Renal Artery Blood Flow Velocity Research Articles

Indole-3-carboxaldehyde alleviates cisplatin-induced acute kidney injury in mice by improving mitochondrial dysfunction via PKA activation

Cisplatin (DDP) is widely used in the treatment of cancer as a chemotherapeutic drug. However, its severe nephrotoxicity limits the extensive application of cisplatin, which is characterized by injury and apoptosis of renal tubular epithelial cells. This study aimed to reveal the protective effect and its underlying mechanism of Indole-3-carboxaldehyde (IC) against DDP-induced AKI in mice and NRK-52E cells pretreated with PKA antagonist (H-89). Here, we reported that IC improved renal artery blood flow velocity and renal function related indicators, attenuated renal pathological changes, which were confirmed by the results of HE staining and PASM staining. Meanwhile, IC inhibited the levels of inflammatory factors, oxidative stress, CTR1, OCT2, and the levels of autophagy and apoptosis. Mitochondrial dysfunction was significantly improved as observed by TEM. To clarify the potential mechanism, NRK-52E cells induced by DDP was used and the results proved that H-89 could blocked the improvement with IC effectively in vitro. Our findings showed that IC has the potential to treat cisplatin-induced AKI, and its role in protecting the kidney was closely related to activating PKA, inhibiting autophagy and apoptosis, improving mitochondrial function, which could provide a theoretical basis for the development of new clinical drugs.

Effect of high-intensity interval exercise on renal artery hemodynamics in healthy young adults.

High-intensity interval exercise is useful for sustained exercise; however, its effect on renal artery hemodynamics is unclear. This study aimed to evaluate changes in renal artery blood flow velocity due to high-intensity interval exercise. Ten healthy adults (age, 23.5±1.2 years) completed high-intensity interval exercise and moderate-intensity continuous exercise protocols on separate days. The high-intensity interval exercise protocol (total duration, 26 min) comprised eight sets of high-intensity exercise sessions at 85% maximum oxygen uptake for 1 min, with intervals of 40% maximum oxygen uptake for 2 min between sets. The moderate-intensity continuous exercise protocol comprised 40 min of exercise at 40% maximum oxygen uptake. Renal artery blood flow velocity and natural log-transformed high frequency spectral power (an index of cardiac parasympathetic nervous system activity) were measured before and after exercise. Additionally, exercise enjoyment was measured using a questionnaire. Renal artery blood flow velocity did not significantly differ between protocols or timepoints for either protocol. However, the natural log-transformed high frequency spectral power was significantly lower with high-intensity interval exercise than with moderate-intensity continuous exercise (P<0.001, F=25.97) during exercise and at 10 min after exercise, and it did not return to pre-exercise levels with high-intensity interval exercise. Moreover, there was no significant difference in exercise enjoyment between the two protocols. In healthy young adults, high-intensity interval exercise reduces parasympathetic activity; however, it does not produce any significant changes in renal artery hemodynamics after exercise.

Wavelet Coherence as a Tool for Visualizing the Relationship between Glomerular Filtration Rate and Renal Artery Blood Flow Velocity

Wavelet Coherence as a Tool for Visualizing the Relationship between Glomerular Filtration Rate and Renal Artery Blood Flow Velocity

Effects of intravenous bolus injection of nicorandil on renal artery flow velocity assessed by color Doppler ultrasound

