Static intra-access pressure ratio does not correlate with access blood flow

Area of Science:

• Nephrology
• Vascular Access Surveillance
• Medical Device Technology

Background:

• Kidney Disease Outcomes Quality Initiative (K/DOQI) recommends access flow (Qa) as the primary method for access surveillance.
• Static intra-access pressure ratio (SIAPR) is a secondary surveillance method.
• The study investigated the relationship between SIAPR and Qa to validate SIAPR's premise as a surrogate for low Qa indicating stenosis.

Purpose of the Study:

• To investigate the relationship between SIAPR and Qa.
• To examine if high SIAPR is a reliable indicator of low Qa associated with hemodynamically significant stenosis.

Main Methods:

• Prospective, multicenter study involving 242 patients with arteriovenous fistulas (AVF) and grafts (AVG).
• Simultaneous monthly measurements of SIAPR and Qa using K/DOQI protocols.
• Data collected from three centers over the study period.

Main Results:

• No correlation was found between SIAPR and Qa in either AVGs or AVFs.
• A significant percentage of high SIAPR measurements were associated with high Qa (>= 600 or >= 1000 mL/min).
• High-functioning AVGs (high Qa) were erroneously flagged for referral based on SIAPR criteria, misrepresenting their actual status.

Conclusions:

• SIAPR does not correlate with Qa and cannot reliably distinguish between high and low flow rates.
• Current K/DOQI SIAPR thresholds for intervention are not justified due to their lack of correlation with Qa.
• The use of absolute SIAPR thresholds for intervention should be discontinued; further studies on SIAPR trend analysis are needed.