Background: This study is aimed at comparing ultrasound dilution (UD) and thermodilution (TD) with color Doppler ultrasound (CDU) for arteriovenous fistula (AVF) assessment in children on hemodialysis (HD).
Material and methods: All patients were dialysed with the Fresenius 5008 HD machine. UD was performed using the Transonic device. The two methods were compared with CDU performed on a non-HD day. AVF flow rate was expressed as ml/min/1.73 m2.
Results: Sixteen measurements of AVF flow rate and recirculation with UD and TD were compared with CDU in 16 patients with a median weight of 39 kg. Both UD and TD overestimated AVF flow rate when compared with CDU (+437 (95% CI + 200, + 674) and + 476 (95% CI + 80, + 871) ml/min/1.73 m2 for UD and TD, respectively). CDU flow rate was significantly correlated to UD flow rate (r2 = 0.761, p < 0.001), but not to TD flow rate (r2 = 0.164, p = 0.120). Although recirculation in all AVF was estimated to be 0% and < 15% with UD and TD, respectively, 7 significant stenoses were diagnosed by CDU. AVF with stenosis had lower flow rates when measured by CDU, UD or TD, but only CDU measurements reached statistical significance (p = 0.008, p = 0.142 and p = 0.174, respectively).
Conclusion: UD and TD overestimate AVF flow rate when compared with CDU, which is the most reliable non-invasive method for screening vascular access for stenosis. UD seems more accurate than TD for AVF flow rate assessment. Recirculation via UD or TD should not be used for early screening of AVF stenosis in children on HD.
Keywords: AVF; Color Doppler ultrasound; Pediatric; Thermodilution; Ultrasound dilution.