Blood flow dynamics in patients with hemodialysis access-induced hand ischemia

Objective: Hand ischemia may occur in the presence of a hemodialysis arteriovenous fistula (AVF), but its pathophysiology is partly unclear. The aim of this observational study was to investigate flow characteristics of forearm arteries in patients with a brachial artery-based AVF suffering from hemodialysis access-induced distal ischemia (HAIDI). Methods: A questionnaire scored hand ischemia in patients with HAIDI scheduled for revisional surgery (no symptoms of ischemia, 0 points; maximal ischemia, 500 points). Systolic index finger pressures (P-dig) and digital brachial index (DBI) were determined with open and compressed AVF. Blood flow direction and peak systolic velocity (PSV) were measured in radial and ulnar arteries using Doppler ultrasonography. Age-and sex-matched hemodialysis patients without HAIDI served as controls (CONT). Results: Questionnaire scores were 258 +/- 30 in patients with HAIDI (n = 10) compared with 31 +/- 16 in CONT (n = 10; P <.01). P-dig and DBI with open AVF were lower in the HAIDI group than the CONT group (P-dig 22 +/- 10 vs 102 +/- 10 mm Hg; DBI 0.18 +/- 0.08 vs 0.70 +/- 0.04; both P <.01). Ulnar artery PSV was lower in HAIDI compared with CONT patients (38 +/- 4 vs 56 +/- 3 cm/s; P <.01). Mean ulnar artery PSV was significantly correlated to P-dig (r = 0.87; P <.01) in contrast to mean radial artery PSV (r = 0.06; P = .81). Ulnar artery blood flow direction was always toward the ischemic hand (n = 20). However, blood flow was reversed in just a short segment of the proximal radial artery in one HAIDI patient but also in two CONT patients. Conclusions: Hand ischemia in hemodialysis patients with a brachial artery-based AVF is not caused by a reversed blood flow direction in forearm arteries. However, forearm blood flow is diminished in these patients leading to critically reduced arterial pressures in the hand.