|Year : 2019 | Volume
| Issue : 3 | Page : 889-894
The role of color Doppler ultrasonography in evaluation of hemodialysis graft dysfunction
Aya H El-Sabbagh1, Mohammed S El-Zawawi2, Yasmin H Hemida2
1 Department of Radiology, Shebien El Kom Teaching Hospital, Menoufia, Egypt
2 Department of Radiology, Faculty of Medicine, Menoufia University, Shebien El Kom, Menoufia, Egypt
|Date of Submission||12-Mar-2018|
|Date of Acceptance||12-Jun-2018|
|Date of Web Publication||17-Oct-2019|
Aya H El-Sabbagh
Department of Radiology, Shebien El Kom Teaching Hospital, Menoufia
Source of Support: None, Conflict of Interest: None
To evaluate role of duplex Doppler ultrasound in assessing arteriovenous graft (AVG) function, detecting complications and analyzing the resistance index (RI) and flow in the afferent artery.
End-stage renal disease causes serious health problems all over the world. The numbers of patients requiring dialysis have grown. In Egypt, it is the cause of 1.3% of all deaths, with much more incidence in later years of life. A well-functioning dialysis access is the lifeline for those patients.
Patients and methods
This study included 20 patients (male/female: 11/9) with end-stage renal disease and on regular hemodialysis using AVG. The prospective analyses of vascular access-related data included examination of graft morphology, shunt complications, and measurement of RI and volume of blood flow at the afferent artery.
The most common complication seen was thrombosis (53.8%). Significant relation was found between graft function and flow volume of afferent artery (P < 0.001), with mean 1011.0 ± 135.9 ml/min in functional grafts and mean 220.8 ± 202 ml/min in dysfunctional grafts. There was a highly significant relation between graft function and afferent artery RI (P < 0.005), as 57.1% of functional grafts had their RI less than 0.5, with mean of 0.45 ± 0.05; 28.6% of complicated graft had their RI more than 0.5, with mean of 0.44 ± 0.12; and all dysfunctional graft had RI more than 0.5, with mean of 0.66 ± 0.09.
Duplex sonography has high accuracy in diagnosing and assessing most hemodialysis AVG-related complications while providing us with anatomic and hemodynamic information.
Keywords: Duplex ultrasonography, end-stage kidney disease, hemodialysis, surgical arteriovenous shunt
|How to cite this article:|
El-Sabbagh AH, El-Zawawi MS, Hemida YH. The role of color Doppler ultrasonography in evaluation of hemodialysis graft dysfunction. Menoufia Med J 2019;32:889-94
|How to cite this URL:|
El-Sabbagh AH, El-Zawawi MS, Hemida YH. The role of color Doppler ultrasonography in evaluation of hemodialysis graft dysfunction. Menoufia Med J [serial online] 2019 [cited 2019 Nov 14];32:889-94. Available from: http://www.mmj.eg.net/text.asp?2019/32/3/889/268802
| Introduction|| |
Chronic kidney disease is an increasingly important health issue, and its incidence and prevalence have skyrocketed during the past years. End-stage renal disease (ESRD) is defined as the situation in which native kidneys fail, which are the metabolic regulating organs of the internal environment, leading to the necessary substitution of such kidneys through hemodialysis or kidney transplant .
A well-functioning dialysis access is the lifeline for patients with ESRD on hemodialysis. Dialysis access includes both arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) . Prosthetic vascular grafts are inevitably used for patients whose vessels are unsuitable for an autogenous AVF owing to several reasons, especially diabetes mellitus-derived atherosclerosis .
The increase in the prevalence of patients with chronic renal failure on hemodialysis has made the maintenance of long-term patency of hemodialysis vascular access (VA) essential, and VA failure is a crucial problem in chronic hemodialysis patients. VA primary patency is 79.5% per year and 48% every 4 years ,.
Doppler ultrasound is a noninvasive imaging modality for evaluation of dialysis access which are typically superficial . So the aim of this study is to highlight the role of duplex Doppler ultrasound in assessment of AVG function and detecting complications, in addition to analyzing the resistance index (RI) and flow in the afferent artery.
| Patients and Methods|| |
After approval of the Local Ethical Committee of Shebin El Kom Teaching Hospital and obtaining written consents from all patients to participate in our study, this study was done in Radiodiagnosis Department at Shebin El Kom Teaching Hospital. The prospective study was done during 8 months from April 2017 to November 2017. The study was carried on randomly selected 20 patients with suspicion of hemodialysis graft dysfunction presented to the Nephrology or Vascular Surgery Departments.