BackgroundPrevious animal studies have shown that a potassium channel opener, nicorandil, provokes vasodilation in renal microvasculature and increases renal blood flow. We conducted a clinical study that aimed to evaluate the effect of nicorandil on renal artery blood flow in comparison with nitroglycerin by using color Doppler ultrasound. MethodsThe present study enrolled 40 patients with stable coronary artery disease who had no renal arterial stenosis and renal parenchymal disease. The patients received intravenous administration of nicorandil (n=20) or nitroglycerin (n=20). Before and after the administration, renal artery blood flow velocity was measured by color-guided pulsed-wave Doppler. ResultsThe peak-systolic, end-diastolic, and mean renal artery blood flow velocities before the administration were not different between the nicorandil group and the nitroglycerin group. The peak-systolic (79±15cm/s to 99±21cm/s, p<0.001; and 78±19cm/s to 85±19cm/s, p=0.004), end-diastolic (22±5cm/s to 28±8cm/s, p<0.001; and 24±6cm/s to 26±6cm/s, p=0.005) and mean (41±6cm/s to 49±9cm/s, p<0.001; and 43±9cm/s to 45±9cm/s, p=0.009) renal artery flow velocities increased significantly in either group. The nominal changes in the peak-systolic (20±10cm/s vs. 7±8cm/s, p<0.001), end-diastolic (5±4cm/s vs. 2±3cm/s, p=0.001), and mean (8±5cm/s vs. 2±2cm/s, p<0.001) renal artery blood flow velocities were significantly greater in the nicorandil group compared with the nitroglycerin group. ConclusionIntravenous nicorandil increased renal artery blood flow velocity in comparison with nitroglycerin. Nicorandil has a significant effect on renal hemodynamics.

Abstract 073: Expression of Axl in Innate Immune Cells Contributes to Kidney Dysfunction and Onset of Hypertension

Introduction: We previously reported that expression of the receptor tyrosine kinase Axl in hematopoietic cells is critical for kidney dysfunction in early hypertension. Here we investigated the role of Axl expression in innate immune cells in deoxycorticosterone acetate (DOCA)-salt induced hypertension. Methods and Results: RAG1-/- mice lack adaptive immune cells and displayed the same (~25 mmHg) increase in systolic blood pressure (BP) as C57BL/6J mice after 1 week of DOCA-salt. While in metabolic cages RAG1-/- drank more (14.3±0.9 mL) than C57BL/6J mice (10.6±2.5 mL) per day after 1 week of DOCA-salt. Ultrasound imaging confirmed that RAG1-/- had ~20 % larger kidneys vs. C57BL/6J mice after DOCA-salt. RAG1-/- kidneys accumulated 2 times more fluid (2.8±0.1 %) compared to C57BL/6J mice (1.4±0.5 %) after DOCA-salt. Flow cytometry on kidneys from RAG1-/- confirmed absence of T and B lymphocytes, while DOCA-salt increased presence of macrophages (1.1±0.3 x10 9 ) compared to C57BL/6J mice (0.6±0.1 x10 9 ). We successfully generated Axl/RAG1 double knockout mice and subjected the littermates to 1 week of DOCA-salt. Increases in systolic BP were the same in Axl/RAG1+/+ and Axl/RAG1-/- littermate mice. No differences were found in kidney volumes between the Axl/RAG1 genotypes as well. However, 24 hrs excretion volumes increased in Axl/RAG1-/- (50±6 %) compared to Axl/RAG1+/+ (31±6 %) littermates. Finally, renal artery blood flow velocity (611±52 mm/s) and resistive index (0.62±0.03) were reduced in Axl/RAG1+/+ but not in Axl/RAG1-/- mice (665±45 mm/s and 0.68±0.01, respectively) when compared to their controls. Conclusions: Our findings suggest that mice lacking lymphocytes compensate by increasing kidney macrophages that contribute to initial increase in BP. Depletion of Axl in innate immune cells partially reverses kidney dysfunction by improving renal artery function in early hypertension.

A Randomized, Controlled, Double-Blind Crossover Study on the Effects of 1-L Infusions of 6% Hydroxyethyl Starch Suspended in 0.9% Saline (Voluven) and a Balanced Solution (Plasma Volume Redibag) on Blood Volume, Renal Blood Flow Velocity, and Renal Cortical Tissue Perfusion in Healthy Volunteers

