Prospective evaluation of the intra-access flow of recently created native arteriovenous fistulae.

Background: The aim of this study is to assess the evolution of intra-access flow (Q(ac)) in recently created native arteriovenous fistulae (AVFs) during the first few months of use.

Methods: All AVFs were monitored by means of ultrasound dilution using Transonic (Transonic Systems Inc, Ithaca, NY). First Q(ac) measurements were obtained between 6 to 10 weeks after creation and subsequently every 3 to 6 weeks during the following 4 months. Per routine, AVFs are cannulated 6 weeks after their creation in our unit. Fifty-seven patients with new AVFs were initially enrolled, but 12 patients were lost at follow-up. There was a 69% to 31% ratio of brachiocephalic (BC) to radiocephalic (RC) AVFs, and diabetes affected an equal proportion of patients in both subtypes.

Results: Mean initial and final Q(ac)s were 1,132 +/- 681 and 1,097 +/- 644 mL/min, respectively; there was no significant difference during the study period. However, the Q(ac) of BC AVFs remained approximately twice as high as the Q(ac) of RC AVFs during the observation period (initial Q(ac), 1,336 +/- 689 versus 645 +/- 332 mL/min; final Q(ac), 1,285 +/- 652 versus 647 +/- 331 mL/min, respectively). Male sex was associated with a greater Q(ac) throughout the evaluation (1,263 +/- 754 versus 852 +/- 375 mL/min for women). No significant difference was noted between different age groups, and diabetes did not significantly affect Q(ac). Finally, the initial Q(ac) of a BC AVF was influenced by the presence of a previously functioning RC AVF on the same arm. The initial Q(ac) in BC AVFs was 1,800 +/- 919 mL/min in that subgroup (and decreased to 1,302 +/- 733 mL/min by the end of the study, therefore becoming similar to the mean Q(ac) of other BC AVFs).

Conclusion: From these results, we conclude that newly created native AVFs have an initial Q(ac) that does not vary significantly during the first 6 months and may already be maximal at 6 weeks or at the time of first needle puncture in our hands. Among demographic factors, sex influences the Q(ac) of native AVFs, whereas age and diabetes do not.