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Published on: November 24, 2014
Predictive value of access blood flow and stenosis in detection of graft failure
E Wang1, D Schneditz, N W Levin
1Renal Research Institute and Division of Nephrology and Hypertension, Beth Israel Medical Center, New York 10128, USA.
Insights
Monitoring access flow trends is more effective than single measurements or stenosis degree in predicting hemodialysis graft failure. A declining access flow indicates a higher risk of graft dysfunction.
Area of Science:
- Nephrology
- Vascular Surgery
- Radiology
Background:
- Prophylactic angioplasty for hemodialysis grafts is often indicated by low access flow or high-grade venous stenosis.
- However, evidence suggests that angioplasty for >50% stenosis does not improve graft patency, and single flow measurements may be unreliable for predicting failure.
Purpose of the Study:
- To compare the efficacy of monthly access flow measurements versus maximal stenosis degree in predicting graft failure over a three-month period.
- To evaluate the trend of access flow decline as an indicator of graft dysfunction.
Main Methods:
- Thirty-nine hemodialysis patients with polytetrafluoroethylene (PTFE) grafts were monitored monthly for three months using Doppler ultrasound.
- Graft failure was defined as thrombosis or the need for revision due to access recirculation.
- Patients experiencing graft failure were observed for one month post-event.
Main Results:
- Twelve graft failures occurred within the three-month observation period.
- Significantly increased risk of graft failure was observed at access flows below 300 ml/min.
- Grafts failing in months two and three showed significant decreases in access flow (25.8% and 36.5% respectively), while stenosis levels did not significantly increase.
- Patent grafts maintained stable access flow and stenosis levels throughout the study.
Conclusions:
- Access flow is a more sensitive predictor of graft failure than stenosis degree.
- Analyzing the trend of declining access flow is a more powerful method for detecting graft dysfunction compared to single flow value measurements.
Aims:
Low access flow and the diagnosis of high degrees of venous stenosis have been recommended as indications for prophylactic angioplasty. However, recent studies have shown that prophylactic angioplasty for > 50% stenosis did not prolong graft patency, and that a single flow measurement may not accurately predict graft failure. In this study we compared the value of monthly measurement of access flow and of the maximal degree of stenosis in the detection of graft failure over a three-month period.
Methods:
Thirty-nine hemodialysis patients with polytetrafluoroethylene (PTFE) grafts were evaluated by Doppler ultrasound at monthly intervals for three months. Graft failures were defined as thrombosis, or surgical and angioplastic revisions required because of the presence of access recirculation, and patients with graft failure were followed within the subsequent one-month periods of observation.
Results:
Twelve graft failures occurred during the three-month period of observation. The risk for subsequent graft failure significantly increased at flows < 300 ml/min. Nine (20%) graft failures occurred with stenoses of 30 to 50%, and three (13%) with stenoses of> 50%. The grafts that failed in the second and the third study months had a 25.8% (380 +/- 62 vs. 287 +/- 190 ml/min, p < 0.05) and a 36.5% (393 +/- 142 vs. 226 +/- 41 ml/min, p < 0.05) decrease in access flow, respectively. There was no significant change in access flow for the grafts patent throughout the study (911 +/- 333, 794 +/- 302, and 919 +/383 ml/min, p = ns). No significant increases in maximal stenosis were found for the grafts that failed in the second month (44 +/- 6.1 vs. 48 +/- 15%, p = ns) and the third month (48 +/- 9 vs. 51 +/- 16%, p = ns). There were no significant changes in the maximum stenosis for the grafts patent throughout the three-month study periods (37 +/- 15,43 +/- 11, and 44 +/- 15%, p = ns).
Conclusions:
Access flow is a more sensitive predictor of graft failure than stenosis. Examination of trend in decline of access flow is a more powerful indicator to detect graft dysfunction than an individual single flow value.
