1.5 Renal Dialysis Fistulas & Grafts Flashcards
What is the most common Brescia-Cimino fistula presentation?
Anastomosing the side of a radial artery to the end of a cephalic vein. (most common)
or
The brachial artery to cephalic or basilic vein
Reasons for doppler Ultrasound? (9)
- Inadequate dialysis
- Thrombosed access
- Perigraft mass
- UE welling
- Decreased thrill or pulse
- Suspected steal
- Infection
- Bleeding
- Post revison follow up
What are the methods of evaluation?
3) (one more common
Most common = Duplex ultrasound
Arteriography
Fistulography
What frequency probe is preferred for duplex ultraosund
10-12Mhz
Do you want high or low flow settings for the Ultrasound?
High
Why do you need to decrease color gain?
To minimize bruit
What position should the patient be in for duplex ultrasound
Supine
What does the doppler angle need to be?
60 degrees
Record PSV at the native artery prox, the ______, ___,____, _______ (4)
arterial anastomosis, graft, venous anastomosis, venous outflow
With an AV fistula how many sites should be sampled distal to arterial anastomosis?
2-3 sites
What is the volume flow rate formula?
Volume flow rate (q) ml/min = TAV (Time average velocity) x area (cross sectional area of the vessel) x 60 (60 seconds)
Q= TAV x area x 60
To rule out steal from native circulation with duplex what do you look for?
Retrograde flow in the inflow artery distal to the anastomosis
Which vessel is there a high occurrence of thrombus in dialysis graft patients?
Subclavian vein
Which exam is used to rule out central vein thrombosis?
UE DVT scan
What does a normal Arterial limb waveform look like?
1) High velocity
2) continuous forward flow through diastole
3) Marked spectral broadening
What does a normal venous limb waveform look like?
1) slightly lower velocity than arterial
2) most common site of stenosis/ thrombosis
What is the Normal PSV for grafts/AV fistulas
PSV= 100-400 cm/s
What is the Normal EDV for grafts/AV fistulas
EDV= 60- 200 cm/s
Normal grafts and AV fistulas have ____ flow and ____ resistance
high;low
will color flow be seen in an graft with an occlusion?
No
With an occlusion There will be no flow in vein_______ to the fistula
distal
_________ resistance flow will be seen in the artery leading to the graft or fistula
High
____ venous outflow with an occlusion from a graft or fistula
low
> 50% stenosis in GRAFT & FISTULA has a PSV of greater than..
> 400 cm/s
> 50% stenosis in GRAFT & FiSTULA has a velocity ratio of greater than…
> /= 2:1
> 75% stenosis in GRAFT& FISTULA has a velocity ratio of greater than…
> /= 3:1
Velocity values may be unreliable due to variations in vein _________ and limited when estimating doppler angle in __________fistuala’s anastomosis
diameter; tortuous
Graft Flow volume with poor dialysis, pending graft failure
<300 ml/min
Graft Flow volume < 500ml/min means?
Increased risk of graft failure
Graft Flow volume & AV FISTULA normal range?
> 800 ml/min
Graft Flow volume with possible congestive heart failure?
> 1500 ml/min
AV fistula adequate dialysis has a flow volume of greater than _____ with _____mm outflow vein
500; 4
What is the most common abnormality in renal dialysis, fistulas and grafts
Venous anastomosis stenosis (50-90%)
Other abnormalities include in renal dialysis, fistulas and grafts(8)
- Venous outflow obstruction
- Pseudoanerysm
- Diffuse aneurismal dilation
- hematoma
- perigraft abcess
- Hematoma
- Intimal flaps (from needle punctures)
- Arterial anatomic stenosis (15%)
Ultrasound maybe used to identify/monitor grafts and lesions as well as (3)
- baseline exam for F/U studies
- Assess maturity of an AV fistula/graft
- Identify grafts in jeopardy of failure