The minimal sample size was calculated based on a study 'Clinical and Doppler ultrasonography data of a polyurethane VA graft for haemodialysis: a prospective study' . A sample size of 16 patients (total sample size = 16 patients) is the enough required sample to detect an standardized effect size of 27% change in the primary outcome, as statistically significant, with 80% power and at a significance level of 95% (accepted of 0.05). Sample size will be increased to 20 patients (total sample size = 20) to control for attrition bias. The sample size was calculated using GPower version 184.108.40.206 (Düsseldorf, Germany).
Obviously decreased thrill through the shunt, reduced shunt flow by palpation or auscultation, difficulty in cannulation of the AVG with inadequate blood flow even after multiple attempts, suspicion of aneurysm formation, suspicion of graft thrombosis or occlusion, upper extremity swelling and frequent prolonged bleeding after cannulation were the inclusion criteria.
Patients on hemodialysis through autogenous AVF were excluded.
All patients were subjected to the following:
- Short history taking regarding clinical state to confirm the clinical data and laboratory investigation (fasting blood glucose, HbA1c, Low density lipoprotein (LDL), and High density lipoprotein (HDL)) done in Shebin El Kom Teaching Hospital, Menoufia
- Duplex Doppler sonography of hemodialysis graft: the patient was supine, with the arm positioned at ∼45° from the body in a comfortable position. Initial scanning of the entire limb provided an overview of the site graft and arterial and venous connections.
Sites of examination included the following: the afferent artery, AVG, sites of anastomosis, the draining veins, and the arterial tree distal to the AVG.
All vessels were examined in both transverse and longitudinal planes. Representative gray scale and color images of all vessels and anastomosis were then obtained using 7.5–10 MHz linear probe of an ultrasound machine (Sunhwan-ro 214beon-gi1, Jungwon-gu, Seongnam-si, Gyeonggi do, Jungwon-gu seongnam-city; GE Ultrasound Korea Ltd, Korea). First, the vein was examined by B-mode to determine the site and type of AVG. B-mode aided also in detection of wall echo pattern and dilatations and in measuring the vessel's diameter. For any alteration was found you can provide B-mode to describe the nature of the alteration and its content (aneurysm, pseudoaneurysm, hematoma, fluid collection, and edema). Moreover, the B-mode in two different scans describes the dimensions. Color Doppler describe any alteration, such as blood flow, present owing to the continuity with the VA or other vessels. Moreover, color images were obtained to assess the direction of blood flow and identify aliasing in the lumen (stenosis and thrombosis). Finally, Doppler studies were performed.
Doppler parameters and measurements
Each of the following parameters was measured at the afferent artery and graft and anastomosis sites: Peak systolic velocity (PSV) (cm/s), End diastolic velocity (EDV) (cm/cm), and RI, which reflects the grade of peripheral resistance and is represented by the formula RI=(PSV − EDV)/PSV. Volume of blood flow was measured at the afferent artery, either automatically, or electronically calculated [Figure 1], [Figure 2], [Figure 3].
|Figure 1: A 68-year-old male patient. Ultrasound demonstrates a pseudoaneurysm (PSA) arising from ant wall of an access graft. Color Doppler shows the classic swirling ‘yin-yang’ pattern of blood flow typically seen in PSAs.|
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|Figure 2: A 56-year-old male patient. Color doppler ultrasonography (CDU) shows complete obstruction of AVG, no color intake and absent Doppler signal (graft occlusion) by old echogenic thrombus.|
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|Figure 3: A 66-year-old male patient. CDU show leakage of graft with perigraft hematoma formation, which does not take color.|
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Data were collected, tabulated, and statistically analyzed using an IBM personal computer with statistical package of the social sciences (SPSS) version 22 (SPSS Inc., Chicago, Illinois, USA), where the following statistics were applied:
In which quantitative data were presented in the form of mean, SD, and range, and qualitative data were presented in the form numbers and percentages.
It was used to find out the possible association between studied factors and the targeted disease. The used tests of significance included the following:
χ2 Was used to study association between two qualitative variables.
Analysis of variance (f) test: it is a test of significance used for comparison between three or more groups having quantitative variables.
