血液透析中自体动静脉内瘘流量的连续监测

目的检测血液透析过程中不同时间点内瘘流量的变化及患者血流动力学变化对其的影响,以探讨超声稀释法检测内瘘流量的合适时机。方法使用Transonic HD02型血液透析监测仪对49例应用自体动静脉内瘘的维持性血液透析患者在透析过程中30min、90min、150min及210min时内瘘流量(Qa)、心输出量(CO)、心脏指数(CI)等参数进行监测,观察Qa的变化趋势及血流动力学参数在不同时间点对Qa的影响。结果4个时间点测得的Qa和平均动脉压(MAP)校正后的内瘘流量(Qa’)无明显差别。Qa与MAP呈正相关,且透析过程中Qa的变化与MAP的变化呈正相关。各时间点的MAP均为该点Qa的独立影响因素。透析210min时超滤量大于干体重5%的患者Qa的变化显著大于超滤量小于干体重5%的患者。结论血液透析过程中的各个时段均可进行内瘘流量的检测,但是存在MAP显著下降时不宜进行Qa检测。此外,超滤量超过干体重5%的患者,不建议在透析150min后测定其内瘘流量。     

GPT法和超声稀释法在动静脉内瘘流量监测中的应用和比较

目的观察和比较GPT法（glucose pump test）、超声稀释法在监测动静脉内瘘流量中的应用。方法选择第二军医大学附属长征医院肾内科,全军肾脏病研究所透析中心长期维持性透析的39例患者,上机前用GPT法测定内瘘流量,正常上机后0.5h后用HD02型血液透析监测仪测定内瘘流量,对GPT法、超声稀释法测得流量〈500ml/min的患者2周内行内瘘彩超检查。结果2例患者GPT法、超声稀释法均未能测出流量,4例患者GPT法前后血糖变化轻微无法计算流量。33例患者数据纳入分析,GPT法测定的内瘘流量均值高于超声稀释法,且具有统计学差异,两种方法测得内瘘流量存在直线相关。对GPT法、超声稀释法流量〈500ml6例患者行内瘘彩超检查,动静脉内瘘均有吻合口狭窄或近吻合口静脉段狭窄。结论两种方法测定动静脉内瘘流量在临床均是可行的,能预先发现存在的血管通路狭窄。     

Accuracy of Volumetric Flow Rate Measurements

Objective. Volumetric flow measurement with Doppler ultrasound is useful in assessing blood flow as part of an evaluation of arteriovenous fistula maturity in patients undergoing hemodialysis. In this study, we assessed both accuracy and variability in volumetric flow measurements obtained using modern and commercially available ultrasound systems and an in vitro experimental setup. Methods. Volumetric flow measurements using duplex ultrasound were obtained by 3 users operating 5 different systems for randomized flow in the range of 100 to 1000 mL/min. Users performed 3 consecutive measurements at a given flow rate. Data were analyzed using statistical techniques to assess measurement accuracy and variability. Results. Over the span of flow rates studied, the root mean square error (RMSE) for the 5 ultrasound systems ranged from 38.8 to 79.7, 36.8 to 52.0, 73.0 to 85.3, 26.7 to 44.6, and 43.9 to 93.5 mL/min. Corresponding average RMSE values were 60.3, 42.7, 81.1, 37.2, and 64.4 mL/min, respectively. A linear regression analysis of mean interobserver measurements revealed an excellent correlation for all ultrasound systems (r² > 99.1%). Assessment of intraobserver measurements revealed no statistically significant differences for any ultrasound system evaluated (P > .94). Comparison of interobserver measurements indicates no statistically significant differences between any of the 5 systems (P > .14). Conclusions. Modern ultrasound systems are reasonably accurate in blood flow measurement in an experimental setup mimicking clinically relevant blood flow ranges in a hemodialysis fistula. Users need adequate training and experience to perform multiple measurements and use appropriate techniques to minimize errors in flow measurement.     

