Renal Transplants & Dialysis

Atrophy, high resistance flow, RI usually >0.8

Describe medical renal disease

End-stage renal disease

What is hemodialysis usually used to treat

Filters waster from the blood through a semi-permeable membrane while being circulated outside the body

Describe how hemodialysis works

High flow in an easily accessed vessel

What is required for hemodialysis to work

Needs lots of flow to come out fast, filtered, and then get back in the patient fast

Why does hemodialysis require high flow

Tube goes into the peritoneum. The patient will has ascites and the tube will drain the fluid from the peritoneum. Then they will have filtered clear fluid go back into the patient

Describe peritoneum dialysis

Fluid will go out yellow and go back in clear

Describe the colour difference of the ascites fluid with peritoneum dialysis

Pt can do peritoneum dialysis at home but has to be responsible enough to do this whereas a pt doing hemodialysis will have to come into the hospital every few days

Describe the difference between peritoneum and hemodialysis

Hemodialysis

What does this image show

No, it is just kinda of a bandaid fix to buy the patient more time until they can get a kidney transplant

Is hemodialysis a permanent fix

Fistula or graft

What are the 2 different ways that doctors may alter the pts vasculature to allow them to have hemodialysis

Create an AV connection to facilitate high volume flow with superficial access

What does a fistula and a graft both accomplish

Direct anastomosis created between a artery and vein (have to go in surgically and create the fistula)

Describe a fistula

Lower complication rates

What is the advantage of fistulas

Lower rate of maturation and higher risk of thrombus

What is the disadvantages of fistulas

10 weeks

About how long does it take for a fistula to be ready to be used for hemodialysis

The artery will gradually make the vein bigger from the higher pressure flow going into it but needs to be nice big and juicy in order to do dialysis (bc it requires high flow)

Describe what causes the vein to enlarge after a fistula surgery and why it takes a while to mature

Fistula

What does this image show

Indirect connection created between artery and vein using graft material (introducing foreign body into body)

Describe a graft for dialysis

Higher rate of complication rates

What is the disadvantage of graft

Higher rate of maturation (pretty much ready to go right away) and lower risk of thrombus

What are the advantages of a graft

Bc will have higher flow right away (whereas the fistula may have some areas of low flow which can cause thrombus)

Why are grafts at a lower risk for thrombus formation

Graft

What does this image show

From high pressure artery to low pressure vein

Describe how the blood flows in grafts and fistulas

As distal as possible in the non dominant hand (like to start at the wrist)

Where do they usually to the grafts or fistulas

Groin but it affects day to day life so is last resource

What is another possible location for a graft or fistula

Starting at the wrist allows them to keep moving up if it fails. The kidney transplant list is long so they often have to keep going through fistulas and grafts

Explain why they usually start distally in the arm with grafts and fistulas

Cephalic V to radial A, basically V to radial A, upper arm connections (above the antecubital fossa)

What are the 3 major fistula types

Cephalic vein to radial artery

What fistula is more commonly preferred/most common

Brescia-cimino fistula

What is the name given to the cephalic vein to radial artery fistula

At the wrist

Where is a Brescia-Camino fistula located

Basilic vein to radial artery

What would be the next choice for a fistula

Above the ante cubital fistula

Where would an upper arm fistula be located

Brescia-Camino fistula

What does this image show

Forearm fistula

What does this image show

Av grafts

What does AVG stand for

AV fistula

What does AVF stand for

50%

What % of people is it not possible to make an AVF (fistula)

Graft

What would be used if a fistula is not possible in the patient

Teflon

What are the grafts usually made out of

PTFE or gortex

What are 2 examples of grafts commonly used

Straight graft

What does this image show

Loop graft

What does this image show

Assess artery and veins for fistula suitability

What is the purpose of us in the pre op assessment

Assess of stenosis, occlusion, or non-stenotic indications

What is the purpose of us in the post op assessment

Full UE arterial and venous study plus the vessels down into the forearm

What vasculature do we assess pre op

Radial and brachial

What arteries do we assess

Cephalic, basilic, medial cubital

What veins do we assess

Plaque, irregularities, atypical connections, vessel caliber, anatomical variants

