[Color-Doppler imaging and arteriovenous fistula: preoperative evaluation and surveillance]. / Eco-color-Doppler e fistola artero-venosa: utilizzo pre e post-chirurgico.

The native arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis because of the lower incidence of complications and longer survival in comparison to grafts and central venous catheters. The use of color-Doppler sonography in the surgery of vascular accesses has increased the number of patients that are eligible for AVF as it allows to optimize the search for vessels suitable for surgical intervention (preoperative vascular mapping). Furthermore, color-Doppler imaging (CDI) has improved the survival of native AVF by increasing the early diagnosis of complications (postoperative surveillance). CDI is the only imaging technique able to provide both morphological and functional information about native vascular access and it is the only tool directly available to the nephrologist. This aspect is undoubtedly an additional value. Here we present a survey of the applications of CDI in the surgery and followup of AVF, with particular reference to preoperative mapping, AVF maturation and surveillance.

Hyporesponsiveness to erythropoiesis-stimulating agents and renal survival in non-dialysis CKD patients.

BACKGROUND: Lower responsiveness to erythropoiesis-stimulating agents (ESA-R) predicts cardiovascular (CV) events. Whether ESA-R also affects the risk of end-stage renal disease (ESRD) is unknown. METHODS: We evaluated ESA-R in 194 consecutive chronic kidney disease (CKD) patients, regularly seen in outpatient nephrology clinics, who started erythropoiesis-stimulating agent (ESA) therapy between 2002-06. Exclusion criteria were causes of anaemia other than CKD or recent transfusion. ESA-R was calculated as (Hb1-Hb0)/time/ESA dose (g/dL/month/10 µg/week of ESA). Patients were classified, from lower to higher tertile of ESA-R, as poor, intermediate and good responders. Time to ESRD was the primary outcome. RESULTS: Age was 64±16 years, 48% were male, 34% had diabetes and 32% had CV disease, glomerular filtration rate (GFR) 24±13 mL/min/1.73 m2 and proteinuria 0.6 g/dL (interquartile range 0.2-1.9). First ESA dose was 23.7±10.8 µg/week; haemoglobin (Hb) increased from 9.9±0.8 g/dL to 11.0±1.2 g/dL at first control, obtained after 1.4±0.4 months. These changes corresponded to an ESA-R of 0.37±0.38 g/dL/month/10 µg/week of ESA and tertiles limits were 0.17 and 0.47. Poor responders were younger and had lower GFR and higher proteinuria than intermediate and good responders. During the first 6 months of ESA therapy, poor responders showed lower Hb levels and sustained longer periods of Hb level<11 g/dL. During follow-up (median 3.0 years), 99 patients reached ESRD. At multivariable Cox's analysis, poor responsiveness was associated with higher risk of ESRD (hazard ratio 2.49, 95% confidence interval 1.28-4.84). CONCLUSION: ESA-R predicts renal prognosis in CKD patients followed in nephrology practice, where ESRD is the predominant outcome and ESA is commonly used at low dose.