|Year : 2017 | Volume
| Issue : 2 | Page : 313-317
|Factors influencing patency of Brescia-Cimino arteriovenous fistulas in hemodialysis patients
Venu Manne, Surya Prakash Vaddi, Vijaya Bhaskar Reddy, Sridhar Dayapule
Department of Urology and Renal Transplant, Narayana Medical College and Hospital, Nellore, Andhra Pradesh, India
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|Date of Web Publication||23-Mar-2017|
| Abstract|| |
Autologous arteriovenous fistula is gold standard to maintain vascular access for hemodialysis patients. As per the Kidney Disease Outcomes Quality Initiative guidelines, distal veins are preferred as the first choice. In this study, a total of 134 patients and 138 fistulas were evaluated from April 2015 to March 2016. Demographic factors and clinical factors were taken into consideration. Our study showed that age, sex, diabetes, and type of construction (end-to-side vs. side-to-side) had no influence over fistula patency rates. Intradialytic hypotension was one of the risk factors for loss of fistula patency. Smoking and history of hypertension were associated with reduced patency rates (P<0.001). Primary failure was more with distal fistulas (15.2%).
|How to cite this article:|
Manne V, Vaddi SP, Reddy VB, Dayapule S. Factors influencing patency of Brescia-Cimino arteriovenous fistulas in hemodialysis patients. Saudi J Kidney Dis Transpl 2017;28:313-7
|How to cite this URL:|
Manne V, Vaddi SP, Reddy VB, Dayapule S. Factors influencing patency of Brescia-Cimino arteriovenous fistulas in hemodialysis patients. Saudi J Kidney Dis Transpl [serial online] 2017 [cited 2019 Apr 26];28:313-7. Available from: http://www.sjkdt.org/text.asp?2017/28/2/313/202759
| Introduction|| |
End-stage renal disease is a chronic disease requiring treatment with dialysis or renal transplantation. Patients require an adequate vascular access for hemodialysis (HD). Autologous arteriovenous fistula (AVF) is gold standard to maintain vascular access for HD.
AVFs are constructed using radial artery and cephalic vein in the forearm and brachial artery and cephalic or basilic vein in the upper arm. Anastomosis may be either end-to-side or side-to-side from vein to artery. Upper limb fistulas are preferable over lower limb or any other site of the body. In order of preference as given in the Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines, the Brescia-Cimino fistula, i.e., radiocephalic (RC) fistulas are the first choice, followed by brachiocephalic and brachiobasilic transposition and synthetic graft fistulas, either straight or loop, in upper or lower arm.
The patency rates depend on various factors such as site of anastomosis, side of anastomosis, caliber of the vein and artery used for anastomosis, type of anastomosis and patient factors.
| Methods|| |
This is a prospective study to evaluate various parameters influencing patency of vascular access. Demographic and clinical factors taken into consideration included age, gender and site, side, vessel caliber, and type of anastomosis.
Patient factors such as smoking and comorbidities including diabetes, hypertension were also considered as these have adverse effects on vessel health. Primary failure was defined as the loss of patency before cannulation and early failure was defined as loss of patency within three months from the time of fistula surgery.
- All cases who underwent forearm RC fistula surgery for the first time in our hospital from April 2015 to March 2016
- Cases who lost AVF patency after the first surgery and underwent one or more surgeries for vascular access.
Patients who underwent two or more fistula surgeries were considered as multiple surgeries.
As per the KDOQI guidelines, first preference for fistula creation is the RC fistula; for failed first RC fistula, the next preference is opposite upper limb RC fistula. No cutoff has been described for vessel diameter.
A successful fistula was defined as one which should be mature, ready for cannulation with minimal risk for infiltration, and able to deliver the prescribed blood flow throughout the dialysis procedure.
