|Year : 2021 | Volume
| Issue : 5 | Page : 55-59
Factors affecting the long term patency of arteriovenous access for hemodialysis: A single center experience
Ashwini Naveen Gangadharan, Rajendra Basavanthappa Prasad, Ranjith Kumar Anandasu, J P Vivek Vardhan, Chandrashekar Anagavalli Ramswamy, Sanjay C Desai, Adharsh Kumar Maruthu Pandian, Nivedita Mitta, Hemanth Kumar
Department of Vascular and Endovascular Surgery, Ramaiah Medical College, Bengaluru, Karnataka, India
|Date of Submission||07-Nov-2020|
|Date of Acceptance||07-Dec-2020|
|Date of Web Publication||30-Aug-2021|
Ranjith Kumar Anandasu
Department of Vascular and Endovascular Surgery, Ramaiah Medical College, Bengaluru, Karnataka
Source of Support: None, Conflict of Interest: None
Objective: The objective of the study was to analyze and evaluate the possible factors in the long-term patency of arteriovenous (AV) access for hemodialysis (HD). Materials and Methods: This was a cross-sectional study recruiting patients from January 2019 to December 2019. All patients who have a working HD vascular access, either AV fistula (AVF) or AV graft which has been working for at least 2 years were included and collected demographic data along with other parameters such as timing of creation, interventions, dialysis sessions, and antiplatelet therapy among others. Results: We included 81 patients with AV access patent more than 2 years; 22.5% were aged >65 years, 39.6% were diabetic, 68.5% were hypertensive, and 26.1% had vascular disease. Analysis revealed that the patient factors such as current tobacco usage and side of creation and technical factors such as maturation time, number of dialysis sessions, and single-center dialysis have a significant effect on the patency of the AV access, while the factors such as past tobacco usage, diabetes, hypertension, use of jugular catheter before access creation, and cannulation technique could not establish any statistical effect on the patency of AV access. Conclusion: There is a complex interaction of factors that may affect the patency of an individual AV access. These need to be carefully considered when selecting surgical site or technique, adjuvant treatments, and follow-up protocols for AVFs.
Keywords: Arteriovenous access, factors, hemodialysis, patency
|How to cite this article:|
Gangadharan AN, Prasad RB, Anandasu RK, Vardhan J P, Ramswamy CA, Desai SC, Maruthu Pandian AK, Mitta N, Kumar H. Factors affecting the long term patency of arteriovenous access for hemodialysis: A single center experience. Indian J Vasc Endovasc Surg 2021;8, Suppl S1:55-9
|How to cite this URL:|
Gangadharan AN, Prasad RB, Anandasu RK, Vardhan J P, Ramswamy CA, Desai SC, Maruthu Pandian AK, Mitta N, Kumar H. Factors affecting the long term patency of arteriovenous access for hemodialysis: A single center experience. Indian J Vasc Endovasc Surg [serial online] 2021 [cited 2021 Dec 1];8, Suppl S1:55-9. Available from: https://www.indjvascsurg.org/text.asp?2021/8/5/55/324936
| Introduction|| |
The mid-20th century saw the dawn of hemodialysis (HD) with which arose the requirement for a dependable and recurrent access to circulation. Globally, in patients with end-stage renal disease (ESRD), the utilization of chronic HD as renal replacement therapy is extensively practiced. Curtailment of maintenance costs along with reduced mortality and morbidity rates has led to the adoption of autologous AV fistula (AVF) as the choicest method for HD access. Although “Fistula first” is recommended by current dialysis outcome quality initiatives, some patients might be ineligible for a fistula, while the substitute treatment of graft placement carries a possibility of graft failure. Thus, maintenance of a working HD access is arduous.
