Cheat Sheet

This is a ultrasound cheat sheet for your reference. Enjoy.

ABI Criteria

  • ABI > 0.9 to 1.3 is considered normal. Some labs interpret ABI 0.9 to 1.0 as borderline
  • Resting ABI of 1.3 or greater is considered non-compressible. Some institutions use the value of 1.4
  • ±0.15 in ABI is considered normal variance in measurement, not true change in ABI

Criteria for positive exercise treadmill ABI:

  1. Absolute ankle pressure drop 20 mmHg or more
  2. Ankle pressure drop 20% or more
  3. ABI decrease 0.2 more more
  4. Failure of ankle pressure to return to baseline in 3 minutes after rest

Lower Extremity Velocity Criteria

Pre-stenosis to stenosis ratio > 2.0

AV Fistula

  • Ideal flow 800 to 1200 mL/min
  • Flow volume calculated by cross section area x time-averaged velocity x 60 seconds
    • < 450 mL/min Poor dialysis, patency limited for prosthetic graft, although native AVF may remain patent
    • > 500 mL/min Normal AVF
    • > 700 mL/min Normal AV graft
    • > 1400 mL possible high output heart failure
  • Anastomotic velocity greater than 400 cm/s with Vr > 3.0 (ratio between highest anastomotic velocity and inflow artery PSV 2 cm proximal to anastomosis) suggests >50% stenosis
  • Other segments with PSV 300-400, EDV > 240, and Vr of > 2.0 is suggestive of a >50% stenosis