What do we assess for pre op

At least 2mm

What is the mmt requirement for an artery if wanting to use it for fistula or graft

At least 2.5mm

What is the mmt requirement for a vein if want to use it as a AVF

At least 4mm

What is the mmt requirement for a vein if want to use it for a graft

True

T/F: the mmt for a vein is different depending if they are using a graft or fistula but the artery mmt is the same regardless which one they are planning on us using

Stenosis

What is the most common complication of an fistula or graft

At or within 2cm of the anastomosis of the graft/fistula

Where is the most common site for stenosis

Yes, but not that common bc tends to have a wide body

Can you also get a stenosis directly in the graft

Thrombosis of the graft

What is the most common cause of failure within the first month of a graft or fistula

Hyperplasia forming around the graft or vein which will obstruction the venous outflow

What is another cause of failure

Thrombosis downstream within the subclavian vein

What else may be see with a thrombus of the graft/fistula

All along the veins of the arm, not JUST where the graft/fistula is

Where in the body is at an increase risk for thrombosis after a fistula or graft

AVF maturity, pseudoaneurysm, hematoma, peri-graft abscess, aneurysmal fistula dilation

What are some non stenotic indications of post op assessment

500ml/min flow, >/=4mm, within 5mm of the skin surface

What are the 3 parameters of a AVF maturity

The fistula may get big enough that it can lead to dilation of the fistula due to the weak vein walls

Why is there an increase of anuerysmal fistula dilation over time

Aneurysmal dilation

What does this image show

Regular surveillance, pulsatile mass, decrease thrill, poor dialysis, arm edema, infection, arterial steel syndrome

What are some indications for a Doppler ultrasound

Highest frequency possible (9-12MHz)

What probe should you use

High flow settings, increase the scale and decrease the gain

How should you adjust your Doppler settings

Supine or sitting

What should the patient position be

Survey entire arm, assess pre/graft/fistula/post, document draining veins (bc increased risk of thrombus here)

Describe the graft and fistula ultrasound technique

Fistula diameter an depth from the surface

What should you measure in 2D

Tributaries

What else should you try to document in 2D

Colour bruit

Describe the normal colour

Low resistance before and within the graft with constant antegrade flow

Describe the waveform of the fistula and graft

Normal flow in fistula or graft

What does this image show

Double line

What appearance allows us to tell when there is a graft present

Radial artery to cephalic vein straight graft-> showing colour bruit so normal

What does this image show

Proximal to anastomosis, throughout the fistula/graft, and venous outflow

Where should you record the PSV

Outflow volume

What do you need to calcite

Timed average velocity

What does TAV stand for

3 cycles

How many cycles is considered in the TAV

Dimeter of vessel and TAV

What 2 things do you need to calculate outflow volume

Q = TAV x area x 60

What is the equation for outflow volume

Ml/min

What units is outflow volume expressed in

>800ml/in

What is a normal flow volume

500-800 ml/min

What flow volume indicates mild stenosis

<500ml/min

What flow volume indicates severe stenosis

500mL/min

If a graft or fistula is demonstrating a outflow volume of anything less than ________________ it indicates severe stenosis which is very worrisome

Determine degree of stenosis

What does flow ratios are used for

At stenosis and >2cm prox to the stenosis

Where do you take mmts for the flow ratios

<3

What is the normal flow ratio of the fistula at the anastomosis

<2

What is the normal flow ratio for the fistula at the draining vein

<2

What is the normal flow ratio for the gray

Bc it is just naturally higher at this location due to the size difference

Why is the flow ratio at the fistula at the anastomosis

<400cm/s

What is the normal PSV for grafts and fistulas

Around 30-100cm/s

What is the normla graft outflow vein PSV

Bc is receiving flow from the artery

Why is the graft outflow vein normal PSV pretty high

Normal PSV in a graft/fistula

What does this image show

Increased velocity, lack of Respirophasicity, occluded grafts showing high resistance

What are some abnormla flow characteristics

>400cm/s

What is considered increased velocity in graft and fistula

Subclavian and IJ veins

Where would the lack of Respirophasicity be in