We compared the effects of intravenous administration of 6% hydroxyethyl starch (maize-derived) in 0.9% saline (Voluven; Fresenius Kabi, Runcorn, United Kingdom) and a "balanced" preparation of 6% hydroxyethyl starch (potato-derived) [Plasma Volume Redibag (PVR); Baxter Healthcare, Thetford, United Kingdom] on renal blood flow velocity and renal cortical tissue perfusion in humans using magnetic resonance imaging. Hyperchloremia resulting from 0.9% saline infusion may adversely affect renal hemodynamics when compared with balanced crystalloids. This phenomenon has not been studied with colloids. Twelve healthy adult male subjects received 1-L intravenous infusions of Voluven or PVR over 30 minutes in a randomized, double-blind manner, with crossover studies 7 to 10 days later. Magnetic resonance imaging proceeded for 60 minutes after commencement of infusion to measure renal artery blood flow velocity and renal cortical perfusion. Blood was sampled, and weight was recorded at 0, 30, 60, 120, 180, and 240 minutes. Mean peak serum chloride concentrations were 108 and 106 mmol/L, respectively, after Voluven and PVR infusion (P = 0.032). Changes in blood volume (P = 0.867), strong ion difference (P = 0.219), and mean renal artery flow velocity (P = 0.319) were similar. However, there was a significant increase in mean renal cortical tissue perfusion after PVR when compared with Voluven (P = 0.033). There was no difference in urinary neutrophil gelatinase-associated liopcalin to creatinine ratios after the infusion (P = 0.164). There was no difference in the blood volume-expanding properties of the 2 preparations of 6% hydroxyethyl starch. The balanced starch produced an increase in renal cortical tissue perfusion, a phenomenon not seen with starch in 0.9% saline.

Gender Differences In Renal Blood Flow In Response To Endothelin-1 In a Mouse Model Of Sickle Cell Disease

There is increasing evidence that Endothelin-1 (ET-1) plays a significant role in the pathogenesis of complications of sickle cell disease (SCD. SCD patients have elevated levels of endothelin-1 both in plasma and urine and ET-1 has been implicated in SCN, pain modulation, vaso-occlusive episodes, and acute chest syndrome. In the kidney, ET-1 is a potent vasoconstrictor, anti-natriuretic, and hypertrophic factor when signaling through the ETA receptor. ET-1 is released in response to shear stress, hypoxia, thrombin activation, and inflammatory cytokines, all of which are prevalent in SCD. Gender differences exist in other disease models, in which ET-1 plays a contributory pathophysiological role, with males typically exhibiting increased ET-1 mRNA expression, exaggerated ETA-mediated effects, and higher levels of renal injury. Little research exists highlighting the differences between males and females in SCD. It has been observed that the level of Hb F, a major modifier of disease severity in SCD, is higher in females compared to males. In addition, one study examined responses to chronic transfusion therapy, finding males to have increased vascular resistance and resulting decrease in oxygen delivery in response to transfusion when compared to females. We hypothesized that male SCD mice have enhanced ETA mediated responses to ET-1, ultimately leading to renal injury. To test this, we used male and female ‘HbS only' knock in SCD mice to measure renal artery blood flow velocity (BFV) via laser Doppler flowmetry in response to an ET-1 bolus (1nm/kg in 100uL saline). Male mice had an exaggerated decrease in BFV relative to females at 1, 5, and 10 minutes post ET-1 infusion while renal artery diameter remained unchanged throughout the experiment (84.4±5.8 vs. 56±5.7% of BFV baseline at 10 minutes, p<0.05, n=6). A follow up experiment was performed to determine ET-1, ETA receptor, and ETB receptor mRNA expression in the cortex of male and female SCD mice via qPCR. Males and females surprisingly exhibited no significant difference in these parameters although there was a strong trend suggesting females have increased levels of ET-1 mRNA expression compared to males (1.62±0.51 fold increase vs. males, p=0.056, n=5-6). While the exaggerated sensitivity to an ET-1 bolus is partially explained by the relative decrease in ET-1 mRNA expression in males, we nevertheless expected to see differences in ETA/ETB receptor expression. However, receptor-ligand binding could perhaps offer an alternate explanation for this phenomenon. Sex hormones are heavily implicated in other sex differences studies and the potential protective role of estrogen and/or detrimental role for testosterone are both viable explanations for the dichotomy seen in SCD. These data demonstrate a novel sexual dimorphism for SCD, revealing new insights into sex-specific pathophysiology that could have broad effects on treatment strategies in sickle cell nephropathy. Disclosures:No relevant conflicts of interest to declare.