超声引导PTA在动静脉内瘘狭窄中的应用研究

目的:探究分析超声引导下经皮穿刺腔内血管成型术(PTA)在动静脉内瘘狭窄治疗中的应用效果。方法:选择2017年9月-2019年9月在我院进行超声引导下经皮穿刺腔内血管成型术治疗的78例动静脉内瘘狭窄患者为研究对象,记录技术成功率、临床治疗成功率,并比较治疗前后狭窄处内径、内瘘自然流量以及透析血流量。结果:101例次在超声引导下进行PTA治疗的技术成功率达到97.03%,临床成功率93.07%,且治疗后患者的狭窄处内径、内瘘自然流量以及透析血流量平均值均显著大于术前治疗(P<0.05)。术后有3例局部出现肿胀,经弹力绑带加压包扎后症状消失。结论:超声引导下进行经皮穿刺腔内血管成型术具有操作简单、无辐射、治疗成功率高、并发症少等优点,将其应用于动静脉内瘘狭窄治疗中能够直观观察到动静内瘘血管血流及管腔变化情况,并实时察看导丝、球囊的行进情况,临床应用价值高。     

B-Flow技术在尿毒症患者人工造瘘血管监测的应用价值

目的 探讨二维血流显示（B-Flow)技术在肾衰血透患者动静脉瘘中的应用价值。方法 本文对31例尿毒症患者人工动静脉瘘进行超声检查,分别采用CDFI、PDI和B-Flow三种模式显示瘘口和动静脉侧血管情况,郑重观察吻口和动静脉侧血管形态、管壁情况以及管腔内血流显示情况。并进行血流动力学检测。结果 本组病例共３例检查对象,端端吻合２例,人造血管吻合３例,吻合口平均内径５mim。吻合口狭窄６例、血栓形成４例。Ｂ－Ｆlow技术能同时清晰显示血流和邻近背景组织。与ＣＤＦＩ、ＰＤＩ结合使用可提高异常图像显示率。Ｂ－Ｆlow与ＣＤＦＩ、ＰＤＩ比较,具有更高帧频、高分辨力和全景显示功能。结论 B-Flow技术是监测血透患者治疗过程中造瘘血管善的有效的辅助检测手段之一。动静脉瘘主要并发症是吻合口狭窄、静脉段瘤样扩张和血栓形成。     

超声在自体动静脉内瘘成熟障碍中的应用进展

随着终末期肾病(ESRD)发病率的增加,血液透析的需求日益增长。然而ESRD患者常合并其他血管性病变及慢性疾病,患者血管条件差,易致负责液体补给的自体动静脉内瘘(AVF)手术失败,降低术后AVF成熟率,因此术前评估、监测、诊断并治疗AVF成熟障碍对ESRD患者至关重要。本文就超声在AVF成熟障碍中的应用进展进行综述。     

二维血流显像在尿毒症造瘘血管监测的应用价值

目的 探讨二维血流显像（B-Flow)技术在肾衰血透患者动静脉瘘中的应用价值。方法 对31例尿毒症患者人工动静脉瘘分别采用彩色多普勒血流图（CDFI）、血流功率图（PDI）和B-Flow三种模式显示瘘口和动静脉侧血管情况,郑重观察吻合和动静脉侧血管形态、管壁情况以及管腔内血流显示情况,并进行血流动力学检测。结果 本组31例检查对象,端端吻合23例,端侧吻合3例,侧侧吻合2例,人造血管吻合3例,吻合口平均内径5mm。吻合口狭窄6例,血栓形成4例,B-Folw技术能同时清晰显示血流和邻近背景组织,与CDFI、PDI结合使用可提高异常图像显示率,B-Flow与CDFI、PDI比较,具有更高帧频、高分辨力和全景显示功能。结论 B-Folw技术是监测血透患者治疗过程中造瘘血管状况的有效检测手段之一。动静脉瘘主要并发症是吻合口狭窄、静脉段瘤样扩张和形成血栓。     

超声诊断外周血管动静脉瘘的价值

目的探讨超声诊断外周血管动静脉瘘的价值.方法回顾性分析9例经临床证实的动静脉瘘患者二维超声、彩色多普勒超声、灰阶血流成像对动静脉瘘及周围组织显示情况.结果 9例患者超声对瘘口均正确诊断,表现为瘘口处高速湍流、瘘口近端动脉血流为低阻型、远端为高阻型、静脉内血流动脉化;二维超声、彩色多普勒超声结合灰阶血流成像更清晰显示动静脉瘘.结论超声对外周血管动静脉瘘有较高的诊断价值.     

