Chronic renal failure (CRF) is a progressive and permanent deterioration in renal function [1]. Number of patients who need hemodialysis has increased due to the advance in the diagnosis and treatment of renal diseases. Hemodialysis is the renal replacement modality in 70% of patients with ESRD [6].
Artreriovenous fistula is the favored form of dialysis access according to the guidelines on hemodialysis vascular access, and its dysfunction is a chief cause of morbidity and hospitalization in hemodialysis patients [6]. Well-timed intervention for retrieving early fistula failure is very important. However, clinically, it could take 3–4 months for nephrologists to confirm immature fistula. So, well-defined criteria applied in the early postoperative period after fistula creation for identification of fistulas that possible to fail would be very useful [7].
Blood flow increases rapidly after fistula creation and reaching its maximum within 4 to 12 weeks, about 40 to 60% of the total increase in blood flow occurs in the 1st 24 h after creation of the fistula [7]. In this study, we measured blood flow at the fistula site in the early postoperative period (day 7–14) to assess if that has a predictive value in fistula failure by follow-up of the fistula maturity up to 6 months.
Our data revealed that age shows significant difference between the two groups (mature and failure group), but BMI shows no difference. However, Wiese et al. [8] reviewed that age and BMI show significant difference.
In agreement with previous studies, Sedlacek et al. [9] and Miller et al [10], our study revealed that DM is a risk factor for AV fistula failure. However, female sex was not a risk factor in our study as these studies reported.
Awareness of the primary renal disease helps the clinicians to expect problems during renal replacement therapy (RRT) and plan preventive measures for the community. In agreement with other studies, Zhu et al. [7] and Malekmakan et al. [1], our study detected that the most common causes of ESRD are chronic nephritis and diabetic nephropathy (47% and 24% respectively).
Preoperative vascular mapping was done to identify its predictive role in fistula failure, in agreement with previous studies, Zhu Y et al. [7] and Niyyar VD et al. [11], we reported that in addition to the diameters of cephalic vein, radial artery, and brachial artery, the peak systolic velocity of the radial artery and brachial artery was significantly lower in the failure group than in the mature group in our study, which indicated that the PSV and the vascular diameter are associated with the AV fistula failure.
Eighty-three percent of patients have their AV fistula by end to side technique and 17% by end to end technique. We noticed that there was no significant relation between outcome of the fistula and type of anastomosis. 20.7% of the mature group were end to end type, and 79.3% were end to side; 27.8% of the failure group were end to end, and 72.2% were end to side.
Failure group shows a significant decrease in blood flow at the early postoperative period (day7–14) compared to the mature group, which indicated that blood flow measurement at the early postoperative period could be used to differentiate the fistulas that were likely to fail and the ones that would ultimately mature. We detected that 200.5 ml/min is the cutoff value for discriminating functioning and non-functioning fistulas. Ladenheim et al. [12] found that 200 ml/min blood flow in the postoperative 1st week is indicator of mature fistula.
A mature AV fistula in our study was one that could support pump-controlled blood flow of 377 mL/min for 3 dialysis sessions at least.
Robbin et al. [13] considered an arteriovenous fistula mature when it could support blood flow of 350–450 mL/min, for 3–4 h three times per week. A fistula blood flow less than 350 mL/min results in inadequate dialysis.
However, Zhu et al. [7] perceived in their study that blood flow have to be more than 200 mL/min for at least 6 dialysis sessions in Chinese patients, probably because the body type and dietary structure of Chinese people.
In the follow-up period, 18% of arteriovenous fistulas (18 of 100) developed failure in our study.
Early AV fistula failure and insufficient flow rate are the most common problem [14]. Primary failure occurs if an access is unable to provide adequate blood flow for dialysis after reasonable period of maturation. It mostly occurs because the draining vein does not adequately dilates or the feeding artery does not provide sufficient blood flow [1].
Our study agrees with that as the most common cause of failure was failure to mature, and it represented 50% of failure group (9 patients), followed by hematoma (4 patients), followed by partial thrombosis (3 patients), and followed by total thrombosis and infection (1 patients each).