G Zasuwa, S Frinak, A Besarab, J Yee. Henry Ford Health System, Detroit MI, U.S.

Poster presented at the 2005 American Nephrology Society Meetings

BACKGROUND: Vascular access thromboses result in missed treatments (Tx), disrupted patient Tx schedules and reduce dialysis facility revenues. Detection of hemodynamically significant stenoses should reduce vascular access thrombosis rates (VATR). Adoption of KDOQI Vascular Access Surveillance (VAS) Guidelines by hemodialysis centers is anticipated to reduce VATR, while duplex ultrasonography (DU) stenosis detection does. DU is cost-prohibitive for large-scale implementation. Consequently, we developed an algorithm that derived access pressure ratios (intra access pressure/MAP) Vasc-Alert and explored the following hypothesis: Vasc-Alert usage followed by referral for correction decreases VATR.

METHODS: A single dialysis center contributed data from 07/2003 through 05/2005 for analysis. Tx with permanent and temporary catheters were excluded. Baseline data were accrued from 06/03-12/03 and data were analyzed at 6-mo intervals by linear regression and results expressed as means +/- s.e.m.

RESULTS: A total of 48,678 Tx were analyzed by the Vasc-Alert surveillance algorithm. The baseline VATR prior to the completion of Vasc-Alert implementation equaled 0.06 +/- 0.12. A persistent and steady decline of VATR was demonstrated during interval follow-up: 0.54 +/- 0.12, 0.33 +/- 0.11 and 0.21 +/- 0.05 (linear regression: = -0.18; R = 0.41; P = 0.048). The last VATR mean approaches the previously reported minimum VATR (Besarab et al. Kidney Int. 47:1364-1373,1995).

DISCUSSION: We conclude that Vasc-Alert surveillance reduces VATR in a heterogeneous dialysis population. The largest dataset compiled from each patient with Vasc-Alert facilitates large-scale trend analysis that is unavailable with current existing technologies.

Vascular access thromboses result in missed treatments (Tx), disrupted patient Tx schedules and reduce dialysis facility revenues. Adoption of KDOQI Vascular Access Surveillance Guidelines by hemodialysis (HD) centers is anticipated to reduce the vascular access thrombosis rate (VATR) by detecting hemodynamically significant stenoses, thereby permitting appropriate "elective" intervention prior to vascular access thrombosis. Methods of VAS include access flow, duplex ultrasonography (DU) and some form of intra-access pressure monitoring. DU is cost-prohibitive for large-scale implementation. We have developed an algorithm that derives intra-access pressure ratios (intra-access pressure / MAP) from routinely collected venous drip chamber pressure and blood pump setting (Vasc-Alert) and explored this hypothesis: Vasc-Alert usage, followed by referral to a vascular surgeon for correction, reduces VATR.

• Thrombotic events for native fistulas and synthetic grafts were tracked for 24 months in a large urban dialysis center.
• The inability to cannulate, obtain blood flow from a permanent access, with consequent inability to perform HD was defined as a thrombotic event.
• Vascular access surveillance was introduced in the first 6-month period and utilized until the present time.
• Thrombotic events were calculated using the following considerations:
• Event rate = [Thrombotic events / Tx No.] in a specified interval of time = VATR
• Rate per treatment year (events / pt-yr) = VATR x 156 ( assuming 12 treatment months with 13 treatments per month)

To determine if access surveillance benefits can be demonstrated in reducing the vascular access thrombosis rate in a large urban dialysis center.

Monthly date is shown (Table 1). An average of 96 +/- 7 graft and 69 +/- 5 fistula patients were treated each month. During the study 104 grafts and 30 fistulas thrombosed. Baseline VATR for 6 months prior to the completion of Vasc-Alert implementation was during interval follow-up periods (Table 2 and Figure 1.)

We conclude that access pressure surveillance with Vasc-Alert reduces VATR in a heterogeneous dialysis population. The large dataset compiled from each patient with Vasc-Alert facilitates large-scale trend analysis that is unavailable with current existing technologies. Aggressive monitoring provided with each "treatment pressure surveillance" reduces thrombotic events in the treatment setting.

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