Real-time texture analysis for identifying optimum microbubble concentration in 2-D ultrasonic particle image velocimetry

Many recent studies on ultrasonic particle image velocimetry (Echo PIV) showed that the accuracy of two-dimensional (2-D) flow velocity measured depends largely on the concentration of ultrasound contrast agents (UCAs) during imaging. This article presents a texture-based method for identifying the optimum microbubble concentration for Echo PIV measurements in real-time. The texture features, standard deviation of gray level, and contrast, energy and homogeneity of gray level co-occurrence matrix were extracted from ultrasound contrast images of rotational and pulsatile flow (10 MHz) in vitro and in vivo mouse common carotid arterial flow (40 MHz) with UCAs at various concentrations. The results showed that, at concentration of 0.8∼2 × 10³ bubbles/mL in vitro and 1∼5 × 10⁵ bubbles/mL in vivo, image texture features had a peak value or trough value, and velocity vectors with high accuracy can be obtained. Otherwise, poor quality velocity vectors were obtained. When the texture features were used as a feature set, the accuracy of K-nearest neighbor classifier can reach 86.4% in vitro and 87.5% in vivo, respectively. The texture-based method is shown to be able to quickly identify the optimum microbubble concentration and improve the accuracy for Echo PIV imaging.     

Hemodynamic changes in the early phase of artificially created arteriovenous fistula: color Doppler ultrasonographic findings.

The objective of this study was to evaluate hemodynamic variables in arteriovenous fistulas by color Doppler ultrasonography. This study involved 28 patients with chronic renal failure who were sent to surgery clinic for creation of an arteriovenous fistula of the Brescia-Cimino type. Patients were evaluated preoperatively and on the first and seventh days postoperatively by a color Doppler ultrasound machine with a 7.5 MHz linear probe. The distal radial artery was examined preoperatively and the fistula itself postoperatively. Changes in the fistula size and the velocity, volume, and resistive index of the distal radial artery were recorded. Postoperatively the radial artery diameter, systolic flow rates, and volume flow had increased significantly, especially on the first day, in comparison to preoperative values. Resistive index values has decreased significantly at both the first and the seventh days postoperatively. Color Doppler ultrasonography is a very effective method in the evaluation of hemodynamics of arteriovenous fistulas in hemodialysis patients. It will allow an understanding of the pathology in nonfunctioning fistulas or of the cause of complications that develop secondarily.     

Novel Flow Quantification of the Carotid Bulb and the Common Carotid Artery with Vector Flow Ultrasound

Abnormal blood flow is usually assessed using spectral Doppler estimation of the peak systolic velocity. The technique, however, only estimates the axial velocity component, and therefore the complexity of blood flow remains hidden in conventional ultrasound examinations. With the vector ultrasound technique transverse oscillation the blood velocities of both the axial and the transverse directions are obtained and the complexity of blood flow can be visualized. The aim of the study was to determine the technical performance and interpretation of vector concentration as a tool for estimation of flow complexity. A secondary aim was to establish accuracy parameters to detect flow changes/patterns in the common carotid artery (CCA) and the carotid bulb (CB). The right carotid bifurcation including the CCA and CB of eight healthy volunteers were scanned in a longitudinal plane with vector flow ultrasound (US) using a commercial vector flow ultrasound scanner (ProFocus, BK Medical, Denmark) with a linear 5 MHz transducer transverse oscillation vector flow software. CCA and CB areas were marked in one cardiac cycle from each volunteer. The complex flow was assessed by medical expert evaluation and by vector concentration calculation. A vortex with complex flow was found in all carotid bulbs, whereas the CCA had mainly laminar flow. The medical experts evaluated the flow to be mainly laminar in the CCA (0.82 ± 0.14) and mainly complex (0.23 ± 0.22) in the CB. Likewise, the estimated vector concentrations in CCA (0.96 ± 0.16) indicated mainly laminar flow and in CB (0.83 ± 0.07) indicated mainly turbulence. Both methods were thus able to clearly distinguish the flow patterns of CCA and CB in systole. Vector concentration from angle-independent vector velocity estimates is a quantitative index, which is simple to calculate and can differentiate between laminar and complex flow.     

