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Patients on hemodialysis (HD) experience systemic and cerebral hemodynamic changes that are associated with cognitive impairment. It has not been studied whether having an arteriovenous fistula (AVF) may be a factor associated with the decrease in cerebral blood flow during HD. The objective of this study was to quantify and compare hemodynamic changes at the cerebral level during an HD session in patients with AVF vs. those with a high-flow catheter (HFC).
Cross-sectional study, controls were sought for AVF patients matched for age, sex, and time on HD. Three measurements of mean cerebral blood flow velocity (CBFV) were performed using transcranial Doppler ultrasound (during the first 15 minutes,120 minutes, and 240 minutes after HD). Other interventions were carried out before and after HD, including measurement of cardiac output (CO), cognitive evaluation using the Montreal Cognitive Assessment (MoCA), and measurement of AVF flow velocity.
Fifty patients were included, 20 women, average age 56 years, time on HD 3.2 years, 25 patients with AVF (50%). The groups were not different in their baseline characteristics. All patients presented a drop in CBFV, on average -26.5%, with the drop being greater in AVF vs. HFC (-28.2% vs -21.2%, p=0.27). The change in CO pre and post HD was also greater in those with AVF vs. HFC (-12.5% vs -7.6%, p=0.73). Regarding mean arterial pressure (MAP), the change was -11.3% in patients with AVF and -9.4% in HFC (p=0.90). (Fig. 1). There was no difference in MoCA score between the groups.
All patients studied presented a significant decrease in cerebral blood flow, CO and MAP during the HD session. Interestingly, these changes are more pronounced in patients with AVF, but no statistically significant difference was observed between the study groups.