Wave reflections in the umbilical artery measured by Doppler ultrasound as a novel predictor of placental pathology.

BACKGROUND: The umbilical artery (UA) Doppler pulsatility index is used clinically to detect elevated feto-placental vascular resistance. However, this metric is confounded by variation in fetal cardiac function and is only moderately predictive of placental pathology. Our group developed a novel ultrasound methodology that measures wave reflections in the UA, thereby isolating a component of the Doppler signal that is specific to the placenta. The present study examined whether wave reflections in the UA are predictive of placental vascular pathology. METHODS: Standard clinical Doppler ultrasound of the UAs was performed in 241 pregnant women. Of these, 40 women met narrowly defined preset criteria for the control group, 36 had maternal vascular malperfusion (MVM) and 16 had fetal vascular malperfusion (FVM). Using a computational procedure, the Doppler waveforms were decomposed into a pair of forward and backward propagating waves. FINDINGS: Compared to controls, wave reflections were significantly elevated in women with either MVM (p<0.0001) or FVM pathology (p = 0.02). In contrast, the umbilical and uterine artery pulsatility indices were only elevated in the MVM group (p<0.0001) and there were no differences between women with FVM and the controls. INTERPRETATION: The measurement of wave reflections in the UA, combined with standard clinical ultrasound parameters, has the potential to improve the diagnostic performance of UA Doppler to detect placental vascular pathology. Identifying women with FVM pathology is particularly challenging prenatally and future investigations will determine if women at risk of this specific placental disease could benefit from this novel diagnostic technique.

Fetal cardiac filling and ejection time fractions by pulsed-wave Doppler: reference ranges and potential clinical application.

OBJECTIVES: Fetal cardiac function can be evaluated using a variety of parameters. Among these, cardiac cycle time-related parameters, such as filling time fraction (FTF) and ejection time fraction (ETF), are promising but rarely studied. We aimed to report the feasibility and reproducibility of fetal FTF and ETF measurements using pulsed-wave Doppler, to provide reference ranges for fetal FTF and ETF, after evaluating their relationship with heart rate (HR), gestational age (GA) and estimated fetal weight (EFW), and to evaluate their potential clinical utility in selected fetal conditions. METHODS: This study included a low-risk prospective cohort of singleton pregnancies and a high-risk population of fetuses with severe twin-twin transfusion syndrome (TTTS), aortic stenosis (AoS) or aortic coarctation (CoA), from 18 to 41 weeks' gestation. Left ventricular (LV) and right ventricular inflow and outflow pulsed-wave Doppler signals were analyzed, using valve clicks as landmarks. FTF was calculated as: (filling time/cycle time) × 100. ETF was calculated as: (ejection time/cycle time) × 100. Intraclass correlation coefficients (ICC) were used to evaluate the intra- and interobserver reproducibility of FTF and ETF measurements in low-risk fetuses. The relationships of FTF and ETF with HR, GA and EFW were evaluated using multivariate regression analysis. Reference ranges for FTF and ETF were then constructed using the low-risk population. Z-scores of FTF and ETF in the high-risk fetuses were calculated and analyzed. RESULTS: In total, 602 low-risk singleton pregnancies and 54 high-risk fetuses (nine pairs of monochorionic twins with severe TTTS, 16 fetuses with AoS and 20 fetuses with CoA) were included. Adequate Doppler traces for FTF and ETF could be obtained in 95% of low-risk cases. Intraobserver reproducibility was good to excellent (ICC, 0.831-0.905) and interobserver reproducibility was good (ICC, 0.801-0.837) for measurements of all timing parameters analyzed. Multivariate analysis of FTF and ETF in relation to HR, GA and EFW in low-risk fetuses identified HR as the only variable predictive of FTF, while ETF was dependent on both HR and GA. FTF increased with decreasing HR in low-risk fetuses, while ETF showed the opposite behavior, decreasing with decreasing HR. Most recipient twins with severe TTTS showed reduced FTF and preserved ETF. AoS was associated with decreased FTF and increased ETF in the LV, with seemingly different patterns associated with univentricular vs biventricular postnatal outcome. The majority of fetuses with CoA had FTF and ETF within the normal range in both ventricles. CONCLUSIONS: Measurement of FTF and ETF using pulsed-wave Doppler is feasible and reproducible in the fetus. The presented reference ranges account for associations of FTF with HR and of ETF with HR and GA. These time fractions are potentially useful for clinical monitoring of cardiac function in severe TTTS, AoS and other fetal conditions overloading the heart. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.

