[Study of vascular access (VA) by color Doppler ultrasonography (CDU). Comparison between delta-H and CDU methods in measuring VA blood flow rate].

INTRODUCTION

The color Doppler ultrasonography (CDU) is a noninvasive vascular access (VA) monitoring technique that provides both structural and hemodynamic information from VA. On the other hand, the delta-H (AH) method is another noninvasive technique that measures the VA blood flow rate during hemodialysis (HD).

OBJECTIVE

1. To analyze some anatomic and functional parameters of VA by CDU. 2) To compare AH and CDU methods in measuring VA blood flow rate.

PATIENTS AND METHODS

We explored the VA (radial arteriovenous fistula AVF 60.6%, brachial AVF 24.2%, femoral graft 15.2%; mean VA duration 33.5 +/- 31.5 months) of 33 stable ESRD (mean age 61.7 +/- 13.3 yr, sex M: 48.5%; F: 51.5%; mean time on hemodialysis HD 39.3 +/- 33.3 months; 9.1% diabetes) patients (pts) by CDU over 3 months period. All CDU examinations were performed off HD by the same radiologist using a 5-10 MHz linear transducer. The arterial and venous blood flow rates were calculated by CDU using the equation: flow (ml/min) = time average velocity (mean of three cardiac cycles) (m/s) x cross-sectional area (mm2) x 60. No VA explored had any sign of dysfunction prior to CDU evaluation. All pts with significant VA stenosis by CDU (> or = 50% reduction in the luminal diameter) were referred for angiography (AG). All functional parameters were measured in duplicate and the values were averaged. In addition, QA was also calculated in the same week by the deltaH method during HD using the Crit Line III Monitor.

RESULTS

Feeding artery (FA) results. Mean FA diameter (FAd): 0.7 +/- 0.2 cm. Mean peak systolic velocity: 161.8 +/- 44.5 m/s. Mean FA blood flow rate (FA flow) (n = 27): 2,030.8 +/-987.1 ml/min. We found a positive correlation between mean FA flow and mean FAd (R2 = 0.39, p < 0.001). Arterialized vein (AV) results. Mean AV diameter (AVd): 0.7 +/- 0.2 cm. Mean AV blood flow rate (AVflow): 1,783.8 +/- 1,009.7 ml/min (range, 398-5,843 ml/min). Mean coefficient of variation for duplicate AV flow measurements: 9.2%. We found a positive correlation between mean AV flow and: mean FAd (R2 = 0.22, p = 0.005), mean FAflow (R2 = 0. 19, p = 0.022) and mean AVd (R2 = 0.14, p = 0.034). Three pts (9.1%) showed significant VA stenosis by CDU and in, all cases, the location and degree of stenoses were confirmed by AG. The mean AVflow was lower in VA with significant stenosis (511.0 +/- 179.1 ml/min) compared to VA without stenosis (1,911.1 +/- 968.7 ml/min) (p = 0.006). The calculated values of VA blood flow rate obtained by the CDU technique (AV flow) were highly correlated with those determined by the AH method (QA) when considering all comparison values (n = 33, ICC = 0.74, p < 0.0001), for AV flow < 2,000 ml/min (n = 23, ICC = 0.82, p < 0.0001) and for AV flow < 1,500 ml/min (n = 14, ICC = 0.73, p = 0.001). No significant difference was found when QA (1,593.8 +/- 645.7 ml/min, range 559-2,778 ml/min) and AV flow were compared (p = 0.082).

CONCLUSIONS

1. The CDU technique is a valuable and reproducible method for AV flow measurement and for early diagnosis of significant VA stenosis. 2) The AV flow is related to FA parameters. 3) Both methods, CDU and AH, correlated highly with each other when were applied on VA blood flow rate measurement.