Our prospective study shows that the relationship between Qa of AVFs and CO is complex and a third-order polynomial regression model best fits this relationship. Furthermore, it is the first study to clearly show the high predictive power for high-output cardiac failure occurrence of Qa cut-off values >or= 2.0 l/min.

Clinically there are some autogenous arteriovenous fistulas (AVFs) that are obviously mature. The real problem in clinical evaluation is in predicting the ultimate outcome of AVFs that are not clearly mature. Thus it would be advantageous to develop objective quantitative criteria to be applied early after vascular access placement in order to evaluate the suitability of AVFs for dialysis. The goal of this study was to document the blood flow rate modifications that the construction and maturation of a radiocephalic wrist AVF produce in the brachial artery by means of duplex Doppler ultrasonography. All incident uremic patients who needed the construction of a radiocephalic wrist AVF in the last 9 months of 2003 were enrolled in the study: 18 patients underwent such an operation. A linear color Doppler ultrasound scan was performed with a 7.0 MHz imaging/5.0 MHz Doppler probe by sampling the brachial artery 2 cm above the elbow: the internal diameter of the artery was measured and its blood flow rate calculated just before AVF construction and 1, 7, 28 days, and at least 6 months after AVF construction. The internal diameter and blood flow rate of the brachial artery were, respectively, 4.3 +/- 0.7 mm and 56.1 +/- 19.2 ml/min at baseline. A new AVF was constructed in one patient whose brachial artery blood flow rate was 80.0 ml/min at 28 days. When excluding this AVF, the mean brachial artery blood flow rate of the 17 AVFs was 720.4 +/- 132.8 ml/min (median 750 ml/min, range 480-890 ml/min) at 28 days and 997.6 +/- 259.7 ml/min 258.0 +/- 63.0 days after AVF construction. When analyzing the percent increase in brachial artery blood flow rate of the 17 AVFs at the different time points, the most dramatic one occurred at day 1 compared to the baseline (549.0%; mean blood flow rate at day 1, 365.0 +/- 129.3 ml/min). Thus the blood flow rate at day 1 represents more than half (50.7%) of the blood flow rate that will be measured at day 28. Then the increase was less steep, with a 20.1% increase between day 7 and day 1 (mean blood flow rate at day 7, 438.4 +/- 86.0 ml/min), a 64.3% increase between day 28 and day 7, and a 38.5% increase at 258.0 +/- 63.0 days compared to 28 days. The present study was able to document the changes in brachial blood flow rate consequent to a radiocephalic wrist AVF maturation by means of duplex Doppler ultrasonography of the brachial artery. This measure may be helpful in monitoring which AVFs will probably fail. This screening should integrate clinical assessment, thus allowing sound judgment of the level of maturation of an AVF and of its outcome.

No abstract

Vascular access (VA) is the lifeline for the hemodialysis patient and the native arterio-venous fistula (AVF) is the first-choice access. Among the different tests used in the VA domain, color Doppler ultrasound (CD-US) plays a key role in the clinical work-up. At the present time, three are the main fields of CD-US application: (i) evaluation of forearm arteries and veins in surgical planning; (ii) testing of AVF maturation; (iii) VA complications. Specifically, during the AVF maturation, CD-US allows to measure the diameter and flow volume in the brachial artery and calculate the peak systolic velocity (PSV) of the arterial axis, anastomosis and efferent vein, to detect critical stenosis. The borderline stenosis, revealed by the discrepancies between access flow rate and PSV, should be followed up with subsequent tests to detect progression of stenosis; the cases with significant changes in brachial flow should be referred to angiography. In conclusion, clinical monitoring remains the backbone of any VA program. CD-US is of utmost importance in a patient-centered VA evaluation, because it allows the appropriate management of all aspects of VA care. These are the main reasons why we strongly advocate the adoption of a VA surveillance program based on CD-US.

A relatively "fixed" and individual osmolar setpoint in HD patients was shown for the first time in a long-term follow-up. A dialysate sodium concentration of 140 mmol/L determined a dialysate to plasma sodium gradient.