Assessment of Dog Testis Perfusion by Colour and Pulsed-Doppler Ultrasonography and Correlation With Sperm Oxidative DNA Damage.

The assessment of testicular artery blood flow by colour and pulsed-Doppler ultrasonography is an important diagnostic technique to assess vascular perfusion. Recently, it has been suggested as a good predictor of sperm quality. On the other hand, through the alkaline Comet Assay, it is possible to quantify sperm oxidative DNA damage. The aim of this study was to evaluate the relationship between routine sperm parameters, testicular artery blood flow and oxidative DNA damage in canine sperm. Testicular ultrasonography and sperm collection were performed on 12 male dogs, with the animals being allocated into 2 groups, according to the classification of the ejaculates' quality, as normozoospermic (N; n = 7) or non-normozoospermic (OAT; n = 5). Seven dogs aged between 1.5 and 8.0 years old were included in group N and 5 dogs, aged between 2.0 and 11.0 years old, were included in group OAT. The sperm-rich fraction of the ejaculates was evaluated for sperm routine parameters and DNA damage by comet assay. Colour and pulsed-Doppler ultrasonography were used to evaluate the blood flow of the supratesticular and marginal arteries of right and left testis. Group OAT presented higher levels of sperm oxidative DNA damage (A.U.) in comparison to group N (N:11.7 ± 9.9; OAT:34.2 ± 6.1; P< .001). The peak of systolic velocity was positively correlated with sperm concentration (r = 0.685; P= .005). The resistive and pulsatility indexes (RI and PI) of the supratesticular artery were negatively correlated with sperm membrane integrity (HOST+) (r = -0.594; P = .042; r = -0.612; P = .035, respectively). The end diastolic velocity (EDV) of the supratesticular artery was positively correlated with sperm concentration (r = 0.748; P = .005) and negatively correlated with sperm oxidative DNA damage (r = -0.766; P = .004). Our results suggest that the assessment of the testicular artery blood flow by colour and pulsed-Doppler ultrasonography could be a good predictor of sperm quality in dogs in terms of sperm concentration, membrane integrity and sperm oxidative DNA damage.

A new index of ultrasonography for estimating cerebral circulation in newborn infants.

PURPOSE: To quantitatively estimate the influence of ductal shunt on cerebral blood flow and establish a new index of ultrasonography for estimating cerebral circulation without the influence of ductal shunt in newborn infants. METHODS: We retrospectively examined the records of anterior cerebral artery (ACA) and left pulmonary artery (LPA) blood flow velocity curves recorded by pulsed Doppler ultrasonography within 6 h after birth in 123 newborn infants without asphyxia (normal group) and in 31 newborn infants with asphyxia (asphyxia group). RESULTS: In the normal group, the resistance index (RI) of the ACA showed a positive correlation with the ratio of LPA diastolic-to-systolic flow velocities (LPAD/LPAS) (P < 0.001, r = 0.58), and the estimated RI (eRI) of the ACA was calculated using the following formula: Y = 0.47X + 0.67 (Y estimated RI; X LPAD/LPAS). In the asphyxia group, the RI of the ACA showed a weak correlation to base excess (BE) (P < 0.05, r = 0.46). The eRI of the ACA was calculated by the LPAD/PLAS in the asphyxia group, and the difference between the RI and eRI showed a better correlation to BE than RI (P < 0.001, r = 0.64). CONCLUSION: We determined the relation between cerebral blood flow RI and ductal shunt, and (RI - eRI) may be a new useful ultrasonographic index indicating cerebral circulation without the influence of ductal shunt in newborn infants.

Haemodynamic and cerebrovascular effects of intermittent lower-leg compression as countermeasure to orthostatic stress.

