AVFs:
| Advantages | Disadvantages |
|---|
| Lowest rate of infection | Long time to first dialysis; may require short term catheter placement (3-4 mos+) |
| Lowest rate of thrombosis | Failure to mature |
| Best potential flow volumes | |
| Least expensive | |
| Best long-term access | |
Access options
- DOQI (Disease Outcomes Quality Initiative) now NKF-KDOQI (National Kidney Foundation Kidney DOQI)
- Nondominant arm first
- Start distal and work up proximal
- Preferred order of vascular access placement per KDOQI is radiocephalic (wrist) > brachiocephalic (elbow) > transposed brachial-basilic
| |
|---|
| #1 | Forearm cephalic vein fistula |
| #2 | Upper arm cephalic vein fistula |
| #3 | Upper arm basilic vein transposition fistula |
| #4 | Forearm loop graft |
| #5 | Upper arm straight graft |
| #6 | Upper arm loop graft (axillary artery to axillary vein) |
- For AVF radiocephalic then bachiocephalic preferred
- Upper arm fistulas possibly easier to work on because larger vessel diameter?
- Radiocephalic preferred since most distal and lower rate of steal compared to uppoer arm
- Second line, brachiobasilic vein transpotion or transportation (BVT) vs. radiobasilic vein transposition (radiobasilic can be looped or straight)
- Brachial veins in upper arm are last resort
Radiocephalic
- Most common stenosis is juxta-anastomostic (major cause of maturity failure in radiocephalic 25-64% of time)
- Start with radiocephalic since most distal
- Lower rate of steal
Brachiocephalic
- Cephalic arch stenosis (CAS) most common, seen in 30-77% of these fistulas (rarely seen in radiocephalic)
- AKA the confluence where the cephalic vein joins with the axillary vein to form subclavian
- Arch is the most central portion of the cephalic vein as it arcs through the deltopectoral groove to join the axillary vein.
- 5-20x rate of steal syndrome vs radiocephalic
BVT Fistulas
- Only if radiocephalic or brachiocephalic can’t be created
- Basilic needs to be transposed from its deep medial spot
- 70-75% stenoses occur at proximal swing point
- Proximal swing point: surgically created curve of the basilic vein peripheral to its confluence with the brachial vein
- At this site the basilic transitions from its surgically created superficial and lateral location to its naturally deeper more medial location
Rule of 6s (KDOQI guidelines)
- Before access should be 0.6 cm diameter
- 0.6 cm or less from the skin surface
- Flow of at least 600 ml/min at 6 wks (measured 10 cm from anastomosis)
- Maturation in less than 6 weeks
- 6 cm in length for two needle cannulation
Failing AVF
- Inflow or outflow stenosis >50% associated with
- Decreased flow
- Increased static venous pressure
- Pseudoaneurysm
- Prolonged bleeding after needle removal
- Arm swelling
- Recirculation
- Abnormal physical exam
Physical exam signs of stenosis
- Normal fistula should be softly pulsatile
- Hyperpulsatility suggests outflow stenosis
- Hypopulsatile or flat fistula suggests inflow stenosis
- Pulse augmentation: compress venous outflow -> should plump up and become hyperpulsatile proximal
- If inflow stenosis then there is reduced pulse augmentation
- If already hyperpulsatile at baseline and becomes more with augmentation, suggests partial outflow stenosis
- If doesn’t change then suggests severe outflow stenosis
- Loss of thrill
- Weak thrill
- Excessive bleeding during or after
US criteria
- 50% or greater diameter reduction with the following:
- Focal color aliasing
- Elevated velocities when compared to the adjacent segment on the inflow side of the stenosis
- Specreal broadening
HD signs of stenosis
- Inflow
- More negative arterial pressure at HD
- Outflow
- Increased positive venous pressure (needs to push harder)
- Juxta-anastomostic (within 2-5 cm of outflow vein adjacent to the AV anastomosis)
- More negative arterial pressure (needs to pull a harder negative vacuum)
AVGs:
| Advtanges | Disadvantages |
|---|
| Shorter time to first dialysis | Does not last as long as an AVF |
| Minimal morbidity | Prone to thrombosis |
| Increase risk of infection |
| Higher rate of intervention needed to maintain patency when compared to an AVF |
- Rate of infection, steal, and symptomatic central venous stenosis lower in AVFs compared to AVGs
- 20% decreased mortality rate in pts with ESRD receiving HD via AVF compared to AVGs
- AVGs can be used in as little as 24 hrs depending on the material
- Time to first dialysis typically 3-6 wks
- Select for pts with limited lift expectancy, small vein size, feeding artery size. Comorbidities such as CAD, PAD, pulmonary dz, pulm HTN, or DM
- Preferred order of AVG placement is
- Forearm loop graft
- Upper arm straight or curved graft
- Axillary loop
- Thigh graft
Access Stenosis
- Graft vein anastomosis
- Outflow vein stenosis
- Graft conduit stenosis
- Artery graft anastomosis
CVCs
- Vessel injury, stenosis, and scarring
- Preferred right IJ > left IJ > R EJ > L EJ
- Subclavians not recommended
- Highest risk of infxn and thrombosis
- Can compromise central veins limiting future long-term access
Declots and fistulagrams
- Emergent declot indicated for acute loss of thrill
- Should be done w/in 24 hrs to salvage fistula
- Indications for imaging (US vs fistulagram)
- Elevated venous pressures during dialysis (>200 mm Hg with a 300 cm2/min pump)
- Elevated recirculation time of 15% or greater
- Low urea reduction rate of <60%
- Peri-graft bulging (aneurysm, pseudoaneurysm)
- Difficult cannulation (operator dependent)
- Thrombus aspiration
- Indications for fistulagram
- Poorly matured fistula
- Bleeding after dialysis
- Distal limb ischemia
- The other indications listed above
A Note on Cimino
- Cimino fistula invented by Brescia and Cimino at Bronx VA
- Prior a Scribner shunt was used which was a Teflon tube with a needle at each end (only lasting a few days to weeks)
- Cimino previously was a phlebotomist and saw traumatic AVFs and that they were easy places to access