Kruskal–Wallis test (nonparametric test): it is a test of significance used for comparison between three or more groups not normally distributed having quantitative variables.
| Results|| |
The study included 20 patients with ESRD for AVG evaluation, aged from 12 to 68 years, with a mean range of 50.6 ± 13.6 years. Overall, 11 (55%) were male and nine (45%) female. There were nine patients with curved brachioaxillary graft (45%), five patients with loop brachioantecubital graft (25%), three with loop brachiobasalic graft (15%), two with curved brachiobasalic graft (10%) and one patient with loop femoral graft (5%). The most common site of graft was the arm (55%). The patient population consisted of seven normal functional graft (35.0%), seven complicated functional graft (35%) and six complicated dysfunctional graft (30%). There were nine patients with previous failure (45%). The most common complication was thrombosis (53.8%).
There was no significant relation between graft function and site of graft (P > 0.05). Highly significant relation was found between graft function and flow volume of afferent artery (P < 0.001), as all functional graft had flow volume more than 800 ml/min, with mean of 1011.0 ± 135.9, and all dysfunctional graft had flow volume less than 600 ml/min, with mean of 220.8 ± 202.1 [Table 1].
|Table 1: Relation between graft function and site of graft, flow volume, resistive index and wave pattern at afferent artery among studied group|
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There was a strong correlation between graft function and afferent artery RI (P < 0.001), as 57.1% of the functional grafts had their RI less than 0.5, with mean of 0.45 ± 0.05; 28.6% of the complicated graft had their RI more than 0.5, with mean of 0.44 ± 0.12; and all dysfunctional graft had RI more than 0.5, with mean of 0.66 ± 0.09. There was a highly significant relation between graft function and afferent arterial wave (P < 0.007), as all functional grafts showed low resistance wave, 28.6% of complicated graft showed high resistance triphasic wave and 83.3% of dysfunctional graft showed high resistance triphasic wave [Table 1].
The most common cause of graft failure was thrombosis (83.3%), and a significant relation was found between graft dysfunction and thrombosis (P = 0.048). There was a significant relation between graft function and infection (P < 0.008) [Table 2].
|Table 2: Relation between graft function and graft complication among studied group|
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The cutoff point of flow volume in functional graft was 855 ml/min. The sensitivity of Doppler ultrasound in detection of dysfunctional graft was 86% with negative predictive value of 93%, accuracy of 95%, specificity of 100%, and positive predictive value of 100%.
| Discussion|| |
The number of patients requiring dialysis for ESRD is increasing rapidly. The prolonged survival of this group of patients depends on the long-term functioning and patency of the VA for hemodialysis .
The ability to study the VA allows the nephrologist to identify the early dysfunction and establish an effective follow-up .
Duplex ultrasound imaging lends itself well to the evaluation of hemodialysis access, as grafts and fistulas are superficial structures. This modality allows identification and localization of abnormalities, which may potentially threaten access function and patency .
In this study, upper arm graft AVG represented 55%, forearm grafts AVG 40% and thigh 5%, being similar to AVG included in the study of Farber et al. , which showed equal distribution between forearm AVG (50%) and upper arm AVG (50%).
In this study, the patient population consisted of seven (35.0%) normal functional grafts, seven (35%) complicated functional grafts and 6 (30%) complicated failure graft. Nearly similar results were obtained by Wiese et al. , as in their study, there were 40% with patent functional graft and 33.3% with graft failure.
In this study, there were nine (45%) patients with previous failure, which is similar to a study done by Wiese et al. where seven (46.6%) patients had one or more previous permanent VAs that had failed . It was found that when previous grafts have failed, the risk of following grafts failure increases significantly stated by the study done by Van Tricht et al. .
In this study, 13 (53.8%) patients showed complications such as thrombosis, infection (15.4%), hematoma (15.4%), steal syndrome (7%) and pseudoaneurysm (7%), which are similar to the study done by Wiese et al. , in which thrombosis was seen in 60%, infection in 20% and peripheral ischemia in 20%.
This study showed no significant relation between graft function and site or type of graft (P > 0.05), which agreed with the study done by Farber et al.  in which graft configuration and outflow vein were not significantly associated with graft patency.
Konner et al.  stated that the calculation of volume flow holds promise to become the most significant predictor of access dysfunction in both fistulas and grafts, and this study proved highly significant relation between graft function and flow volume of afferent artery (P < 0.001).
