Proactive monitoring of pediatric hemodialysis vascular access: effects of ultrasound dilution on thrombosis rates.

Background: Hemodialysis vascular access thrombosis (VAT) is a significant cause of morbidity for hemodialysis patients and results, in part, from decreased access flow potentially caused by venous outflow stenosis. We have previously shown ultrasound dilution (UD) to be a practical and reliable predictor of venous outflow in children receiving hemodialysis.
Methods: The current study is the first to our knowledge to assess the impact of a proactive UD monitoring program upon VAT in pediatric patients. Nine patients experienced 18 VAT over the two-year study. Mean values for variables potentially associated with VAT were compared to values from a size-matched seven patient group without VAT during the study period. VAT rates were compared between the year-before (pre-UD era) and year-after (UD era) UD was initiated. During the latter half of the UD era (rapid referral period), patients with VA flow rate (QAcorr) <650 mL/min/1.73 m2 were referred for balloon angioplasty within 48 hours.
Results: Mean QAcorr was lower for patients with subsequent VAT (562 +/- 290 mL/min/1.73 m2) versus patients without VAT (1005 +/- 372 mL/min/1.73 m2; P = 0.02). The VAT rate was significantly lower in the UD era (4.1 VAT/100 patient-months) versus the pre-UD era (11.0 VAT/100 patient-months; P = 0.03). The decrease in VAT rates was caused predominantly in the rapid referral period, where the VAT rate dropped to 0.96 VAT/100 patient-months (P < 0.001). Cost of vascular access management was 65% higher ($1264 vs. $765/patient-month) in the pre-UD era, reflecting the increased cost for treatment of VAT.
Conclusions: Monthly QAcorr <650 mL/min/1.73 m2 is predictive of imminent VAT in children receiving hemodialysis. Prompt referral for angioplasty of VA with QAcorr <650 mL/min/1.73 m2 leads to decreased VAT rates in children.