Criteria for a failed fistula
- On clinical examination, if no thrill is felt on palpation and no bruit is heard on auscultation
- If color Doppler shows no flow in the vein. Thus, in this study, clinical examination and color Doppler were used to diagnose the loss of patency of fistula.
| Results|| |
All patients who underwent RC AVF surgeries in our hospital from April 2015 to March 2016 were evaluated. A total of 138 RC fistulas were performed in 134 patients. Among them, 103 (76.9%) were male and 31 (23.1%) were female patients.
Out of the 138 RC fistulas, 98 were on the left forearm and 40 were on the right side. Age of the patients in this study ranged from 8 to 77 years (mean age 44.4 years). Of the total RC fistulas, 36 cases failed (left RC 27, right RC 9) of whom, 28 were male and eight were female patients. In this study, the diameter of the cephalic vein ranged from 1.2 to 3.2 mm, with an average of 2.1 mm at the wrist, and the diameter of the radial artery ranged from 1.6 to 4 mm with an average of 2.2 mm.
In failed RC cases, the average diameter of the vein was 1.8 mm with a range of 1.3–2.6 mm and the diameter of the radial artery was 2.9 mm with a range of 1.7–4 mm.
Out of the 138 RC fistulas, 94 were constructed with side-to-side anastomosis, which means that side of the vein is anastomosed to the side of the artery. Among them, 27 failed and 67 are functional. Totally, 44 fistulas were constructed with end-to-side configuration (end of the vein anastomosed to the side of the artery); of them, nine fistulas lost patency, and 35 fistulas are functional.
In this study, out of 59 smokers, 58 required multiple surgeries and out of 75 nonsmokers, only 12 patients underwent multiple surgeries, and 63 were managed with single fistula surgery (P <0.01). In 36 diabetic patients, 19 patients underwent multiple surgeries, and 17 underwent single fistula surgery (P <0.1). Furthermore, out of 134 patients, 88 were hypertensive; of them, 72 underwent multiple surgeries and 16 had single vascular access surgery. Among the 46 nonhypertensive patients, nine underwent multiple surgeries and 37 were with single surgery (P <0.1).
Out of 36 RC AVF failures, 21 cases were primary failures (15.2%) and among them, three cases had vein diameter <1.5 mm. In one patient, there was primary failure despite having vein and artery of good caliber; on exploration postsurgery to find out the cause; there was narrowing of the vein 10 cm distal to the anastomotic site. In the remaining 15 cases, nine cases failed because of intradialytic hypotension and four patients developed blowout of fistula which is rare with RC fistulas. Two cases failed because of early cannulation since there was no other vascular access.
In our center, we do not perform a fistulogram for failed RC fistulas. In addition, we do not perform any salvage procedure for failed RC fistulas; our overall success rate 73.18%.
| Discussion|| |
A total of 134 patients who underwent fistula surgery at our institute were evaluated. In this study, no significant increased failure rates were seen in the female sex (P >0.1). Monroy-Cuadros et al did not find a significant association between sex and the risk of AVF failure, even after adjusting for age, presence of diabetes mellitus, hypertension, history of peripheral vascular disease, smoking history, and type of procedure.
Navuluri and Regalado described that primary failures were more with RC fistulas when compared with brachiocephalic fistulas. In our study, 36 RC fistulas failed among whom, 21 were primary failures (15.2%), which is comparable with other studies from Ascher et al and Wolowczyk et al, who reported a primary failure rate of 18 and 20%, respectively., The probable reasons were vessels of smaller caliber and damage to the vessel wall due to frequent venipunctures. Bahadi et al in their study reported an incidence of early failure of AVFs of 23.9%, which is similar to other published series (23%–53%). In our series, the early failure rate was 26%.
The most accepted reason for failure for Brescia-Cimino fistulas is poor flow through veins of small diameter which are more prone for early thrombosis. The primary factors that determine the resistance to blood flow within a single vessel include vessel diameter (or radius), vessel length, and viscosity of the blood. Of these three factors, the most important quantitatively and physiologically is vessel diameter. Poiseuille’s Equation describes that vessel resistance (R) is inversely proportional to the radius to the fourth power (r4).