A Randomized, Controlled, Double-Blind Crossover Study on the Effects of 2-L Infusions of 0.9% Saline and Plasma-Lyte® 148 on Renal Blood Flow Velocity and Renal Cortical Tissue Perfusion in Healthy Volunteers

We compared the effects of intravenous infusions of 0.9% saline ([Cl] 154 mmol/L) and Plasma-Lyte 148 ([Cl] 98 mmol/L, Baxter Healthcare) on renal blood flow velocity and perfusion in humans using magnetic resonance imaging (MRI). Animal experiments suggest that hyperchloremia resulting from 0.9% saline infusion may affect renal hemodynamics adversely, a phenomenon not studied in humans. Twelve healthy adult male subjects received 2-L intravenous infusions over 1 hour of 0.9% saline or Plasma-Lyte 148 in a randomized, double-blind manner. Crossover studies were performed 7 to 10 days apart. MRI scanning proceeded for 90 minutes after commencement of infusion to measure renal artery blood flow velocity and renal cortical perfusion. Blood was sampled and weight recorded hourly for 4 hours. Sustained hyperchloremia was seen with saline but not with Plasma-Lyte 148 (P < 0.0001), and fall in strong ion difference was greater with the former (P = 0.025). Blood volume changes were identical (P = 0.867), but there was greater expansion of the extravascular fluid volume after saline (P = 0.029). There was a significant reduction in mean renal artery flow velocity (P = 0.045) and renal cortical tissue perfusion (P = 0.008) from baseline after saline, but not after Plasma-Lyte 148. There was no difference in concentrations of urinary neutrophil gelatinase-associated lipocalin after the 2 infusions (P = 0.917). This is the first human study to demonstrate that intravenous infusion of 0.9% saline results in reductions in renal blood flow velocity and renal cortical tissue perfusion. This has implications for intravenous fluid therapy in perioperative and critically ill patients. NCT01087853.

P93Comparison of renal artery blood flow velocity waveform and renal volume in normal and growth‐retarded fetuses

ObjectiveThe purposes of this study are to evaluate renal artery blood flow velocity waveform and renal volume in growth‐retarded fetuses compared with normal fetuses.MethodDoppler flow velocity waveform of renal artery and renal volume measured by three‐dimensional ultrasonography were obtained in 78 normal fetuses at gestational age from 25 to 39 weeks and 18 cases of IUGR fetuses weighted below the tenth percentile at birth.Results;Fetal renal artery pulsatility index (PI) decreased throughout the gestational period (r = 0.703, p 0.0001). In growth‐retarded fetuses, although all of them had abnormal Doppler velocity waveform of middle cerebral artery, renal pi was not increased significantly. Fetal renal volume increased throughout the gestational period (r = 0.834, p 0.0001). and in growth‐retarded fetuses, renal volume of all was below the fifth percentile of normal fetuses.ConclusionFetal renal volume measured by three‐dimensional ultrasonography may be the helpful parameter in the evaluation of growth‐retarded fetus.

Postnatal change of renal artery blood flow velocity and its relationship with urine volume in very low birth weight infants during the first month of life.

Although the renal artery blood flow velocity has been investigated recently using the ultrasound Doppler method, little is known about the longitudinal change of renal artery blood flow velocity and its relationship with urine volume in very low birth weight infant. Thus, we measured renal artery blood flow velocities by means of the pulse Doppler method in 28 very low birth weight infants. Maximum, minimum, and mean blood flow velocities were determined at postnatal days 0, 1, 2, 3, 4, 5, 6, 13, 20, and 27. The resistance index was also calculated. The maximum and mean blood flow velocities increased gradually after birth, and were significantly higher at 13, 20, and 27 days after birth. The minimum blood flow velocity and the resistance index were relatively constant during the study period. The mean blood flow velocities were also analyzed for any correlation with urine volume. There was a poor correlation between urine volume (ml/kg/day) and mean blood flow velocity (cm/s) (Y = 2.38X + 57.4, Y: urine volume, X: mean blood flow velocity, n = 161, r = 0.338, P < 0.01). However, if the mean renal artery blood flow velocity was less than 10 cm/s, oliguria was observed in most cases. The measurement of the renal artery blood flow velocities appears to be useful in understanding the background condition of renal function in very low birth weight infants.