NEW FINDINGS: What is the central question of this study? Does smartly timed intermittent compression of the lower legs alter cerebral blood velocity and oxygenation during acute orthostatic challenges? What is the main finding and its importance? Intermittent compression timed to the local diastolic phase increased the blood flux through the legs and heart after two different orthostatic stress tests. Cerebral blood velocity improved during the first minute of recovery, and indices of cerebral tissue oxygenation remained elevated for 2 min. These results provide promise for the use of lower-leg active compression as a therapeutic tool for individuals vulnerable to initial orthostatic hypotension and orthostatic stress. ABSTRACT: Intermittent compression of the lower legs provides the possibility of improving orthostatic tolerance by actively promoting venous return and improving central haemodynamics. We tested the hypothesis that intermittent compression of 65 mmHg timed to occur only within the local diastolic phase of each cardiac cycle would attenuate the decrease in blood pressure and improve cerebral haemodynamics during the first minute of recovery from two different orthostatic stress tests. Fourteen subjects (seven female) performed four squat-to-stand transitions and four repeats of standing bilateral thigh-cuff occlusion and release (TCR), with intermittent compression of the lower legs applied in half of the trials. Blood flow in the superficial femoral artery, mean arterial pressure, Doppler ultrasound cardiac output, total peripheral resistance, middle cerebral artery blood velocity (MCAv) and cerebral tissue saturation index (TSI%) were monitored. With both orthostatic stress tests, there was a significant compression × time interaction for superficial femoral artery flow (P < 0.001). The hypotensive state was attenuated with intermittent compression despite decreased total peripheral resistance (squat-to-stand, compression × time interaction, P < 0.001; TCR, compression × time interaction, P = 0.002) as a consequence of elevated cardiac output in both tests (P < 0.001). Intermittent compression also increased MCAv (P = 0.001) and TSI% (P < 0.001) during the squat-to-stand transition and during TCR (MCAv and TSI%, compression × time interaction, P < 0.001). Intermittent compression of the lower legs during quiet standing after an active orthostatic challenge augmented local, central and cerebral haemodynamics, providing potential as a therapeutic tool for individuals vulnerable to orthostatic stress.

Right Diaphragmatic Peak Motion Velocities on Pulsed Wave Tissue Doppler Imaging in Neonates: Method, Reproducibility, and Reference Values.

OBJECTIVES: To test the reproducibility and report the reference ranges of the right diaphragmatic excursion's peak velocities recorded by pulsed wave tissue Doppler imaging in healthy term neonates. METHODS: We formerly assessed intraobserver and interobserver variability of the method for the right hemidiaphragm in a small group of neonates, including ventilated neonates. We did not attempt to test the approach for the left hemidiaphragm because of the recognized high failure rate of visualization. Next, we recorded the peak velocities of both hemidiaphragms throughout inspiration and expiration in 229 healthy term neonates near birth to establish weight-dependent reference ranges for the measurements. RESULTS: The study population included 116 male and 113 female neonates. The reproducibility of the technique was excellent even in neonates supported by ventilation. We always recorded the right diaphragmatic peak velocities in the normative study group, whereas the left ones were only recorded in 110 of 229 (48%) and 148 of 229 (65%) neonates from the anterior and lateral views, respectively. The modality of delivery and sex showed no influence on diaphragmatic kinetics. The mean inspiratory peak velocities ± SD were 1.4 ± 0.2 cm/s for the right hemidiaphragm and 1.5 ± 0.3 cm/s for the left hemidiaphragm. The mean expiratory peak velocities were 1.3 ± 0.2 cm/s for the right hemidiaphragm and 1.4 ± 0.3 cm/s for the left hemidiaphragm. CONCLUSIONS: Measurement of right diaphragmatic kinetics as assessed by pulsed wave tissue Doppler imaging was found to be a reliable technique. Its clinical applicability for the prompt diagnosis and effective management of neonatal respiratory failure deserves further investigation.

The new clinical standard of integrated quadruple stress echocardiography with ABCD protocol.

BACKGROUND: The detection of regional wall motion abnormalities is the cornerstone of stress echocardiography. Today, stress echo shows increasing trends of utilization due to growing concerns for radiation risk, higher cost and stronger environmental impact of competing techniques. However, it has also limitations: underused ability to identify factors of clinical vulnerability outside coronary artery stenosis; operator-dependence; low positivity rate in contemporary populations; intermediate risk associated with a negative test; limited value of wall motion beyond coronary artery disease. Nevertheless, stress echo has potential to adapt to a changing environment and overcome its current limitations. INTEGRATED-QUADRUPLE STRESS-ECHO: Four parameters now converge conceptually, logistically, and methodologically in the Integrated Quadruple (IQ)-stress echo. They are: 1- regional wall motion abnormalities; 2-B-lines measured by lung ultrasound; 3-left ventricular contractile reserve assessed as the stress/rest ratio of force (systolic arterial pressure by cuff sphygmomanometer/end-systolic volume from 2D); 4- coronary flow velocity reserve on left anterior descending coronary artery (with color-Doppler guided pulsed wave Doppler). IQ-Stress echo allows a synoptic functional assessment of epicardial coronary artery stenosis (wall motion), lung water (B-lines), myocardial function (left ventricular contractile reserve) and coronary small vessels (coronary flow velocity reserve in mid or distal left anterior descending artery). In "ABCD" protocol, A stands for Asynergy (ischemic vs non-ischemic heart); B for B-lines (wet vs dry lung); C for Contractile reserve (weak vs strong heart); D for Doppler flowmetry (warm vs cold heart, since the hyperemic blood flow increases the local temperature of the myocardium). From the technical (acquisition/analysis) viewpoint and required training, B-lines are the kindergarten, left ventricular contractile reserve the primary (for acquisition) and secondary (for analysis) school, wall motion the university, and coronary flow velocity reserve the PhD program of stress echo. CONCLUSION: Stress echo is changing. As an old landline telephone with only one function, yesterday stress echo used one sign (regional wall motion abnormalities) for one patient with coronary artery disease. As a versatile smart-phone with multiple applications, stress echo today uses many signs for different pathophysiological and clinical targets. Large scale effectiveness studies are now in progress in the Stress Echo2020 project with the omnivorous "ABCD" protocol.