It is estimated that yearly more than a billion dollars is spent in maintaining the patency of vascular access and managing its complications, while the population of patients with ESRD escalates by around 6%. Loss of patency indicated by diminished AVF blood flow or AVF thrombosis emanates from neointimal hyperplasia and results in inefficient HD and the necessity of interventional or surgical procedures. Numerous studies are available which demonstrate various factors influencing arteriovenous (AV) access patency, a majority of which have mere 18–24 months as the mean follow-up duration. Hence, here is a pressing requirement to improve access patency, thus decreasing morbidity and alleviating the rising financial burden. Greenberg et al. in their study titled long-term outcomes of fistula first initiative indicated that the overall primary patency for AVF was 40.7%, 28.9%, and 25.3% at 1, 2, and 3 years respectively, while the overall primary patency for AV graft (AVG) was 33.9%, 25.3%, and 21.1%, respectively. Kazemzadeh et al. conducted a long-term follow up for primary patency of native AVF and demonstrated patency rates of 79.5%, 70%, 65%, 60.5%, and 48% at 6 months, 1, 2, 3 and 4 years, respectively, while also exhibiting that fistula patency rates could be increased with dialysis. Puskar et al. studied survival of primary AVF in 463 patients undergoing chronic HD and revealed fistula patency rates of 73%, 63%, 52%, 44%, 36%, 10%, 3%, and <1% after 1, 2, 3, 4, 5, 10, 15, and 20 years, respectively. They also surmised that survival of primary AVF was truncated in end-stage patients with hypertension, diabetes, and those who underwent <3 HD sessions (<12 h) per week without heparin administration.
AVG patency outcomes and prognostic factors – a single-center study by Basavanthappa et al. revealed primary AVG patency rates of 61.5% and 49% at the end of years 1 and 2, respectively, while the secondary patency rates were 70% at 1 year and 59% at 2 years.
A meta-analysis by Smith et al. on factors affecting the patency of AVFs for dialysis inferred that AVF patency was directly influenced by patient factors such as advanced age, comorbidities such as diabetes, peripheral vascular disease (PVD), smoking, predialysis hypotension, and vessel characteristics. Vessels with decreased distensibility or small caliber (<2 mm) are improbable to establish a functional AVF. Raised body mass index (BMI) (<35 kg/m2) or sex does not contribute to altered patency as per the current evidence. Preoperative vessel mapping, early referral for AVF, use of vascular staples, and intraoperative flow measurements were noted to influence AVF patency, while medical adjuvant therapies showed no benefits. Gheith et al. in their study risk factors of vascular access failure in patients on HD demonstrated that younger age resulted in longer survival of fistulas, while sex had no appreciable effect on duration of fistulas. Nondiabetics were more likely to have patent vascular access than diabetics and prolonged fistula survival was also noted in patients having optimal hemoglobin levels between 10 g/dL and 12 g/dL. The study concluded that age, diabetes mellitus, severe anemia, and smoking were the main risk factors of vascular access failure.
There are only a few studies regarding long-term patency (>2 years) and to analyze the factors responsible, hence the need for this study. This article presents a sample of 81 patients with HD access patency of at least more than 2 years. We analyzed and evaluated the possible factors in the long-term patency of AV access for HD and is being presented here.
| Materials and Methods|| |
This study was conducted in the Department of Vascular and Endovascular Surgery, M. S. Ramaiah Medical College, on patients who have a patent AV access which was created 2 years back or more, undergoing dialysis through the same.
All patients who have a working HD vascular access, either AVF or AVG, which has been working for at least 2 years were included in the study.
Patients not willing for the study were excluded from the study.
This was a cross-sectional study recruiting patients from January 2019 to December 2019.
This study was conducted from January 2019 to December 2019 (1 year).
Method of collection of data
Ethical clearance was obtained from the Institution Ethics Committee. Informed consent was obtained from all patients. All patients included in the study were retrospectively analyzed by recording relevant demographic details and other parameters such as duration of AV access before starting dialysis, whether dialysis is in single center or multiple centers, dialysis frequency, comorbidities, whether vascular access created before or after initiating the patient on dialysis, tobacco usage, use of antiplatelets and was entered in a structured proforma. Data were then evaluated to identify the factors for long-term patency, if any, and whether it is statistically significant.