Renal Blood Flow Velocity in Preterm and Term Neonates during the Fourth Day of Life: Changes in Relation to Gestational Age and Birth Weight

Measurements of renal artery blood flow velocity have been previously reported during prenatal life and during the first month of life in neonates. Since renal flow velocity increases during the first 3 days of postnatal age we determined, during the fourth day of life, the changes of renal blood flow velocity in relation to gestational age and birth weight in 109 healthy preterm and term infants with gestational age between 26 and 42 weeks and birth weight between 750 and 3,730 g. Renal arteries were insonated about 3 mm from the abdominal aorta, by placement of a microconvex 7-MHz transducer below the costal margin in the dorsolateral area of the right or left flank. Mean flow velocity significantly increased with advancing of gestational age and birth weight. This study provides normative data for renal artery blood flow velocity in healthy preterm and term infants during the fourth day of life.

Cerebral and renal artery blood flow velocity before and after birth.

To document perinatal changes in cerebral and renal artery haemodynamics in premature growth-retarded and normal term infants. Longitudinal study of individual infants. Doppler ultrasound measurements of blood flow velocity (BFV) in the middle cerebral and renal arteries were obtained before delivery, soon after delivery and during the first week of postnatal life. Teaching hospital obstetric and neonatal units. 13 severely growth retarded infants born at 28-36 weeks gestation, and eight normally grown infants born at term. In both groups, BFV in the cerebral artery was significantly lower in the first few hours after birth than in fetal life, but subsequently increased to reach pre-delivery values by the end of the first week. In contrast, BFV in the renal artery during the first postnatal day was not significantly different from fetal values, but it also increased during the subsequent week. In six of the preterm growth-retarded infants, fetal blood gases were measured in samples obtained by cordocentesis, and in these cases an increase in blood oxygen content at birth was documented. Cerebral artery BFV falls at birth and is relatively low during the time that premature infants are at the greatest risk of developing periventricular haemorrhage.

Developmental changes in renal artery blood flow velocity during the first three weeks of life in preterm neonates

Changes in color Doppler imaging measurements of renal artery blood flow velocity have been reported previously during fetal life and during the first week postnatally in term and preterm infants. This study reports longitudinal, developmental changes in renal artery and aortic blood flow velocities occurring postnatally, from birth to day 1 of life, at 1 week, and at 2 to 3 weeks of age in 14 premature babies (mean gestation, 30 ± 4 [SD] weeks; birth weight, 1.45 ± 0.57 kg), and identified by means of color Doppler imaging and pulsed Doppler spectral analysis. Results indicate that a significant increase in renal artery systolic blood flow velocity occurs within the first week of life (from 40 ± 3 [SEM] cm/sec at birth or on day 1, to 53 ± 3 cm/sec on day 7, to 51 ± 4 cm/sec on day 14 to 21; repeated-measures analysis of variance, p = 0.004), concurrently with a significant increase in abdominal aortic blood flow velocities, both systolic (from 40 ± 4 at birth or on day 1, to 70 ± 8 on day 7, to 76 ± 8 cm/sec on day 14 to 21; p <0.001) and diastolic (from 4 ± 2 at birth or on day 1, to 11 ± 2 on day 7, to 11 ± 2 cm/sec on day 14 to 21; p = 0.001). Systemic blood pressure did not increase concomitantly during the same period. Neither the presence of respiratory distress syndrome or patent ductus arteriosus nor treatment with indomethacin altered developmental increases in observed renal artery blood flow velocities. The presence of an umbilical artery catheter in the high thoracic position in five infants, however, created turbulence at the level of the renal arteries, significantly increasing renal artery systolic flow velocity from 32 ± 4 to 44 ± 5 cm/sec ( p = 0.009) and increasing renal resistive index from 0.90 ± 0.03 to 0.96 ± 0.04 ( p = 0.046). These results suggest that renal artery blood flow velocity increases during the first postnatal week in preterm infants and is likely related to increases in aortic blood flow velocity and reduction in renal vascular resistance. (J P EDIATR 1996;129:251-7)

Cardiovascular and sympathoadrenal responses to heat stress following water deprivation in rats.