Real-Time Blood Velocity Vector Measurement Over a 2-D Region.

Quantitative blood velocity measurements, as currently implemented in commercial ultrasound scanners, are based on pulsed-wave (PW) spectral Doppler and are limited to detect the axial component of the velocity in a single sample volume. On the other hand, vector Doppler methods produce angle-independent estimates by, e.g., combining the frequency shifts measured from different directions. Moreover, thanks to the transmission of plane waves, the investigation of a 2-D region is possible with high temporal resolution, but, unfortunately, the clinical use of these methods is hampered by the massive calculation power required for their real-time execution. In this paper, we present a novel approach based on the transmission of plane waves and the simultaneous reception of echoes from 16 distinct subapertures of a linear array probe, which produces eight lines distributed over a 2-D region. The method was implemented on the ULAO-OP 256 research scanner and tested both in phantom and in vivo. A continuous real-time refresh rate of 36 Hz was achieved in duplex combination with a standard B-mode at pulse repetition frequency of 8 kHz. Accuracies of -11% on velocity and of 2°on angle measurements have been obtained in phantom experiments. Accompanying movies show how the method improves the quantitative measurements of blood velocities and details the flow configurations in the carotid artery of a volunteer.

Terlipressin-induced modifications of Doppler ultrasound signals of systemic arteries in preterm infants with vasoactive-resistant patent ductus arteriosus: A pilot study.

PURPOSE: To study the effects of terlipressin (TP) infusion on systemic perfusion, estimated with pulsed-wave Doppler ultrasonography of systemic arteries, in a population of extremely low birth-weight (ELBW) preterm infants with vasoactive-resistant ductus arteriosus. METHODS: This prospective, observational cohort included, during five years, 12 ELBW infants with hemodynamically significant patent ductus arteriosus and absent or reversed diastolic flow at Doppler ultrasonography of systemic arteries, despite treatment and high-dose vasoactive support. We measured flow velocity of the anterior cerebral, right renal, and superior mesenteric arteries before and after TP infusion. Changes were evaluated by Spearman's rho coefficient analysis, Wilcoxon signed-rank, and Friedman test. RESULTS: Time-averaged mean velocity of the renal artery (P = .028) increased, while renal pulsatility (P = .010) and resistance (P = .004) indexes, and cerebral artery resistance index (P = .021) decreased after TP infusion. Time-averaged mean velocity of the anterior cerebral artery proportionately increased with dopamine dose (rho = 0.678; P = .015), but showed opposite shifts after TP (rho = -0.662; P = .024). CONCLUSIONS: These changes suggest that TP may improve systemic perfusion in the ELBW infants with vasoactive-resistant ductus arteriosus.

Vector Flow Imaging Compared with Pulse Wave Doppler for Estimation of Peak Velocity in the Portal Vein.

The study described here investigated whether angle-independent vector flow imaging (VFI) technique estimates peak velocities in the portal vein comparably to pulsed wave Doppler (PWD). Furthermore, intra- and inter-observer agreement was assessed in a substudy. VFI and PWD peak velocities were estimated with from intercostal and subcostal views for 32 healthy volunteers, and precision analyses were conducted. Blinded to estimates, three physicians rescanned 10 volunteers for intra- and inter-observer agreement analyses. The precision of VFI and PWD was 18% and 28% from an intercostal view and 23% and 77% from a subcostal view, respectively. Bias between VFI and PWD was 0.57 cm/s (p = 0.38) with an intercostal view and 9.89 cm/s (p <0.001) with a subcostal view. Intra- and inter-observer agreement was highest for VFI (inter-observer intra-class correlation coefficient: VFI 0.80, PWD 0.3; intra-observer intra-class correlation coefficient: VFI 0.90, PWD 0.69). Regardless of scan view, VFI was more precise than PWD.

