Duplex Evaluation of Hemodialysis Access

Hemodialysis

treatment for kidney failure that uses a machine to send the patient’s blood through a filter, called a dialyzer, outside the body

arteriovenous (AV) fistula

connecting an artery to a nearby vein, may take weeks to months before it is mature enough to use

arterial needle

carries the blood away from the body in a AVF fistula in the forearm

venous needle

needle that carries blood back to the body

radiocephalic fistula

anastomosis between the radial artery and the cephalic vein at the wrist

most preferred AVF placement

radiocephalic fistula

brachiocephalic fistula

anastomosis of the brachial artery and cephalic vein near the antecubital fossa

basilic vein transposition

anastomosis of the basilic vein to the brachial artery at the antecubital fossa

AV graft

(a piece of manmade tube) – sewn between an artery and a vein if a fistula is not available; usually ready to use in a few weeks

most common to have infections and clotting

arteriovenous graft

venous catheter

this may be used if neither a fistula nor a graft works for the patient or on a temporary basis (short-term hemodialysis)

symptoms of access dysfunction

• aneurysm

• arm edema

• venous dilation

• prolong bleeding

downstream

blood moving away from the anastomosis

inflow

blood going towards the anastomosis

palpation/pulsatility

compressible with little pulse

hyperpulsatility

indicates downstream resistance (venous stenosis)

hypopulsatile

suggest inflow stenosis (arterial stenosis)

thrill

palpable vibration “buzz”; indicates flow

normal thrill

continuous (systolic & diastolic) thrill

absent thrill

lack of flow; thromboses/clotted access

bruit

auditory manifestation of a thrill

normal bruit

low-pitched, soft rumbling, machinery-like sound

abnormal bruit

higher pitch

mature AVF

at least 4 mm with a volume flow > 500 mL/min and no evidence of narrowing

normal hemodialysis access

• Vessels as well as fistula or graft are free of internal echoes • PSV measurements between 150 to 300 cm/s
• Low resistance waveforms with high diastolic flow
• Intact fistula or graft walls

• High volume flow (>500 mL/min)

diseased hemodialysis access

stenosis at the anastomosis sites or within the vein itself