Introduction:

Doppler ultrasound and dilutional methods allow monitoring of vascular access flow. The presence of collateral veins may influence the determination of vascular access flow.

Objective:

To determine the influence of collateral veins on the vascular access flow measurement by Doppler ultrasound and by the thermodilution method.

Material and Method:

Observational and prospective study. Native arteriovenous fistulas that met the selection criteria were selected. An annual measurement of vascular access flow by Doppler ultrasound and two quarterly thermodilution measurements (thermodilution-1 and thermodilution-2) were performed. Ultrasound was used to determine the presence of collateral veins.

Results:

Thirty-eight native arteriovenous fistulae were analysed. Males accounted for 78.9% of the sample. Collateral veins were present in 23.6% of cases. Analysing the whole sample, a linear correlation was obtained between ultrasound-Doppler flows with thermodilution-1 (0.694) and thermodilution-2 (0.678), (both p<0.001). When stratified by collateral veins, when no collateral veins were present, there was a significant correlation between Doppler ultrasound with thermodilution-1 (0.698) and thermodilution-2 (0.696) (both p<0.001)); whereas the correlation was non-significant when collateral veins were present.

Conclusions:

There is correlation between vascular access flow measurement obtained by Doppler ultrasound and thermodilution; the presence of collateral veins modifies such relationship. It is necessary to implement vascular access surveillance programs that include different monitoring methods in order to mitigate the effect of collateral veins on vascular access flow determination.

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