With the decrease in vein diameter, there is enormous increase in resistance to the flow. In their meta-analysis, Rooijens et al concluded that, although the autologous RC AVF is considered to be the primary choice for vascular access, it has a high primary failure rate and only moderate patency rates at one year of follow-up.
In our series, nine AVFs (6.52%) failed because of intradialytic hypotension. Hypotension is one of the important causes of failure of vascular access. Chang et al, reported that more frequent episodes of intradialytic hypotension and lower predialysis systolic blood pressure were associated with increased rates of vascular access thrombosis. Talaiezadeh et al described that the major reason for primary and secondary AVF failure was fall in blood pressure (70% and 73%, respectively).
The diagnosis of intradialytic hypotension can be made based on the history given by the patient and checking the patients’ blood pressure records from the dialysis machine; if the records show one or more episodes of systolic blood pressure <90 mm Hg, it suggests that intradialytic hypotension is the cause for failure of fistula.
Four patients developed blow-out of fistula which is rare with RC fistulas. Two cases failed because of early cannulation (within 2 weeks of fistula construction) as there was no other vascular access. Early cannulation of fistula is one of the factors in loss of patency of vascular access. Minimum maturation period required is four to eight weeks.
Although it is not fully clear as to why fistulas fail, several studies have provided insight into the problem of nonmaturation. A review by Asif et al summarizes the pathophysiology of early AVF failure. Genetic predisposition, low shear stress, increase in transmural pressure, turbulence, differences in compliance between arteries and veins, and vascular injury of the mobilized segment may all contribute to neointimal hyperplasia and adverse vascular remodeling.
Zangan et al described that failure due to thrombosis immediately following surgery is usually secondary to technical error, judgment error regarding vessel adequacy, or a period of extreme hypotension. Peripheral location of the first fistula, female sex, diabetes mellitus, and surgical expertise are the other predictive factors of early fistula failure.
Current literature supports patient factors such as the presence of diabetes, smoking, peripheral vascular disease, predialysis hypotension, and vessel characteristics, as directly influencing AVF patency. In our study, smoking had a strong correlation with loss of patency of fistula.
In this study, diabetes did not affect the patency of fistulas (P <0.1). Fernström et al have shown that diabetes did not influence failure rate, but significantly shortened the mean patency time.
Hypertension profoundly affects vascular access patency. Among 88 hypertensives, 72 required multiple surgeries (P <0.01). Monroy-Cuadros et al found an increased relative risk (2.5) of primary functional patency loss in their series. Hypertension increases vascular stiffness and promotes arteriosclerosis, which will decrease the blood flow across the anastomosis.
In this study, failed RC AVF cases had an average vein diameter of 1.8 mm with a range of 1.3–2.6 mm and average radial artery diameter of 2.9 mm with a range of 1.7–4 mm. Parmar et al described that the diameter of the radial artery plays an important role in patency of RC AVFs. Radial arteries with a diameter of <1.5 mm had an almost 50% risk of immediate fistula dysfunction as compared with larger radial arteries.
In this study, construction of AVF at distal forearm by either end-to-side or side-to-side anastomosis carried the same patency rates (P <0.4). However, Wedgwood et al, have reported early loss of patency in the end-to-side group.
Before this study, we did not follow any criteria for selection of cases on the basis of vein diameter. However, after this study, we have made a cutoff point for vein diameter which should be ≥1.8 mm, and the cutoff the diameter of the radial artery to be ≥2 mm for RC AVF.
| Conclusion|| |
Vascular access is necessary for HD and autologous fistulas are proved to be better over central catheters. Smoking and hypertension were shown to have adverse effects over patency of vascular access. In addition, vein diameter <1.8 mm in forearm fistulas showed early loss of patency. Intradialytic hypotension is one of the preventable causes for loss of fistula patency. More studies and long-term follow-up are required to confirm the influence of these factors on patency of vascular access.
Conflict of interest:
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Narayana Medical College and Hospital, Chintareddy Palem, Nellore, Andhra Pradesh
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