Cephalic vein and hemodialysis fistula: surgeon's observation versus color Doppler ultrasonographic findings.

The aim of this study was to evaluate whether preoperative color Doppler ultrasonography improves immediate success rates of arteriovenous fistulas for dialysis. One hundred twenty-four patients with chronic renal failure underwent color Doppler ultrasonographic examination of both arms, including the cephalic vein, before arteriovenous fistula construction. Patients were randomly divided into 2 groups: A and B. In group A, there were 52 patients, and the surgeon planned to construct arteriovenous fistulas depending only on physical examination. In group B, which comprised 72 patients, surgeons performed arteriovenous fistula construction on sites labeled by color Doppler ultrasonography. In group A, of 52 patients who had surgery for arteriovenous fistula construction, 13 had fistulas that did not function. Among these 13 patients, 8 were found to have chronic thrombotic changes in the cephalic vein on color Doppler ultrasonography, and 5 had none of these changes. When we checked the color Doppler ultrasonographic findings, we noted that these 5 patients had decreased volume flow in the radial artery. On the whole, the arteriovenous fistulas worked in 39 patients (75%) and did not function in 13 patients (25%). In group B, surgeons followed the color Doppler ultrasonographic results. Of 72 patients who underwent the procedure, 68 patients (94.4%) had functioning fistulas, whereas 4 (5.6%) had fistulas that did not work. These 4 patients were found to have low volume flow in the radial artery. When both groups were compared by chi2 analysis, the difference was statistically significant (P = .002). Group B, in which patients were preoperatively evaluated by color Doppler ultrasonography, had a high success rate. We found that color Doppler ultrasonography is very helpful as a noninvasive procedure for this evaluation. Although many surgical clinics still perform arteriovenous fistula construction without the aid of color Doppler ultrasonographic findings, we think that the use of color Doppler ultrasonography should be emphasized before surgeons proceed with arteriovenous fistula construction.     

Flow Quantification with Nakagami Parametric Imaging for Suppressing Contrast Microbubbles Attenuation

Flow quantification with contrast-enhanced ultrasound is still limited by the effects of contrast microbubble attenuation. Nakagami parametric imaging (NPI) based on the m parameter, which is related to the statistical property of echo envelope, is implemented to suppress contrast attenuation. Flow velocity (FV) and volumetric flow rate (VFR) are estimated through the least square fitting of burst depletion kinetic model to time m parameter curves (TMCs). A non-recirculating flow phantom is imaged as contrast microbubbles are infused at 10, 15, 20, 25, and 30 mL/min. Contrast microbubbles with two different concentrations are used to generate variations of contrast microbubble attenuation. The results suggest that 4 × 4 mm² is the optimal size of a sliding window of NPI for flow quantification under current experiment condition. At a lower microbubble concentration, the FV calculated from TMCs correlates strongly with actual FV in both unattenuated (R² = 0.97; p < 0.01) and attenuated regions (R² = 0.92; p < 0.01) within phantom. And there is a strong correlation (R² = 0.98; p < 0.01; slope = 0.96; intercept = 0.68) between VFR calculated from TMCs and actual VFR within the whole phantom. Similar results are obtained at higher microbubble concentrations. Compared with conventional ultrasound imaging that is intensity dependent, NPI achieves better performance on flow quantification in the presence of contrast microbubble attenuation.     

