Evaluation Of Renal Perfusion Research Articles

Shock Resuscitation - the Necessity and Priority of Renal Blood Perfusion Assessment.

Improving organ perfusion is the aim of shock resuscitation; therefore, improving organ blood perfusion is a direct indicator for shock resuscitation. During shock, different organs have different capacities for blood flow autoregulation. The kidney is an important organ with excellent ability to autoregulate the blood flow and with vulnerability to poor organ perfusion, which places kidney perfusion in a position of necessity and priority relative to that of other organs in shock. Critical-care ultrasonography provides the best evaluation of renal perfusion.

Ultrasonic evaluation of systemic and renal perfusion in sepsis patients before and after fluid resuscitation.

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.

AIUM Practice Parameter for the Performance of Duplex Sonography of Native Renal Vessels

AIUM Practice Parameter for the Performance of Duplex Sonography of Native Renal Vessels

Evaluation of Renal Perfusion in Hyperthyroid Cats before and after Radioiodine Treatment

BackgroundHyperthyroidism and chronic kidney disease (CKD) are common in elderly cats. Consequently, both diseases often occur concurrently. Furthermore, renal function is affected by thyroid status. Because changes in renal perfusion play an important role in functional renal changes in hyperthyroid cats, investigation of renal perfusion may provide novel insights.ObjectivesTo evaluate renal perfusion in hyperthyroid cats with contrast‐enhanced ultrasound (CEUS).AnimalsA total of 42 hyperthyroid cats was included and evaluated before and 1 month after radioiodine treatment.MethodsProspective intrasubject clinical trial of contrast‐enhanced ultrasound using a commercial contrast agent (SonoVue) to evaluate renal perfusion. Time‐intensity curves were created, and perfusion parameters were calculated by off‐line software. A linear mixed model was used to examine differences between pre‐ and post‐treatment perfusion parameters.ResultsAn increase in several time‐related perfusion parameters was observed after radioiodine treatment, indicating a decreased blood velocity upon resolution of the hyperthyroid state. Furthermore, a small post‐treatment decrease in peak enhancement was present in the renal medulla, suggesting a lower medullary blood volume.Conclusions and Clinical ImportanceContrast‐enhanced ultrasound indicated a higher cortical and medullary blood velocity and higher medullary blood volume in hyperthyroid cats before radioactive treatment in comparison with 1‐month post‐treatment control.

Contrast enhanced ultrasonography of kidney in conscious and anesthetized beagle dogs.

Contrast enhanced ultrasound (CEUS) is useful to evaluate tissue perfusion in the kidney. In veterinary medicine, sedation or anesthesia may be required in uncooperative or panting patients. The aim of this study was to evaluate and compare the normal kidney perfusion patterns in conscious and anesthetized dogs using CEUS. Eight healthy beagles were used in this study. Scanning was performed in conscious dogs using manual restraint (conscious group), or under general anesthesia using tiletamine-zolazepam and medetomidine (TZM group) or medetomidine (M group). The contrast agent (Sonovue®) was administered as an IV bolus. The peak intensity (PI), time to peak enhancement from injection (TTP0) and the time to peak enhancement from the initial rise (TTPup), upslope, downslope and area under the curve (AUC) were analyzed. Compared to the cortical values in the conscious group, TTP0 was significantly delayed in the TZM group, and upslope, TTP0 and TTPup were significantly different in the M group. The AUCs in the TZM and M groups were not different from those in the conscious group. The upslope of renal medullary perfusion was significantly decreased in the TZM and M groups. TTP0 and TTPup were also significantly delayed in these groups. The AUC of the medulla was significantly decreased in the M group. Therefore, TZM is useful as an anesthetic protocol when performing CEUS, and the obtained data may serve as reference values in the evaluation of renal perfusion using CEUS in dogs under anesthesia.

