Introduction:

Measurement of vascular access flow through dilutional methods requires retrograde puncture of the arterial needle. The latest cannulation recommendations defend the antegrade puncture.

Aim:

Quantify the measurement error due to the anterograde puncture and analyse its clinical repercussion.

Material and Method:

Multicentric cross-sectional study. Flow measurements were analysed with Termodilution and dilutional Ultrasonography in antegrade and retrograde punctures. We used the Bland-Altman method, the intraclass correlation coefficient and the Kappa index for contrast with Eco-Doppler.

Results:

Thirty-seven fistulas were analysed. The anterograde puncture with respect to the retrograde one generated measures that overestimated the diagnosis by 65% with Thermodilution and 59% with Dilutional Ultrasonography. The intraclass correlation coefficient was 0.831 for Thermodilution and 0.724 for Dilutional Ultrasonography. The degree of clinical agreement between both types of puncture, to classify fistulas with flow less than 500ml/min, was 95% (Kappa Index = 0.841) for Thermodilution and 91% (Kappa Index = 0.760) for Dilutional Ultrasonography. The degree of agreement, according to the antegrade and retrograde puncture (respectively), with Eco-Doppler was 86% (Kappa Index=0.586) and 92% (Kappa Index=0.720); and with Termodilution and Dilutional Ultrasonography of 78% (Kappa Index=0.349) and 81% (Kappa Index=0.400).

Conclusions:

The anterograde puncture presents a significant bias increasing in high flows. Clinically, the degree of agreement with both dilutional methods in different types of puncture and Eco-Doppler indicate a good tool as a discarding intervention.