Blood Flow May Affect Graft Survival Rates
Post-PTA flow greater than 600 mL/min lessens graft failure at one year.
“This is one of the first studies of its kind and these findings are important because they identify a predictor and may help improve the management of these patients,” said Maxim Itkin, MD, assistant professor of radiology at the
“Eventually every graft fails and the idea is to maintain the patency as long as possible, and this [approach] may help with that.” He presented findings here at the Society of Interventional Radiology annual meeting.
The end point of preventive maintenance and flow restoration procedures in hemodialysis access can be determine by physical exam, angiographic appearance, and/or intra-access pressure, he explained. The relative values of these criteria remain uncertain, however. He and his colleagues used a thermodilutional catheter to measure blood flow at the end of interventional procedures.
For their study, they screened all patients referred for hemodialysis access maintenance procedures between February 2003 and September 2005. Access blood flow was measured at the beginning and end of percutaneous transluminal angioplasty (PTA).
A total of 60 patients were screened and 47 patients were enrolled. Of these, 45 patients (26 females and 19 males) were available for analysis. Their mean age was 59 years. Thirty-seven patients had grafts and eight had fistulas.
The mean access flow, pre-procedure, was 786 mL/min and 1,077 mL/min after PTA, a 37% increase. The mean graft flow was 772 mL/min pre-procedure and 1,035 mL/min post-procedure. Mean fistula flow was 849 mL/min pre-procedure and 1,249 mL/min post-procedure.
The researchers observed a statistically significant difference in graft survival at one year between patients with blood flow over 600 mL/min post-procedure compared with flow below 600 mL/min. Fistula group survival analysis could not be performed because of the small sample size, he said.
The mean time period between blood flow measured at dialysis and catheter-based flow was 39 days pre-procedure and 38 days post-procedure. The researchers found a strong correlation between blood flow at hemodialysis and catheter-based flow before and after the procedure.
Dr. Itkin said these findings are in line with guidelines from the National Kidney Foundation's Kidney Disease Outcome Quality Initiative (K/DOQI), which state that a patient should be referred for fistulography if flow is below 600 mL/min or less than 1000 mL/min and decreased by 25% during a four-month period.