In this study, the mean flow volume in functional graft was 1011.0 ± 135.9 and the mean flow volume in dysfunctional graft was 220.8 ± 202.1. Nearly similar results were obtained by Wiese et al.  in their study, as all patent grafts mean flow was 930 ± 90 ml/min and all access volume flow with thrombotic event was 375 ± 143 ml/min.
In this study, the most common cause of graft failure was thrombosis represented 83.3%, as there was a significant relation between graft dysfunction and thrombosis (P < 0.048). A similar study done by Allon  stated that thrombosis accounted for ∼80% of graft failures.
Infection in this study showed significant relation with graft function (P < 0.008), which was agrees with the study by Padberg et al.  which stated that infection was the second leading cause of failure of prosthetic arteriovenous accesses and autogenous arteriovenous accesses.
Our study proved that there was significant relation between graft function and afferent artery RI (P < 0.001), as 57.1% of functional grafts had their RI less than 0.5, with mean of 0.45 ± 0.05, and all dysfunctional graft had RI more than 0.5, with mean of 0.66 ± 0.09. This is similar to the results obtained by Moreno Sánchez et al.  where the RI was less than 0.5 in 78.5% of the peripheral VAs with normal function and greater than 0.5 in 86.1% of the dysfunctional peripheral VAs.
So Moreno Sánchez et al.  suggested that both flow reductions and RI elevations should be used together as predictors of dysfunctions (stenosis and thrombosis) as there were hemodialysis VA morphological alterations and local complications not associated with graft dysfunction, included infection, hematomas, aneurysms, and pseudoaneurysms.
In this study, we found that there was a highly significant relation between graft function and afferent arterial wave (P < 0.007), as all functional graft show low resistance wave, 28.6% of complicated graft show high resistance triphasic wave and 83.3% of dysfunctional graft show high resistance triphasic wave, which is similar to the guidelines for dialysis access testing using duplex ultrasound stated by Back and Bandyk , which suggest 'high resistance flow pattern suggests low volume flow and impending graft occlusion'.
In this study, the cutoff point of flow volume in functional graft was 855 ml/min which was similar to study done by Back et al.  that recommended 'A threshold conduit flow rate of 800 ml/min better discriminated failing and functional fistulae and bridge grafts (accuracy 77%) than a flow rate greater or less than 500 ml/min (accuracy 67%)'.
In this study, the diagnostic validity of Doppler ultrasound in detecting graft dysfunction showed sensitivity of 86%, negative predictive value of 93%, accuracy of 95%, specificity of 100%, and positive predictive value of 100%, which are similar to the study was done by Moreno Sánchez et al.  where the sensitivity, specificity, positive predictive value and negative predictive value were 98, 74, 96, and 82%, respectively.
The tortuosity of efferent vein, the wide variations in diameter and how easy the ultrasound probe compresses the vein are the causes of inaccuracy. On the contrary, the diameter of the afferent arteriole is constant and its course is straight which allows us to perform accurate measurements of flow .
The sensitivity and specificity of duplex doppler ultrasound (DDU) in the diagnosis of thrombosis is 100%, and its utility is not only diagnostic, as it is far more efficient in the location of the segment of the patent proximal efferent vein and the stenosis responsible for thrombosis .
According to Back and Bandyk , diagnostic errors are primarily due to the limited ability of duplex testing to identify central vein obstruction or stenosis, so angiography is still considered the standard of reference to find these stenosis, and further therapy is through angioplasty or surgery .
So we recommended that afferent artery flow volume reduction less than 800 ml/min, RI more than 0.5 and changes in wave pattern, compared with the previous analysis, or the presence of not typical low resistance pattern with triphasic waves can relieve the presence of a dysfunction not still identified by the extracorporeal circulation.
| Conclusion|| |
A threshold conduit flow rate of 800 ml/min better discriminated failing and functional bridge grafts. Effective dialysis needs high access flow ideally in the range 800–1200 ml/min.
Complications occurred with use of AVG, which include complications affected by flow and graft function, for example, stenosis and thrombosis, and local complications not associated with dysfunction, which included hematoma, infection, seroma and pseudoaneurysm. Therefore, the flow reductions together with RI elevations are the ones that would more likely be associated with dysfunctions.
This study proved that Doppler sonography has high accuracy in diagnosing and assessment of most hemodialysis AVG-related complications, so in sum, the DDU is a safe and efficient modality in the study of AVG function and patency while providing us with anatomic and hemodynamic information.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]