Therapeutic ultrasound after sciatic nerve compression of Wistar rats.

OBJECTIVES: The present study analyzed the effect of therapy with therapeutic ultrasound on the sciatic nerve after compression injury, comparing two similar doses of SATA. METHODS: In total, 32 Wistar rats were used, divided into the following groups: CG - control; IG - compression injury of the sciatic nerve; IGCU - injury and continuous ultrasound; and IGPU - injury and 20% pulsed ultrasound. The treatment with ultrasound started on the 3rd postoperative day, with a frequency of 1 MHz, 0.4 W/cm² (SATA) for IGCU. IGPU received 2.0 W/cm2 (SATP), with 20% of the active cycle, for 3 minutes. The treatment was performed on a daily basis, totaling 15 days of therapy. Evaluations were performed for functional, histological, and morphometric forms. RESULTS: Both the Sciatic Functional Index and the withdrawal threshold and grip strength failed to show an advantage of using therapeutic ultrasound. For the morphometric evaluations of nerve fiber diameter and axons, myelin sheath thickness, and G quotient and nerve fiber estimates, IGPU values were estimated to be significantly lower. The morphological analysis revealed intense inflammatory response and neovascularization, as well as degeneration of axons and the myelin sheath, for the injury group and IGCU; however, IGPU showed greater tissue disorganization. CONCLUSION: There were no significant differences, showing functional or nocicepitive recovery of the treated groups, including with characteristics pointing to the pulsed group with worse results.

Can Renal Resistive Index Predict Acute Kidney Injury After Acute Type A Aortic Dissection Repair?

BACKGROUND: This study sought to determine whether assessment of the renal resistive index (RRI) can predict the short-term reversibility of acute kidney injury (AKI) after repair of acute type A aortic dissection (TAAD). METHODS: This prospective study included 62 patients undergoing repair of acute TAAD. Doppler-based RRIs were obtained preoperatively, immediately after the surgical procedure, and 6, 24, and 48 hours postoperatively. The occurrence of AKI was evaluated daily according to Acute Kidney Injury Network criteria. Persistent AKI was defined as AKI lasting longer than 3 days. The association between the maximum RRI level at different time points and persistent AKI was analyzed by the receiver-operating characteristic curve. RESULTS: Of the 62 patients, 22 (35.5%) had no AKI, 21 (33.9%) had transient AKI, and 19 (30.6%) had persistent AKI. The maximum RRI was 0.67 ± 0.03 (0.62 to 0.71), 0.71 ± 0.05 (0.59 to 0.79), and 0.78 ± 0.05 (0.70 to 0.92) in the no AKI, transient AKI, and persistent AKI groups, respectively. The maximum level of RRI was significantly correlated with that of SCr during the first 48 hours postoperatively (rho = 0.606; p < 0.001). RRI could predict persistent AKI with an area under the receiver-operating characteristic curve of 0.918 (95% confidence interval, 0.850 to 0.986; p < 0.001). A postoperative RRI of 0.725 or higher was a marker for early detection of persistent AKI with high sensitivity and specificity (94.7% and 72.1%, respectively). CONCLUSIONS: An elevated maximum RRI may be a predictor of persistent AKI after repair of acute TAAD. This is helpful for management decision making and improving the prognosis of patients with AKI.

Test-Retest Reliability of Measuring the Vertebral Arterial Blood Flow Velocity in People With Cervicogenic Dizziness.

OBJECTIVES: The purpose of this study was to determine the within-session and between-sessions reliability of measuring the vertebral artery blood flow velocities in people with cervicogenic dizziness using Doppler ultrasound at both upper and lower cervical levels. METHODS: Outcome measures were taken on 2 occasions 3 weeks apart with no active treatment provided in between the assessments on 12 participants. Pulsed-wave Doppler ultrasound was used to quantify time-averaged mean velocities through the vertebral artery at upper cervical (C0-1) and lower cervical vertebrae (C5-6). The clinical outcome measures were also recorded in people with cervicogenic dizziness. The intraclass correlation coefficient (ICC) was used to determine the within-session and between-session repeatability. Paired t test was used to determine the differences in the time-averaged mean velocities of blood flow at the same site of the vertebral artery and the clinical outcome measures in 2 sessions 3 weeks apart. RESULTS: In people with cervicogenic dizziness, there was no significant change in both clinical outcome measures and the time-averaged mean velocities when the patients were measured 3 weeks apart (P > .05). This study identified good within-session (ICC: 0.903-0.967) and between-session (ICC: 0.922-0.984) repeatability in measuring the vertical blood flow velocities in patients with cervicogenic dizziness when the clinical outcome measures were unchanged. CONCLUSIONS: This study supports the use of Doppler ultrasound to identify changes in mean vertebral arterial blood flow velocities before and after intervention in people with cervicogenic dizziness in future studies.

