Correlation of venography, venous pressure, and hemoaccess function

Abstract

We analyzed the anatomic features of both grafts and fistulas and correlated these features with access function. We also attempted to determine venous pressures predicting access dysfunction (critical venous pressures) at various blood flow rates (BFRs). Therefore, accesses of 46 chronic hemodialysis patients were studied by venography in a prospective fashion. We defined the incidences of various lesions and the effects of venous collaterals on graft function, and determined critical venous pressures at various BFRs. Eighty-three percent of the accesses had outflow obstruction. Five types of anatomic lesions were identified. The incidences were venous stenosis of the draining vein immediately proximal to the venous anastomosis, 38.4%; central vein, 23.6%; venous anastomosis, 25.5%; arterial anastomosis, 10.9%; and intragraft hyperplasia, 3.6%. Twelve patients had multiple lesions. When the homogenous polytetrafluoroethylene arm graft population was studied for the effect of venous collaterals, we found that venous collaterals conferred protection but did not prevent graft failure. Venous pressure measurements were good predictors of access failure at the lower BFRs. Venous pressures increased with increasing BFRs. A critical venous pressure of 145 mm Hg was found for a BFR of 250 mL/min. At a BFR of 300 mL/min, the critical venous pressure was 170 mm Hg. A critical venous pressure could not be found for a BFR of 400 mL/min.