Statistical analysis of data
All the quantitative parameters such as age of patient and duration of disease were described as mean and standard deviation/median with interquartile range. Qualitative/categorical variables were expressed as frequency and percentages. Association of the various factors was studied by employing Chi-square test of significance. All statistical calculations and graphical representations were done using computer programs (Statistical Package for the Social Science; SPSS Inc., Chicago, IL, USA) version 20 and Microsoft Excel for Office 365 (Microsoft Corporation, NY, USA).
| Results|| |
In this study, a total of 81 patients were included between January 2019 and December 2019 and were analyzed. The baseline characteristics of the patients are given in [Table 1]. The significance of each variable was measured by Chi-square test of significance and finding the P value. The mean age of the patients was 57 years ranging from 38 to 77 years. Sixty-three patients were <65 years of age at the time of access creation but could not establish a significance. About 30.9% of patients were female. Fifty-nine patients had AVF as an access for HD of which 69.5% were upper arm brachiocephalic AVF and 30.5% were forearm radio cephalic and majority of the patent access were on the left upper limb (81.5%). The side of access creation was also found to be a significant factor. Prosthetic AVG between brachial artery and Axillary vein was 27.2% [Chart 1]. Survey of underlying disease showed that 32 patients (39.6%) were diabetic, hypertension was found in 55 patients (68.5%), and 21 patients (26.1%) had some kind of vascular disease (ischemic heart disease [IHD]/Stroke/PVD). Twenty-one patients had either HBsAg or hepatitis C virus-positive status. This is shown in [Chart 2]. None of the comorbidities mentioned were found to have any significance on the access patency. Of the 81 patients, 59 (72.8%) of patients had a patent access for <4 years and 22 (27.2%) had a working access for more than 4 years [Chart 3]. Twenty-four patients (29.6%) had a presence of central venous catheter for HD access at the time of access creation on the same side, whereas 57 patients (70.4%) did not. Seventy-three patients (90.1%) in the group were given at least 3 weeks of maturation time after AV access creation, whereas eight patients (9.9%) in this group were not given the 3 weeks of maturation time which was statistically significant. Cannulation technique used in majority of the patients was the buttonhole technique (77.8%), Rope ladder technique was used in 16 patients (19.8%), and area technique in two patients (2.5%). Current tobacco usage was seen in 19 patients (23.5%), past tobacco usage was seen in 34 patients (42%). Sixty-three patients (77.8%) were undergoing dialysis at a single center and 61 of the patients were having at least 3 dialysis sessions per week, both of which helped in keeping the AV access patent. Antiplatelet medications, either aspirin or clopidogrel, were taken daily by 47 patients (58%) and were not statistically significant. The data of the variables are summarized in [Table 2].
| Discussion|| |
Long-term HD of patients with chronic renal failure is dependent on maintaining a patent and functioning vascular access. A systematic review and meta-analysis by Almasri et al. of outcomes of vascular access (AVFs and AVGs) for HD showed that the overall primary patency at 2 years was higher for fistulas than for grafts (55% and 40%, respectively). Patency was lower in individuals with diabetes, coronary artery disease, older individuals, and in women.
Increased use of prosthetic grafts is seen in diabetic patients compared to nondiabetic patients for HD access. Despite this, literature shows evidence of satisfactory AVF outcomes in diabetic patients., Sedlacek et al. reported despite increased arterial calcification, vessel diameters and Peak Systolic Velocity (PSV) were not significantly different from nondiabetic patients. Subsequent AVF creation in diabetic patients gave similar outcome. In our study, almost 40% of the patients had diabetes and there was no statistical significance relating to the patency.
Tobacco use is a risk factor for IHD and PVD. The direct link to AVF failure was first described by Wetzig et al., who reported a higher incidence of primary and secondary failure in patients with tobacco usage, findings confirmed by other studies.,, In our study also, we present tobacco usage status as significant statistical, with a negative impact on the patency, whereas past tobacco usage did not have any statistical significance.