Evaluación funcional de la etapa faríngea de la deglución utilizando sonar Doppler. Revisión crítica de la literatura / Functional assessment of pharyngeal phase of swallowing with sonar Doppler. Critic revision of the literature

El sonar Doppler es una herramienta que permite captar lo que sucede durante la etapa faríngea de la deglución, siendo el sonido percibido y observado un reflejo parcial de la actividad motora que se desencadena. El presente trabajo indaga acerca de las posibilidades del sonar Doppler y su aplicación en la evaluación funcional de la deglución. Se desarrolla un diseño de investigación observacional y retrospectivo, bajo la metodología de revisión sistemática a partir de material bibliográfico, investigaciones y publicaciones de artículos de revistas en inglés, portugués y español, consultando las bases de datos PubMed, SciELO, EBSCO Host, Scopus, Springer, Cochrane, además de revistas especializadas en ASHA, MedLine, CEFAC y Redalyc. Aunque la fiabilidad y validez en el uso del sonar Doppler para la evaluación funcional de la etapa faríngea de la deglución no están aseguradas, podría llegar a brindar enorme ayuda en el diagnóstico de las aspiraciones y/o penetraciones durante el proceso deglutorio. Se insiste en una constante revisión de la metodología para la detección correcta de los sonidos de la deglución y su posterior análisis e interpretación clínica (AU)

Sonar Doppler is a tool that can capture what happens during the pharyngeal stage of swallowing, being the sound perceived and the noting a partial reflection of the motor activity that is triggered. This paper focuses on the possibilities of sonar Doppler and its application in functional assessment of swallowing. The design of this research is retrospective and observational, developed under the systematic review methodology, from bibliographical material, pieces of research and publications of journal articles in English, Portuguese and Spanish, taking the databases of PubMed, SciELO, EBSCO Host, Scopus, Springer, Cochrane, besides specialized magazines in ASHA, MedLine, CEFAC and Redalyc. Although the reliability and validity in the use of sonar Doppler for the functional evaluation of the pharyngeal stage of swallowing are uncertain, it could provide enormous help in diagnosing aspirations and/or penetrations during the swallowing process. We insist on a constant review of the methodology for the correct detection of sounds of swallowing and subsequent analysis and clinical interpretation (AU)

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

OBJECTIVE: To investigate whether an elevated preoperative renal resistive index (RRI) predicts acute kidney injury (AKI) in patients undergoing cardiac surgery. DESIGN: Prospective cohort study. SETTING: University hospital. PARTICIPANTS: Cohort of 96 adult cardiac surgical patients. INTERVENTIONS: Resistive index was measurement the day before surgery. MEASUREMENTS AND MAIN RESULTS: Renal Doppler was used to measure the resistive index in renal cortical or arcuate arteries the day before surgery. An elevated RRI was defined as≥0.7. AKI was defined as an absolute increase in postoperative compared with preoperative serum creatinine levels by≥26 µmol/L or a relative increase by≥50% or a postoperative urine output<0.5 mL/kg for 6 hours or longer. The relative risk of AKI in patients with an elevated RRI compared with those without an elevated RRI was analyzed using logistic regression. Among patients with an RRI<0.7, 6 (16%) developed AKI compared with 21 (36%) with an RRI≥0.7. The mean increases in postoperative serum creatinine levels were 12 µmol/L in those with an RRI<0.7 and 30 µmol/L in those with an RRI≥0.7. The crude odds ratio for AKI in patients with an RRI≥0.7 was 3.03 (1.09-8.42) compared with those with an RRI<0.7. After multivariable adjustment, the odds ratio was 2.95 (0.97-9.00). CONCLUSIONS: Patients with an elevated preoperative RRI have an increased risk of developing AKI after cardiac surgery. In combination with other markers, the RRI might be a tool for identifying patients with an increased risk of developing AKI.