Physical examination versus normalized pressure ratio for predicting outcomes of hemodialysis access interventions

The ratio of intragraft venous limb pressure (VLP) to systemic pressure (S) has been proposed to help determine the endpoint of hemodialysis access interventions. It was hypothesized that physical examination of the access could be used in the same way and these techniques were compared as predictors of outcome.

With use of a quality-assurance database, records from 117 hemodialysis access interventions were retrospectively reviewed. Only interventions in grafts were included. The database included physical examination (to establish thrill, thrill with slight pulsatility [TSP], pulse with slight thrill [PST], and pulse) at three locations along the graft (proximal, midportion, and distal), normalized pressure ratio calculated with S from a blood pressure cuff (S(cuff)) and S within the graft with outflow occluded (S(direct)), graft configuration and location, indication, operator, and time to next intervention (outcome of primary patency). Only procedures with complete follow-up data were included in the analysis (n = 97; declotting, n = 51; prophylactic percutaneous transluminal angioplasty [PTA], n = 46). Statistical analysis was performed with use of Cox proportional-hazards regression.

Graft configuration, location, side, VLP, S(direct), and S(cuff) did not affect outcomes. An operator effect was noted for two physicians and was adjusted for in all analyses. Pressure ratios were weak predictors of outcome (VLP/S(direct), P =.07; VLP/S(cuff), P =.08) and suggested that patency increased with increasing pressure ratio, contrary to earlier studies. Procedure type predicted outcome (declotting, median patency of 50 days; PTA, median patency of 105 days; P =.01). Thrill at distal physical examination was predictive of outcome (P =.04) and even more so when thrill and TSP combined were compared with PST and pulse combined (P =.03). Similar but less-pronounced effects were seen at midportion and proximal physical examinations.

The presence of a thrill or slightly pulsatile thrill at the distal (venous) end of a dialysis graft is the best predictor of outcome after percutaneous intervention. Based on the present study, the authors believe that physical examination of dialysis access should supplant pressure measurements as an endpoint of intervention and should serve as an essential component of quality assurance of access interventions.