Practical utility of thermodilution versus doppler ultrasound to measure hemodialysis blood access flow.

ABSTRACT

INTRODUCTION: The current clinical guidelines recommend indirect access blood flow (Qa) measurement as one of the most important components in vascular access maintenance programs. The best-know methods are doppler ultrasound (DU) and saline dilution method. OBJECTIVE: This study evaluates the efficiency of Qa measurement with thermodilution method (TD) in comparison with the DU. MATERIAL AND METHODS: Transversal study in 64 patients in hemodialysis (41 men); mean age 59.9 years with 54 AVFs and 10 PTFE. Qa reference value was obtained with DU in brachial artery (AVFs) or at the zone of arterial puncture (AVGs). Bland-Altman and interclass correlation coefficient (ICC) were used to study accuracy. RESULTS: Mean values obtained with DU-Qa were 1426 ± 753 mL/min AVFs and 1186 ± 789 mL/min AVGs. The mean Qa with TD was 1372 ± 770 AVFs (bias 54.6; ICC 0.923) and 1176 ± 758 AVGs (bias 10.2; ICC 0.992). In the subgroup of 28 patients with radiocephalic latero-terminal AVFs the DU-Qa was 1232 ± 767 mL/min. The Qa was in radial artery 942 (ICC 0.805); radial-ulnar artery 1103 (ICC 0.973); cephalic vein 788 (ICC 0.772) and TD 1026 (ICC 0.971). We detected 5 cases of significant stenosis. After endovascular treatment the Kt was 79 liters (61; p=0.043) and TD-Qa 895 mL/min (663; p=0.043). CONCLUSIONS: TD represents a good indirect method of Qa measurement. In the subgroup of patients with radiocephalic AVFs, Qa measurements in the radial and ulnar artery are more accurate. Therefore, in this situation the TD method obtained an excellent correlation in comparison to brachial artery.