This study was designed to characterize the regional and systemic hemodynamic and sympathoadrenal responses to heating after 24 and 48 h of water deprivation in chloralose-anesthetized, male Sprague-Dawley rats (n = 7 per group). Water deprivation produced significant decreases in body weight of 8.1 and 13.7% in the 24- and 48-h groups (P < 0.05), respectively. After water deprivation, rats were exposed to an ambient temperature of 43 degrees C. After correction for body weight differences, heating rates were faster in the 48-h group compared with both euhydrated and 24-h groups. Mean arterial blood pressure (MAP), heart rate, and colonic (Tco) and tail (Ttail) temperatures increased above baseline in all groups during heating. Renal and mesenteric artery blood flow velocities decreased, and vascular resistances increased in response to heating. Compared with euhydrated controls, 48-h water-deprived rats exhibited attenuated pressor (delta MAP = 36 +/- 3 vs. 18 +/- 3 mmHg) and visceral vasoconstrictor (% delta in mesenteric resistance = 122.6 +/- 27.3 vs. 54.9 +/- 6.9%) responses during heating. Tail-skin blood flow estimated from Ttail was also lower at baseline and the onset of heating in water-deprived rats. However, peak Ttail and Tco values were similar across groups. Plasma catecholamines measured in separate groups of rats (n = 6 per group) were significantly higher at baseline and the end of heating in the 48-h group compared with euhydrated and 24-h groups. Despite this exaggerated sympathoadrenal response, the 48-h group exhibited attenuated hemodynamic responses to nonexertional heating compared with euhydrated and 24-h water-deprived rats. These data suggest that cardiovascular and thermoregulatory adjustments can compensate for small changes in hydration state (i.e., 24 h), but more severe levels of hypohydration significantly alter blood pressure and body temperature regulation during heat stress.

Superior mesenteric artery (SMA) and renal artery (RA) blood flow velocity measurements in neonates: Technique and interobservery reliability: F.J. Weir, K. Fong, M.L. Ryan, et al. J Pediatr Radiol 25:145–148, (March), 1995

Superior mesenteric artery (SMA) and renal artery (RA) blood flow velocity measurements in neonates: Technique and interobservery reliability: F.J. Weir, K. Fong, M.L. Ryan, et al. J Pediatr Radiol 25:145–148, (March), 1995

Augmented mesenteric and renal vasoconstriction during exercise in senescent Fischer 344 rats

The purpose of this study was to test the hypothesis that vasoconstriction in the mesenteric and renal circulations is greater at both submaximal and maximal exercise intensities with advancing age. Arterial blood pressure, heart rate, and mesenteric, renal, and iliac (hindlimb) artery blood flow velocities were measured before and during graded treadmill exercise in mature (12 mo) and senescent (24 mo) male Fischer 344 rats. During treadmill running at mild, moderate, and maximal exercise intensities (approximately 45, 70, and 100% of maximal oxygen uptake), the increases in arterial pressure were similar in the mature and senescent animals, whereas heart rate rose less in the older group (P < 0.05). Mesenteric and renal flow velocities declined and vascular resistances increased from resting levels in both groups in response to graded exercise; however, the magnitudes of the increases in both mesenteric and renal vascular resistance were significantly augmented in the older rats at the moderate and maximal workloads. Hindlimb blood flow velocity increased and resistance declined from resting levels at each exercise intensity in both groups. In contrast to the visceral and renal adjustments, the magnitudes of the changes in both hindlimb flow and resistance were similar for the two age groups at all exercise intensities. These findings support the hypothesis that mesenteric and renal vasoconstriction is augmented in senescent Fischer 344 rats during exercise at moderate and maximal intensities but not at mild workloads. Despite these regional differences, the maintenance of arterial pressure is not altered at either submaximal or maximal exercise intensities with advancing age.

