[The measurement of vascular access recirculation and intra-access pressure in arteriovenous fistula monitoring in hemodialysis]. / La misura del ricircolo e delle pressioni statiche dell'accesso vascolare nel monitoraggio delle fistole artero-venose in emodialisi.

BACKGROUND: The main objective of monitoring vascular access flow in haemodialysis is maintenance of adequate access blood flow (Qac ) to prevent underdialysis and detection of haemodynamically significant stenosis prior to thrombosis. METHODS: Recirculation and intra-access pressure were measured to monitor arteriovenous fistulae in a group of haemodialysed patients, for a period of six months. Vascular access blood flow measurements were taken at the first (t0), second (t1) and sixth month (t2) by recirculation measurements using the thermodilution technique (BTM) consistent with Krivitsky's theory. Intra-access pressure measurements were made using the simplified Besarab's method. RESULTS: No statistically significant differences were noted in recirculation, vascular access blood flow, cardiac output and intra-access measurements during the three periods of the study. Vascular access blood flow was significantly and positively correlated with the arterial blood pressure measured at the same time, but not with the intra-access and venous pressures. Data indicate that mean Qac values = 300 mL/m. and induced recirculation values (Rp) = 45 and = 50 are correlated with angiographic findings of vascular access dysfunction. We observed that patients with mean Qac values between 300 and 650 mL/m had negative angiograms. CONCLUSIONS: We conclude that calculation of access flow by the double recirculation technique is a better and earlier predictor of access dysfunction whereas intra-access pressure measurements are not as useful for this purpose.