Lymphatic Leakage in a Renal Transplant: The Role of Lymphoscintigraphy

Lymphatic leak is a common cause of perirenal fluid collection in renal transplant patients in whom early recognition and therapy is essential for the survival of the kidney. Nuclear medicine offers dynamic renal scintigraphy for the evaluation of renal perfusion, function, and recognition of urologic complications. We present a renal transplant recipient in whom renal scintigraphy showed abnormal radiotracer collection adjacent to the bladder, which caused urinary stasis in the renal pelvis. Lymphoscintigraphy, which can be used to identify lymphatic collections, revealed abnormal radiotracer accumulation in the transplant fossa and confirmed that the perirenal fluid collection was the result of a lymphatic leak. We have described a patient with perirenal fluid collection after renal transplantation surgery in whom lymphoscintigraphy was used to confirm the diagnosis.

MR IMAGING OF RENAL FUNCTION

MR imaging has advantages over both computed tomography and nuclear scintigraphy for assessing renal function, because it combines high spatial resolution with information on perfusion and function. A further advantage is the lack of ionizing radiation. Quantitation of flow rate by phase contrast in the renal arteries and veins has the potential to provide estimation of renal blood flow, which could prove useful in a number of clinical situations, especially for studying renal vascular disorders and the effects of treatment, and for assessing renal transplants. Evaluation of renal perfusion with MR imaging has become feasible with the development of rapid data acquisition techniques, which provide adequate temporal resolution to monitor the rapid signal changes during the first passage of the contrast agents in the kidneys. More recently, magnetically labeling water protons in blood flowing into kidneys has been used to noninvasively quantitate regional measurement of cortical and medullary perfusion. Other techniques being investigated with MR imaging for assessment of renal function include diffusion imaging GFR estimation and blood oxygenation level dependent imaging to evaluate intrarenal oxygenation levels.

First-pass evaluation of renal perfusion with TurboFLASH MR imaging and superparamagnetic iron oxide particles.

First-pass intrarenal hemodynamics were studied with superparamagnetic iron oxide particles and a T2-weighted TurboFLASH (fast low-angle shot) magnetic resonance (MR) imaging sequence. Four groups of five rabbits each were imaged after bolus injection of 40, 100, 140, and 200 mumol/kg iron, respectively. Images were acquired every 1.2 seconds, with an acquisition time of 700 msec. The signal intensity was measured in the cortex, outer medulla, inner medulla, and globally. In preliminary pathologic applications, two rabbits were imaged after ligation of the lumbar ureter and two after embolization of the renal artery. The reproducibility of the normal dynamics was evaluated with a cross-correlation test. On the images, the intravascular progression of the iron particles could be visualized within the cortex and the two compartments of the medulla in all cases. The maximal reduction in signal intensity in the cortex and medulla increased with the dose. The relationship between signal intensity decrease and dose was not linear, and the reproducibility of the signal intensity versus time plots was acceptable only at the 140 and 200 mumol/kg doses. The decrease in signal intensity was reduced and delayed in the embolized and hydronephrotic kidneys.

Use of the xenon-133 washout technique in diagnosing renovascular disease in hypertension.

In this paper several aspects of the evaluation of renal perfusion by means of the xenon-133 washout technique are reviewed. Although the method requires arterial catheterization, and is difficult to carry out in the face of far-advanced renal artery stenosis, in many patients it may provide useful information on the intrarenal hemodynamic pattern. In patients with renal artery stenosis the percentage of total flow perfusing the rapid compartment (= outer cortex) is maintained, but absolute flow in that compartment is reduced to a variable degree. It is suggested that this reflects recruitment of fast-flow nephrons in response to a fall in perfusion pressure.

Parameters of 99mTc-DTPA transfer function in renal artery stenosis.

A new method is presented for decomposition of 99mTc-DTPA renal transfer functions (TF) into their capillary and tubular parts. Amplitudes and mean transit times of both parts were calculated and used for quantitative evaluation of renal perfusion, extraction and transport in 21 patients with renal artery stenosis. The amplitudes showed a positive correlation to the effective renal plasma flow and a negative correlation to the grade of stenosis. The parameters of TF are independent of the contralateral kidney, so they can be used for screening for renovascular disease as well as for pre- and postoperative evaluation of kidneys even in cases of bilateral disease.