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Predictive measures of vascular access thrombosis: a prospective study
R E May1, J Himmelfarb, M Yenicesu
1Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
Kidney International
|January 4, 1998
Summary
Low access blood flow in hemodialysis patients predicts PTFE graft thrombosis. Measuring access blood flow using ultrasound dilution or Doppler ultrasound is a reliable method for early detection of vascular access dysfunction.
Area of Science:
- Nephrology
- Vascular Surgery
- Medical Imaging
Background:
- Permanent vascular access malfunction is a common complication in chronic hemodialysis (CHD) patients.
- This complication leads to significant morbidity and healthcare costs.
- Routine monitoring for incipient failure is recommended, but effective methods are debated.
Purpose of the Study:
- To evaluate multiple indicators of incipient vascular access dysfunction in chronic hemodialysis patients.
- To assess the short-term predictive power of these indicators for access thrombosis.
- To identify reliable methods for screening polytetrafluoroethylene (PTFE) graft dysfunction.
Main Methods:
- Simultaneous evaluation of "venous" and "arterial" pressures, percent urea recirculation, Doppler ultrasound, and access blood flow by ultrasound dilution technique.
- Study included 220 vascular accesses in 170 CHD patients over two periods.
- Thrombosis rates were determined within 12 weeks; analysis focused on PTFE grafts due to low event rate in AVFs.
Main Results:
- Access blood flow, measured by ultrasound dilution (P=0.001) or Doppler ultrasound (P=0.001), was significantly lower in grafts that thrombosed.
- Ultrasound-determined stenosis grade was a significant predictor of thrombosis (P=0.02).
- Multivariate analysis revealed decreasing access blood flow as the primary risk factor for thrombosis (RR=2.39 at 300 ml/min).
Conclusions:
- Access blood flow measurement by ultrasound dilution or Doppler ultrasound is a reliable indicator of short-term thrombosis risk in PTFE grafts.
- Other evaluated methods, including pressure monitoring, were not useful predictors in this cohort.
- Cost-effective, user-friendly devices for measuring access blood flow could establish it as the preferred screening method for PTFE vascular access dysfunction.