在线监测血液透析过程中血流速对心功能的影响

目的 通过在线监测心脏相关指数及外周血管阻力,了解血液透析过程中提高泵控血流速 (Blood flow rate,BFR)对心脏功能的影响.方法 选择北京协和医学院肾内科采用自体动静脉内瘘,且内瘘流量＞600ml/min的规律血液透析患者34例,男性21例,女性13例,平均年龄为(55.06±13.20)岁(22～75岁).于透析开始后30～60min内,应用超声稀释技术监测BFR 200ml/min、250ml/min及300ml/min)对心输出量(Cardiac output,CO)、心脏指数(cardiac index,CI)、中心血容量(central blood volume,CBV)、中心血容量指数(central blood volume Index,CBVI)、外周阻力(peripheral resistance,PR)等参数的影响.结果 采用one-way ANOVA方差分析及配对t检验,BFR 200ml/min、250ml/min、300ml/min各流速时,患者CO、CI、CBV、PR、CBVI、系统心搏量指数及心搏出量均无明显统计学差异.结论 透析机泵控BFR 200～300ml/min范围内增加血流速对血液透析过程中心脏功能无明显影响.     

扩张动静脉内瘘局部狭窄的穿刺技巧及护理对策

目的通过良好的穿刺技巧和有效的护理干预使狭窄的动静脉内瘘逐渐扩张,延长内瘘的使用寿命。方法通过对15例动静脉内瘘狭窄的血透患者（血流量〈150mL／min,1个月以上）采取不同的穿刺技巧和护理对策,使狭窄的内瘘逐渐扩张。结果9例狭窄的内瘘得以扩张,血流量达250mL／min左右,再次使用达2年以上,2例吻合口狭窄者血流量达200mL／min左右,使用不到1年闭塞。结论良好的穿刺技巧及切实有效的护理干预,可挽救濒临闭塞的内瘘,延长动静脉内瘘的使用寿命,提高患者的生存质量。     

Thermography and colour duplex ultrasound assessments of arterio-venous fistula function in renal patients

Vascular and clinical assessments of arterio-venous fistula (AVF) function and access are important in patients undergoing or preparing to undergo renal dialysis. Objective assessment techniques include colour duplex ultrasound and more recently medical infrared thermography. Ideally, these should help assess problems relating to fistula failure or to vascular steal from the hand which can result from excessive fistula blood flow. The clinical value of thermography, as yet, has not been assessed for this patient group. The aims of this study were therefore to investigate the relationships between thermography skin temperature measurement and (a) quantitative ultrasound measurement of AVF blood flow, and (b) qualitative clinical assessment of vascular steal from the hands. Fifteen adult patients underwent thermal imaging of the upper limbs, colour duplex ultrasound to derive AVF blood flow from brachial artery blood flow measurements, and a clinical evaluation for vascular steal. Temperature measurements were extracted from the thermograms, including bilateral arm and hand (Fistula -- Non-Fistula) differences, for comparison with derived AVF blood flow and steal grading. Derived AVF blood flow ranged from 30 to 1,950 ml min(-1), with a mean rate close to one litre per minute. Thermography detected the warmer superficial veins in proximity to the patent fistulas, with bilateral differences in fistula region skin temperature correlated with derived AVF blood flow (using maximum temperature measurements the correlation was +0.71 [p < 0.01]; and using mean temperature measurements the correlation was +0.56 [p < 0.05]). When thermography measurements were compared with the clinical assessment of steal the mean hand temperature differences separated steal from non-steal patients with an accuracy of greater than 90%. In summary, we have now demonstrated the potential clinical value of medical infrared thermography for assessing AVF function in renal patients.     

血管穿刺溶栓治疗血液透析患者内瘘血栓临床效果观察

目的 观察内瘘穿刺溶栓治疗内瘘血栓的疗效及并发症.方法 因血栓形成动静脉内瘘失功的14例血液透析患者共17例次.其中自体血管内瘘13例次,人造血管内瘘4例次.经自体内瘘静脉置入深静脉导管或将留置针置入人造血管内,经上述通路向内瘘血栓注入尿激酶(25～75)万U/d进行溶栓治疗.结果 治疗后11例次内瘘血管在3～25小时内溶通,平均(11.82±7.31)小时,成功率为64.7%;6例次溶栓失败.溶栓成功的患者治疗前血栓形成时间[(8.27±7.35)小时]明显短于不成功者[(29.33±21.30)小时].6例自体动静脉内瘘患者在溶栓后出现轻度的前臂肿胀.所有患者均未出现身体器官的栓塞现象.结论 内瘘血管穿刺溶栓治疗血栓形成是一种经济、有效、安全的方法.     