Superior mesenteric artery and renal artery blood flow velocity measurements in neonates: technique and interobserver reliability.

The objective of this study was to establish the interobserver reliability for superior mesenteric artery (SMA) and renal artery (RA) Doppler blood flow velocity (BFV) measurements in neonates. Forty-two clinically stable infants were enrolled, mean (SD) gestational age 33 (2) weeks, birthweight 2.00 (0.54) kg, postnatal age 10 (11) days. Doppler recordings were made by two trained observers. The SMA and RA were studied with a 5.0-MHz phased array transducer. The optimal spectral trace from each artery containing a minimum of five consecutive waveforms was analysed. The peak systolic velocity (PS), end diastolic velocity (ED) and mean peak velocity (MV) were measured and the time-averaged mean velocity (TAV) and waveform indices were calculated. Using the intraclass correlation coefficient (ICC) the estimates of interobserver reliability for different measurements varied from 0.40 to 0.83. Substantial agreement was obtained between observers in the TAV, PS, ED and MV; the ICC varied from 0.72 to 0.83 demonstrating that Doppler BFV measurements of the SMA and RA are reliable in neonates.

Renal blood flow velocity in neonates with and without umbilical artery catheters.

We performed an observational prospective cohort study on the applicability of two-dimensional echocardiography with pulsed Doppler technique as a noninvasive modality to serially evaluate renal blood velocities in premature neonates with and without umbilical artery catheters. We also sought to determine the incidence of umbilical artery catheter-related thrombus formation in our neonatal intensive-care unit. We established normative values for renal artery blood flow velocities in premature neonates and postulate that this echo-Doppler technique is valid and can be used to evaluate renal developmental physiology in the neonatal population. In addition, we observed that even in the absence of clinical sequelae due to thrombus formation, the presence of a thrombus in the aorta caused abnormalities in renal hemodynamics.

The effects of postural change and exercise on renal haemodynamics in familial dysautonomia.

Cardiovascular instability is a prominent manifestation of familial dysautonomia [FD] while renal insufficiency occurs in a large number of adult FD patients. To determine if there was a causative relationship, renal artery blood flow velocity using Doppler technology, was recorded and the ratio of the peak systolic velocity (point A) to the end diastolic velocity (point B) was calculated. The A/B ratio was assessed in response to change of position and exercise, and was correlated with renal function, heart rate and systemic blood pressure. Studies were performed in 54 FD patients with a mean age of 24 years +/- 9.8 years, and 20 controls, with a mean age of 24.7 +/- 7.6 years. In the supine position, the mean A/B ratios were not significantly different, but FD subjects had a significantly higher mean blood pressure and heart rate than controls. When erect and post exercise, the mean A/B ratios in FD subjects were significantly higher than controls, p = 0.0004 and p = 0.0001, respectively. In contrast to controls, when FD subjects were standing erect and post exercise, mean blood pressure decreased significantly without a significant change in heart rate. When FD subjects were divided into two groups based on their creatinine clearance value, the group with the lower creatinine clearances had a significantly greater fall in diastolic pressure when they moved from the supine to the erect position. Our results indicate that noninvasive Doppler techniques are helpful in detecting changes in renal blood flow in subjects with familial dysautonomia.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal artery blood flow velocity in very low birthweight infants with intrauterine growth retardation.

Doppler ultrasound was used to measure left renal artery blood flow velocity and pulsatility index on the first, third, and seventh day of postnatal life in 18 very low birthweight small for gestational age (SGA) infants. The values were compared with those from 18 weight matched and 18 gestation matched controls. SGA infants had significantly lower blood flow velocity than their gestation matched controls throughout the first postnatal week (day 1: SGA 10 cm/s, controls 15 cm/s; day 7: SGA 17 cm/s, controls 28 cm/s). These data suggest that abnormalities of renal artery blood flow velocity persist after delivery in the SGA infant.