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Reducing vascular access morbidity: a comparative trial of two vascular access monitoring strategies
Charmaine E Lok1, Cynthia Bhola, Ruth Croxford
1Department of Medicine, University Health Network, The Toronto General Hospital, Toronto, Canada. charmaine.lok@uhn.on.ca
Insights
The saline ultrasound dilution technique (Transonic) significantly reduced access thrombosis in dialysis patients compared to Duplex ultrasonography. This new monitoring strategy lowered thrombosis rates and decreased the need for procedures like angioplasty.
Area of Science:
- Vascular access monitoring in hemodialysis
- Clinical effectiveness of monitoring techniques
- Thrombosis prevention strategies
Background:
- Thrombosis is a major cause of failure for hemodialysis grafts and fistulas, leading to significant patient morbidity.
- Current interventions focus on maintaining access patency through early detection and treatment of lesions.
- The optimal monitoring strategy for preventing access thrombosis remains unclear.
Purpose of the Study:
- To compare the efficacy of Duplex ultrasonography and the saline ultrasound dilution technique (Transonic) in preventing access thrombosis.
- To identify risk factors associated with access thrombosis.
- To evaluate the performance of two distinct monitoring strategies over a three-year period.
Main Methods:
- A prospective, three-year study in a large dialysis center comparing monitoring strategies.
- Year 1: Duplex ultrasonography; Year 3: Transonic monitoring (Year 2: transition).
- Multivariate survival analysis was used to determine thrombosis risk factors and assess monitoring technique performance.
Main Results:
- The total thrombosis rate decreased from 1.01/1000 access days in Year 1 to 0.66/1000 access days in Year 3.
- This reduction was achieved with decreased rates of angiograms (55%), angioplasties (13%), and thrombolysis (31%).
- Low flow rates detected by Transonic monitoring correlated with increased thrombosis risk.
Conclusions:
- The saline ultrasound dilution technique (Transonic) demonstrated superior effectiveness in reducing access thrombosis compared to Duplex ultrasonography.
- Stenosis identified by Duplex ultrasonography was a weaker predictor of impending thrombosis.
- Different monitoring techniques may be best suited for specific clinical scenarios in managing vascular access.
Background:
Thrombosis is the primary cause of access failure in polytetrafluoroethylene grafts and arteriovenous fistulas. It can lead to significant patient and access morbidity and mortality, and is difficult to prevent medically. Intervention is largely limited to maximizing access patency by detecting culprit lesions early and intervening with angioplasty or surgical revision. The most efficacious monitoring strategy is undetermined.
Methods:
This 3 year prospective study took advantage of a change in monitoring strategy used in a large dialysis centre to compare the efficacy of two methods used to monitor grafts and fistulas in order to prevent access thrombosis. Accesses were monitored using Duplex ultrasonography in year 1, while the saline ultrasound dilution technique (Transonic) became the primary monitoring strategy in year 3 (year 2 was a transition year). Risk factors for thrombosis were determined using multivariate survival analysis, and the performance of Duplex ultrasonography and Transonic monitoring was assessed.
Results:
A total of 303 656 access days at risk were assessed, with 344, 385 and 425 accesses in years 1, 2 and 3, respectively. The total thrombosis rate was 1.01/1000 access days in year 1 compared with 0.66/1000 access days in year 3. This was accomplished despite a reduction in procedure rates of 55% for angiograms, 13% for angioplasties and 31% for thrombolysis.
Conclusion:
Low flow rates detected using Transonic monitoring were associated with increased thrombosis, while stenosis detected using Duplex ultrasonography was not a strong predictor of incipient thrombosis; however, these different access characteristics were compared using monitoring techniques that may be ideal in different clinical situations.