Superficial veins are not apparent clinically in obese patients, use of preoperative duplex may have a significant effect on the incidence, site, and patency of AVFs. A trial used routine preoperative imaging to compare AVF outcomes in patients with a BMI >27 versus <27 kg/m2 found no difference in rates between the two groups. Furthermore, Chan et al. examined AVF outcomes for 1486 HD patients and compared those with a BMI <30 versus >30 kg/m2 but were unable to confirm BMI as a factor in predicting AVF revision or failure. In our study, we segregated patients according to BMI as <26 versus >26 kg/m2. We also could not find any significance of BMI with the patency of the AV access.
The use of antiplatelets in maintaining AVF patency was supported by the antiplatelet Trialists' Collaboration report. Cochrane systematic review was generally in favor of antiplatelet therapy; however, trials have shown considerable heterogeneity in outcomes. A more recent large-scale, double-blind randomized controlled trial on clopidogrel taken for 6 weeks after surgery demonstrated a significantly lower rate of AVF thrombosis compared with placebo. This reduction in thrombosis rate did not, however, alter the flow rate in AVF suitable for dialysis. Comparing it with our study, 58% of patients were on antiplatelets, but there was no statistical significance with patency of the AV access.
Brescia and Cimino cannulated their pioneering AVF the 1st day after creation. Timing of cannulation differs according to the center but usually around 3–6 weeks depending on native/prosthetic AV access. Data from the dialysis outcomes and practice patterns study suggest that first cannulation <14 days after AVF formation is associated with a 2.1-fold increase in AVF failure. Current consensus is that cannulation <14 days should be avoided and minimum of 28 days should be allowed for AVF maturation, the extent of which could be assessed by blood flow and diameter measurement in the draining vein. We also recorded the maturation times given for the access before first cannulation and found that more than 90% of the patients had a maturation time of atleast 2 weeks. We also got the same results with a significant decrease in patency with maturation time of <2 weeks.
Techniques to puncture AVF/AVG include rope ladder, area puncture, and buttonhole, but comparison between AV access patency and technique employed is not clear. Some suggest that buttonhole patients may have more unsuccessful cannulations compared with the rope ladder method. Area puncture is very rarely done in our center and the most common method is buttonhole. In our study, we could not find any statistical relation of the puncturing technique with access patency.
A long-term follow-up for primary patency rate of native AVF by Kazemzadeh et al. showed that dialysis could increase the fistula patency rate. A study on survival of primary AVF in 463 patients on chronic HD by Puskar et al. concluded that primary AVF survival was shorter in end-stage renal disease patients with diabetes and hypotension, who underwent less than 3 HD sessions (<12 h) per week without heparin administration. In our study also, we found that patients with <3 dialysis sessions per week had lower patency rates than patients with at least 3 sessions per week.
| Conclusion|| |
Thus, the patient factors such as current tobacco usage and side of AV access creation and technical factors such as maturation time, number of dialysis sessions per week, and single center dialysis have a significant effect on the patency of the AV access, while the factors such as past tobacco usage, diabetes, hypertension, use of jugular catheter before access creation, and cannulation technique could not establish any statistical effect on the patency of AV access.
Modifiable risk factors should be addressed. Nonmodifiable risk factors may influence the choice of site or surgical technique for AVF creation.
Hence, it can be inferred that the patency of an AV access is determined by a complex interplay of factors which require to be carefully scrutinized when deciding the surgical site or technique, follow-up protocols, and adjuvant treatments for AVFs.
There are some limitations to our study. These analyses were based on retrospective data collected from a single-center cohort, so we cannot generalize these results to all populations. We did not investigate the etiology of these patients' ESRD. Furthermore, since the accesses were created a tleast 2 years before interviewing the patient, a strong chance of recall bias cannot be ruled out. The study is also limited by the granularity of the clinical details available. We cannot account for factors which might affect patency such as vein/conduit quality, surgeons experience, and skill.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]