healthy dogs between 4 months and 7 years of age. An association between the RI and plasma renin activity was investigated. The mean RI in the older dogs was 0.65 +/- 0.05 vs. 0.75 +/- 0.05 in dogs <4 months of age. The mean plasma renin activity in the older dogs was 1.18 +/- 1.03 vs. 4.23 +/- 3.09 ng/ml/h in dogs <4 months of age. There was a weak linear relationship between the RI and plasma renin activity (r2 = 0.280, P < 0.01) in dogs <4 months of age. Also in these younger dogs, RI was negatively correlated with age (r2 = 0.682, P < 0.01). The RI was higher in dogs <4 months of age than in older dogs. Therefore, the mean renal RI is slightly higher in young dogs than reported for an older population and interpretation of the RI must include an assessment of patient age.