Measurement of placental volume with real-time ultrasound in mid-pregnancy

A new method to measure placental volume in mid-pregnancy using realtime ultrasound is described. The method is an adaptation of the B-mode parallel planimetric technique. The mean error of in vitro measurements on 45 balloons (mean volume 186 mL range: 88–485 mL) was ?2.24 mL, standard deviation 6.76 mL. The error standard deviation of in vivo placental volume measurements was 16.4 mL (volume range: 173–396.5 mL). Placental measurements were made on 175 women between 14.3 weeks and 21.4 weeks, menstrual age (MA) and a smooth centile curve derived. Median volume increased linearly from 144 to 329 mL. The size of the ultrasound probe limits the technique to use before 20 weeks, MA. © 1994 John Wiley & Sons, Inc.     

Intracavitary Contrast-Enhanced Ultrasound in the Management of Post-Surgical Gastrointestinal Fistulas

The goal of this study was to investigate intracavitary contrast-enhanced ultrasound (IC-CEUS) measures in the management of post-surgical gastrointestinal (GI) fistula throughout detection, treatment and follow-up. From June 2010 to August 2016, patients who were administered ultrasound contrast agent (UCA) via a drainage tube for IC-CEUS were enrolled and retrospectively analyzed. They were suspected of having GI anastomotic fistulas or had been found to have fluid collections with ultrasound that were accompanied by abdominal pain or fever after surgical procedures. Forty-two patients met the inclusion criteria and were enrolled into this study. Twenty-two were confirmed to have GI fistulas confirmed by standard references. None were detected by conventional ultrasound. Although IC-CEUS successfully detected GI fistulas in 16 patients, it missed GI fistulas in 6 patients. One patient was misdiagnosed with a GI fistula. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the diagnosis of GI fistulas by IC-CEUS were 72.7% (16/22), 95.0% (19/20), 94.1% (16/17), 76.0% (19/25) and 83.3% (35/42), respectively. Twenty peritoneal fluid collections in 14 patients were related to fistulas by IC-CEUS based on the distribution of ultrasound contrast agents. Additional drainage was performed in 14 fistula-related fluid collections. Eight GI fistulas were judged to be cured after IC-CEUS re-evaluation, and the drainage tubes were removed from these patients. In conclusion, IC-CEUS can greatly improve the ability to diagnose post-surgical GI fistulas and may also play an important role in interventional treatment and follow-up.     

Validation of ultrasound contrast destruction imaging for flow quantification

Our purpose was to validate in vitro a kinetic flow model based on microbubble signal decay curve. Using a 3.5 MHz transducer and phase-inversion (1.8 MHz central transmit frequency), a renal dialysis cartridge oriented vertically was imaged in the transverse plane as 1:1000 dilution of AF0150 was infused at 50, 100, 200, 300 and 400 mL/min. Ten gray-scale images were acquired at each infusion rate using 2.5, 5 and 10 frames/s at 100%, 40%, 15% or 1% of maximum transmit power. Video-intensity measured on each 10 images was fit to a kinetic model using Sigma Plot that yielded microbubble concentration, velocity and destruction per frame. These were correlated with the experimental conditions. At 100% power, video-intensity on the first frame (microbubble concentration at equilibrium) was similar for all flow and frame rates. The model fit the experimental data for all flows at 10 frames/s and for flows lower than 400 and 100 mL/min at 5 frames/s and 2.5 frames/s, respectively. The calculated flow was similar to the experimental flow rates, regardless of technique (r² = 0.98). Microbubble fraction destroyed per frame was similar for all flow and frame rates and increased linearly with transmit power (r² > 0.98). These results suggest that using appropriate power and frame rate for a given flow rate, estimates of fractional blood volume, flow and destruction fraction can be calculated from the decay curve using 10 frames that can be acquired in 1 to 4 s. (E-mail: rmattrey@ucsd.edu)